Balance of Th1 and Th17 effector and peripheral regulatory T cells

Effect of huankuile on colon injury in rats with ulcerative colitis by reducing TNF-α and MMP9

OBJECTIVE

To explore the mechanism of huankuile (HKL) in colon injury repair in rats with ulcerative colitis (UC).

METHODS

Fifty SPF Wistar male rats were divided randomly into a normal group, a negative control group, an HKL intervention group ('HKL group') and a 5-aminosalicylic acid intervention group ('5-ASA group'). After 14 days of intervention with corresponding drugs, pathological scores were obtained using the results of immunohistochemical staining; morphological changes were observed by hematoxylin-eosin staining, and the mRNA expression levels of tumour necrosis factor-α (TNF-α), matrix metalloproteinase 9 (MMP9) and interleukin-13 (IL-13) were detected by real-time quantitative PCR.

RESULTS

After the successful construction of the rat model, it was compared with the rats in the normal group. In the negative group, it was found that the expression of TNF-α and MMP9 was significantly increased in the colonic mucosal epithelia of the rats, the pathological score was significantly increased (P < 0.05), and the mRNA expression levels of TNF-α, MMP9 and IL-13 were increased (P < 0.05). After treatment with HKL, the colonic morphology of the rats returned to normal, the expression of TNF-α and MMP9 in the colonic mucosal epithelium of the rats returned to normal, the pathological score grade was significantly reduced (P < 0.05), and the mRNA expression levels of TNF-α, MMP9 and IL-13 were reduced; these results were largely consistent with those of the normal group, with no statistically significant difference.

CONCLUSION

HKL effectively improved the general symptoms and tissue injury in UC rats, and the therapeutic effect was better than that of 5-ASA group. Ulcerative colitis in rats increased the expression of TNF-α, MMP9 and IL-13. HKL repaired UC-induced colonic injury in rats by decreasing the expression of TNF-α, MMP9 and IL-13.

Role of MicroRNAs in Inflammatory Joint Diseases: A Review

Inflammatory arthritis commonly initiates in the soft tissues lining the joint. This lining swells, as do the cells in it and inside the joint fluid, producing chemicals that induce inflammation signs such as heat, redness, and swelling. MicroRNA (miRNA), a subset of non-coding small RNA molecules, post-transcriptionally controls gene expression by targeting their messenger RNA. MiRNAs modulate approximately 1/3 of the human genome with their multiple targets. Recently, they have been extensively studied as key modulators of the innate and adaptive immune systems in diseases such as allergic disorders, types of cancer, and cardiovascular diseases. However, research on the different inflammatory joint diseases, such as rheumatoid arthritis, gout, Lyme disease, ankylosing spondylitis, and psoriatic arthritis, remains in its infancy. This review presents a deeper understanding of miRNA biogenesis and the functions of miRNAs in modulating the immune and inflammatory responses in the above-mentioned inflammatory joint diseases. According to the literature, it has been demonstrated that the development of inflammatory joint disorders is closely related to different miRNAs and their specific regulatory mechanisms. Furthermore, they may present as possible prognostic and diagnostic biomarkers for all diseases and may help in developing a therapeutic response. However, further studies are needed to determine whether manipulating miRNAs can influence the development and progression of inflammatory joint disorders.

BIOINFORMATICS APPLICATIONS UNDER CONDITION CONTROL: HIGH DIAGNOSTIC VALUE OF DDX47 IN REAL MEDICAL SETTINGS

ABSTRACT

Sepsis is an organ dysfunction caused by a dysregulated host response to infection and remains an ongoing threat to human health worldwide. Septic shock is the most severe subset of sepsis as characterized by abnormalities in cells, circulation, and metabolism. As a time-dependent condition, early recognition allowing appropriate therapeutic measures to be started in a timely manner becomes the most effective way to improve prognosis. However, because of the lack of a criterion standard, most diagnoses merely rely on medical history, empirical diagnosis, and blood culture results. Gene expression profiles have specific diagnostic value, as they reflect a subjective host response to pathogens. We propose a method, Condition Control based on Real-life Medical Scenarios, to control for factors in realistic medical scenarios. Restricted variables are used as much as possible to identify unique differential genes and progressively test their diagnostic value by relaxing restrictions. In total, three data sets were included in the study; the first two data sets were from the Gene Expression Omnibus database, and the third involved patients who were diagnosed with sepsis or septic shock within 7 days of admission to the intensive care unit at West China Hospital of Sichuan University from 2020 to 2021. DDX47 showed preferable diagnostic value in various scenarios, especially in patients with common infections or sepsis and septic shock. Here we also show that hub genes may regulate immune function and immune cell counts through the interaction of different apoptotic pathways and immune checkpoints based on the high correlation. DDX47 is closely associated with B cells according to single-cell sequencing results.

