Immunoregulation therapy changes the frequency of interleukin (IL)-22+ CD4+ T cells in systemic lupus erythematosus patients

Target in Sight: A Comprehensive Review of Hydroxychloroquine-Induced Bull's Eye Maculopathy

Purpose of Review

We review the latest screening and diagnostic techniques, and the most recent recommendations on the management of hydroxychloroquine retinopathy.

Recent Findings

Hydroxychloroquine (HCQ) has been shown to cause retinal toxicity in a dose-dependent fashion. Early diagnosis is critical as the resultant retinopathy is not reversible. New imaging modalities, such as adaptive optics (AO), microperimetry, and retro-mode imaging, may show promise in the timely diagnosis of HCQ retinopathy.

Summary

Automated visual fields and spectral-domain optical coherence tomography (SD-OCT) are the primary tests used in routine screening for HCQ retinopathy, but fundus autofluorescence (FAF) and multifocal electroretinogram (mfERG) have also been shown to be useful. A baseline ophthalmologic examination is recommended in all patients beginning long-term hydroxychloroquine therapy within the first year of starting therapy. Automated visual fields and SD-OCT should be included during this baseline exam in patients with pre-existing macular conditions. Afterwards, annual screening can be deferred for the first 5 years of HCQ treatment unless the patient has a major risk factor.

The role of the aryl hydrocarbon receptor (AhR) in modulating intestinal ILC3s to optimise gut pathogen resistance in lupus and benefits of nutritional AhR ligands

BACKGROUND AND AIMS

Dysbiosis is emerging as a potential trigger of systemic lupus erythematosus (SLE). Group 3 innate lymphoid cells (ILC3s) are recognised as key regulators of intestinal homeostasis. The aryl hydrocarbon receptor (AhR) is critical to intestinal ILC3 development and function. This mechanistic review aimed to investigate whether AhR activation of gut ILC3s facilitates IL-22-mediated antimicrobial peptide (AMP) production to enhance colonisation resistance and ameliorate SLE pathology associated with intestinal dysbiosis. Furthermore, nutritional AhR ligand potential to enhance pathogen resistance was explored.

METHODOLOGY

This mechanistic review involved a three-tranche systematic literature search (review, mechanism, intervention) using PubMed with critical appraisal. Data was synthesised into themes and summarised in a narrative analysis.

RESULTS

Preclinical mechanistic data indicate that AhR modulation of intestinal ILC3s optimises pathogen resistance via IL-22-derived AMPs. Pre-clinical research is required to validate this mechanism in SLE. Data on systemic immune consequences of AhR modulation in lupus suggest UVB-activated ligands induce aberrant AhR signalling while many dietary ligands exert beneficial effects. Data on xenobiotic-origin ligands is varied, although considerable evidence has demonstrated negative effects on Th17 to Treg balance. Limited human evidence supports the role of nutritional AhR ligands in modulating SLE pathology. Preclinical and clinical data support anti-inflammatory effects of dietary AhR ligands.

CONCLUSION

Current evidence is insufficient to fully validate the hypothesis that AhR modulation of intestinal ILC3s can enhance pathogen resistance to ameliorate lupus pathology driven by dysbiosis. However, anti-inflammatory effects of dietary AhR ligands suggest a promising role as a therapeutic intervention for SLE.

Efficacy and safety of belimumab/low-dose cyclophosphamide therapy in moderate-to-severe systemic lupus erythematosus

Objectives

We have reported previously that Belimumab, a human monoclonal antibody that inhibits B-cell activating factor(BAFF) could be an effective and safe option to treat Neuropsychiatric manifestations of SLE (NPSLE). To avoid inadequate efficacy of Belimumab and significant adverse events of often-used dose of cyclophosphamide (CYC) for SLE, we evaluated the efficacy, safety, and possible immune mechanisms of Belimumab treatment in combination with intermittent low-dose intravenous CYC for moderate-to-severe SLE.

Methods

In this non blinded and parallel-group trial, we collected 82 cases of moderate-to-severe SLE patients, 40 received Belimumab treatment and 42 received conventional treatments as historical controls for 24 weeks. The demographic features, clinical manifestations, and laboratory indicators including peripheral blood lymphocyte subgroups or subsets were compared before and after the treatments.

