- Expression of Th1- Th2- and Th17-associated cytokines in laryngeal carcinoma
- Western blot analysis
- Statistical analysis
- Pro-Inflammatory Th1 and Th17 Cells Are Suppressed During Human Experimental Endotoxemia Whereas Anti-Inflammatory IL-10 Producing T-Cells Are Unaffected
- Factors that May Lower An Elevated Th17 Immune System
- Reconciling Th1/Th2 Discrepancies
- Link to Kynurenine
- Other Pathways
- Gender Differences
- Diseases Associated With Increased Th17
- Exceptions to the Rule
- STAT3 and mTOR
- Salt is new culprit in autoimmunity
- Role of Th17 cells in the pathogenesis of rheumatoid arthritis
Expression of Th1- Th2- and Th17-associated cytokines in laryngeal carcinoma
Cancer progression is a complex process thatinvolves host-tumor interactions, which occur via multiplemolecular and cellular factors within the tumor microenvironment(1). Previous findings have shownthat inflammation contributes to the proliferation, migration andsurvival of cancer cells, which may lead to tumor invasion andmetastasis (2–5).
However, inflammation in the tumormicroenvironment is an important component of the tumor-associatedimmune response. Inflammatory cells and molecules may function toinitiate and maintain tumor immunity (6,7).
Clusterof differentiation (CD)4+ T-helper (Th) cells, as ahighly heterogenic and plastic population, exhibit a criticalfunction in tumor immunological responses (8).
CD4+ Th cells are classifiedinto 4 subtypes, Th1, Th2, Th17 and T regulatory (T reg) cells,according to their distinct cytokine repertoire, which governs theoverall immune response via an intricate network (9).
Th1 cells produce interferon (IFN) γ,interleukin (IL)-2, IL-12 and tumor necrosis factor α cytokines,which are involved in the cell-mediated pro-inflammatory response.
Th1-associated cytokines exhibit potent anti-tumor effects byactivating CD8+ cytotoxic T lymphocytes and naturalkiller (NK)-mediated cytotoxicity, as well as upregulating majorhistocompatibility complex expression on antigen presenting cells.
Conversely, Th2 cells secrete IL-4, IL-5, IL-6, IL-10 and IL-13cytokines, which mediate anti-inflammatory humoral response andimmune suppression via the inhibition of Th1 cytokine production(10). Th17 cells are characterizedas IL-17-producing CD4+ T cells, which also produceIL-21, −22 and −26 (11,12). It has been demonstrated that theretinoid orphan nuclear receptor is a key regulator of Th17 celllineage differentiation (13).Furthermore, Th17 cells are hypothesized to exhibit a criticalfunction in the development of autoimmunity and allergic reactions(14,15). TGFβ1, a member of the TGFβ family thatis predominantly secreted by Tregs, is another multi-functionalcytokine. It promotes tumor progression by inducing mesenchymaltransition, tumor escape by antagonizing IL-2 functions andinducing immune suppression (16,17), tumorinvasion and metastasis (18).
Laryngeal cancer represents one of the most commonhead and neck malignancies, accounting for ~20% of all cases. Thevast majority of tumors are squamous cell carcinomas (19). Up to 40% of patients present withadvanced disease.
Due to the important physiological functions ofthe larynx, advanced laryngeal lesions are associated withsignificant morbidity and mortality for the patient and increasedfinancial costs for society (20,21).
Whenpatients experience postoperative recurrence and/or distantmetastasis, it is not sensitive to radiation and chemotherapy. Thisresults in a poor prognosis (22).
In the present study, the mRNA and proteinexpression of Th1-, Th2- and Th17-associated cytokines was analyzedat the tissue level by reverse transcription-polymerase chainreactions (RT-PCR) and western blot analysis to investigate thefunction and clinical significance of Th1, Th2 and Th17 cells inlaryngeal carcinoma and their involvement in laryngeal carcinomapathogenesis.
The present study included 57 patients with a meanage of 54.2±10.25 years (range, 37–73 years) who werehistologically diagnosed with laryngeal carcinoma and 7 throatinjury patients, with a mean age of 45.1±10.35 years (range, 32–61years), that served as age- and gender-matched controls.
Thepatients were recruited at The Second Hospital of ShandongUniversity (Jinan, China) between March 2011 and December 2014.Fresh surgical specimens were collected from patients undergoingsurgery for different stages of squamous carcinoma of the larynx.Tumors were staged in accordance with the American Joint Committeeon Cancer tumor-node metastasis (TNM) classification (23).