Biomedicine and traditional Chinese medicine: a fruitful scientific and cultural interaction

Over the years, the approach of traditional Chinese medicine has changed, as has the concept of the health status. Particularly in this article we will focus on the importance of some techniques that we can define millennial, as acupuncture. We will highlight the relationship between a millenary system and the principles of modernity, emphasizing the relevance of a technique that appears to be in line with the latest scientific research and numerous studies of effectiveness, proposing therapeutic integration as a usable way. We will see how acupuncture has an anti-inflammatory effect, and has a beneficial role in subjects suffering from allergic or autoimmune diseases, including an antihistamine action and downregulation of proinflammatory cytokines (e.g. IL-1β, IL-6 and TNF-α). In addition, acupuncture could also act as an immunomodulatory agent, involving the neuroimmune network, T helper and natural killer cells. Traditional Chinese medicine, acupuncture in particular, is widely used within Western health systems and there are many studies done regarding its efficacy in the clinical field. In addition to scientific validation, however, a comparison on a cultural level is also necessary. To build a constructive dialogue, indeed, it is necessary to deconstruct the preconceptions and prejudices concerning both biomedicine and traditional Chinese medicine. In fact, only through deconstruction we can understand that biomedicine and traditional Chinese medicine are both culturally connoted knowledge. In this article it will first be underlined how clinical observations can be better understood if we pay attention to analyzing the cultural context of the medical systems that here interact with each other. (www.actabiomedica.it).

Respiratory epithelium: Place of entry and / or defense against SARS-CoV-2 virus

Coronavirus Disease (COVID-19) is caused by the RNA virus SARS-CoV-2. The primary receptor for the virus is most likely Angiotensin-converting enzyme 2 (ACE2), and the virus enters the body by infecting epithelial cells of the respiratory tract. Through the activation of Toll Like Receptors (TLRs), epithelial cells begin to synthesize various biologically active molecules. The pathophysiology of the COVID 19 is primarily attributed to the hyperactivation of host's immune system due to direct damage to the cells, with consequent release of proinflammatory substances, but also due to the activation of the innate immune response through the activation of alveolar macrophages and dendrite cells (DC). A strong proinflammatory reaction causes damage to alveolar epithelial cells and vascular endothelium. Respiratory epithelial cells, alveolar macrophages and DC are likely to be the most important cells involved in the innate immune response to the virus, since prolonged and excessive SARS-CoV-2-induced activation of these cells leads to the secretion of cytokines and chemokines that massively attract leukocytes and monocytes to the lungs and cause lung damage.

An Improved DNA Vaccine Against Bovine Herpesvirus-1 Using CD40L and a Chemical Adjuvant Induces Specific Cytotoxicity in Mice