Results

Compared with the baseline, 6 months post Belimumab group treatment, disease activity score SLEDAI (13.78 to 3.82, P<0.05) and BILAG scores (16.40 to 5.48, P<0.05) were reduced; C3 (0.19 to 1.14, P<0.05) and C4 (0.04 to 0.22, P<0.05) increased; the absolute numbers of B and T cells were the first decreased and then significantly increased, tended to balance. Moreover, Belimumab group treatment significantly reduced the serum levels of IL-6, the ratio of B and T cells, and the proportion of infections and menstrual disorders.

Conclusion

Compared with conventional treatment, Belimumab with low-dose intravenous CYC significantly reduced disease activity scores and maintained the B/T cell balance for SLE patients at 24 weeks. It was more efficacy and safe (adverse events such as infection were significantly lower). It should be the mechanism that Belimumab combined with low-dose intravenous CYC therapy restores the balance of T and B cells, which proposes a potential treatment strategyfor SLE.

The Role of T Helper 22 Cells in Dermatological Disorders

T helper 22 (Th22) cells are a newly identified subset of CD4+ T cells that secrete the effector cytokine interleukin 22 (IL-22) upon specific antigen stimulation, barely with IFN-γ or IL-17. Increasing studies have demonstrated that Th22 cells and IL-22 play essential roles in skin barrier defense and skin disease pathogenesis since the IL-22 receptor is widely expressed in the skin, especially in keratinocytes. Herein, we reviewed the characterization, differentiation, and biological activities of Th22 cells and elucidated their roles in skin health and disease. We mainly focused on the intricate crosstalk between Th22 cells and keratinocytes and provided potential therapeutic strategies targeting the Th22/IL-22 signaling pathway.

Hydroxychloroquine in systemic lupus erythematosus: overview of current knowledge

The antimalarial hydroxychloroquine (HCQ) has demonstrated several crucial properties for the treatment of systemic lupus erythematosus (SLE). Herein, we reviewed the main HCQ pharmacologic features, detailed its mechanism of action, and summarized the existing guidelines and recommendations for HCQ use in rheumatology with a systematic literature search for the randomized controlled trials focused on lupus. HCQ has been shown to decrease SLE activity, especially in mild and moderate disease, to prevent disease flare and to lower the long-term glucocorticoid need. The numerous benefits of HCQ are extended to pregnancy and breastfeeding period. Based on cohort studies, antithrombotic and metabolic HCQ’s effects were shown, including lipid-lowering properties, which might contribute to an improved cardiovascular risk. Moreover, early HCQ use in antinuclear antibodies positive individuals might delay the progression to SLE. Finally, HCQ has a significant favorable impact on long-term outcomes such as damage accrual and mortality in SLE. Based on these multiple benefits, HCQ is now the mainstay long-term treatment in SLE, recommended by current guidelines in all patients unless contraindications or side effects. The daily dose associated with the best compromise between efficacy and safety is matter of debate. The concern regarding retinal toxicity rather than proper efficacy data is the one that dictated the daily dosage of ⩽5 mg/kg/day actual body weight currently agreed upon.

Role of Th22 Cells in the Pathogenesis of Autoimmune Diseases

Upon antigenic stimulation, naïve CD4+T cells differentiate into different subsets and secrete various cytokines to exert biological effects. Th22 cells, a newly identified CD4+T cell subset,are distinct from the Th1, Th2 and Th17 subsets. Th22 cells secrete certain cytokines such as IL-22, IL-13 and TNF-α, but not others, such as IL-17, IL-4, or interferon-γ (IFN-γ), and they express chemokine receptors CCR4, CCR6 and CCR10. Th22 cells were initially found to play a role in skin inflammatory diseases, but recent studies have demonstrated their involvement in the development of various autoimmune diseases. Here, we review research advances in the origin, characteristics and effector mechanisms of Th22 cells, with an emphasis on the role of Th22 cells and their main effector cytokine IL-22 in the pathogenesis of autoimmune diseases. The findings presented here may facilitate the development of new therapeutic strategies for targeting these diseases.