None of the patients had receivedchemotherapy, radiation therapy or immunotherapy in the 2 monthsprior to surgery. Control non-neoplastic tissues consisted ofsamples (~1×1×2 mm sections) from the irregular mucosal edgeobtained during tissue repair of the larynx and hypopharynx of thethroat injury patients.
Cancer tissues and pericancerous tissueswere identified by stereoscopy and quick frozen sectioning. Twotissue sections were collected from each patient and snap-frozenfor RNA extraction and protein preparation, respectively.
Patientspresenting with any other chronic disease, such as diabetes,tuberculosis, other malignancies or autoimmune disease at the timeof specimen collection were excluded. Similarly, normal controlsthat had presented with fever or viral infection in the week priorto surgery, were pregnant or had been involved in a recent accidentwere also excluded from the study.
The protocol of the present study was approved bythe Ethics Committee of Shandong University School of Medicine andall participants provided written informed consent.
Representativesamples of tumors from the larngeal cancer patients and normalcontrol tissues from teh patients with laryngeal trauma wereobtained during surgery. The samples were snap-frozen immediatelyin Eppendorf tubes (1.
5 ml) and stored at −80°C to avoid RNA andprotein degradation prior to sectioning for RT-PCR and western blotanalysis.
The total RNA extraction kit (Transgen Biotech Co.,Beijing, China) was prepared at The Second Hospital of ShandongUniversity. M-MLV reverse transcriptase and Taq DNA polymerase werepurchased from Promega Corporation (Madison, WI, USA).
PCR primers(BioSune Biotechnology Corporation, Shanghai, China) for thedetection of IFN-γ, IL-2, IL-4, IL-6, IL-10, IL-17A and β-actinmRNA were designed using the OLIGO Primer Analysis Software,version 5.0 (NBA, Software and Research Services for Tomorrow'sDiscoveries, National Biosciences, Plymouth, MN, USA).
The PCRoligomers were synthesized using a DNA/RNA synthesizer (AppliedBiosystems; Thermo Fisher Scientific, Inc., Waltham, MA, USA) atBioSune Biotechnology Corporation. Primer sequences are listed inTable I. Mouse anti-human IFN-γmonoclonal antibody (catalog no. sc-47700; dilution, 1:200), mouseanti-human IL-4 monoclonal antibody (catalog no.
sc-13555;dilution, 1:200), mouse anti-human IL-17 monoclonal antibody(catalog no. sc-374218; dilution, 1:200) and rabbit β-actinpolyclonal antibody (catalog no. sc-1616; dilution, 1:200) werepurchased from Santa Cruz Biotechnology, Inc. (Santa Cruz, CA,USA). Horseradish peroxidase-labeled goat anti-mouse (catalog no.
ZB2305; dilution, 1:5,000) and anti-rabbit IgG (catalog no. ZB2301;dilution, 1:5,000) secondary antibodies were purchased fromZhongshan Golden Bridge Biotechnology Co., Ltd. (Beijing,China).
|Primer sequences of Th1-, Th2- andTh17-associated cytokines used for reverse transcription-polymerasechain reaction in the present study.|
Primer sequences of Th1-, Th2- andTh17-associated cytokines used for reverse transcription-polymerasechain reaction in the present study.
RT-PCR was performed as described previously(24). Briefly, RNA was extractedfrom tissues using the guanidine thiocyanate phenol-chloroformmethod (25). The quality of the RNAyield was assessed by electrophoresis on a 1.5% agarose gel in 0.5mol Tris/Borate/EDTA buffer.
The optical density of the RNA sampleswas measured by microplate reader (Thermo Fisher Scientific Inc.)and samples exhibiting an A260-A280 ratio of 1.8–2.0 were used toobtain cDNA. RT-PCR was performed using a RNA PCR kit(Perkin-Elmer, Norwalk, CT, USA).
Cellular RNA (1 µg) wasreverse-transcribed into cDNA in a reaction mixture containing 5mmol MgCl2, 1 mmol dNTP, 2.5 µmol oligo (dT) primer, 1unit RNase inhibitor and 200 units reverse transcriptase (M-MLV).Following incubation at 37°C for 60 min, the reaction wasterminated by heating at 95°C for 5 min.
PCR was performed usingthe forward and reverse primers listed in Table I. The PCR reaction buffer (25 µl)consisted of 2 mmol MgCl2, 0.5 µmol of each primer, 1unit Taq DNA polymerase and 5 µl reverse-transcription product.
