Effector CD8+ T cells in systemic sclerosis patients produce abnormally high levels of interleukin-13 associated with increased skin fibrosis

Granzyme serine proteases in inflammation and rheumatic diseases

Granzymes (granule-secreted enzymes) are a family of serine proteases that have been viewed as redundant cytotoxic enzymes since their discovery more than 30 years ago. Predominantly produced by cytotoxic lymphocytes and natural killer cells, granzymes are delivered into the cytoplasm of target cells through immunological synapses in cooperation with the pore-forming protein perforin. After internalization, granzymes can initiate cell death through the cleavage of intracellular substrates. However, evidence now also demonstrates the existence of non-cytotoxic, pro-inflammatory, intracellular and extracellular functions that are granzyme specific. Under pathological conditions, granzymes can be produced and secreted extracellularly by immune cells as well as by non-immune cells. Depending on the granzyme, accumulation in the extracellular milieu might contribute to inflammation, tissue injury, impaired wound healing, barrier dysfunction, osteoclastogenesis and/or autoantigen generation.

Alterations in peripheral T- and B-cell subsets in patients with systemic sclerosis

OBJECTIVES

To determine the alteration of peripheral T and B cell subsets in patients with systemic sclerosis (SSc) and to evaluate their correlation with the progression of SSc.

METHODS

We recruited 47 SSc patients and 45 healthy controls (HCs) in this study. Demographic and clinical data were then collected. Flow cytometry was used to detect the proportions of 44 different T and B cell subsets in circulating blood.

RESULTS

The proportion of total B cells (p = .043) decreased in SSc patients, together with similar frequencies of total T cells, CD4+ T cells, and CD8+ T cells in both groups. Several subsets of T and B cells differed significantly between these two groups. Follicular helper T cells-1 (Tfh1) (p < .001), helper T cells-1 (Th1) (p = .001), regulatory T cells (Treg) (p = .004), effector memory CD8+ T cells (p = .041), and cytotoxic T cells-17 (Tc17) (p = .01) were decreased in SSc patients. Follicular helper T cells-2 (Tfh2) (p = .001) and, helper T cells-2 (Th2) (p = .001) levels increased in the SSc group. Regulatory B cells (Breg) (p = .015) were lower in the SSc group, together with marginal zone (MZ) B cells (p < .001), memory B cells (p = .001), and non-switched B cells (p = .005). The modified Rodnan skin score (mRSS) correlated with helper T cells-17 (Th17) (r = -.410, p = .004), Tfh1 (r = -.321, p = .028), peripheral helper T cells (Tph) (r = -.364, p = .012) and plasma cells (r = -.312, p = .033).

CONCLUSIONS

The alterations in T and B cells implied immune dysfunction, which may play an essential role in systemic sclerosis.

Periostin expression in uninvolved skin as a potential biomarker for rapid cutaneous progression in systemic sclerosis patients: a preliminary explorative study

Objectives

This study aimed to evaluate periostin serum levels and skin expression in patients with systemic sclerosis (SSc).

Methods

We enrolled 35 patients with diffuse (d-SSc) or limited (l-SSc) SSc, 15 patients with very early diagnosis of systemic sclerosis (VEDOSS), and 30 sex-matched healthy controls. Periostin serum levels were determined by an enzyme-linked immunosorbent assay (ELISA). Periostin skin expression was determined by immunohistochemistry (IHC) on paired involved and uninvolved 5-mm skin biopsy samples in a subgroup of 10 d-SSc and 10 L-SSc patients. A 12-month follow-up was considered.

Results

We included 50 patients (mean age 53.1 ± 16.1 years; women 94%; mean disease duration 38.2 ± 45.1 months; anti-centromere 50%; anti-Scl70 40%), 35 of them with a definite SSc (68.8% l-SSc; 31.4% d-SSc; mean mRSS 9.0 ± 7.2) and 15 with VEDOSS; 30 controls were also included in this study. Periostin serum levels were higher in SSc patients compared to controls (32.7 ± 8.0 ng/mL vs. 27.7 ± 7.3 ng/mL; p < 0.001), while these levels were comparable among different groups of patients (29.7 ± 6.9 ng/mL in VEDOSS, 33.4 ± 7.8 ng/mL in lc-SSc; and 34.0 ± 8.5 in dc-SSc; p = ns). SSc patients with digital ulcers had higher periostin serum levels (36.2 ± 7.9 ng/mL vs. 30.6 ± 7.3 ng/mL, p < 0.02). Samples from the involved skin of l-SSc and d-SSc patients showed a significant dermal expression of periostin; an identical periostin expression was evident in the uninvolved skin of patients with d-SSc. In 7 out of 10 L-SSc patients, periostin expression was absent on uninvolved skin. In the remaining three l-SSc patients, a mild periostin expression on IHC was detectable on uninvolved skin and all of these three l-SSc patients presented a dramatic skin progression.

Conclusion

Periostin skin expression may be a useful biomarker to indicate the presence of a disease at a higher risk of rapid cutaneous involvement.

Novel Therapeutic Strategies in the Treatment of Systemic Sclerosis

Systemic sclerosis is a connective tissue disease of unknown origin and with an unpredictable course, with both cutaneous and internal organ manifestations. Despite the enormous progress in rheumatology and clinical immunology, the background of this disease is largely unknown, and no specific therapy exists. The therapeutic approach aims to treat and preserve the function of internal organs, and this approach is commonly referred to as organ-based treatment. However, in modern times, data from other branches of medicine may offer insight into how to treat disease-related complications, making it possible to find new drugs to treat this disease. In this review, we present therapeutic options aiming to stop the progression of fibrotic processes, restore the aberrant immune response, stop improper signalling from proinflammatory cytokines, and halt the production of disease-related autoantibodies.

Drug suspending during wound healing effectively weakens immunosuppression-related complications by preserving CD8+ T cell function

Immunosuppressive medications, which interfere with the activation and proliferation of T and B cells, increase the risk of wound healing complications. To address it, this study aimed to validate the feasibility of drug suspending during wound healing, whilst exploring the mechanisms exerted by T cells, which are important in the wound healing process. For this, a mouse skin wound model was set up. Tacrolimus (FK506) and fingolimod (FTY720) were both administered intraperitoneally prior to wounding to inhibit the T cell activation and migration, respectively. Flow-cytometric analysis subsequently revealed the functional T cell subtypes detected during the healing process. A CD8a antibody was also administered to deplete CD8+ T cells in vivo to verify their specific function. It was found that FK506 or FTY720 administration delayed the early phase of wound healing by reducing collagen production, which was also supported by the downregulation of col1a1, col3a1 and tgfb1. However, there was no significant difference in the total healing period. Both spleen- and skin-derived CD8+ T cells were proliferated and activated after injury without intervention, whereas CD4+ T cells showed no significant changes. Furthermore, selectively depleting CD8+ T cells retarded the healing process by downregulating collagen production-associated genes (col1a1, col3a1, tgfβ1 and en1) and proteins (collagen type 1 and 3). In addition, the CD8a antibody decreased the expression of genes lta, tnfa, il13 and il13ra, and protein interleukin-13Rα. In conclusion, suspending immunosuppressive drugs during wound healing was shown to be feasible through restraining the migration of activated T cells. CD8+ T cells represented the primary functional subtype positively associated with wound healing.

Human Regulatory T Cells: Understanding the Role of Tregs in Select Autoimmune Skin Diseases and Post-Transplant Nonmelanoma Skin Cancers

Regulatory T cells (Tregs) play an important role in maintaining immune tolerance and homeostasis by modulating how the immune system is activated. Several studies have documented the critical role of Tregs in suppressing the functions of effector T cells and antigen-presenting cells. Under certain conditions, Tregs can lose their suppressive capability, leading to a compromised immune system. For example, mutations in the Treg transcription factor, Forkhead box P3 (FOXP3), can drive the development of autoimmune diseases in multiple organs within the body. Furthermore, mutations leading to a reduction in the numbers of Tregs or a change in their function facilitate autoimmunity, whereas an overabundance can inhibit anti-tumor and anti-pathogen immunity. This review discusses the characteristics of Tregs and their mechanism of action in select autoimmune skin diseases, transplantation, and skin cancer. We also examine the potential of Tregs-based cellular therapies in autoimmunity.