Interleukin-22 and connective tissue diseases: emerging role in pathogenesis and therapy

Interleukin-22 (IL-22), a member of the IL-10 family of cytokines, is produced by a number of immune cells involved in the immune microenvironment of the body. IL-22 plays its pivotal roles by binding to the IL-22 receptor complex (IL-22R) and subsequently activating the IL-22R downstream signalling pathway. It has recently been reported that IL-22 also contributes to the pathogenesis of many connective tissue diseases (CTDs). In this review, we will discuss the role of IL-22 in several CTDs, such as system lupus erythematosus, rheumatoid arthritis, Sjögren’s syndrome, systemic sclerosis and dermatomyositis, suggesting that IL-22 may be a potential therapeutic target in CTDs.

Analysis of IL-22 and Th22 Cells by Flow Cytometry in Systemic Lupus Erythematosus

Interleukin (IL)-22 belongs to the IL-10 family of cytokines. IL-22 exerts its biological effects via members of the cytokine receptor family class 2. CD4+ T helper (Th) cells predominantly producing IL-22 have been designated as Th22 cells. IL-22/Th22 cells are functionally related to IL-17/Th17 cells, but are distinctly different. Both IL-22 and IL-17 are cytokines recruiting neutrophils in response to microbe invasion. In chronic inflammation, IL-22 mediates protective and regenerative processes, whereas IL-17 cytokines tend to induce inflammation. Studies found that increased IL-22 levels and Th22 cells in peripheral blood were associated with disease activity in patients with systemic lupus erythematosus (SLE), but decreased IL-22 and Th22 cells were also reported. Here we describe analysis of IL-22 and Th22 cells in peripheral blood quantified by flow cytometry, and correlate our findings with SLE disease activity.

Effect of induction therapy on circulating T-helper 17 and T-regulatory cells in active proliferative lupus nephritis

INTRODUCTION

T-helper 17 (Th17) cells and T-regulatory (Treg) cells have been suggested to play pathogenic roles in lupus nephritis. The in vivo effects of current therapies for lupus nephritis (LN) on these cells have not been adequately studied.

METHODS

We conducted a prospective observational study among patients with active proliferative lupus nephritis (LN) who received Eurolupus induction therapy and assessed them as per the European League Against Rheumatism criteria for renal response. Peripheral circulatory Th17 and Treg cell numbers were enumerated at start of therapy, at 3 and 6 months follow-up periods using flow cytometry. Baseline values were compared with inactive lupus patients (iSLE) and healthy controls (HC).

RESULTS

Thirty patients with LN, 20 iSLE and 22 HC were enrolled into the study. In LN, Th17 frequency was significantly higher compared to HC, and Treg frequency significantly lower compared to both iSLE and HC. Nineteen patients fulfilled criteria for response (partial or complete) at 6 months. Responder group showed a significant decline in Th17 frequency and an increasing trend in Treg frequency compared to baseline after 6 months of therapy.

CONCLUSION

Circulating Th17 cells were significantly raised in patients with active proliferative LN and showed a significant reduction in responder patients following therapy.

The Mechanisms of Shcisandrol A in Immune Function Modulation in Immunosuppressed Mice

The population of people with immunodeficiency is increasing due to the accelerating pace of life, increase in work pressure, and lack of exercise, irregularity of diet and rest, and problems of environmental pollution. Chinese herbal medicines have been shown to improve immunity, with little to no side effects. In recent years, studies have shown that Shcisandrol A (Sch A) regulates immune functioning and inhibits inflammation of the nervous system. The current study used gene expression profiling of spleen tissue to screen differentially expressed genes related to Sch A treatment on cyclophosphamide (Cy)-induced immunosuppressed mice. The differentially expressed gene-related pathways were analyzed by gene ontology function cluster analysis and qPCR. Five genes related to immune functioning were found to be regulated by Sch A treatment: Mapk3, Pik3r1, Pik3r5, Ikbkg, and Cd247. qPCR analysis showed that all five genes were significantly down-regulated in mice treated with Sch A compared to untreated immunosuppressed mice. These results suggest potential mechanisms through which Sch A regulates immune functioning.