PCRwas performed under the following conditions: Initial denatureationat 95°C for 5 min, then 33 cycles of 95°C for l min, 58°C for l minand 72°C for l min. Aliquots (15 µl) of the amplified product werethen fractionated on a 1.5% agarose gel and visualized by ethidiumbromide staining.
The band intensity of ethidium bromidefluorescence was measured using NIH/1D Image Analysis Software 1.61(National Institutes of Health, Bethesda, MD, USA). The relativeintensity (RI) of each band was determined according to thefollowing equation: RI = density of target gene/density of β-actin.To exclude the possibility of contamination, reactions containingRT-PCR reagents including cytokine PCR primers without sample RNAwere used as the negative control groups.
Western blot analysis
SDS-PAGE and immunoblotting were performed accordingto standard techniques (24).Briefly, the prepared tissues were lysed at 4°C for 30 min in lysisbuffer [20 mmol Tris-HCl (pH 7.5), 1% Nonidet P-40, 150 mmol NaCl,1 mmol ethylenediamine tetraacetic acid, 50 U/ml aprotinin, 1 mmolphenylmethylsulfonyl fluoride and 1 mmol sodium orthovanadate;Beijing Leagene Biotech. Co., Ltd.
, Beijing, China]. The lysateswere centrifuged at 21,100 × g for 20 min at 4°C to remove nucleiand undisrupted tissues. Protein concentration was determined usingBio-Rad protein assay solution (Bio-Rad Laboratories, Inc.,Hercules, CA, USA) with bovine serum albumin as the standard(24,26).
The protein samples were boiled for 10min and loaded onto a 14% SDS-PAGE gel followed by electrophoresisfor 2 h. The proteins were electrophoretically transferred onto a0.22 µm nitrocellulose membrane and immunoblotted with monoclonalmouse anti-human IFN-γ, IL-4, IL-17 and polyclonal rabbit β-actinprimary antibodies (Santa Cruz Biotechnology, Inc.).
After themembrane was washed three times at 5-min intervals inphosphate-buffered saline-Tween 20 (PBS-T), the membrane wassubsequently incubated with goat anti-mouse IgG-horseradishperoxidase (HRP) or goat anti-rabbit IgG-HRP (Zhongshan GoldenBridge Biotechnology Co., Ltd.) diluted to 1:5,000 for 1 h at roomtemperature.
After the membrane was washed three times at 5-minintervals in PBS-T, the immunoblots were then visualized using anImageQuant LAS 4000 chemiluminescence imager (GE Healthcare,Piscataway, NJ, USA).
To determine the levels of Th1, Th2 and Th17 cellsin laryngeal carcinoma, data analysis was performed using SPSS 11.5statistical software (SPSS, Inc., Chicago, IL, USA). Data werepresented as the mean ± standard deviation.
The paired samplest-test was used to compare differences between laryngeal carcinomaand pericarcinoma tissues. One-way analysis of variance analysiswas used to compare the differences between groups at differentclinical stages.
Pro-Inflammatory Th1 and Th17 Cells Are Suppressed During Human Experimental Endotoxemia Whereas Anti-Inflammatory IL-10 Producing T-Cells Are Unaffected
Sepsis is one of the leading causes of deaths in hospitals. Therapeutic options for sepsis patients are limited and mortality rates remain high (1–3). This life-threatening syndrome develops as a result of a dysregulated immune response to a pathogen (4).
In this case, the clearance of the pathogen is inefficient and there is continuous activation of specific pro-inflammatory pathways (5). At the same time, the effector response of the immune system is disturbed; and the innate as well as the adaptive immune system are hypo-responsive (4, 5). In addition, a post-mortem study by Boomer et al.
revealed that patients with fatal clinical course of sepsis showed signs of severe immunological dysfunction (6). Splenocytes had a reduced capacity to produce pro-inflammatory cytokines upon stimulation, and splenic T-cells were diminished in numbers (6).
This so-called “immunoparalysis” is a severe immunosuppressive state that makes the host susceptible for secondary infections (4, 5, 7). Experimental human endotoxemia, in which lipopolysaccharide (LPS) is administered to healthy volunteers, has been established as a model to study the diverse effects of endotoxemia (8–12).
In this model, features of dysfunctional immunity can be observed. Leukocytes from healthy volunteers with LPS exposure show reduced responsiveness to ex vivo stimulation with LPS and other toll–receptor agonists (7–11, 13).
Therefore, the human experimental endotoxemia model was also used in a double-blind placebo-controlled pilot study to investigate agents, which may reverse immunoparalysis (7). Recent studies emphasize the growing importance of effector T-cells and regulatory T-cells (Tregs) in sepsis (14).
