Interleukin-22 and rheumatoid arthritis: emerging role in pathogenesis and therapy

Interleukin-22 promotes proliferation and reverses LPS-induced apoptosis and steroidogenesis attenuation in human ovarian granulosa cells: implications for polycystic ovary syndrome pathogenesis

OBJECTIVE

Interleukin 22 (IL-22) plays a role in inflammatory diseases. However, whether IL-22 affects the function of ovarian granulosa cells (GCs) and its relationship with Polycystic Ovary Syndrome (PCOS)remains unclear.

METHODS

We investigated the level of IL-22 in human follicular fluid using ELISA. The expression and localization of the IL-22 receptor 1 (IL-22R1) in GCs were investigated by RT-PCR and immunofluorescence staining, respectively. The proliferation of KGN cells (human GCs line) was assessed by CCK-8 assay and EdU assay after treatment with recombinant human IL-22 (rhIL-22) and lipopolysaccharide (LPS). Apoptosis was assessed using flow cytometry. Apoptotic proteins and steroidogenic genes were detected by western blotting.

RESULTS

ELISA's results showed that compared with the control group, PCOS patients showed lower expression of IL-22 in follicular fluid. Immunofluorescence showed that IL-22R1 is expressed and localized in human granulosa cell membranes. IL-22 promoted cell proliferation and reversed LPS-induced inhibition of cell proliferation. IL-22 alone did not affect apoptotic or steroidogenic protein expression, however, it reversed LPS-induced apoptosis via downregulation of Bcl-2, upregulation of Bax and cleaved caspase-3, and restoration of LPS-downregulated StAR, CYP11A1, and CYP19A1 expression. Western blotting confirmed that IL-22 activated the JAK2/STAT3 signaling.

CONCLUSION

IL-22 promotes cell proliferation, inhibits apoptosis, and regulates KGN cell steroidogenesis confronted with LPS, and decreased IL-22 may be involved in the development of PCOS.

IL-22 Plays a Dual Role in the Amniotic Cavity: Tissue Injury and Host Defense against Microbes in Preterm Labor

IL-22 is a multifaceted cytokine with both pro- and anti-inflammatory functions that is implicated in multiple pathologies. However, the role of IL-22 in maternal-fetal immunity in late gestation is poorly understood. In this study, we first showed that IL-22+ T cells coexpressing retinoic acid-related orphan receptor γt (ROR-γt) are enriched at the human maternal-fetal interface of women with preterm labor and birth, which was confirmed by in silico analysis of single-cell RNA sequencing data. T cell activation leading to preterm birth in mice was preceded by a surge in IL-22 in the maternal circulation and amniotic cavity; however, systemic administration of IL-22 in mice did not induce adverse perinatal outcomes. Next, using an ex vivo human system, we showed that IL-22 can cross from the choriodecidua to the intra-amniotic space, where its receptors (Il22ra1, Il10rb, and Il22ra2) are highly expressed by murine gestational and fetal tissues in late pregnancy. Importantly, amniotic fluid concentrations of IL-22 were elevated in women with sterile or microbial intra-amniotic inflammation, suggesting a dual role for this cytokine. The intra-amniotic administration of IL-22 alone shortened gestation and caused neonatal death in mice, with the latter outcome involving lung maturation and inflammation. IL-22 plays a role in host response by participating in the intra-amniotic inflammatory milieu preceding Ureaplasma parvum-induced preterm birth in mice, which was rescued by the deficiency of IL-22. Collectively, these data show that IL-22 alone is capable of causing fetal injury leading to neonatal death and can participate in host defense against microbial invasion of the amniotic cavity leading to preterm labor and birth.

