Traitor or warrior-Treg cells sneaking into the lesions of psoriatic arthritis

Carnosol Alleviates Collagen-Induced Arthritis by Inhibiting Th17-Mediated Immunity and Favoring Suppressive Activity of Regulatory T Cells

Current approaches are incurable for rheumatoid arthritis (RA). Regulatory T (Treg) cells and T helper cells (Th1 and Th17) are crucial in controlling the process of RA, which is characterized by inflammatory cell infiltration and bone destruction. Carnosol is an orthodiphenolic diterpene that has been extensively applied in traditional medicine for the treatment of multiple autoimmune and inflammatory diseases. Herein, we indicate that administration of carnosol dramatically alleviated the severity of collagen-induced arthritis (CIA) model with a decreased clinical score and inflammation reduction. Cellular mechanistically, carnosol inhibits the Th17 cell differentiation and maintains Treg cell suppressive function in vitro and in vivo. Meanwhile, it also restrains Treg cells from transdifferentiation into Th17 cells under inflammatory milieu. Furthermore, carnosol modulates the function of Th17 and Treg cells possibly via limiting IL-6R (CD126) expression. Collectively, our results suggest that carnosol can alleviate the severity of CIA via hiding Th17 cell differentiation and maintain the stability of Treg cells. Administration of carnosol can be applied as a potential therapy for patients with RA.

Regulatory T cells in psoriatic arthritis: an IL-17A-producing, Foxp3intCD161 + RORγt + ICOS + phenotype, that associates with the presence of ADAMTSL5 autoantibodies

In psoriatic arthritis (PsA), predisposing class I HLA alleles, the presence of synovial clonally proliferated CD8 + T cells and autoantibodies all point towards the loss of immune tolerance. However, the key mechanisms that lead to immune dysregulation are not fully understood. In other types of inflammatory arthritis, T regulatory cell (Treg) dysfunction and plasticity at sites of inflammation were suggested to negatively affect peripheral tolerance. We here addressed if Treg variances associate with psoriatic disease. We collected clinical data, sera and peripheral blood mononuclear cells from 13 healthy controls, 21 psoriasis and 21 PsA patients. In addition, we obtained synovial fluid mononuclear cells from 6 PsA patients. We studied characteristics of CD4 + CD25 + CD127^loFoxp3 + Tregs by flow cytometry and used ELISA to quantify antibodies against ADAMTSL5, a recently discovered autoantigen in psoriatic disease. In comparison with their circulating counterparts, Tregs from inflamed joints express increased levels of ICOS, CTLA-4 and TIGIT. Furthermore, synovial fluid-derived Tregs have a distinct phenotype, characterized by IL-17A production and upregulation of CD161 and RORγt. We identified a subset of Tregs with intermediate Foxp3 expression as the major cytokine producer. Furthermore, ICOS + Tregs associate with PsA disease activity as measured by PASDAS. Lastly, we observed that presence of the Foxp3^int Tregs associates with an increased abundance of anti-ADAMTSL5 autoantibodies. Tregs derived from the inflammatory environment of inflamed PsA joints exhibit a distinct phenotype, which associates with loss of peripheral immune tolerance in psoriatic disease.

The Regulatory-T-Cell Memory Phenotype: What We Know

In immunology, the discovery of regulatory T (Treg) cells was a major breakthrough. Treg cells play a key role in pregnancy maintenance, in the prevention of autoimmune responses, and in the control of all immune responses, including responses to self cells, cancer, infection, and a transplant. It is currently unclear whether Treg cells are capable of long-term memory of an encounter with an antigen. Although the term “immunological memory” usually means an enhanced ability to protect the body from reinfection, the memory of the suppressive activity of Treg cells helps to avoid the state of generalized immunosuppression that may result from the second activation of the immune system. In this review, we would like to discuss the concept of regulatory memory and in which tissues memory Treg cells can perform their functions.

Four emerging immune cellular blood phenotypes associated with disease duration and activity established in Psoriatic Arthritis

BACKGROUND

Psoriatic Arthritis (PsA) is an immune-mediated disease with heterogenous symptoms indicating differences in the underlying immunopathogenesis. The primary objective of the study explored the dynamic mechanisms and interplay between immune cell subtypes constituting the immune response driving PsA to evaluate possible differences in immune cellular phenotypes, and secondary examined associations between emerging immune cellular phenotypes and disease outcomes.