Effector T-cell subsets have pro-inflammatory function, are classified according to signature cytokines, and have pivotal role in defense against pathogens—Th1 cells produce interferon gamma (IFNγ) and interleukin (IL)-2 to support cell-mediated immunity; Th17 cells produce IL-17 (Th17) and have a crucial role in the inflammatory response against parasites, extracellular, and fungal pathogens (15, 16). Treg subsets with anti-inflammatory capacity limit pro-inflammatory T-cell responses (17). Tregs balance T-cell homeostasis, activation, and function via numerous different mechanisms including secretion of IL-10 (17, 18). IL-10 has been suggested as an important regulator in sepsis (4, 19).
It has not been well studied which type of T-cell subsets are affected by endotoxemia, and the kinetics of the T-cell dysfunction are not exactly known. The aim of this study was to characterize T-cell responses during endotoxemia. Therefore, T-cell function of pro-inflammatory effector T-cells and anti-inflammatory Tregs was analyzed in a human endotoxemia model.
The study is a single-center, placebo-controlled, randomized, and single-blinded trial in a cross-over study design. Healthy men aged 18–40 years were recruited by public advertisement.
The extensive screening and safety procedure consisted of personal interview, conducted by a physician, a physical examination including an assessment of blood and clinical chemistry parameters (complete blood cell count, C-reactive protein, coagulation factors, lactate-dehydrogenase, myoglobin, creatinkinase, liver enzymes, renal, and hormonal parameters).
Laboratory screening was conducted before each study day (LPS vs. placebo) and up to 1 week after completing the study. Participants were excluded with reported or current medical and psychological conditions, body mass index (BMI)
Factors that May Lower An Elevated Th17 Immune System
Th17 cells produce inflammatory cytokines IL-17 and TNF-alpha. As part of a series on immune health, this post goes over the Th17 response, associated diseases, and complementary approaches — including lifestyle, food, and supplement choices — that may help keep the immune system in good health.
Reconciling Th1/Th2 Discrepancies
You’ve probably heard about the Th1 and Th2 response. To rewind, the Th1/Th2 theory is one attempt at understanding immune regulation, and Th1 and Th2 cells are its key players.
This theory dates back to studies on mouse immune cells in the 80s. However, it is still considered controversial and it’s not without limitations and discrepancies .
According to the Th1/Th2 theory :
- Th1 cells drive the so-called type-1 pathway (“cellular immunity”). They are thought to be involved in fighting viruses and other pathogens that enter cells, getting rid of cancerous cells, and triggering delayed-type hypersensitivity (DTH) skin reactions.
- Th2 cells drive the type-2 pathway (“humoral immunity”). They are hypothesized to increase antibody production and fight invaders that are outside cells. They may be involved in tolerance of organ transplants (xenografts) and of the fetus during pregnancy
But the human immune system is incredibly complex. We have many other types of immune cells that are orchestrated by various factors — from our encounter with microbes, to our health status, genetics, mood, and more.
That’s where Th17 cells come in. These cells were identified only recently and scientists think they can fill the missing gaps and explain some inconsistencies with the Th1/Th2 theory .
For example, Th17 cells are implicated in several human diseases and their cytokines are linked to inflammation and tissue damage .
In turned out that about a third of the progenitors — T helper cells — develop into Th17 cells, a third into Th1, and a third into Th2 cells .
However, Th17 science is new and the findings so far have been inconclusive. Let’s take a look at how much we know about this newly-discovered immune pattern.
T helper cells start off as “naive” T cells and can turn into Th1, Th2, or Th17 cells.
A naive T cell can either become an inflammatory Th17 cell or an anti-inflammatory Treg cell. According to some researchers, the goal in inflammation is to convert more Th17 cells to Treg cells .
Cytokines or the lack of them influence which cell the naive helper cell will convert into. The two necessary cytokines are TG and IL-6, which we’ve spoken about .
Scientists claim that IL-6 (some say IL-21) is what ultimately determines if it turns into an inflammatory or anti-inflammatory cell. IL-23 is a cytokine that may determine if these Th17 will cause disease, though more research is needed .
IL-1β can also increase the production of Th17 cells .Th17 cells produce the cytokine IL-17, as well as TNF and others .
Link to Kynurenine
Kynurenine is a metabolite of the amino acid tryptophan, used by the body while producing niacin. Recently, this pathway has been linked with everything from inflammation to immune imbalances and brain disorders .
Studies are still trying to decipher its impact on disease and whether it can be a therapeutic target .