An updated review of the immunological mechanisms of keloid scars

Keloid is a type of disfiguring pathological scarring unique to human skin. The disorder is characterized by excessive collagen deposition. Immune cell infiltration is a hallmark of both normal and pathological tissue repair. However, the immunopathological mechanisms of keloid remain unclear. Recent studies have uncovered the pivotal role of both innate and adaptive immunity in modulating the aberrant behavior of keloid fibroblasts. Several novel therapeutics attempting to restore regulation of the immune microenvironment have shown variable efficacy. We review the current understanding of keloid immunopathogenesis and highlight the potential roles of immune pathway-specific therapeutics.

Effector Memory-Expressing CD45RA (TEMRA) CD8+ T Cells from Kidney Transplant Recipients Exhibit Enhanced Purinergic P2X4 Receptor-Dependent Proinflammatory and Migratory Responses

BACKGROUND

The mechanisms regulating CD8+ T cell migration to nonlymphoid tissue during inflammation have not been fully elucidated, and the migratory properties of effector memory CD8+ T cells that re-express CD45RA (TEMRA CD8+ T cells) remain unclear, despite their roles in autoimmune diseases and allotransplant rejection.

METHODS

We used single-cell proteomic profiling and functional testing of CD8+ T cell subsets to characterize their effector functions and migratory properties in healthy volunteers and kidney transplant recipients with stable or humoral rejection.

RESULTS

We showed that humoral rejection of a kidney allograft is associated with an accumulation of cytolytic TEMRA CD8+ T cells in blood and kidney graft biopsies. TEMRA CD8+ T cells from kidney transplant recipients exhibited enhanced migratory properties compared with effector memory (EM) CD8+ T cells, with enhanced adhesion to activated endothelium and transmigration in response to the chemokine CXCL12. CXCL12 directly triggers a purinergic P2×4 receptor-dependent proinflammatory response of TEMRA CD8+ T cells from transplant recipients. The stimulation with IL-15 promotes the CXCL12-induced migration of TEMRA and EM CD8+ T cells and promotes the generation of functional PSGL1, which interacts with the cell adhesion molecule P-selectin and adhesion of these cells to activated endothelium. Although disruption of the interaction between functional PSGL1 and P-selectin prevents the adhesion and transmigration of both TEMRA and EM CD8+ T cells, targeting VLA-4 or LFA-1 (integrins involved in T cell migration) specifically inhibited the migration of TEMRA CD8+ T cells from kidney transplant recipients.

CONCLUSIONS

Our findings highlight the active role of TEMRA CD8+ T cells in humoral transplant rejection and suggest that kidney transplant recipients may benefit from therapeutics targeting these cells.

Changes in peripheral T-lymphocyte subsets and serum cytokines in patients with systemic sclerosis

Objective: T cells represent a predominant cell type in autoimmune disease. However, their exact roles are not fully clear in systemic sclerosis (SSc). This study aimed to mainly investigate the alteration in the absolute numbers of T-lymphocyte subsets and the serum levels of cytokines in SSc patients. Methods: A total of 76 patients with SSc and 76 age- and sex-matched healthy controls (HCs) were enrolled. The levels of circulating T cell subsets and serum cytokines were measured by flow cytometry. T cell subsets or serum cytokines correlations with disease activity and organ involvement were analyzed. Results: The absolute numbers of Th2 and Treg cells in SSc patients were lower than those in HCs (p < 0.05), resulting in the ratios of Th1/Th2 [25.01 (12.24, 38.61) vs. 11.64 (6.38, 20.34)] and Th17/Treg [0.42 (0.17, 0.66) vs. 0.17 (0.13, 0.29)] were increased significantly (p < 0.001). The absolute numbers of total T, Th, and Treg cells were negatively correlated with CRP (r = -0.406, p = 0.002; r = -0.263, p < 0.05; r = -0.367 p < 0.01). The serum levels of IL-2, SIL-2R, IL-6, IL-10, INF-γ, and TNF-α were significantly higher than those in HCs (p < 0.001). Increasing IL-2 in the wake of the augment of ESR (r = 0.671, p = 0.004), so did IL-6 (r = 0.378, p < 0.05). The ratio of Th17/Treg in SSc-ILD patients had lower levels than that in other patients [0.35 (0.14, 0.53) vs. 0.64 (0.26, 0.93) p = 0.028]; Treg cells were lessened in patients with Raynaud's phenomenon relative to controls [3.00 (2.41, 4.28) vs. 3.55 (2.86, 4.53) p < 0.05]. The levels of IL-2, IL-10 and INF-γ [3.32 (1.05,11.73) vs. 2.32 (0.44,6.45), p = 0.045], [8.08 (3.63, 355,77) vs. 4.89 (0.78, 21.44), p = 0.02], [6.31 (2.66, 44.03) vs. 4.03 (0.22, 16.96), p = 0.009] were elevated in patients with arthralgia, while the level of Th17 was decreased [0.62 (0.20,2.16) vs. 1.26 (0.22,10.93), p = 0.026]. ROC curve analysis yielded an optimal cut-off IL-2, IL-10, and INF-γ levels of 2.67, 5.93, and 5.32 pg/ml for the presence of arthralgia. Conclusion: We exhibited abnormalities in T subsets and the production of their cytokines in SSc, as compared with those in HCs. This may allow the pathogenesis of SSc and the development of novel therapeutic interventions aimed at targeting these cells and the cytokines they produce.

Lymphocyte subset abnormalities in early severe scleroderma favor a Th2 phenotype and are not altered by prior immunosuppressive therapy

OBJECTIVES

The Scleroderma: Cyclophosphamide or Transplantation (SCOT) trial compared hematopoietic stem cell transplant to CYC treatment in patients with early SSc with progressive skin and lung or kidney involvement. Here we describe lymphocyte phenotype abnormalities at study entry and the relation to prior DMARD therapy.

METHODS

Lymphocyte subsets (n = 26) measured by flow cytometry were compared in 123 heathy controls and 71 SCOT participants, including those given (n = 57) or not given (n = 14) DMARDs within 12 months of randomization.

RESULTS

Compared with healthy controls, individuals with SSc showed significant reductions in central memory CD8 T cells, activated total and CD4 T cells, γ/δ T cells, memory B cells, myeloid and plasmacytoid dendritic cells and FOXP3+CD25+ Treg cells and increases in naïve CD4 T cells, effector memory CD4 T cells and effector CD8 T cells. A greater bias towards a IL-4+ Th2/T cytotoxic 2 (Tc2) phenotype based on the Th2:Th1 CD4 ratio and Tc2:Tc1 CD8 T cells was also found. Notably, no difference in any lymphocyte subset was observed between those given or not given prior DMARDs.

CONCLUSIONS

In patients with early, severe SSc, significant lymphocyte subset abnormalities were observed. Prior treatment with immunosuppressive therapy did not impact the immunophenotype, suggesting that lymphocyte disturbances in scleroderma appeared to be due to the disease itself.

TRIAL REGISTRATION

ClinicalTrials.gov (https://clinicaltrials.gov), NCT00114530.

CD8+ T Cell Phenotype and Function in Childhood and Adult-Onset Connective Tissue Disease

CD8+ T cells are cytotoxic lymphocytes that destroy pathogen infected and malignant cells through release of cytolytic molecules and proinflammatory cytokines. Although the role of CD8+ T cells in connective tissue diseases (CTDs) has not been explored as thoroughly as that of other immune cells, research focusing on this key component of the immune system has recently gained momentum. Aberrations in cytotoxic cell function may have implications in triggering autoimmunity and may promote tissue damage leading to exacerbation of disease. In this comprehensive review of current literature, we examine the role of CD8+ T cells in systemic lupus erythematosus, Sjögren's syndrome, systemic sclerosis, polymyositis, and dermatomyositis with specific focus on comparing what is known about CD8+ T cell peripheral blood phenotypes, CD8+ T cell function, and CD8+ T cell organ-specific profiles in adult and juvenile forms of these disorders. Although, the precise role of CD8+ T cells in the initiation of autoimmunity and disease progression remains to be elucidated, increasing evidence indicates that CD8+ T cells are emerging as an attractive target for therapy in CTDs.