Bovine herpesvirus-1 (BoHV-1) uses many mechanisms to elude the immune system; one of them is spreading intracellularly, even in the presence of specific antiviral antibodies. Cytotoxic T lymphocytes (CTLs) are necessary to eliminate the virus. The main preventive strategy is vaccination based on inactivated virus. These vaccines are poor inducers of cellular immune responses, and complicate serological diagnosis and determination of the real prevalence of infection. DNA vaccines are a good option because of the capacity of Differentiating Infected from Vaccinated Animals-(DIVA vaccine)-and may be the best way to induce cytotoxic responses. Although this type of vaccines leads to only weak "in vivo" expression and poor immune responses, incorporation of molecular and/or chemical adjuvants can improve the latter, both in magnitude and in direction. In this study, we have investigated the specific immune responses elicited in mice by DNA vaccines based on the BoHV-1 glycoprotein D (pCIgD) with and without two different adjuvants: a plasmid encoding for murine CD40L (pCD40L) or Montanide™ 1113101PR (101). Mice vaccinated with pCIgD⁺CD40L, pCIgD⁺101, and pCIgD⁺CD40L⁺101 developed significantly higher specific antibody titers against BoHV-1 than the pCIgD group (p < 0.01). The animals vaccinated with pCgD⁺pCD40L⁺101 raised significantly higher levels of IgG2a and IgG2b (p < 0.01 and p < 0.001, respectively) than mice vaccinated with pCIgD alone. On the contrary, when the activity of CTL against cells infected with BoHV-1 was measured, the vaccine pCgD⁺pCD40L⁺101 induced significantly higher levels of cytotoxicity activity (p < 0.001) than pCIgD alone. A significant increase in the CD4⁺ populations in the group receiving pCIgD⁺CD40L⁺101 in comparison with the pCIgD group was observed and, also, interferon gamma, interleukin (IL)-6, and IL-17A levels were higher. Considering the results obtained from this study for humoral and cellular responses in mice, the inclusion of pCD40L and 101 as adjuvants in a BoHV-1 DNA vaccine for cattle is highly recommendable.

Multiple Sclerosis: New Aspects of Immunopathogenesis

SUMMARY – Multiple sclerosis (MS) is a multicomponent disease characterized by inflammation, neurodegeneration, and cancellation of the central nervous system recovery mechanisms. The cause of MS is still unknown, but it is undeniable that genetic, environmental and immune factors are involved in the etiopathogenesis of this complex and heterogeneous disease. From the aspect of immunopathogenesis, until recently the opinion prevailed that autoreactive T lymphocytes played a major role, the activation of which is a key step in MS. The knowledge of the effector and regulatory roles of B cells supports a new concept of MS immunopathogenesis that is based on the highly complex interaction of T and B cells, with B cells actively participating in cellular immunity by directing the intensity and quality of cellular immune response. The mechanisms of B cell activity in MS immunopathogenesis are multiple and include antigen presentation and T cell costimulation, cytokine secretion, antibody synthesis, and formation of ectopic lymphoid B cell aggregates in the intrameningeal spaces. The importance of B cells has been confirmed by modern therapeutic options for the treatment of MS.

The relationship between the immune system and oral manifestations of inflammatory bowel disease: a review

Inflammatory bowel diseases (IBDs) are chronic, relapsing inflammatory diseases characterized by exacerbations and remissions of the gastrointestinal tract, clinically manifested as Crohn's disease and ulcerative colitis. The etiology of IBDs is considered to be multi factorial, comprising environmental, immune, microbial and genetic factors. Clinical signs may include abdominal pain, frequent bloody diarrheas, mucorrhea, vomiting, fever, fatigue or weight loss. Changes in the oral cavity often precede intestinal symptoms. Inflammatory bowel disease leads to a significant deterioration of oral health, which indicates that cooperation between the dentist and the gastroenterologist is necessary when considering patients' welfare. Patients with IBD have an altered immune response, but microorganisms of the oral cavity may also be responsible for its modification. This review paper discusses the correlation between the immune system and inflammatory bowel disease manifestations in the oral cavity.

Vitamin A supplementation reduces the Th17-Treg - Related cytokines in obese and non-obese women

OBJECTIVE

The objective of the present study was to investigate the effect of vitamin A supplementation on serum Th17 (IL-6, IL-17, IFNγ) and Treg (TGF-β, IL-10) related cytokines in obese and non-obese women.

SUBJECTS AND METHODS

In a randomized double blind placebo controlled design, 56 obese women were randomly assigned to receive either an oral dose of 25,000 IU retinyl palmitate or placebo per day for 4 months. Twenty eight ages matched non-obese women were also received vitamin A. At the study entry, anthropometric variables were measured and serum Th17 and Treg related cytokine profile were determined at baseline and 4 months after intervention.

RESULTS

Significantly higher baseline concentrations of IL-6 were observed in obese compared with non-obese women (P < 0.05). However, the initial concentrations of other cytokines were not significantly different between groups. The mean concentrations of IL-17 and TGF-β were significantly decreased after vitamin A supplementation in non-obese and obese women respectively. Positive relationships between IL-17 and IL-10 (r = 0.42, P < 0.001), TGF-β and IL-17 (r = 0.35, P < 0.001) and between IL-10 and IFN-γ (r = 0.41, P = 0.002) in total participants were also observed.