LncRNA Expression Profiles in Systemic Lupus Erythematosus and Rheumatoid Arthritis: Emerging Biomarkers and Therapeutic Targets

Systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) are two common multisystem autoimmune diseases that share, among others, many clinical manifestations and serological features. The role of long non-coding RNAs (lncRNAs) has been of particular interest in the pathogenesis of autoimmune diseases. Here, we aimed to summarize the roles of lncRNAs as emerging novel biomarkers and therapeutic targets in SLE and RA. We conducted a narrative review summarizing original articles on lncRNAs associated with SLE and RA, published until November 1, 2021. Based on the studies on lncRNA expression profiles in samples (including PBMCs, serum, and exosomes), it was noted that most of the current research is focused on investigating the regulatory mechanisms of these lncRNAs in SLE and/or RA. Several lncRNAs have been hypothesized to play key roles in these diseases. In SLE, lncRNAs such as GAS5, NEAT1, TUG1, linc0949, and linc0597 are dysregulated and may serve as emerging novel biomarkers and therapeutic targets. In RA, many validated lncRNAs, such as HOTAIR, GAS5, and HIX003209, have been identified as promising novel biomarkers for both diagnosis and treatment. The shared lncRNAs, for example, GAS5, may participate in SLE pathogenesis through the mitogen-activated protein kinase pathway and trigger the AMP-activated protein kinase pathway in RA. Here, we summarize the data on key lncRNAs that may drive the pathogenesis of SLE and RA and could potentially serve as emerging novel biomarkers and therapeutic targets in the coming future.

Advances in the role of helper T cells in autoimmune diseases

Autoimmune diseases are primary immune diseases in which autoreactive antibodies or sensitized lymphocytes destroy and damage tissue and cellular components, resulting in tissue damage and organ dysfunction. Helper T cells may be involved in the pathogenesis of autoimmune diseases under certain conditions. This review summarizes recent research on the role of helper T cells in autoimmune diseases from two aspects, helper T cell-mediated production of autoantibodies by B cells and helper T cell-induced activation of abnormal lymphocytes, and provides ideas for the treatment of autoimmune diseases. The abnormal expression of helper T cells promotes the differentiation of B cells that produce autoantibodies, which leads to the development of different diseases. Among them, abnormal expression of Th2 cells and T follicular helper cells is more likely to cause antibody-mediated autoimmune diseases. In addition, abnormal activation of helper T cells also mediates autoimmune diseases through the production of abnormal cytokines and chemokines. Helper T cells play an essential role in the pathogenesis of autoimmune diseases, and a full understanding of their role in autoimmune diseases is helpful for providing ideas for the treatment of autoimmune diseases.

Inhibition of Ras GTPases prevents Collagen-Induced Arthritis by Reducing the Generation of Pathogenic CD4+ T Cells and the Hyposialylation of Autoantibodies

OBJECTIVE

RasGTPases are master regulators of multiple intracellular signaling cascades. Perturbation of this pathway has been implicated in the pathogenesis of rheumatoid arthritis (RA). In this study we aimed to define the therapeutic potential of a novel RasGTPases inhibitor, farnesylthiosalicylate (FTS), in the preclinical mouse model of collagen-induced arthritis (CIA) and better delineate its immunomodulatory effects both ex vivo and in the mouse.

METHODS

We analyzed in vitro the immunomodulatory effects of FTS on various CD4⁺ T-cell functions such as activation, proliferation, T-helper polarization, and production of proinflammatory cytokines. Using the CIA model, we further determined the efficacy of FTS to inhibit clinical, histopathologic, and diverse immunological outcomes of arthritis.

RESULTS

FTS treatment of CD4⁺ T cells in vitro effectively targeted distinct kinases (extracellular signal-regulated kinase 1/2, p38, protein kinase B/AKT, and mammalian target of rapamycin), the production of interleukin (IL)-17A, IL-22, and granulocyte-macrophage colony-stimulating factor, and Th17 polarization. FTS therapy in the mouse CIA model significantly reduced clinical disease severity and joint inflammation/damage by histology. Importantly, FTS suppressed the in vivo induction of splenic IL-17⁺ IL-22⁺ Th17 cells and the secretion of proinflammatory cytokines. The production of pathogenic autoantibodies and their abnormal hyposialylation was significantly attenuated by FTS therapy. Importantly, in vivo generation of collagen type-II specific effector CD4⁺ T cells was likewise repressed by FTS therapy.

CONCLUSION

The RasGTPases inhibitor FTS attenuates the production of proinflammatory cytokines by in vitro-activated T cells and is a potent immunomodulatory compound in the CIA model, primarily targeting the generation of autoreactive Th17 cells and the production of autoantibodies and their subsequent pathogenic hyposialylation.