Dendritic cells drive profibrotic inflammation and aberrant T cell polarization in systemic sclerosis

OBJECTIVES

Systemic sclerosis (SSc) is a devastating autoimmune disease characterized by fibrosis and obliterative vasculopathy affecting the skin and visceral organs. While the processes mediating excessive extracellular matrix (EM) deposition and fibroblast proliferation are clear, the exact link between autoimmunity and fibrosis remains elusive. Th17 cells have been proposed as critical drivers of profibrotic inflammation during SSc, but little is known about the immune components supporting their pathogenic role.

METHODS

Dendritic cells (DCs) activate and shape T cell differentiation by producing polarizing cytokines. Hence, we investigated the cytokine responses of monocyte-derived DCs (Mo-DCs) from patients with limited cutaneous SSc (lcSSc), diffuse cutaneous SSc (dcSSc), and healthy controls (HC) after stimulation with toll-like receptor (TLR) agonists. Also, using co-culture assays, we analyzed T cell subpopulations after contact with autologous TLR-activated Mo-DCs.

RESULTS

In general, we observed an increased production of Th17 related cytokines like IL-1β, IL-17F, IL-21, IL-22 by SSc compared with HC Mo-DCs, with variations between lcSSc vs. dcSSc and early- vs. late-stage subgroups. Noticeably, we found a significant increment in IL-33 production by Mo-DCs in all SSc cases regardless of their clinical phenotype. Strikingly, T cells displayed Th2, Th17, and dual Th2/Th17 phenotypes after exposure to autologous TLR-stimulated Mo-DCs from SSc patients but not HC. These changes were pronounced in individuals with early-stage dcSSc and less significant in the late-stage lcSSc subgroup.

CONCLUSIONS

Our findings suggest that functional alterations of DCs subsidize the immune mechanisms favoring the aberrant T cell polarization and profibrotic inflammation behind the clinical SSc heterogeneity.

Targeting Systemic Sclerosis from Pathogenic Mechanisms to Clinical Manifestations: Why IL-6?

Systemic sclerosis (SS) is a chronic autoimmune disorder, which has both cutaneous and systemic clinical manifestations. The disease pathogenesis includes a triad of manifestations, such as vasculopathy, autoimmunity, and fibrosis. Interleukin-6 (IL-6) has a special role in SS development, both in vascular damage and in the development of fibrosis. In the early stages, IL-6 participates in vascular endothelial activation and apoptosis, leading to the release of damage-associated molecular patterns (DAMPs), which maintain inflammation and autoimmunity. Moreover, IL-6 plays an important role in the development of fibrotic changes by mediating the transformation of fibroblasts into myofibroblasts. All of these are associated with disabling clinical manifestations, such as skin thickening, pulmonary fibrosis, pulmonary arterial hypertension (PAH), heart failure, and dysphagia. Tocilizumab is a humanized monoclonal antibody that inhibits IL-6 by binding to the specific receptor, thus preventing its proinflammatory and fibrotic actions. Anti-IL-6 therapy with Tocilizumab is a new hope for SS patients, with data from clinical trials supporting the favorable effect, especially on skin and lung damage.

Immune Mechanisms and Related Targets for the Treatment of Fibrosis in Various Organs

Inflammation and fibrosis are two inter-related disease pathologies with several overlapping components. Three specific cell types, macrophages, T helper cells and myofibroblasts, each play important roles in regulating both processes. Following tissue injury, an inflammatory stimulus is often necessary to initiate tissue repair, where cytokines released from infiltrating and resident immune and inflammatory cells stimulate the proliferation and activation of extracellular matrix-producing myofibroblasts. However, persistent tissue injury drives an inappropriate pro-fibrotic response. Additionally, activated myofibroblasts can take on the role of traditional antigen-presenting cells, secrete pro-inflammatory cytokines, and recruit inflammatory cells to fibrotic foci, amplifying the fibrotic response in a vicious cycle. Moreover, inflammatory cells have been shown to play contradictory roles in the initiation, amplification and resolution of fibrotic disease processes. The central role of the inflammasome molecular platform in contributing to fibrosis is only beginning to be fully appreciated. In this review, we discuss the immune mechanisms that can lead to fibrosis, the inflammasomes that have been implicated in the fibrotic process in the context of the immune response to injury, and also discuss current and emerging therapies that target inflammasome-induced collagen deposition to treat organ fibrosis.

Molecular Basis of Accelerated Aging with Immune Dysfunction-Mediated Inflammation (Inflamm-Aging) in Patients with Systemic Sclerosis

Systemic sclerosis (SSc) is a chronic connective tissue disorder characterized by immune dysregulation, chronic inflammation, vascular endothelial cell dysfunction, and progressive tissue fibrosis of the skin and internal organs. Moreover, increased cancer incidence and accelerated aging are also found. The increased cancer incidence is believed to be a result of chromosome instability. Accelerated cellular senescence has been confirmed by the shortening of telomere length due to increased DNA breakage, abnormal DNA repair response, and telomerase deficiency mediated by enhanced oxidative/nitrative stresses. The immune dysfunctions of SSc patients are manifested by excessive production of proinflammatory cytokines IL-1, IL-6, IL-17, IFN-α, and TNF-α, which can elicit potent tissue inflammation followed by tissue fibrosis. Furthermore, a number of autoantibodies including anti-topoisomerase 1 (anti-TOPO-1), anti-centromere (ACA or anti-CENP-B), anti-RNA polymerase enzyme (anti-RNAP III), anti-ribonuclear proteins (anti-U1, U2, and U11/U12 RNP), anti-nucleolar antigens (anti-Th/T0, anti-NOR90, anti-Ku, anti-RuvBL1/2, and anti-PM/Scl), and anti-telomere-associated proteins were also found. Based on these data, inflamm-aging caused by immune dysfunction-mediated inflammation exists in patients with SSc. Hence, increased cellular senescence is elicited by the interactions among excessive oxidative stress, pro-inflammatory cytokines, and autoantibodies. In the present review, we will discuss in detail the molecular basis of chromosome instability, increased oxidative stress, and functional adaptation by deranged immunome, which are related to inflamm-aging in patients with SSc.

Patterns of T-Cell Phenotypes in Rheumatic Diseases From Single-Cell Studies of Tissue

High-dimensional analyses of tissue samples from patients with rheumatic diseases are providing increasingly detailed descriptions of the immune cell populations that infiltrate tissues in different rheumatic diseases. Here we review key observations emerging from high-dimensional analyses of T cells within tissues in different rheumatic diseases, highlighting common themes across diseases as well as distinguishing features. Single-cell RNA sequencing analyses capture several dimensions of T-cell states, yet surprisingly, these analyses generally have not demonstrated distinct clusters of paradigmatic T-cell effector subsets, such as T helper (Th) 1, Th2, and Th17 cells. Rather, global transcriptomics robustly identify both proliferating T cells and regulatory T cells and have also helped to reveal new effector subsets in inflamed tissues, including T peripheral helper cells and granzyme K⁺ T cells. Further characterization of the T-cell populations that accumulate within target tissues should enable more precise targeting of biologic therapies and accelerate development of more specific biomarkers to track activity of relevant immune pathways in patients with rheumatic diseases.

Cytokines Involved in the Pathogenesis of SSc and Problems in the Development of Anti-Cytokine Therapy

Systemic sclerosis (SSc) is a connective tissue disease of unknown etiology. SSc causes damage to the skin and various organs including the lungs, heart, and digestive tract, but the extent of the damage varies from patient to patient. The pathology of SSc includes ischemia, inflammation, and fibrosis, but the degree of progression varies from case to case. Many cytokines have been reported to be involved in the pathogenesis of SSc: interleukin-6 is associated with inflammation and transforming growth factor-β and interleukin-13 are associated with fibrosis. Therapeutic methods to control these cytokines have been proposed; however, which cytokines have a dominant role in SSc might differ depending on the extent of visceral lesions and the stage of disease progression. Therefore, it is necessary to consider the disease state of the patient to be targeted and the type of evaluation method when an anti-cytokine therapy is conducted. Here, we review the pathology of SSc and potential cytokine targets, especially interleukin-6, as well as the use of anti-cytokine therapy for SSc.