CONCLUSIONS

The results of the present study showed for the first time that vitamin A supplementation reduces serum concentrations of IL-17 and TGF-β in reproductive age women. Further studies are needed to explore the possible underlying mechanisms.

Elevated serum levels of IL-6 and IL-17 may associate with the development of ankylosing spondylitis

PURPOSE

A meta-analysis was undertaken to examine the correlation between ankylosing spondylitis (AS) progression and serum levels of pro-inflammatory cytokines, Interleukin-6 (IL-6) and Interleukin-17 (IL-17) in AS patients.

METHODS

PubMed, EBSCO, Cochrane Library database, Ovid, Springer link, WANFANG, China national knowledge infrastructure (CNKI) and VIP databases(last updated search in October, 2014) were exhaustively searched for published case-control studies using keywords related to IL-6, IL-17 and AS. The search results were screened using stringent inclusion and exclusion criteria, and the data from selected high-quality studies was analyzed with Comprehensive Meta-analysis 2.0 software.

RESULTS

Thirteen case-control studies were selected for this meta-analysis and contained a pooled total of 514 AS patients and 358 healthy controls. Our main result revealed strikingly higher serum levels of IL-6 and IL-17 in AS patients, compared to healthy controls (IL-6: SMD = 2.51, 95% CI = 1.33~3.70, P = 0.01; IL-17: SMD = 3.05, 95% CI = 2.09~4.02, P < 0.001). Ethnicity-based subgroup analysis showed a statistically correlation of high IL-6 and IL-17 serum levels with AS both in Asian (IL-6: SMD = 3.15, 95% CI = 0.75~5.55, P < 0.001; IL-17: SMD = 3.30, 95% CI = 1.93~4.66, P < 0.001) and Caucasian populations (IL-6: SMD = 1.34, 95% CI = 0.33~2.35, P = 0.009; IL-17: SMD = 2.52, 95% CI = 1.06~3.98, P = 0.001).

CONCLUSION

Meta-analysis of pooled data from thirteen high-quality studies revealed a strong correlation between elevated IL-6 and IL-17 serum levels and the development of AS. Therefore, IL-6 and IL-17 could be used as markers for diagnosis and assessment of treatment outcomes in AS patients.

B subunits of cholera toxin and thermolabile enterotoxin of Escherichia coli have similar adjuvant effect as whole molecules on rotavirus 2/6-VLP specific antibody responses and induce a Th17-like response after intrarectal immunization

The purpose of this study was to evaluate the adjuvant effect of the B subunits of cholera toxin (CT) and the thermolabile enterotoxin of Escherichia coli (LT) by the intrarectal route of immunization and compare them to the whole molecules CT and LT-R192G, a non toxic mutant of LT, using 2/6-VLP as an antigen, in mice. All molecules induced similar antigen specific antibody titers in serum and feces, whereas different T cell profiles were observed. CTB and LTB, conversely to CT and LT-R192G, did not induce detectable production of IL-2 by antigen specific T cells. Moreover, CTB, conversely to LT-R192G, CT and LTB, did not induce antigen specific CD4+CD25+Foxp3- and Foxp3+ T cells, thus showing different effects between the B subunits themselves. However, all molecules induced an antigen specific Th17 response. In conclusion, B subunits are potent adjuvants on B cell responses by the intrarectal route. Although their impact on T cell responses are different, all molecules induce a 2/6-VLP-specific Th17 T cell response that may play a major role in helping B cell responses and thus in adjuvanticity and protection.

Effect of resveratrol on Treg/Th17 signaling and ulcerative colitis treatment in mice

AIM: To determine the therapeutic efficacy of resveratrol on ulcerative colitis (UC) and its underlying mechanisms.

METHODS: The mouse UC model was developed using 5% dextran sulfate sodium. Mice were randomly divided into four groups: normal control, UC model group, resveratrol low-dose group (RLD; 50 mg/kg per day), and resveratrol high-dose group (RHD; 100 mg/kg per day).