METHODS

Peripheral blood was collected from 70 PsA patients. Frequencies of nine immune cell subtypes were determined by multicolor flow cytometry. The interplay between immune cells were examined with principal component analysis (PCA) to establish immune cellular phenotypes. Disease characteristics, Disease Activity in Psoriatic Arthritis (DAPSA) and Psoriasis Area Severity Index (PASI) were retrieved to examine associations to individual cellular phenotypes.

RESULTS

Four components were identified using PCA resembling four immune cellular phenotypes. Component 1, explaining 25.6% of the variance with contribution from T-helper 17 cells (Th17), memory T regulatory cells (mTregs), dendritic cells and monocytes, was associated with longer disease duration and higher DAPSA. Component 2, driven by Th1, naïve Tregs and mTregs, was associated with shorter disease duration. Component 3 was driven by both Th1, Th17 and CD8+ T cells, while component 4 was characterized by a reverse correlation between CD8+ T cells and natural killer cells.

CONCLUSION

Four immune cellular phenotypes of PsA were suggested at baseline demonstrating complex immune cellular mechanisms in PsA implying the possibility of improving PsA patient stratification based on both clinical and immune cellular phenotypes.

New Frontiers in Psoriatic Disease Research, Part I: Genetics, Environmental Triggers, Immunology, Pathophysiology, and Precision Medicine

Psoriasis is a chronic inflammatory condition characterized by systemic immune dysregulation. Over the past several years, advances in genetics, microbiology, immunology, and mouse models have revealed the complex interplay between the heritable and microenvironmental factors that drive the development of psoriatic inflammation. In the first of this two-part review series, the authors will discuss the newest insights into the pathogenesis of psoriatic disease and highlight how the evolution of these scientific fields has paved the way for a more personalized approach to psoriatic disease treatment.

Immune responses and therapeutic options in psoriasis

Psoriasis is a chronic inflammatory disease of the skin that affects about 2-3% of the population and greatly impairs the quality of life of affected individuals. Psoriatic skin is characterized by excessive proliferation and aberrant differentiation of keratinocytes, as well as redness caused by increased dilation of the dermal blood vessels and infiltration of immune cells. Although the pathogenesis of psoriasis has not yet been completely elucidated, it is generally believed to arise from a complex interplay between hyperproliferating keratinocytes and infiltrating, activated immune cells. So far, the exact triggers that elicit this disease are still enigmatic, yet, it is clear that genetic predisposition significantly contributes to the development of psoriasis. In this review, we summarize current knowledge of important cellular and molecular mechanisms driving the initiation and amplification stages of psoriasis development, with a particular focus on cytokines and emerging evidence illustrating keratinocyte-intrinsic defects as key drivers of inflammation. We also discuss mouse models that have contributed to a better understanding of psoriasis pathogenesis and the preclinical development of novel therapeutics, including monoclonal antibodies against specific cytokines or cytokine receptors that have revolutionized the treatment of psoriasis. Future perspectives that may have the potential to push basic research and open up new avenues for therapeutic intervention are provided.

Tregs in Autoimmune Uveitis

Uveitis is a chronic disease with relapsing and remitting ocular attack, which requires corticosteroids and systemic immunosuppression to prevent severe vision loss. Classically, uveitis is referred to an autoimmune disease, mediated by pro-inflammatory Th17 cells and immunosuppressive CD4+CD25+FoxP3+ T-regulatory cells (Tregs). More and more evidence indicates that Tregs are involved in development, resolution, and remission of uveitis. Clinically, many researchers have conducted quantitative and functional analyses of peripheral blood from patients with different subtypes of uveitis, in an attempt to find the changing rules of Tregs. Consistently, using the experimental autoimmune uveitis (EAU) model, researchers have explored the development and resolution mechanism of uveitis in many aspects. In addition, many drug and Tregs therapy investigations have yielded encouraging results. In this chapter, we introduced the current understanding of Tregs, summarized the clinical changes in the number and function of patients with uveitis and the immune mechanism of Tregs involved in EAU model, as well as discussed the progress and shortcomings of Tregs-related drug therapy and Tregs therapy. Although the exact mechanism of Tregs-mediated uveitis protection remains to be elucidated, the strategy of Tregs regulation may provide a specific and meaningful way for the prevention and treatment of uveitis.