A Class II-Restricted CD8γ13 T-Cell Clone Protects During Chlamydia muridarum Genital Tract Infection

BACKGROUND

The T-cell response to chlamydia genital tract infections in humans and mice is unusual because the majority of antigen-specific CD8 T cells are not class I restricted (referred to here as "unrestricted" or "atypical"). We previously reported that a subset of unrestricted murine chlamydia-specific CD8 T cells had a cytokine polarization pattern that included interferon (IFN)-γ and interleukin (IL)-13.

METHODS

In this study, we investigated the transcriptome of CD8γ13 T cells, comparing them to Tc1 clones using microarray analysis. That study revealed that CD8γ13 polarization included IL-5 in addition to IFN-γ and IL-13. Adoptive transfer studies were performed with Tc1 clones and a CD8γ13 T-cell clone to determine whether either influenced bacterial clearance or immunopathology during Chlamydia muridarum genital tract infections.

RESULTS

To our surprise, an adoptively transferred CD8γ13 T-cell clone was remarkably proficient at preventing chlamydia immunopathology, whereas the multifunctional Tc1 clone did not enhance clearance or significantly alter immunopathology. Mapping studies with major histocompatibility complex (MHC) class I- and class II-deficient splenocytes showed our previously published chlamydia-specific CD8 T-cell clones are MHC class II restricted.

CONCLUSIONS

The MHC class II-restricted CD8 T cells may play an important role in protection from intracellular pathogens that limit class I antigen presentation or diminish CD4 T-cell numbers or impair their function.

The clinical and laboratory features associated with cancer in patients with primary biliary cholangitis: a longitudinal survey-based study

OBJECTIVES

To analyze the clinical and laboratory features of primary biliary cholangitis (PBC) patients complicated with cancer, and explore the potential factors associated with cancer.

METHODS

We consecutively enrolled PBC patients from January 2002 to February 2016 in Peking Union Medical College Hospital and performed a structured interview, systemic rheumatologic evaluation, and laboratory tests. The risk factors associated with cancer were analyzed with univariate and multivariable logistic regression and proportional hazard model.

RESULTS

Among the 580 PBC patients enrolled, 51 cancers were identified in 51 patients (8.8%), including 45 (88.2%) solid tumors and 6 (11.8%) hematologic malignancies. Patients with cancer were older (62.1 ± 9.6 vs. 55.4 ± 11.6 years, p < 0.01) than patients without cancer. Additionally, positive anti-centromere antibody (ACA) was more frequently observed in patients without cancer (25.9% vs 4.3%, p = 0.019) compared with patients with cancer diagnosed after establishing PBC. The median follow-up after the diagnosis of PBC was 4 years (IQR 2.0-6.6). Furthermore, multivariable logistic regression confirmed that older age was associated with cancer in PBC patients (odds ratio (OR) = 1.045, 95% confidence interval (CI): 1.006-1.085), and positive ACA was a protective factor (OR = 0.116, 95% CI: 0.015-0.876). Additionally, proportional hazard model analysis revealed that age was a risk factor (hazard ratio = 1.045, 95% CI: 1.012-1.080), and positive ACA was a protective factor (hazard ratio = 0.232, 95% CI: 0.055-0.977) for cancer.

CONCLUSIONS

Both solid tumor and hematologic malignancy were prevalent in PBC patients. Older age was associated with cancer, and positive ACA was a protective factor of cancer in PBC patients. Key Points • Patients with PBC could present with both solid tumors and hematologic malignancies. • Multivariable logistic regression and proportional hazard model analysis revealed that age was a risk factor as we know, and positive ACA was a protective factor.

Serum TARC Levels in Patients with Systemic Sclerosis: Clinical Association with Interstitial Lung Disease

Systemic sclerosis (SSc) is a multisystem fibrotic disorder with autoimmune background. Accumulating evidence has highlighted the importance of T helper (Th) 2 cells in the pathogenesis of SSc and its complications. Because thymus and activation-regulated chemokine (TARC) is a potent chemoattractant for Th2 cells, we measured serum TARC levels in SSc patients and analyzed their correlation with interstitial lung disease (ILD), a major complication of SSc. Serum TARC levels were significantly elevated in patients with SSc, especially in those with the diffuse subtype, compared with healthy controls. In particular, dcSSc patients with SSc-associated ILD (SSc-ILD) showed higher TARC levels than those without SSc-ILD. However, there was no significant correlation between serum TARC levels and pulmonary function in SSc patients. Serum TARC levels did not correlate with serum levels of interleukin-13, an important Th2 cytokine, either. Furthermore, in the longitudinal study, serum TARC levels did not predict the onset or progression of SSc-ILD in patients with SSc. These results were in contrast with those of KL-6 and surfactant protein D, which correlated well with the onset, severity, and progression of SSc-ILD. Overall, these results suggest that serum TARC levels are not suitable for monitoring the disease activity of SSc-ILD.

Calcium Influx Kinetics and the Characteristics of Potassium Channels in Peripheral T Lymphocytes in Systemic Sclerosis

BACKGROUND

Systemic sclerosis (SSc) is a chronic, immune-mediated, connective tissue disease causing microvascular abnormalities and fibrosis. The cytoplasmic calcium influx kinetics in T lymphocytes governs lymphocyte activation in this inflammatory process. The inhibition of Kv1.3 and IKCa1 potassium channels reduces calcium influx.

METHODS

This study aimed to analyze cytoplasmic calcium influx kinetics following activation in Th1, Th2, and CD8 cells in peripheral blood of 12 healthy individuals and 16 patients with systemic sclerosis using flow cytometry. We also evaluated the effect of the specific inhibition of the Kv1.3 and IKCa1 potassium channels.

RESULTS

We observed higher levels of activation in CD8 compared with Th1 cells in SSc. However, the activation of CD8 cells was lower in SSc compared to healthy controls. Moreover, activation of Th1 lymphocytes was slower in SSc than in healthy controls. The inhibition of IKCa1 channels decreased the activation of Th1 cells, while the inhibition of Kv1.3 channels modified the dynamics of activation of Th1 and Th2 lymphocytes in SSc.

CONCLUSION

Th1 and CD8 cells demonstrate specific activation dynamics and sensitivity to potassium channel inhibition in SSc, distinguishing this condition both from healthy controls and other autoimmune diseases.

Cytotoxic CD4+ T lymphocytes may induce endothelial cell apoptosis in systemic sclerosis

Systemic sclerosis (SSc) is an autoimmune fibrotic disease whose pathogenesis is poorly understood and lacks effective therapies. We undertook quantitative analyses of T cell infiltrates in the skin of 35 untreated patients with early diffuse SSc and here show that CD4+ cytotoxic T cells and CD8+ T cells contribute prominently to these infiltrates. We also observed an accumulation of apoptotic cells in SSc tissues, suggesting that recurring cell death may contribute to tissue damage and remodeling in this fibrotic disease. HLA-DR-expressing endothelial cells were frequent targets of apoptosis in SSc, consistent with the prominent vasculopathy seen in patients with this disease. A circulating effector population of cytotoxic CD4+ T cells, which exhibited signatures of enhanced metabolic activity, was clonally expanded in patients with systemic sclerosis. These data suggest that cytotoxic T cells may induce the apoptotic death of endothelial and other cells in systemic sclerosis. Cell loss driven by immune cells may be followed by overly exuberant tissue repair processes that lead to fibrosis and tissue dysfunction.