Bone Marrow Mesenchymal Stem Cells Decrease the Expression of RANKL in Collagen-Induced Arthritis Rats via Reducing the Levels of IL-22

OBJECTIVE

To investigate the transplantation effect of bone marrow mesenchymal stem cells (MSCs) on the expression of interlukin-22 (IL-22) and RANKL in collagen-induced arthritis (CIA) rats.

METHODS

32 CIA models were established. 16 CIA rats were transplanted with MSCs, and others were used as nontreatment CIA controls. The concentrations of IL-22 and RANKL in serum were detected by ELISA and those in synovial tissue of rats' joints by immunohistochemical staining. In addition, the expression of RANKL mRNA was measured by RT-PCR in the fibroblast-like synoviocytes (FLSs), cultured with IL-22 in vitro, which were delivered from the joints of CIA rats treated with or without MSCs.

RESULTS

The transplantation of MSCs into CIA rats relieved the destruction of joints, measured by AI score, X-ray, and histopathology. MSCs also reduced the expression of IL-22 and RANKL in serum by ELISA (P < 0.001) and similarly in FLSs by immunohistochemical staining. In vitro, IL-22 induced significantly the expression of RANKL mRNA in cultured FLSs in a dose-dependent manner, whereas this induction was significantly reduced in FLSs derived from CIA rats transplanted with MSCs (normal controls: F = 79.33, P < 0.001; CIA controls: F = 712.72, P < 0.001; and CIA-MSC rats: F = 139.04, P < 0.001).

CONCLUSION

Our results suggest that the transplantation of MSCs can reduce the expression of RANKL in vivo by downregulating the levels of IL-22, thereby ameliorating the degree of RA bone destruction. This study provides a theoretical basis for a potential therapy of RA with MSCs, and IL-22 and RANKL may become two new targets to treat RA.

IL-22-expressing CD4+ AhR+ T lymphocytes are associated with RANKL-mediated alveolar bone resorption during experimental periodontitis

BACKGROUND AND OBJECTIVE

Over the past few years, the importance of interleukin-22 (IL-22) and T-helper (Th)22 lymphocytes in the pathogenesis of periodontitis has become apparent; however, there are still aspects that are not addressed yet. Cells expressing IL-22 and aryl hydrocarbon receptor (AhR), transcription factor master switch gene implicated in the differentiation and function of Th22 lymphocytes, have been detected in periodontal tissues of periodontitis-affected patients. In addition, IL-22 has been associated with osteoclast differentiation and their bone resorptive activity in vitro. However, the destructive potential of IL-22-expressing AhR+ Th22 lymphocytes over periodontal tissues during periodontitis has not been demonstrated in vivo yet. Therefore, this study aimed to analyze whether IL-22-expressing CD4+ AhR+ T lymphocytes detected in periodontal lesions are associated with alveolar bone resorption during experimental periodontitis.

MATERIAL AND METHODS

Using a murine model of periodontitis, the expression levels of IL-22 and AhR, as well as the Th1-, Th2-, Th17- and T regulatory-associated cytokines, were analyzed in periodontal lesions using qPCR. The detection of CD4+ IL-22+ AhR+ T lymphocytes was analyzed in periodontal lesions and cervical lymph nodes that drain these periodontal lesions using flow cytometry. In addition, the expression of the osteoclastogenic mediator called receptor activator of nuclear factor-κB ligand (RANKL) was analyzed by qPCR, western blot, and immunohistochemistry. Finally, alveolar bone resorption was analyzed using micro-computed tomography and scanning electron microscopy, and the bone resorption levels were correlated with IL-22 and RANKL expression.

RESULTS

Higher levels of IL-22, AhR, and RANKL, as well as IL-1β, IL-6, IL-12, IL-17, IL-23, and TNF-α, were expressed in periodontal lesions of infected mice compared with periodontal tissues of sham-infected and non-infected controls. Similarly, high RANKL immunoreaction was observed in periodontal tissues of infected mice; however, few or absent RANKL immunoreaction was observed in controls. This association between RANKL and periodontal infection was ratified by western blot. Furthermore, a higher detection of CD4+ IL-22+ AhR+ T lymphocytes was found in periodontal lesions and cervical lymph nodes that drain these periodontal lesions in infected mice compared with non-infected controls. Finally, the increased IL-22 and RANKL expression showed positive correlation between them and with the augmented alveolar bone resorption observed in experimental periodontal lesions.