Scientists think that IL-17 increases kynurenine (so does cortisol, IL-1, TNF, and IFNy/Th1 dominance) .
Limited data linked IL-17 to IBS . However, the effects of increasing this pathway are mixed. Some animal studies suggest that it increases oxidative stress and may be associated with low mood .
Kynurenine can turn into kynurenic acid or quinolinic acid. Kynurenic acid blocks NMDA, AMPA, glutamate and nicotinic receptors, all of which are important for learning and memory.
Thus, some scientists hypothesize that kynurenic acid can reduce intelligence . On the other hand, inhibiting Kynurenic acid seems to result in cognitive enhancement in mice . Although intriguing, human data are needed.
Interleukin 17 acts antagonistically with TNF and IL-1  (antagonism is the opposite of synergy).
In some studies, IL-17 was associated with allergic responses. Researchers found that it induces the production of other inflammatory compounds (such as IL-6, IL-1β, TGF-β, TNF, IL-8, MCP-1, and PGE2) that is thought to lead to negative events airway narrowing in people with asthma .
Th17 cells seem to have a circadian rhythm. The amount of Th17 cells changes during the day-night cycle. Animal studies suggest that the production of Th17 is higher at midnight than at noon .
Science reminds us that Th17 and IL-17 aren’t just “bad,” though.
Based mostly on animal findings, Th17 appears to have a protective role in combating fungi  and some bacterial infections (“extracellular”) , along with Tregs .
Researchers are investigating whether Th17 may have anticancer properties, but studies are still in the early phases. Other scientists speak of the “cancer and autoimmune trade-off,” but this theory is still filled with inconsistencies, leaving us with more questions than answers .
Additionally, Th17 cells appear to be resistant to the suppressive effects of Tregs [17, 18].
Studies in animal models of MS suggest that Th1 cells are important in initiating acute attacks, while Th17 cells are hypothesized to be more important in mediating the progression of this disease. This hasn’t been confirmed in humans, but one study found higher IL-17 expression in chronic versus acute MS lesions .
Limited data suggest that in people with food allergies (classical type), IL-17 production was impaired, but not in healthy people. The study found IL-17 was a potential biomarker for tolerance to food antigens. Large-scale studies are needed .
A normal range of IL-17A has yet to be defined. One study proposed levels of 0.89 pg/ml. In people with mild sleep apnea, levels are 1.02 pg/ml, in moderate sleep apnea 1.18 pg/ml, and in severe sleep apnea 1.62 pg/ml. (all median values). More research is needed .
Studies suggest that women are more susceptible than men to autoimmune conditions, including Multiple Sclerosis (female to male ratio of 2:1), Rheumatoid Arthritis (2:1), Systemic Lupus Erythematosus (9:1), Sjogren’s syndrome (9:1), and Hashimoto’s thyroiditis (9:1) .
The higher female prevalence of these diseases may be related to the fact that women might develop more robust immune responses than men .
Limited studies have suggested that men are more prone to Th17 and Th2 dominance, while women are thought to be more prone to Th1 dominance. However, there’s no hard evidence to back this up [22, 19].
For example, one study found that women have higher levels of Th1 cells, IgM, and CD4+ cell counts, and show stronger immune response responses to vaccinations. Other studies had mixed findings .
Additionally, studies indicate that pregnancy is a Th2 state. Scientists think that lower Th1 activity is part of the adaptive physiological response that women go through in pregnancy .
This is said to prevent the mother’s antibodies from mounting an attack against the fetus. It’s also thought to explain why women are more prone to infections during pregnancy. Many women with rheumatoid arthritis — typically seen as a Th1 disease — experience relapses after pregnancy .
On the other hand, male sex hormones or androgens may increase PPAR alpha, which causes inhibition of Th1 dominance in animals. At the same time, men tend to have lower PPAR gamma, which is hypothesized to lead to Th17 dominance .
To some extent, researchers believe that Th1 and Th17 “compete” with each other, but this is also uncertain. Some studies indicate that IL-2 produced by Th1 cells activates STAT5, which competes with STAT3 (thought to be produced in Th17 dominance) .
In line with this, the castration of male mice enhances Th1 autoimmunity and lowers Th2 cytokine production. We can’t extrapolate these findings to humans .
All in all, more human research on these gender-related mechanisms is needed.
Diseases Associated With Increased Th17
The majority of studies covered in this section deal with associations only, which means that a cause-and-effect relationship hasn’t been established.
For example, just because autoimmune diseases have been linked with increased Th17 activity doesn’t mean that and autoimmunity is caused by Th17 dominance. Data are lacking to make such claims.