The IL-4/IL-13 axis in skin fibrosis and scarring: mechanistic concepts and therapeutic targets

Skin fibrosis, characterized by excessive fibroblast proliferation and extracellular matrix deposition in the dermis, is the histopathologic hallmark of dermatologic diseases such as systemic sclerosis, hypertrophic scars, and keloids. Effective anti-scarring therapeutics remain an unmet need, underscoring the complex pathophysiologic mechanisms of skin fibrosis. The Th2 cytokines interleukin (IL)-4 and IL-13 have been implicated as key mediators in the pathogenesis of fibroproliferative disorders. The goal of this article is to summarize the current understanding of the role of the IL-4/IL-13 axis in wound healing and skin fibrosis. We conducted a literature search to identify research studies investigating the roles of IL-4 and IL-13 in fibrotic skin diseases. While transforming growth factor-beta has long been regarded as the main driver of fibrotic processes, research into the cellular and molecular biology of wound healing has revealed other pathways that promote scar tissue formation. IL-4 and IL-13 are important mediators of skin fibrosis, supported by evidence from in vitro data, animal models of fibrosis, and clinical studies. Overactive signaling of the IL-4/IL-13 axis contributes to the initiation and perpetuation of fibrotic skin diseases. Further insights into the IL-4/IL-13 axis may reveal potential targets for the development of novel therapies that prevent or treat fibrotic skin diseases.

Immunopathogenesis of Juvenile Systemic Sclerosis

Juvenile-onset systemic sclerosis (jSSc) is a rare and severe autoimmune disease with associated life-threatening organ inflammation and evidence of fibrosis. The organ manifestations of jSSc resemble adult SSc, but with better outcomes and survival. The etiology of jSSc appears to reflect adult-onset SSc, with similar inflammatory mediators and autoantibodies, but with a significant population of children with uncharacterized anti-nuclear antibodies. The genetics of patients with jSSc differ from women with SSc, resembling instead the genes of adult males with SSc, with additional HLA genes uniquely associated with childhood-onset disease. Current treatments are aimed at inhibiting the inflammatory aspect of disease, but important mechanisms of fibrosis regulated by dermal white adipose tissue dendritic cells may provide an avenue for targeting and potentially reversing the fibrotic stage.

B cell depletion treatment decreases CD4+IL4+ and CD4+CD40L+ T cells in patients with systemic sclerosis

Recent data suggests that rituximab may favorably affect skin fibrosis and lung function in patients with systemic sclerosis. Based on experimental data suggesting a key role of B and T cells in scleroderma we aimed to explore the effect(s) of rituximab treatment on T cell subpopulations. Fifteen patients with scleroderma who received rituximab treatment and six who received standard treatment alone were recruited. Peripheral CD4+IL4+, CD4+INFγ+, CD4+IL17+ and CD4+CD40L+ T cells were assessed using flow cytometry. Using ELISA, serum levels of IL4 were assessed. Skin CD4+IL4+ T cells were assessed with confocal microscopy from skin biopsies. Following rituximab treatment skin CD4+IL4+ T cells obviously decreased as seen with confocal microscopy. Moreover, peripheral CD4+IL4+ T cells decreased significantly compared to those from patients who received standard treatment alone: median (IQR): 14.9 (22.63-12.88) vs 7.87 (12.81-4.9)%, p = 0.005 and 9.43 (19.53-7.50)% vs 14.86 (21.96-6.75)%, p = NS at baseline and 6 months later respectively, whereas there was no difference in serum IL4 levels. Peripheral CD4+CD40L+ T cells also decreased significantly following rituximab treatment compared to those from patients who received standard treatment alone: median (IQR): 17.78 (25.64-14.44)% vs 8.15 (22.85-3.08)%, p = 0.04 and 22.13 (58.77-8.20)% vs 72.11 (73.05-20.45)%, p = NS at baseline and 6 months later respectively. Furthermore, peripheral CD4+INFγ+ and CD4+IL17+ T cells revealed no differences following rituximab treatment. Our study demonstrates a link between rituximab treatment and CD4+IL4+ T cell decrease both in the skin and peripheral blood of patients with SSc.

The Emerging Epigenetic Role of CD8+T Cells in Autoimmune Diseases: A Systematic Review

Autoimmune diseases are usually complex and multifactorial, characterized by aberrant production of autoreactive immune cells and/or autoantibodies against healthy cells and tissues. However, the pathogenesis of autoimmune diseases has not been clearly elucidated. The activation, differentiation, and development of CD8+ T cells can be affected by numerous inflammatory cytokines, transcription factors, and chemokines. In recent years, epigenetic modifications have been shown to play an important role in the fate of CD8+ T cells. The discovery of these modifications that contribute to the activation or suppression of CD8+ cells has been concurrent with the increasing evidence that CD8+ T cells play a role in autoimmunity. These relationships have been studied in various autoimmune diseases, including multiple sclerosis (MS), systemic sclerosis (SSc), type 1 diabetes (T1D), Grave's disease (GD), systemic lupus erythematosus (SLE), aplastic anemia (AA), and vitiligo. In each of these diseases, genes that play a role in the proliferation or activation of CD8+ T cells have been found to be affected by epigenetic modifications. Various cytokines, transcription factors, and other regulatory molecules have been found to be differentially methylated in CD8+ T cells in autoimmune diseases. These genes are involved in T cell regulation, including interferons, interleukin (IL),tumor necrosis factor (TNF), as well as linker for activation of T cells (LAT), cytotoxic T-lymphocyte–associated antigen 4 (CTLA4), and adapter proteins. MiRNAs also play a role in the pathogenesis of these diseases and several known miRNAs that are involved in these diseases have also been shown to play a role in CD8+ regulation.

The benefits and prospects of interleukin-6 inhibitor on systemic sclerosis

Systemic sclerosis (SSc) is a connective tissue disease, the pathogenesis of which is thought to involve interleukin-6 (IL-6), an inflammatory cytokine. This is based on findings of its concentration in patient serum, the results of an IL-6 suppression experiment in an animal model, and the results of a pilot study using IL-6 receptor antibody. However, it appears that a number of factors are involved in the pathology of SSc depending on the state of disease progression. In addition, the degree of involvement of IL-6 differs depending on the difference of organs within particular severe symptoms. Based on the findings from measurements of patient serum, the influence of IL-6 on the pathogenesis of SSc is greater in patients at a relatively early phase of the disease and in patients with lung lesions. Interleukin-13 (IL-13) is one of pro-fibrotic factors, and it is afraid that SSc patients with higher IL-13 have already lost the influence of IL-6. Therefore, although a clinical trial using the anti-IL-6 receptor antibody tocilizumab is underway, it is important to recognize the state of SSc patients prior to selecting treatment.

Interleukin-13: A promising therapeutic target for autoimmune disease

Interleukin-13 (IL-13) was previously thought to be a redundant presence of IL-4, but in recent years its role in immunity, inflammation, fibrosis, and allergic diseases has become increasingly prominent. IL-13 can regulate several subtypes of T helper (Th) cells and affect their transformation, including Th1, Th2, T17, etc., thus it may play an important role in immune system. Previous studies have revealed that IL-13 is implicated in the pathogenesis of autoimmune diseases, such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), systemic sclerosis (SSc), ulcerative colitis (UC), type 1 diabetes (T1D), sjogren's syndrome (SS), etc. In this review, we will briefly discuss the biological features of IL-13 and summarize recent advances in the role of IL-13 in the development and pathogenesis of autoimmune diseases. This information may provide new perspectives and suggestions for the selection of therapeutic targets for autoimmune diseases.

The immunopathogenesis of fibrosis in systemic sclerosis

Systemic sclerosis (SSc) is an idiopathic systemic autoimmune disease. It is characterized by a triad of hallmarks: immune dysfunction, fibrosis and vasculopathy. Immune dysfunction in SSc is characterized by the activation and recruitment of immune cells and the production of autoantibodies and cytokines. How immune abnormalities link the fibrosis and vasculopathy in SSc is poorly understood. A plethora of immune cell types are implicated in the immunopathogenesis of SSc, including T cells, B cells, dendritic cells, mast cells and macrophages. How these different cell types interact to contribute to SSc is complicated, and can involve cell-to-cell interactions and communication via cytokines, including transforming growth factor (TGF)-β, interleukin (IL)-6 and IL-4. We will attempt to review significant and recent research demonstrating the importance of immune cell regulation in the immunopathogenesis of SSc with a particular focus on fibrosis.

Add-on tocilizumab versus conventional treatment for systemic sclerosis, and cytokine analysis to identify an endotype to tocilizumab therapy

OBJECTIVES

To evaluate the anti-interleukin (IL)-6 receptor antibody tocilizumab (TCZ) as a treatment of systemic sclerosis (SSc), a randomised parallel group study was conducted, and compared their results and baseline cytokine/chemokine profiles.