The Imbalance between Foxp3+Tregs and Th1/Th17/Th22 Cells in Patients with Newly Diagnosed Autoimmune Hepatitis

This study is aimed at examining the potential role of regulatory T- (Treg-) Th1-Th17-Th22 cells in the pathogenic process of autoimmune hepatitis (AIH). The numbers of Foxp3⁺Tregs and Th1, Th17, and Th22 cells were measured in 32 AIH patients using flow cytometry. Moreover, a murine model of experimental autoimmune hepatitis (EAH) was also established and used to investigate the function of Treg-Th1-Th17-Th22 cells in disease progression. AIH patients undergoing an active state had significantly decreased numbers of CD3⁺CD4⁺CD25⁺Foxp3⁺Tregs and increased numbers of CD3⁺CD4⁺CD25^-Foxp3⁺T, CD3⁺CD4⁺IFN-γ⁺Th1, CD3⁺CD4⁺IL-17⁺Th17, and CD3⁺CD4⁺IL-2⁺Th22 cells as well as higher levels of Th1/Th17/Th22-type cytokines compared to AIH patients in remission and HC. Additionally, the numbers of CD3⁺CD4⁺CD25⁺Foxp3⁺Tregs were negatively correlated with the numbers of Th1-Th17-Th22 cells. Also, the serum levels of IL-17A and IL-22 were correlated positively with liver injury (ALT/AST), whereas the serum levels of IL-10 were correlated negatively with hypergammaglobulinaemia (IgG, IgM) in AIH patients. Interestingly, the percentages of spleen Tregs, expression of Foxp3 mRNA, and liver IL-10 levels decreased, whereas the percentages of spleen Th1-Th17-Th22 cells, expression of T-bet/AHR/RORγt mRNA, and liver IFN-γ, IL-17, and IL-22 levels increased in the murine model of EAH. Our findings demonstrated that an imbalance between Tregs and Th1-Th17-Th22 cells might contribute to the pathogenic process of AIH.

Autoimmunity and autoinflammation: A systems view on signaling pathway dysregulation profiles

INTRODUCTION

Autoinflammatory and autoimmune disorders are characterized by aberrant changes in innate and adaptive immunity that may lead from an initial inflammatory state to an organ specific damage. These disorders possess heterogeneity in terms of affected organs and clinical phenotypes. However, despite the differences in etiology and phenotypic variations, they share genetic associations, treatment responses and clinical manifestations. The mechanisms involved in their initiation and development remain poorly understood, however the existence of some clear similarities between autoimmune and autoinflammatory disorders indicates variable degrees of interaction between immune-related mechanisms.

METHODS

Our study aims at contributing to a holistic, pathway-centered view on the inflammatory condition of autoimmune and autoinflammatory diseases. We have evaluated similarities and specificities of pathway activity changes in twelve autoimmune and autoinflammatory disorders by performing meta-analysis of publicly available gene expression datasets generated from peripheral blood mononuclear cells, using a bioinformatics pipeline that integrates Self Organizing Maps and Pathway Signal Flow algorithms along with KEGG pathway topologies.

RESULTS AND CONCLUSIONS

The results reveal that clinically divergent disease groups share common pathway perturbation profiles. We identified pathways, similarly perturbed in all the studied diseases, such as PI3K-Akt, Toll-like receptor, and NF-kappa B signaling, that serve as integrators of signals guiding immune cell polarization, migration, growth, survival and differentiation. Further, two clusters of diseases were identified based on specifically dysregulated pathways: one gathering mostly autoimmune and the other mainly autoinflammatory diseases. Cluster separation was driven not only by apparent involvement of pathways implicated in adaptive immunity in one case, and inflammation in the other, but also by processes not explicitly related to immune response, but rather representing various events related to the formation of specific pathophysiological environment. Thus, our data suggest that while all of the studied diseases are affected by activation of common inflammatory processes, disease-specific variations in their relative balance are also identified.

Anti-apoptotic effect of interleukin-22 on fibroblast-like synoviocytes in patients with rheumatoid arthritis is mediated via the signal transducer and activator of transcription 3 signaling pathway

AIM

Inadequate apoptosis of fibroblast-like synoviocytes (FLS) plays a crucial role in the immunopathogenesis of rheumatoid arthritis (RA). Interleukin-22 (IL-22) is a novel member of the cytokine network that has been found to be involved in the immunological process underlying RA. In this study, we investigated the effect of IL-22 on the survival of RA-FLS from RA patients and examined the possible mechanism to determine new therapeutic strategies for RA.

METHODS

FLS obtained from patients with RA were cultured in vitro and treated with sodium nitroprussiate (SNP) to induce apoptosis in the presence or absence of IL-22. RA-FLS viability was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. RA-FLS apoptosis was analyzed by annexin V/propidium iodide staining (AV/PI). The levels of IL-22R1, pSTAT3-Y705, pSTAT3-S727, total STAT3, Bcl-xL and Bcl-2 were detected by Western blot analysis.