Also, even if a study did find that Th17 activity contributes to autoimmune diseases, Th17 cells are highly unly to be the only causative factor. Complex autoimmune disorders always involve multiple possible factors – including biochemistry, environment, health status, and genetics – that may vary from one person to another.
Additionally, some of the studies listed below rely on animal experiments, which can’t be applied to humans. More research is needed before we understand how Th17 cells affect health in humans.
- Several Autoimmune diseases: Hashimoto’s , Grave’s , Multiple Sclerosis , Lupus/SLE , Uveitis , Type 1 diabetes , Systemic Sclerosis , Autoimmune myocarditis , Vitiligo 
- Heart disease [31, 32] (IL-17) – contradictory 
- IBS  – some cases
- Rheumatoid arthritis [34, 29]
- Hashimoto’s , Graves 
- Multiple Sclerosis 
- Asthma , Airway inflammation 
- IBD : Crohn’s , Colitis 
- Sleep apnea [40, 21]
- Skin: Acne Lesions , Psoriasis , Eczema
- Some cancers (extremely limited data) 
- Fibromyalgia  – increased IL-17A
- Osteoporosis in menopausal women [45, 46]
- Depression  (IL17 and TGeta1) 
- Periodontal Disease 
- Lyme arthritis. Lyme or B. burgdorferi seems to increase IL-6, IL-1b, IL-23, and TG, which increases Th17 immunity and may trigger Lyme arthritis .
- Stroke damage (IL-17) 
Th17 overactivity is hypothesized to lead to infertility in women because the Th17 response makes the immune system attack sperm .
On the other hand, Estradiol (E2) inhibits Th17 cell responses, so that sperm is not attacked during ovulation. Some scientists say this sheds light on the connection between fungal infections (which increase Th17) and female infertility, but proper data are lacking to back up this whole Th17-infertility theory .
Th17 is lower in chronic fatigue syndrome. A cause-and-effect relationship hasn’t been established .
Exceptions to the Rule
The Th1/Th2 theory states that overactivation of either the Th1 or the Th2 pattern can cause disease. Similarly, either pathway is thought to down-regulate the other .
this, some studies claim that most substances that decrease Th1 will increase Th2 and vice versa (decreasing Th2 will increase Th1), but this isn’t always the case.
To expand this theory, substances that inhibit Th1 cells are usually thought to also inhibit Th17 cells. But as usual, there are some exceptions.
For example, Lithium only inhibits Th1 but not Th17 in cells and mice .
IL-17 is one of the main cytokines released by Th17 cells. Theoretically, inhibiting this cytokine blocks damage caused by these cells, but this still hasn’t been proven in humans.
There are two proteins that allow the cytokine IL-17 to be produced: STAT3 and Nf-kB .
We discuss factors that inhibit Nf-kB in and probably Lead and Arsenic
- Leptin  – leptin is elevated in obesity.
- Adiponectin  Increases Th1 and Th17 cells; known for its insulin-sensitizing effects. Limited studies indicate that it is present in inflamed tissues of patients with rheumatoid arthritis and inflammatory bowel disease.
- Aldosterone . Aldosterone increases blood pressure. Scientists think it might promote Th17 immunity.
- Insulin 
- IGF-1 
- Desmosterol, an in-between step to cholesterol production in the body 
STAT3 and mTOR
Limited studies have associated certain variations in these genes with Th17 immunity.
- IL23 Receptor
STAT3 is a protein that binds to DNA and increases gene expression.
Scientists believe that STAT3 is essential for the production of the TH17 cells. Theoretically, reducing this protein is supposed to lower Th17 cells .
STAT3 is thought to play an important role in autoimmune and inflammatory diseases. See more about STAT3 and a list of potential natural inhibitors.
Increased mTOR may increase Th1 and Th17, hypothetically leading to increased intestinal inflammation .
mTOR may increase another protein called hypoxia-induced factor (HIF)-1α, which increases Th17 cells .
Some researchers think that inhibiting mTOR may decrease Th1 Cells.
Technical: mTOR increases glycolysis, which allows Th17 cells to proliferate. This might work through HIF1α. Blocking glycolysis inhibited Th17 development while promoting Treg cell generation. Human data are lacking .
Read this post on factors that may inhibit mTOR.
This is a good picture that shows how these four T Cells might interact.
Salt is new culprit in autoimmunity
The health risks of eating high amounts of salt make up quite a laundry list: high blood pressure, heart attacks, stroke, and kidney stones, to name a few.