METHODS

Patients were assigned to a TCZ add-on group (TCZ group, n = 7) and a conventional therapy group (Conv group, n = 6). TCZ (8 mg/kg/month) for 6 months, and the modified Rodnan total skin score (mRSS) were used to compare the efficacy. The association of medical history, baseline pulmonary function tests, blood cell counts, serum C-reactive protein (CRP) and 26 cytokines/chemokines and decrease in mRSS were analysed.

RESULTS

The mean change in mRSS was larger in the TCZ group (6.3) than in the Conv group (3.4), but the difference was not statistically significant because of high variance in the TCZ group. Patients with shorter disease histories and higher CRP had larger decreases in mRSS, and the decrease in mRSS was negatively correlated with IL-13 and C-C motif chemokine ligand (CCL)5.

CONCLUSION

Although significant between-group differences were not observed, some patients had a decrease in mRSS. Short disease duration, high CRP, low IL-13 and low CCL5 may represent an SSc endotype responsive to TCZ therapy.

Increased Expression and Modulated Regulatory Activity of Coinhibitory Receptors PD-1, TIGIT, and TIM-3 in Lymphocytes From Patients With Systemic Sclerosis

OBJECTIVE

Immune dysfunction is an important component of the disease process underlying systemic sclerosis (SSc), but the mechanisms contributing to altered immune cell function in SSc remain poorly defined. This study was undertaken to measure the expression and function of the coinhibitory receptors (co-IRs) programmed cell death 1 (PD-1), T cell immunoglobulin and ITIM domain (TIGIT), T cell immunoglobulin and mucin domain 3 (TIM-3), and lymphocyte activation gene 3 (LAG-3) in lymphocyte subsets from the peripheral blood of patients with SSc.

METHODS

Co-IR expression levels on subsets of immune cells were analyzed using a 16-color flow cytometry panel. The functional role of co-IRs was determined by measuring cytokine production after in vitro stimulation of SSc and healthy control peripheral blood mononuclear cells (PBMCs) in the presence of co-IR-blocking antibodies. Supernatants from cultures of stimulated PBMCs were added to SSc fibroblasts, and their impact on fibroblast gene expression was measured. Mathematical modeling was used to reveal differences between co-IR functions in SSc patients and healthy controls.

RESULTS

Levels of the co-IRs PD-1 and TIGIT were increased, and each was coexpressed, in distinct T cell subsets from SSc patients compared to healthy controls. Levels of TIM-3 were increased in SSc natural killer cells. PD-1, TIGIT, and TIM-3 antibody blockade revealed patient-specific roles of each of these co-IRs in modulating activation-induced T cell cytokine production. In contrast to healthy subjects, blockade of TIGIT and TIM-3, but not PD-1, failed to reverse inhibited cytokine production in SSc patients, indicating that enhanced T cell exhaustion is present in SSc. Finally, cytokines secreted in anti-TIM-3-treated PBMC cultures distinctly changed the gene expression profile in SSc fibroblasts.

CONCLUSION

The altered expression and regulatory capacity of co-IRs in SSc lymphocytes may contribute to disease pathophysiology by modulating the cytokine-mediated cross-talk of immune cells and fibroblasts at sites of inflammation and/or fibrosis.

Th1- and Th17-polarized immune infiltrates in eosinophilic fasciitis-A potential marker for histopathologic distinction from morphea

BACKGROUND

Morphea (localized scleroderma) and eosinophilic fasciitis (EF) are rare fibrosing disorders which may present a diagnostic challenge. While histopathologic features are often distinct, in some cases there may be overlap. T-cells contribute to etiopathogenesis of both autoimmune conditions. We sought to determine whether T-cell immune polarization enables histopathologic distinction.

MATERIALS & METHODS

We retrospectively examined clinicopathologically confirmed cases of morphea (n = 12) and EF (n = 8) using immunohistochemistry for CD3, CD8, and dual staining for CD4 with T-bet, GATA-3, STAT-3 or BNC-2 (transcription factors reported to be specific and mutually exclusive for Th1, Th2, Th17 and Th22 cells, respectively) to characterize the T-cell infiltrate.

RESULTS

No significant difference in CD3+ cells was identified (P = .195), however, the CD4/CD8+ T-cell ratio was significantly greater in morphea compared to EF (1.2 and 0.6, respectively; P = .034). Th1/Th2 was significantly lower in morphea compared to EF (1.7 and 2.7, respectively; P = .027). The percent of Th17+ cells was significantly higher in EF (P = 0.041). No significant difference in percent of Th22+ cells was identified.

CONCLUSION

Morphea and EF may be histopathologically distinguished based on helper T-cell subtype polarization. These findings offer novel insight into our understanding of disease pathogenesis and support a role for Th1/Th2 immune regulation and Th17 inhibition in anti-fibrotic therapeutic strategy.

14-3-3z sequesters cytosolic T-bet, upregulating IL-13 levels in TC2 and CD8+ lymphocytes from patients with scleroderma

BACKGROUND

IL-13-producing CD8⁺ T cells have been implicated in the pathogenesis of type 2-driven inflammatory human conditions. We have shown that CD8⁺IL-13⁺ cells play a critical role in cutaneous fibrosis, the most characteristic feature of systemic sclerosis (SSc; scleroderma). However, the molecular mechanisms underlying production of IL-13 and other type 2 cytokines by CD8⁺ T cells remain unclear.

OBJECTIVE

We sought to establish the molecular basis of IL-13 overproduction by CD8⁺ T cells from patients with SSc, focusing on T-bet modulation of GATA-3 activity, which we showed to underlie IL-13 overproduction in CD8⁺IL-13⁺ cells from patients with SSc.

METHODS

Biochemical and biophysical methods were used to determine the expression and association of T-bet, GATA-3, and regulatory factors in CD8⁺ T cells isolated from the blood and lesional skin of patients with SSc with severe skin thickening. Chromatin immunoprecipitation analysis determined GATA-3 binding to the IL-13 promoter. ImageStream analysis and confocal microscopy visualized the subcellular localization of T-bet and GATA-3. Transcript levels were decreased by small interfering RNAs.

RESULTS

Interaction of T-bet with the adaptor protein 14-3-3z in the cytosol of CD8⁺ T cells from patients with SSc reduces T-bet translocation into the nucleus and its ability to associate with GATA-3, allowing more GATA-3 to bind to the IL-13 promoter and inducing IL-13 upregulation. Strikingly, we show that this mechanism is also found during type 2 polarization of CD8⁺ T cells (T_C2) from healthy donors.

CONCLUSIONS

We identified a novel molecular mechanism underlying type 2 cytokine production by CD8⁺ T cells, revealing a more complete picture of the complex pathway leading to SSc disease pathogenesis.

Toxic Memories in Systemic Sclerosis

Systemic sclerosis is an autoimmune disease characterized by T-cell infiltration in the skin that leads to fibrosis, which can be life-limiting. Although T cells are important, it is not known which types mediate the fibrosis. The work presented by Li et al shows that memory CD8⁺ cytotoxic T cells mediate fibrosis via the secretion of IL-13. IL-13 is profibrotic, and it is released in a higher amount in patients with systemic sclerosis. This suggests that targeting IL-13 may be therapeutically beneficial.

Current perspectives on the role of CD8+ T cells in systemic sclerosis

Despite long-standing recognition of the importance of T cells in systemic sclerosis (SSc; scleroderma), the role of CD8⁺ T cells in disease pathogenesis has not been well studied. Our work has shown that over-production of the pro-fibrotic cytokine IL-13 by peripheral blood effector/memory CD8⁺ T cells is critical for predisposing patients to more severe forms of cutaneous fibrosis. Moreover, IL-13-producing CD8⁺ T cells induce a pro-fibrotic phenotype in normal and SSc dermal fibroblasts, and exhibit a strong cytotoxic activity ex vivo. We also found that CD8⁺ T cells are predominantly abundant in the skin lesions of patients in the early stages of diffuse cutaneous (dc)SSc compare to late-stage disease patients. Isolation of CD8⁺ T cells from the lesional skin of early active dcSSc patients, established that they are skin-resident, express cytolytic molecules and co-express extremely high levels of IL-13 and IFNγ. Other recent studies corroborate these findings and together strongly suggest that CD8⁺ T cells contribute to SSc pathogenesis through the production of high levels of cytokines with pro-inflammatory and pro-fibrotic function as well as by exhibiting a cytotoxic activity.