RESULTS

IL-22R1 was expressed on RA-FLS. IL-22 pretreatment at concentrations ranging from 10 to 100 ng/mL increased RA-FLS viability and prevented SNP-induced apoptosis. Treatment with the STAT3 inhibitors, HO3867 or STA21, reversed the protective effect of IL-22 on SNP-induced apoptosis of RA-FLS. IL-22-induced phosphorylation of STAT3 (pSTAT3-Y705 and pSTAT3-S727) was increased in RA-FLS. Also IL-22 increased Bcl-2 expression in SNP-treated RA-FLS, and the effect was reversed by treatment with HO3867 or STA21.

CONCLUSION

IL-22 protects against SNP-induced apoptosis in RA-FLS by activating the STAT3 pathway and the downstream target gene, Bcl-2. Therefore, therapeutic strategies that target the IL-22/STAT3 pathway are implicated as candidates for RA treatment.

IL-22-producing CD4+T cells in the treatment response of rheumatoid arthritis to combination therapy with methotrexate and leflunomide

T cells are key players in immune-mediated rheumatoid arthritis (RA). We previously reported that interleukin (IL)-22+CD4+T helper (IL-22+ Th) cells and IL-22 critically control the pathogenesis of RA. Here we monitored circulating levels of different IL-22+ Th cell subsets and measured plasma levels of IL-22, IL-17, and interferon (IFN)-γ in 60 patients with active RA following 12-week combination methotrexate (MTX) and leflunomide (LEF) therapy (MTX+LEF) and 20 healthy individuals. We found the frequencies of circulating IFN-γ-IL-17-IL-22+ (Th22), IFN-γ-IL-17+ (total Th17), IFN-γ+IL-17-IL-22+ (IL-22+Th1) cells, and IFN-γ-IL-17+IL-22+ (IL-22+Th17) cells, as well as the plasma levels of IL-22, IL-17 and IFN-γ to be significantly reduced in RA patients that responded to treatment, but not in non-responders. Reductions in plasma IL-22 level significantly correlated with percentage of circulating Th22 cells and the decrease of plasma IL-22 level correlated with the reduction of DAS28 in responders. Our data suggests that circulating Th22 cells and plasma IL-22 level play a detrimental role in RA. The combination MTX+LEF therapy, by targeting Th22 cells and reducing IL-22 level, relieves the immune defects and ameliorates symptoms of RA. This study provides novel mechanistic understanding of the pathogenesis of RA, which may promote a design of better therapies for RA.

Cytokines and Effector/Regulatory Cells Characterization in the Physiopathology of Cutaneous Lupus Erythematous: A Cross-Sectional Study

We compared the presence of diverse cytokines and regulatory T and B cells in skin biopsies of discoid lupus erythematosus (DLE) and subacute cutaneous lupus erythematosus (SCLE). We included 19 patients with DLE, 13 with SCLE, 8 healthy controls, and 5 patients with hypertrophic scars. We assessed the CLASI activity score. To determine IL-22-producing cells and the subpopulation of CD4(+)/IL-17A(+)-, CD4(+)/IL-4(+)-, and CD4(+)/IFN-γ (+)-expressing T cells, CD123(+)/IDO(+) pDCs, CD25(+)/Foxp3(+) Tregs, and CD20(+)/IL-10(+)-producing B cells, an immunostaining procedure was performed. Also intracellular IL-22, IL-17, IL-4, IFN-γ, and Foxp3 in CD4 T cells, IL-10 in B cells, and IDO in pDCs were analyzed by flow cytometry in peripheral blood. The main cellular participation in both lupus groups was IL-17- and IL-22-producing cell responses both at skin and at peripheral blood but prevailed in DLE. The CLASI activity scores negatively correlated with Th22 subpopulation and positively correlated with CD25(+)/Foxp3(+) Treg cells. In conclusion a proinflammatory and regulatory imbalance coexists in cutaneous lupus, both responses being more intense in DLE.