CONCLUSION

This study demonstrates the increase of IL-22-expressing CD4+ AhR+ T lymphocytes in periodontitis-affected tissues and shows a positive correlation between IL-22, RANKL expression, and alveolar bone resorption.

Losartan, but not Enalapril and Valsartan, Inhibits the Expression of IFN-γ, IL-6, IL-17F and IL-22 in PBMCs from Rheumatoid Arthritis Patients

Background:

Rheumatoid Arthritis (RA) is a chronic and inflammatory disease that affects about 1% of the world's population. Almost 70% of RA patients have a cardiovascular disease such as Systemic Arterial Hypertension (SAH). Inflammatory cytokines are clearly involved in the pathogenesis of RA and correlated with SAH.

Objective:

It is necessary to understand whether the antihypertensive drugs have a dual effect as immunomodulators and which one is the best choice for RA SAH patients.

Methods:

Peripheral Blood Mononuclear Cells (PBMCs) from 16 RA patients were purified and stimulated or not stimulated with anti-CD3 and anti-CD28 mAB and were treated with Enalapril, Losartan and Valsartan at 100μM. Patients were evaluated for clinical and laboratory variables including measures of disease activity by Clinical Disease Activity Index (CDAI) and Disease Activity Score (DAS28). Cytokines were quantified by ELISA sandwich.

Results:

Losartan was able to reduce levels of IFN-γ (p = 0.0181), IL-6 (p = 0.0056), IL-17F (0.0046) and IL-22 (p = 0.0234) in RA patients. In addition, patients in remission and mild score (DAS28<3.2 and CDAI<10) had a better response to treatment. On the other hand, patients in moderate and severe activity had poor response to Losartan in cytokine inhibition.

Conclusion:

PBMCs from RA patients are responsive in inhibiting proinflammatory cytokines using Losartan better than Enalapril and Valsartan and it could be a better antihypertensive choice for patients with RA and systemic arterial hypertension treatment.

Long non-coding RNAs in rheumatoid arthritis

Rheumatoid arthritis, a disabling autoimmune disease, is associated with altered gene expression in circulating immune cells and synovial tissues. Accumulating evidence has suggested that long non-coding RNAs (lncRNAs), which modulate gene expression through multiple mechanisms, are important molecules involved in immune and inflammatory pathways. Importantly, many studies have reported that lncRNAs can be utilized as biomarkers for disease diagnosis and prognostication. Recently, dysregulation of lncRNAs in rheumatoid arthritis and other autoimmune diseases has been revealed. Experimental studies also confirmed their crosstalk with matrix metalloproteinases, nuclear factor-κB signalling and T-cell response pertinent to autoimmunity and inflammation. Circulating lncRNAs, such as HOTAIR, differentiated patients with rheumatoid arthritis from healthy subjects. Taken together, lncRNAs are good candidates as biomarkers and therapeutic targets in rheumatoid arthritis. Further investigation on in vivo delivery of these regulatory molecules and large-cohort validation of their clinical applicability may be useful.

Increased circulating Th22 cells in patients with acute gouty arthritis: A CONSORT-compliant article

BACKGROUND

T-helper 22 (Th22) cells are involved in host immunity against pathogen invasion and have been implicated in the pathogenesis of inflammatory diseases. However, the roles of Th22 cells in acute gouty arthritis remain unclear.

METHODS

A case-control study was employed to illustrate the clinical significance of Th22 cells in acute gouty arthritis. In this study, 27 patients with acute gouty arthritis, 22 patients with intercritical gout (IG), and 20 healthy controls were recruited, and peripheral blood cells and plasma were collected for the detection of Th22, Th17, and Th1 cells, and plasma interleukin (IL)-22.