Pathogenesis of systemic sclerosis: recent insights of molecular and cellular mechanisms and therapeutic opportunities

Systemic sclerosis (SSc) is a complex disease characterized by early microvascular abnormalities, immune dysregulation and chronic inflammation, and subsequent fibrosis of the skin and internal organs. Excessive fibrosis, distinguishing hallmark of SSc, is the end result of a complex series of interlinked vascular injury and immune activation, and represents a maladaptive repair process. Activated vascular, epithelial, and immune cells generate pro-fibrotic cytokines, chemokines, growth factors, lipid mediators, autoantibodies, and reactive oxygen species. These paracrine and autocrine cues in turn induce activation, differentiation, and survival of mesenchymal cells, ensuing tissue fibrosis through increased collagen synthesis, matrix deposition, tissue rigidity and remodeling, and vascular rarefaction. This review features recent insights of the pathogenic process of SSc, highlighting three major characteristics of SSc, microvasculopathy, excessive fibrosis, and immune dysregulation, and sheds new light on the understanding of molecular and cellular mechanisms contributing to the pathogenesis of SSc and providing novel avenues for targeted therapies.

Interleukin-13 and age-related macular degeneration

AIM

o identify the effects of interleukin (IL)-13 on retinal pigment epithelial (RPE) cells and the IL-13 level in aqueous humor of age-related macular degeneration (AMD) patients.

METHODS

IL-13 levels in aqueous humor specimens from AMD patients were detected with enzyme-linked immunosorbent assay (ELISA). ARPE-19 cells were treated with 10 ng/mL IL-13 for 12, 24, and 48h. The cell proliferaton was evaluated by the MTS method. The mRNA and protein levels of α-SMA and ZO-1 were evaluated with quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot respectively. The expression of tumor necrosis factor-α (TNF-α), transforming growth factor-β (TGF-β) and vascular endothelial growth factor (VEGF) were assessed by ELISA.

RESULTS

IL-13 levels in the aqueous humor of patients with AMD were significantly higher than those in the control (167.33±17.64 vs 27.12±5.65 pg/mL; P<0.01). In vitro, IL-13 of high concentrations (10, 15, and 20 ng/mL) inhibited ARPE-19 cell proliferation. α-SMA mRNA in ARPE-19 cell were increased (1.017±0.112 vs 1.476±0.168; P<0.001) and ZO-1 decreased (1.051±0.136 vs 0.702±0.069; P<0.001) after treated with 10 ng/mL IL-13 for 48h. The protein expression of α-SMA and ZO-1 also showed the same tendency (α-SMA: P=0.038; ZO-1: P=0.008). IL-13 significantly reduced the level of TNF-α (44.70±1.67 vs 31.79±3.53 pg/mL; P=0.005) at 48h, but the level of TGF-β2 was significantly increased from 34.44±2.92 to 57.61±6.31 pg/mL at 24h (P=0.004) and from 61.26±1.11 to 86.91±3.59 pg/mL at 48h (P<0.001). While expressions of VEGF didn't change after IL-13 treatment.

CONCLUSION

IL-13 in vitro inhibit ARPE-19 cell proliferation and expression in the aqueous may be associated with AMD.

A novel multi-network approach reveals tissue-specific cellular modulators of fibrosis in systemic sclerosis

Background

Systemic sclerosis (SSc) is a multi-organ autoimmune disease characterized by skin fibrosis. Internal organ involvement is heterogeneous. It is unknown whether disease mechanisms are common across all involved affected tissues or if each manifestation has a distinct underlying pathology.

Methods

We used consensus clustering to compare gene expression profiles of biopsies from four SSc-affected tissues (skin, lung, esophagus, and peripheral blood) from patients with SSc, and the related conditions pulmonary fibrosis (PF) and pulmonary arterial hypertension, and derived a consensus disease-associate signature across all tissues. We used this signature to query tissue-specific functional genomic networks. We performed novel network analyses to contrast the skin and lung microenvironments and to assess the functional role of the inflammatory and fibrotic genes in each organ. Lastly, we tested the expression of macrophage activation state-associated gene sets for enrichment in skin and lung using a Wilcoxon rank sum test.

Results

We identified a common pathogenic gene expression signature—an immune–fibrotic axis—indicative of pro-fibrotic macrophages (MØs) in multiple tissues (skin, lung, esophagus, and peripheral blood mononuclear cells) affected by SSc. While the co-expression of these genes is common to all tissues, the functional consequences of this upregulation differ by organ. We used this disease-associated signature to query tissue-specific functional genomic networks to identify common and tissue-specific pathologies of SSc and related conditions. In contrast to skin, in the lung-specific functional network we identify a distinct lung-resident MØ signature associated with lipid stimulation and alternative activation. In keeping with our network results, we find distinct MØ alternative activation transcriptional programs in SSc-associated PF lung and in the skin of patients with an “inflammatory” SSc gene expression signature.

Conclusions

Our results suggest that the innate immune system is central to SSc disease processes but that subtle distinctions exist between tissues. Our approach provides a framework for examining molecular signatures of disease in fibrosis and autoimmune diseases and for leveraging publicly available data to understand common and tissue-specific disease processes in complex human diseases.

Electronic supplementary material

The online version of this article (doi:10.1186/s13073-017-0417-1) contains supplementary material, which is available to authorized users.

Skin-Resident Effector Memory CD8+CD28- T Cells Exhibit a Profibrotic Phenotype in Patients with Systemic Sclerosis

Loss of CD28 expression by CD8⁺ T cells occurs with age and during chronic inflammatory conditions. CD8⁺CD28^- T cells are a heterogeneous cell subpopulation whose function ranges from immunosuppressive to effector. Here we analyzed the role of CD8⁺CD28^- T cells in the pathogenesis of systemic sclerosis (SSc), a connective tissue disorder characterized by autoimmunity, vasculopathy, and extensive cutaneous and visceral fibrosis. We show that the frequency of CD8⁺CD28^- T cells is increased in the blood and affected skin of SSc patients, independent of patient age, and correlates with the extent of skin fibrosis. We found that most skin-tropic CD8⁺CD28^- T cells are resident in the skin lesions of patients in the early stage of the disease, exhibit an effector memory phenotype, and present a strong cytolytic activity ex vivo. Skin-resident and circulating SSc CD8⁺CD28^- T cells produce high levels of the profibrotic cytokine IL-13, which induces collagen production by normal and SSc dermal fibroblasts. Thus, our findings indicate that CD8⁺CD28^- T cells represent a pathogenic T-cell subset in SSc and likely play a critical role in the early stage of SSc skin disease.