RESULTS: The results showed that RLD regulates Treg/Th17 balance mainly through reducing the number of Th17 cells, whereas RHD regulates Treg/Th17 balance through both downregulating the number of Th17 cells and upregulating the number of Treg cells. Resveratrol can also regulate the level of plasma and intestinal mucosal cytokines including interleukin (IL)-10, transforming growth factor-β1, IL-6, and IL-17. The expressions of hypoxia inducible factor (HIF)-1α, mammalian target of rapamycin (mTOR), and signal transducer and activator of transcription 3 were significantly decreased in the intestinal tissues of mice treated with resveratrol.

CONCLUSION: The therapeutic efficacy of resveratrol in UC is dose dependent and closely associated with the regulation of Treg/Th17 balance and the HIF-1α/mTOR signaling pathway.

CD4(+)CD25(high) FOXP3(+) regulatory T cells correlate with FEV1 in North Indian children with cystic fibrosis

Cystic fibrosis (CF) lung disease is characterized by dysregulated inflammatory response in the airways. CD4(+)CD25(+) regulatory T cells play a crucial role in maintaining the immune homeostasis. However their role in the disease pathogenesis of CF remains unexplored.

AIM

To determine the percentage of circulating CD4(+)CD25(high), FoxP3(+) T cell expression in children with CF and controls. Furthermore to evaluate the relationship between CD4(+)CD25(high), FOXP3 T cell % and the clinical status of the disease (lung function).

METHODS

CD4(+)CD25(+), intracellular FoxP3 expression in peripheral blood were estimated using flowcytometry in 20 children with CF and 10 healthy controls. Spirometry was carried out according to the standard guidelines.

RESULTS

We observed a significant difference in CD4(+)CD25(+)T cell% in children with CF (5.2 ± 1.2) versus controls (6.8 ± 1.4, p < 0.05), CD4(+)CD25(high)T cell% in CF (1.72 ± 0.36) versus controls (2.59 + 0.42, p < 0.003). Similarly a significant difference was observed in FoxP3 T cell% CF: (60.7 ± 6.19) versus controls (76.8 ± 5.16), p < 0.001. A significant positive correlation between FoxP3 T cell% and FEV1 in children with CF(r = 0.822, p < 0.01) was observed.CD4(+)CD25(high) T cell% correlated positively with FEV1 (r = 0.742, p < 0.01).

CONCLUSION

Our findings report the first evidence of a decreased expression of circulating CD4(+)CD25(high) FoxP3(+) T cells in children with CF. Furthermore circulating CD4+ CD25(high), FOXP3(+) T cell percentage correlated with FEV1.

Lineage-specific adjacent IFNG and IL26 genes share a common distal enhancer element

Certain groups of physically linked genes remain linked over long periods of evolutionary time. The general view is that such evolutionary conservation confers 'fitness' to the species. Why gene order confers 'fitness' to the species is incompletely understood. For example, linkage of IL26 and IFNG is preserved over evolutionary time yet Th17 lineages express IL26 and Th1 lineages express IFNG. We considered the hypothesis that distal enhancer elements may be shared between adjacent genes, which would require linkage be maintained in evolution. We test this hypothesis using a bacterial artificial chromosome transgenic model with deletions of specific conserved non-coding sequences. We identify one enhancer element uniquely required for IL26 expression but not for IFNG expression. We identify a second enhancer element positioned between IL26 and IFNG required for both IL26 and IFNG expression. One function of this enhancer is to facilitate recruitment of RNA polymerase II to promoters of both genes. Thus, sharing of distal enhancers between adjacent genes may contribute to evolutionary preservation of gene order.

Dynamics of T-cell infiltration during the course of ovarian cancer: the gradual shift from a Th17 effector cell response to a predominant infiltration by regulatory T-cells