Now, School of Medicine scientists have discovered another potential detriment of a high-salt diet.
Salt, they’ve found, may drive the progression and severity of autoimmune diseases, through its interactions with certain immune molecules in the gut.
The research, which appeared in the March 6, 2013 issue of Nature, is experiments with mice, but ly applies to human autoimmune diseases, including multiple sclerosis, says David A. Hafler, M.D., Gilbert H. Glaser Professor and chair of Neurology, professor of immunobiology, and senior author on the new paper.
“This goes to show that the immune system may well be linked to what you eat, in unexpected ways,” Hafler says. He is confident enough in the findings, he adds, that he is already recommending that his patients who are prone to autoimmune disease reduce their salt intake.
Scientists have long known that a type of immune cell, called T helper 17 (TH17) cells, is involved in several autoimmune diseases, including multiple sclerosis, psoriasis, type 1 diabetes, and rheumatoid arthritis. Patients with these conditions, scientists have shown, have higher levels of TH17 cells, which helps to explain why their immune systems are more ly to attack their bodies’ own cells.
But over the past 50 years, the incidence of these autoimmune diseases has increased, and first author Markus Kleinewietfeld, Ph.D.
, associate research scientist, Hafler, and colleagues wondered whether there was something in the environment that affected TH17 cells. When they followed the diets of patients, something jumped out at them.
“People who are at a fast-food restaurant more than once a week had higher levels of TH17 cells,” Hafler says.
To test whether it was the high levels of salt in most fast food that accounted for this difference—rather than levels of fat or other compounds—the researchers first tested TH17 cells growing in the lab. When they added salt to the culture surrounding these cells, more than 10 times as many cells matured.
Hafler’s group then tested the implications of this finding in a strain of mice prone to developing a version of multiple sclerosis. When they added moderate amounts of extra salt to the diets of these mice, the severity of their disease increased. Normally, salt levels are much lower in the blood than in surrounding tissues.
While a high-salt diet doesn’t drastically increase the level of salt in the blood, it does increase the salt that’s free in the gut, and Hafler believes that a high-salt diet could activate TH17 cells there. Such a diet also could change the balance of bacteria living in the gut, which could wise affect the immune system.
There are more than 150 genes linked to autoimmune disease risk in humans, and when Hafler took a fresh look at the genes on the list, he discovered that almost 30 percent of these genes were activated by salt, further supporting the connection.
“This really opens up a whole new area of investigation,” Hafler says, adding that there are ly to be environmental factors other than salt that are responsible for the increased prevalence of autoimmune disease, so there are numerous avenues of research yet to be followed.
David Fox, M.D., a rheumatologist at the University of Michigan, calls Hafler’s results “exciting” but agrees that more research is needed. “The story may be more complicated than it seems,” Fox says. “I don’t think this one paper completely proves that there is a link between diet and multiple sclerosis.”
Moreover, he points out, the effect of salt on TH17 cells is unly to have the same impact on all autoimmune diseases. The incidence of rheumatoid arthritis, for example, has not risen over the time period that multiple sclerosis has, so it may not be as affected by diet.
John O’Shea, M.D., chief of the National Institutes of Health’s Molecular Immunology and Inflammation Branch, agrees. Changing official dietary recommendations without clinical trials would be premature, he says, but also points out that low-salt diets are already recommended for some patients with risk factors for other disorders.
“The findings are interesting and provocative, but we don’t know if this is pertinent to humans with autoimmunity,” says O’Shea. “Lots more work needs to be done to establish this point. Nonetheless, the study raises an exciting possibility for intervention.”
Motivated by that possibility, Hafler and colleagues are beginning a new dietary study in humans to more firmly establish the link between salt intake and autoimmunity.
But in his role as a physician, Hafler says, he’s not waiting to suggest dietary changes to his patients.
“If you have a high susceptibility to autoimmune disease in your family, especially if you have an infant, I would recommend trying to keep salt levels low,” says Hafler. “We have to be careful in extrapolating this to human disease at this point,” but, O’Shea, he believes the potential benefits of a low-salt diet outweigh any risks.
Role of Th17 cells in the pathogenesis of rheumatoid arthritis
CD4+ T LYMPHOCYTE DIVERSITY
Following antigen recognition on antigen presenting cells, naive Th0 lymphocytes go towards maturation into more specialized subsets depending upon various in situ factors including antigen itself, cellular and cytokinin environment (Figure 1).
Differentiation into Th1 cells requires IL-12 induction of signal transducer and activator of transcription (STAT1/4) and subsequent induction of the transcription factor T-bet, with in situ IFN-γ as helper factor.