T and NK Cell Phenotypic Abnormalities in Systemic Sclerosis: a Cohort Study and a Comprehensive Literature Review

Scleroderma (SSc) is a rare and heterogeneous immune-mediated disease involving the connective tissue and microvasculature whose pathogenesis remains unclear. Data concerning T and natural killer (NK) cell abnormalities and cytokine levels in the peripheral blood (PB) from patients with SSc are scarce, and the results are contradictory. The present study aimed to analyze the changes of T lymphocytes, NK cells, and T helper (Th)-related cytokines in the PB of patients with SSc in comparison to healthy individuals and its relation to disease subtype and stage, organ involvement, and nailfold capillaroscopic changes. A non-random convenience sample of 57 scleroderma patients was utilized. Fifty-five out of the 57 patients studied were women (97 %); 10 patients presented pre-scleroderma (pre-SSc) and 47 SSc: 34 limited cutaneous SSc (lcSSc) and 13 diffuse cutaneous SSc (dcSSc). Patients with SSc were classified in early (n = 7), intermediate (n = 10), and late (n = 30) disease. Blood samples were analyzed by flow cytometry for total T cells, CD4+ and CD8+ T cell subsets, total NK cells, and CD56+low and CD56+high NK cell subsets. T cells were further analyzed for the expression of the CD56 adhesion molecule and activation-related markers (HLA-DR, CD45RO). In addition, the serum levels of Th1-, Th2-, and Th17-related cytokines were measured by flow cytometry. Twenty-five healthy individuals recruited from the blood bank were used as controls. Patients had lower numbers of total lymphocytes and T cells comparing to healthy controls. Both CD4+ and CD8+ T cells were decreased, but differences were statistically significant only for CD8+ and CD8+ CD45RO+ T cells. These alterations were seen in patients with SSc but not in patients with pre-SSc, and, in general, they were more pronounced in patients with dcSSc than in patients with lcSSc, in patients with vascular involvement than in those without, as well as in patients having active and late nailfold capillaroscopic patterns. CD56+ T cells were also decreased in SSc patients, especially in those with active/late capillaroscopic patterns or with severe lung disease. Diminished numbers of circulating NK cells were also observed in patients with lcSSc and in those with early disease. No statistically significant changes were found in serum cytokine levels, as compared with controls. Patients with SSc had major alterations in circulating CD8+ and CD56+ T cells, as well as in NK cells, suggesting that these cells may play a relevant role in SSc pathogenesis, probably operating at different phases and/or at different organs. In addition, the serum levels of Th1, Th2, and Th17 cytokines did not provide useful information for evaluating T cell polarization in SSc.

Contribution of CD8+ T cells to inflammatory cytokine production in systemic sclerosis (SSc)

Only limited attention has been paid to the role of CD8 + T cells in the etiopathogenesis and progression of systemic sclerosis (SSc). CD8 + T cells may have autoantigen-specific and pro-inflammatory but also immunomodulatory properties. To investigate the differentiation of CD8 + T cells, staining of cell surface factors and of chemokine receptors were performed. In addition, the cytokine-producing ability of circulating CD8 + T cells and their sensitivity to suppression by regulatory T cells (Tregs) were compared between patients with diffuse (dcSSc) or limited cutaneous SSc (lcSSc) and healthy individuals. We identified CD8 + T cells as producers of pro-inflammatory type-2 cytokines with a significant contribution of memory CD8 + T cells. Memory CD8 + T cells of SSc patients stayed unaltered after suppression with autologous Tregs. Expression of chemokine receptors was significantly correlated with intracellular cytokine production in CD8 + T cells with a clear dichotomy of type 1 and type 2 cytokines. High levels of intracellular cytokines, such as interleukin-(IL)-4, IL-13 and tumor-necrosis-factor-alpha (TNFalpha) were positively associated with the presence of Scl-70 or anti-centromere antibodies and negatively with the administration of glucocorticoids. Administration of glucocorticoids was positively associated with higher IFNgamma production. Lack of anti-centromere antibodies and therapy with methotrexate were positively associated with higher intracellular IL-10 production. CD8 + T cells may significantly contribute to inflammation in SSc. Our findings suggest to not only focus on T helper cells in the development of therapeutic strategies but also to consider the role of CD8 + T cells in the etiopathogenesis and perpetuation of SSc.

IL-13 mediates collagen deposition via STAT6 and microRNA-135b: a role for epigenetics

Systemic sclerosis is an autoimmune connective tissue disease in which T cells play a prominent role. We and others have previously demonstrated a role for T cell-derived IL-13 in mediating the induction of collagen in dermal fibroblasts and that blockade with IL-13 antibodies attenuates this increase. In this study we want to probe the signalling that underpins IL-13 mediated matrix deposition. Isolated dermal fibroblasts were incubated with recombinant IL-13 and gene expression by qRT-PCR was performed for collagen1A1 and TGF-β1. Small interfering RNA (siRNA) was used to knock down STAT6 and a small molecule inhibitor was also used to block this pathway. MiR-135b was transfected into fibroblasts plus and minus IL-13 to see if this miR plays a role. miR-135b was measured in systemic sclerosis fibroblasts isolated from patients and also in serum. Results showed that IL-13 increased collagen expression and that this is independent from TGF-β1. This is dependent on STAT6 as targeting this blocked induction. MiR-135b reduces collagen induction in fibroblasts and scleroderma fibroblasts have lower constitutive levels of the miR. We further demonstrate that miR135b is repressed by methylation and may include MeCP2. In conclusion we show that STAT6 and miR-135b regulate IL-13-mediated collagen production by fibroblasts.

Current perspectives on the immunopathogenesis of systemic sclerosis

Systemic sclerosis (SSc or scleroderma) is a progressive and highly debilitating autoimmune disorder characterized by inflammation, vasculopathy, and extensive fibrosis. SSc is highly heterogeneous in its clinical presentation, extent and severity of skin and internal organ involvement, and clinical course and has the highest fatality rate among connective tissue diseases. While clinical outcomes have improved in recent years, no current therapy is able to reverse or slow the natural progression of SSc, a reflection of its complex pathogenesis. Although activation of the immune system has long been recognized, the mechanisms responsible for the initiation of autoimmunity and the role of immune effector pathways in the pathogenesis of SSc remain incompletely understood. This review summarizes recent progress in disease pathogenesis with particular focus on the immunopathogenetic mechanisms of SSc.

IL-21 Promotes Pulmonary Fibrosis through the Induction of Profibrotic CD8+ T Cells

Type 2 effector production of IL-13, a demonstrated requirement in models of fibrosis, is routinely ascribed to CD4(+) Th2 cells. We now demonstrate a major role for CD8(+) T cells in a murine model of sterile lung injury. These pulmonary CD8(+) T cells differentiate into IL-13-producing Tc2 cells and play a major role in a bleomycin-induced model of fibrosis. Differentiation of these Tc2 cells in the lung requires IL-21, and bleomycin treated IL-21- and IL-21R-deficient mice develop inflammation but not fibrosis. Moreover, IL-21R-expressing CD8(+) cells are sufficient to reconstitute the fibrotic response in IL-21R-deficient mice. We further show that the combination of IL-4 and IL-21 skews naive CD8(+) T cells to produce IL-21, which, in turn, acts in an autocrine manner to support robust IL-13 production. Our data reveal a novel pathway involved in the onset and regulation of pulmonary fibrosis and identify Tc2 cells as key mediators of fibrogenesis.

Transforming growth factor-β increases interleukin-13 synthesis via GATA-3 transcription factor in T-lymphocytes from patients with systemic sclerosis

Introduction

Transforming growth factor (TGF)-β and interleukin (IL)-13 play a crucial role in the pathogenesis of systemic sclerosis (SSc), partly through activation of collagen production that leads to fibrosis. The aim of the present study was to determine whether TFG-β alters IL-13 production in T lymphocytes from patients with SSc from that seen in those of healthy donors.

Methods

IL-13 mRNA and protein synthesis under TFG-β exposure was measured in circulating T lymphocytes from healthy donors and patients with SSc and also in the Jurkat Th2 T-cell line, using quantitative real-time PCR and fluorescence-activated cell sorting analysis, respectively. The involvement of Smad and GATA-3 transcription factors was assessed by using specific inhibitors and small interfering RNA, and the binding capacity of GATA-3 to the IL-13 gene promoter was evaluated by chromatin immunoprecipitation assay.

Results

TGF-β induced a significant decrease in IL-13 mRNA and protein levels in lymphocytes from healthy donors (mean [±SD] inhibition of 30 % ± 10 % and 20 % ± 7 %, respectively; p < 0.05). In contrast, TGF-β promoted a significant increase in IL-13 mRNA levels and IL-13 synthesis by CD4⁺ and CD8⁺ T-cell subtypes from patients with SSc, with respective increases of 2.4 ± 0.3-fold, 1.6 ± 0.05-fold and 2.7 ± 0.02-fold. The involvement of the Smad signaling pathway and upregulation of GATA-3 binding capacity on the IL-13 promoter in lymphocytes from patients with SSc contributed to the effect of TGF-β on IL-13 production.

Conclusions

These results demonstrate that TGF-β upregulates IL-13 synthesis through GATA-3 expression in the T lymphocytes of patients with SSc, confirming that the GATA-3 transcription factor can be regarded as a novel therapeutic target in patients with SSc.