The type of immune cells that are present within the tumor microenvironment can play a crucial role in the survival of patients. However, little is known about the dynamics of the tumor-infiltrating immune cells during disease progression. We studied the immune cells that infiltrated the tumor tissues of ovarian cancer patients at different stages of disease. The early stages of development of ovarian carcinomas were characterized by a strong Th17 immune response, whereas in stage II patients, recruitment of high numbers of Th1 cells was observed. In disseminated tumors (Stages III-IV), we detected a dominant population of Helios(+) activated regulatory T cells (Tregs) along with high numbers of monocytes/macrophages and myeloid dendritic cells (mDCs). Tumor-infiltrating Tregs had markedly lower expression of CCR4 than circulating Tregs, and the numbers of tumor-infiltrating Tregs significantly correlated with the levels of CCL22 in ovarian tumor cell culture supernatants, suggesting their recruitment via a CCR4/CCL22 interaction. CCL22 was mainly produced by tumor cells, monocytes/macrophages and mDCs in the primary ovarian tumors, and its expression markedly increased in response to IFNγ. Taken together, the specific recruitment of Tregs, probably triggered by inflammatory stimuli, leads to a significant immune suppression in the advanced stages of ovarian cancer.

Relationship between susceptibility of Blackface sheep to Teladorsagia circumcincta infection and an inflammatory mucosal T cell response

Teladorsagia circumcincta is the most economically important gastrointestinal (abomasal) nematode parasite of sheep in cool temperate regions, to which sheep show genetically-varying resistance to infection. Lambs, from parents with genetic variation for resistance, were trickle infected with L3 larvae over 12 weeks. 45 lambs were identified with a range of susceptibilities as assessed by: adult worm count at post mortem, faecal egg count (FEC) and IgA antibody levels. This project investigated the correlation of T cell cytokine expression and resistance to infection at the mature stage of response, when the resistant lambs had excluded all parasites.

Histopathology showed only minor changes in resistant animals with a low level lymphocyte infiltration; but in susceptible lambs, major pathological changes were associated with extensive infiltration of lymphocytes, eosinophils and neutrophils.

Absolute quantitative RT-qPCR assays on the abomasal lymph node (ALN) revealed a significant positive correlation between IL6, IL21 and IL23A transcript levels with adult worm count and FEC. IL23A was also negatively correlated with IgA antibody levels. Significantly positive correlation of TGFB1 levels with adult worm count and FEC were also seen in the abomasal mucosa. These data are consistent with the hypothesis that the inability to control L3 larval colonization, adult worm infection and egg production is due to the activation of the inflammatory Th17 T cell subset.

In Vivo Peripheral Blood Proinflammatory T Cells in Patients with Ankylosing Spondylitis

Objective.

Previous reports have shown an increase in peripheral blood mononuclear cells’ (PBMC) Th17 cell subpopulation and tumor necrosis factor-α (TNF-α) secretion after in vitro stimulation with anti-CD3/CD28 or phorbol myristate acetate/ionomycin in ankylosing spondylitis (AS). The aim of our study was to determine whether there is a Th17 polarization not subjected to in vitro stimulation in patients with AS.

Methods.

Nonstimulated PBMC were analyzed from 46 patients with AS, including 7 (15.2%) receiving tumor necrosis factor-α (TNF-α) inhibitors, 20 patients with rheumatoid arthritis, and 25 healthy controls. The surface phenotype of freshly isolated PBMC was determined by flow cytometry. Th1, Th2, Th17, and Treg subsets were defined as CD3+CD4+IFN-γ+, CD3+CD4+IL-4+, CD3+CD4+IL-17A+, and CD3+CD4+FoxP3+, respectively. Serum cytokines and interleukin 8 (IL-8) levels were quantified by Luminex technology.

Results.

The percentages of Th17 and Th1 cells in AS were higher than in healthy controls (7.4% ± 1.8% vs 0.7% ± 0.2% and 4.0% ± 1.3% vs 1.1% ± 0.3%, respectively; p < 0.0001). Th17 and Th1 cell subsets in patients taking TNF-α inhibitors were lower than in those naive to such therapeutics and similar to healthy controls. Serum levels of IL-6, IL-17A, TNF-α, and IL-8 were significantly higher in patients with AS compared to controls.

Conclusion.

The percentages of Th17 and Th1 cells in PBMC without in vitro stimulation, as well as cytokine and IL-8 levels, were significantly increased in patients with AS compared with healthy controls. These T cell subsets and cytokine profiles of patients with AS taking TNF-α inhibitors were similar to those of healthy controls.