These cells are essential for cell-mediated immune response to intracellular pathogens, cellular immunity and clonal lymphocyte multiplication through their ability to produce IL-2[1,2].
Maturation into Th2 cells seems to be dependent upon weaker T cell receptor signaling and IL-4-dependent or independent GATA-3 transcription factor induction. These Th2 lymphocytes help the development of humoral immunity together with limiting Th1 response.
Antibody response is also potentiated by Tfh lymphocytes, characterized by the expression of BCL6 transcription repressor and depends upon the in situ presence of IL-6 and IL-21 (Figure 1). Meanwhile, whether Tfh cells directly derive from Th0 cells or from other subsets is still unclear.
Figure 1 Diversity of CD4+ T helper cell subsets. STAT: Signal transducer and activator of transcription; IL: Interleukin; TGF: Transforming growth factor; TNF: Tumor necrosis factor; HIF1: Hypoxia-inducible factor 1.
Th0-derived Th9 cells produce IL-9 and are polarized by IL-4-induced transcription factors including STAT6, GATA3 together with the presence of TGF-β, required for Smad activation and intracellular expression of PU.1 transcription factor.
Other cytokinin environments were shown to induce Th9 cell differentiation but the exact in vivo maturation pathway of these cells remains to be clarified. The presence of Th9 cells is associated with autoimmune and allergic diseases, but their definitive role remains unclear.
Th22 and Treg cell differentiation is very close to Th17 cells and will be detailed below.
TH17 cell differentiation
If IL-17 (also known as IL-17A) was identified decades ago, the concept that Th17 cells represent an additional Th cell subset is recent[2,12]. Several cytokines are involved for optimal development of Th17 cells, including IL-6, TGF-β, IL-23, and IL-1β.
This cell subset is characterized by the expression of orphan nuclear receptor RORγt together with the production of high levels of IL-17, IL-17F, IL-22, and IFN-γ[7,16-20]. Other factors can regulate differentiation of Th17 cells, such as prostaglandin E2, IL-21 (detailed in).
Since their identification, Th17 cells have been largely described for their critical role during the development of inflammation and autoimmunity. Interestingly, Th22 cells were recently described as an additional effector subset during wound healing and tissue reparation[9,21].
These cells develop in response to tumor necrosis factor (TNF)-α and are characterized by the production of IL-22 but not IL-17.
Differentiation of Th0 towards Th17 vs Treg cells is another important checkpoint for immune response and tolerance and many studies addressed factors that may derive this differentiation step (Figure 2)[2,3,22,23].
Cells receiving strong antigenic signaling differentiate into Th17 cells while those receiving lower activation express the transcription factor Foxp3 and polarize into Treg cells.
In addition, development toward a Th17 or a Treg phenotype is dependent on the cytokinin environment, such as TGF-β concentration and presence of pro- vs anti-inflammatory cytokines[3,24].
Figure 2 Differentiation of T helper 17/Treg cell subsets. STAT: Signal transducer and activator of transcription; IL: Interleukin; TGF: Transforming growth factor; TNF: Tumor necrosis factor; HIF1: Hypoxia-inducible factor 1.
Recently, hypoxia-inducible factor 1 (HIF1)-α and mammalian target of rapamycin (mTOR) were identified as factors positively regulating Th17 differentiation[22,23,25]. In turn, these pathways downregulate Treg cell polarization and constitute potent targets to upregulate Th17 cell development (see below).
In addition to IL-17 and IL-17F, Th17 cells are potent producers of IL-22, IL-21, IL-6, TNF-α, CCL20 and IFN-γ, which cooperate together to define the duality of Th17 role: host defense vs inflammation[7,25].
The Th17/Treg ratio is now considered as a critical target for the modulation of inflammatory response and tolerance.
TH17 cell diversity
Th17 cells were recently shown to comprise distinct subsets defined by their functions and cytokine secretion profile[24,26].
In addition to initial “regulatory” Th17 cells with important role during immunity to extracellular pathogens[24,25], alternative “inflammatory” Th17 subsets have been identified during autoimmune diseases which require IL-23, IL-1β and IL-6 for their differentiation and were less dependent on TGF-β. Critical distinction between these populations is their cytokine production as regulatory Th17 cells secrete higher levels of IL-10 while inflammatory Th17 cells produce more IL-22, granulocyte macrophage colony-stimulating factor (GM-CSF) and IFN-γ which may explain their proinflammatory property. However, inflammatory Th17 cells seem to comprise various subpopulations that differ by their cytokine release and need further characterization.