Association of Plasma IL-32 Levels and Gene Polymorphisms with Systemic Lupus Erythematosus in Chinese Han Population

Systemic lupus erythematosus (SLE) is a multisystemic autoimmune disease. IL-32, a secreted protein, has been reported to be associated with several autoimmune diseases. Our preliminary experiment showed different plasma IL-32 levels than that mentioned in a published report on the same population. In order to elucidate the correlation between IL-32 and SLE, we determined the plasma level and two single nucleotide polymorphisms (SNPs) of IL-32 in 152 patients with SLE and 310 healthy controls and analyzed the relationship based on the clinical parameters. The results showed that plasma IL-32 levels in patients with SLE were markedly lower than that in the healthy controls. In the SLE group, patients with detectable IL-32 presented low serum C3 concentrations. Further studies indicated that the rs28372698 SNP was associated with the susceptibility to SLE. Taken together, our results suggested that IL-32 could possibly be a candidate marker to monitor SLE disease stability and screening in future.

IL-22-producing Th22 cells play a protective role in CVB3-induced chronic myocarditis and dilated cardiomyopathy by inhibiting myocardial fibrosis

BACKGROUND

A new subset of T helper (Th) cells, named IL-22-producing Th22 cells, was identified recently. Th22 cells have been implicated in immunity and inflammation. However, the role of these cells in the progression from acute viral myocarditis (AVMC) to dilated cardiomyopathy (DCM) and myocardial fibrosis remains unknown.

METHODS

BALB/c mice were repeatedly i.p. infected with Coxsackie virus B3 (CVB3) to establish models of AVMC, chronic myocarditis and DCM. On week 2, 12 and 24 post initial injection, the percentage of splenic Th22 cells, the levels of plasma IL-22, cardiac IL-22 receptor (IL-22R) expression, and indicators of myocardial fibrosis were measured. Further, mice with AVMC and chronic myocarditis were treated with an anti-IL-22 neutralizing antibody (Ab). The collagen volume fraction (CVF), the percentage of splenic Th22 cells, plasma IL-22 levels, cardiac IL-22R expression and indicators of myocardial fibrosis were then monitored.

RESULTS

Compared to control mice at the same time points, AVMC, chronic myocarditis and DCM mice have higher percentage of splenic Th22 cells, higher plasma IL-22 levels, increased cardiac IL-22R, as well as increased collagen typeI-A1 (COL1-A1), collagen type III-A1 (COL3-A1) and matrix metalloproteinase-9 (MMP9) expression. However, the expression of tissue inhibitor of metalloproteinase-1(TIMP-1) was decreased. Treatment of AVMC and chronic myocarditis mice with an anti-IL-22 Ab decreased the survival rate and exacerbated myocardial fibrosis. The percentage of splenic Th22 cells, plasma IL-22 levels and cardiac IL-22R expression also decreased in anti-IL-22 Ab treatment group as compared to IgG and PBS treated groups of AVMC and chronic myocarditis mice. Moreover, increased expression of COL1-A1, COL3-A1, MMP9 but decreased expression of TIMP-1 were observed in anti-IL-22 Ab mouse group.

CONCLUSIONS

Th22 cells play an important role in the pathogenesis of CVB3-induced mouse chronic myocarditis and DCM. IL-22 is a myocardium-protective cytokine by inhibiting myocardial fibrosis. Therefore, Th 22 cells may be considered as potential therapeutic targets for DCM.

Role of Th22 cells in inflammatory, autoimmune diseases and tumors

T-helper (Th) 22 cells are a recently identified subset of T cells, which are characterized by abundant secretion of interleukin-22 (IL-22) but not interleukin-17 (IL-17) or interferon-γ (IFN-γ) and are therefore distinct from Th1, Th2 and Th17 cells. The functions of Th22 cells are predominantly executed by their signature cytokine IL-22, which has been shown to play an important role in the pathogenesis of inflammatory, autoimmune diseases and tumors. Th22 cells and related cytokine IL-22 regulate multiple biological functions and have an important role in a number of diseases. The effect of Th22 cells and IL-22 on different cells seems to be quite similar, including improving the innate immunity, protecting from injury, and enhancing their regeneration, but whether its role is protective or pathogenic is dependent on the nature of the affected tissue and local cytokine milieu. Nevertheless, there are still many questions about the role of Th22 and related cytokine IL-22 in various diseases. This article reviews the role of Th22 cells and its cytokine IL-22 in inflammatory, autoimmune diseases and tumors.