Mutated major histocompatibility complex class II transactivator up-regulates interleukin-33-dependent differentiation of Th2 subset through Nod2 binding for NLR (NOD-like receptor) signaling initiation

Dominant-negative mutants of class II transactivator (mCIITAs) with N-terminal depletion have been used to repress the transcription of class II genes in xenotransplantation. Here, we report that mCIITA overexpressing myeloid cell line Ana-1 (Ana-1-mCIITA) derived from a C57BL/6 mouse was able to down-regulate the MHC class II expression and reverse immune responses from Th1 (IL-2(+)IFN-γ(+)STAT4(+)) to Th2 (IL-4(+)IL-5(+)IL-10(+)IL-13(+)STAT6(+)) when cocultured with T cells. Mechanism analysis indicated that the mCIITA protein is able to initiate a NOD-like receptor-related signaling pathway via binding of the cytoplasmic Nod2 protein, which was followed by activating RIP2, caspase 1, and IKK-α/β. This ensures the expression of the genes encoding the cytokines IL-33, IL-1β, and TNF-α; however, only the highly expressed IL-33 is responsible for inducing the type 2 response, with a skewed Th2 cytokine secretion (IL-4(+)IL-5(+)IL-10(+)IL-13(+)IL-2(-)IFN-γ(-)), which was completely prevented by the deactivation of the Nod2 gene with siRNA or by the blockage of the IL-33-related signaling using the mAb ST2L against the IL-33 receptor. mCIITA-mediated Th2 conversion was also successfully induced in vivo in a mCIITA-transgenic C57BL/6 mouse model. These results indicate that the Th1/Th2 balance could be regulated by an N terminus-depleted CIITA molecule via NOD-like receptor-related signaling, a property valuable for disease control, especially for inducing transplantation tolerance via the repression of class II expression and the attenuation of a Th1-dominant response.

The molecular mechanisms of regulatory T cell immunosuppression

CD4⁺CD25⁺Foxp3⁺ T lymphocytes, known as regulatory T cells or T(regs), have been proposed to be a lineage of professional immune suppressive cells that exclusively counteract the effects of the immunoprotective "helper" and "cytotoxic" lineages of T lymphocytes. Here we discuss new concepts on the mechanisms and functions of T(regs). There are several key points we emphasize: 1. Tregs exert suppressive effects both directly on effector T cells and indirectly through antigen-presenting cells; 2. Regulation can occur through a novel mechanism of cytokine consumption to regulate as opposed to the usual mechanism of cytokine/chemokine production; 3. In cases where CD4⁺ effector T cells are directly inhibited by T(regs), it is chiefly through a mechanism of lymphokine withdrawal apoptosis leading to polyclonal deletion; and 4. Contrary to the current view, we discuss new evidence that T(regs), similar to other T-cells lineages, can promote protective immune responses in certain infectious contexts (Chen et al., 2011; Pandiyan et al., 2011). Although these points are at variance to varying degrees with the standard model of T(reg) behavior, we will recount developing findings that support these new concepts.

Differential requirements for Th1 and Th17 responses to a systemic self-antigen

T cell-APC interactions are essential for the initiation of effector responses against foreign and self-antigens, but the role of these interactions in generating different populations of effector T cells in vivo remains unclear. Using a model of CD4(+) T cell responses to a systemic self-antigen without adjuvants or infection, we demonstrate that activation of APCs augments Th17 responses much more than Th1 responses. Recognition of systemic Ag induces tolerance in self-reactive CD4(+) T cells, but induction of CD40 signaling, even under tolerogenic conditions, results in a strong, Ag-specific IL-17 response without large numbers of IFN-γ-producing cells. Transfer of the same CD4(+) T cells into lymphopenic recipients expressing the self-antigen results in uncontrolled production of IL-17, IFN-γ, and systemic inflammation. If the Ag-specific T cells lack CD40L, production of IL-17 but not IFN-γ is decreased, and the survival time of recipient mice is significantly increased. In addition, transient blockade of the initial MHC class II-dependent T cell-APC interaction results in a greater reduction of IL-17 than of IFN-γ production. These data suggest that Th17 differentiation is more sensitive to T cell interactions with APCs than is the Th1 response, and interrupting this interaction, specifically the CD40 pathway, may be key to controlling Th17-mediated autoimmunity.