RESULTS

The relative and absolute numbers of Th22 and Th17 cells were significantly higher in patients with acute gouty arthritis than in patients with IG and healthy controls. Plasma IL-22 levels were consistently higher in patients with acute gouty arthritis than in patients with IG and healthy controls (P < .05). Th22 cell numbers were positively correlated with Th1 (r = 0.648, P < .05) and Th17 (r = 0.379, P < .05) cell numbers in patients with gout. Moreover, Th22 cell numbers and plasma IL-22 levels were positively correlated with C-reactive protein levels (Th22: r = 0.444, P < .05; IL-22: r = 0.282, P < .05).

CONCLUSION

Our results indicate that peripheral blood levels of Th22 cells increase during acute gouty arthritis suggesting a role for these cells in the pathophysiology of the disease.

Effector T helper cell populations are elevated in the bone marrow of rheumatoid arthritis patients and correlate with disease severity

This study is to investigate the frequencies of T-helper (Th)22, Th17 and Th1 cells and the levels of related cytokines in subchondral bone marrow in patients with rheumatoid arthritis (RA). Bone marrow and peripheral blood samples were collected from RA, osteoarthritis (OA) patients and healthy controls. The frequencies of Th22, Th17, and Th1 cells were examined by flow cytometry. Levels of interleukin (IL)-22, IL-17 and IFN-γ were examined by ELISA. Disease Activity Score in 28 joints (DAS28) of RA patients were analyzed. Bone marrow Th22, Th17 and Th1 cells in RA patients were markedly increased comparing to OA or healthy controls. Each T cell subset in bone marrow was elevated comparing with that in the peripheral blood in RA patients. Consistently, plasma levels of IL-22 and IL-17 were elevated in RA patients, and the elevation was more notable in the bone marrow than in the peripheral blood. Additionally, the percentages of Th22, Th17 and Th1 cells as well as the levels of IL-22 and IL-17 in bone marrow were positively correlated with DAS28. These results suggest that local pro-inflammatory Th cells are elevated in bone marrow, which may play an important role in situ in RA and contribute to the pathogenesis of in RA.

Cigarette smoke inhibits ROCK2 activation in T cells and modulates IL-22 production

Gene-environment interactions are known to play a key role in the development of rheumatoid arthritis (RA). Exposure to cigarette smoke (CS) is one of the strongest environmental risk factors associated with RA and has been shown to mediate a range of complex immunomodulatory effects from decreased T and B cell activation to depressed phagocytic function. The effects of CS on the function of TH17 cells, one of the key TH effector subsets implicated in RA pathogenesis, are not fully understood. IRF4 is one of the crucial transcription factors involved in TH-17 differentiation and is absolutely required for the production of IL-17 and IL-21 but, interestingly, inhibits the synthesis of IL-22. The production of IL-17 and IL-21 by IRF4 can be augmented by its phosphorylation by the serine-threonine kinase ROCK2. Given that CS has been reported to increase ROCK activity in endothelial cells, here we investigated the effects of CS on the ROCK2-IRF4 axis in T cells. Surprisingly, we found that CS leads to decreased ROCK2 activation and IRF4 phosphorylation in T cells. This effect was associated with increased IL-22 production. Using a GEF pull-down assay we furthermore identify ARHGEF1 as a key upstream regulator of ROCK2 whose activity in T cells is inhibited by CS. Thus CS can inhibit the ROCK2-IRF4 axis and modulate T cell production of IL-22.

Role of Ets Proteins in Development, Differentiation, and Function of T-Cell Subsets

Through positive selection, double-positive cells in the thymus differentiate into CD4(+) or CD8(+) T single-positive cells that subsequently develop into different types of effective T cells, such as T-helper and cytotoxic T lymphocyte cells, that play distinctive roles in the immune system. Development, differentiation, and function of thymocytes and CD4(+) and CD8(+) T cells are controlled by a multitude of secreted and intracellular factors, ranging from cytokine signaling modules to transcription factors and epigenetic modifiers. Members of the E26 transformation specific (Ets) family of transcription factors, in particular, are potent regulators of these CD4(+) or CD8(+) T-cell processes. In this review, we summarize and discuss the functions and underlying mechanisms of the Ets family members that have been characterized as involved in these processes. Ongoing research of these factors is expected to identify practical applications for the Ets family members as novel therapeutic targets for inflammation-related diseases.