The cecal appendix: one more immune component with a function disturbed by post-industrial culture

This review assesses the current state of knowledge regarding the cecal appendix, its apparent function, and its evolution. The association of the cecal appendix with substantial amounts of immune tissue has long been taken as an indicator that the appendix may have some immune function. Recently, an improved understanding of the interactions between the normal gut flora and the immune system has led to the identification of the appendix as an apparent safe-house for normal gut bacteria. Further, a variety of observations related to the evolution and morphology of the appendix, including the identification of the structure as a "recurrent trait" in some clades, the presence of appendix-like structures in monotremes and some non-mammalian species, and consistent features of the cecal appendix such as its narrow diameter, provide direct support for an important function of the appendix. This bacterial safe-house, which is likely important in the event of diarrheal illness, is presumably of minimal importance to humans living with abundant nutritional resources, modern medicine and modern hygiene practices that include clean drinking water. Consistent with this idea, epidemiologic studies demonstrate that diarrheal illness is indeed a major source of selection pressure in developing countries but not in developed countries, whereas appendicitis shows the opposite trend, being associated with modern hygiene and medicine. The cecal appendix may thus be viewed as a part of the immune system that, like those immune compartments that cause allergy, is vital to life in a "natural" environment, but which is poorly suited to post-industrialized societies.

CD69 association with Jak3/Stat5 proteins regulates Th17 cell differentiation

T-cell differentiation involves the early decision to commit to a particular pattern of response to an antigen. Here, we show that the leukocyte activation antigen CD69 limits differentiation into proinflammatory helper T cells (Th17 cells). Upon antigen stimulation in vitro, CD4(+) T cells from CD69-deficient mice generate an expansion of Th17 cells and the induction of greater mRNA expression of interleukin 17 (IL-17), IL 23 receptor (IL-23R), and the nuclear receptor retinoic acid-related orphan receptor γt (RORγt). In vivo studies with CD69-deficient mice bearing OTII T-cell receptors (TCRs) specific for OVA peptide showed a high proportion of antigen-specific Th17 subpopulation in the draining lymph nodes, as well as in CD69-deficient mice immunized with type II collagen. Biochemical analysis demonstrated that the CD69 cytoplasmic tail associates with the Jak3/Stat5 signaling pathway, which regulates the transcription of RORγt and, consequently, differentiation toward the Th17 lineage. Functional experiments in Th17 cultures demonstrated that the selective inhibition of Jak3 activation enhanced the transcription of RORγt. Moreover, the addition of exogenous IL-2 restored Stat5 phosphorylation and inhibited the enhanced Th17 differentiation in CD69-deficient cells. These results support the early activation receptor CD69 as an intrinsic modulator of the T-cell differentiation program that conditions immune inflammatory processes.

The role of interleukin-17 in the pathogenesis of rheumatoid arthritis

Interleukin (IL)-17 (also known as IL-17A), the signature cytokine of the newly described T helper 17 (Th17) cell population, has been implicated in the pathogenesis of numerous autoimmune diseases including rheumatoid arthritis. IL-17 is the founding member of a new subclass of cytokines that have highly proinflammatory properties. Studies in rodents and mammalian cell culture systems, as well as clinical settings, support a role for IL-17 in promoting rheumatoid arthritis. This article discusses the history of the discovery of Th17 cells, the potential mechanisms of action of IL-17 in autoimmunity, and perspectives for IL-17-targeted cytokine therapy.

T cell epitope: friend or foe? Immunogenicity of biologics in context

Like vaccines, biologic proteins can be very immunogenic for reasons including route of administration, dose frequency and the underlying antigenicity of the therapeutic protein. Because the impact of immunogenicity can be quite severe, regulatory agencies are developing risk-based guidelines for immunogenicity screening. T cell epitopes are at the root of the immunogenicity issue. Through their presentation to T cells, they activate the process of anti-drug antibody development. Preclinical screening for T cell epitopes can be performed in silico, followed by in vitro and in vivo validation. Importantly, screening for immunogenicity is complicated by the discovery of regulatory T cell epitopes, which suggests that immunogenicity testing must now take regulatory T cells into consideration. In this review, we address the application of computational tools for preclinical immunogenicity assessment, the implication of the discovery of regulatory T cell epitopes, and experimental validation of those assessments.