Fibrosis biomarkers in isolated Raynaud's phenomenon: too little, too soon?

Circulating Retinol-Binding Protein 4 as a Possible Biomarker of Treatment Response for Ankylosing Spondylitis: An Array-Based Comparative Study

Objective

To explore proteins associated with ankylosing spondylitis (AS) and to investigate potential proteins that may predict treatment response of adalimumab (ADA) in AS patients.

Methods

In the discovery cohort, 39 AS patients and 20 healthy controls (HCs) were included, and 16 AS patients received ADA treatment for 24 weeks after included. In the validation cohort, 43 AS patients and 39 HCs were enrolled, and all 43 patients received ADA treatment after enrollment. Blood samples and clinical information were collected from two cohorts at baseline from all participants and week 24 from patients received ADA treatment. A human antibody array containing 1,000 proteins was used in the discovery phase, and Elisa kits were used for protein validation.

Results

Compared with HCs, we identified 53 differentially expressed proteins (DEPs) in AS patients. Bioinformatics analysis revealed they were mostly enriched in coagulation function-related pathways, acute response signaling, and LXR/RXR activation. Bone metabolism pathways were also associated. Comparison between samples of pre- and post-ADA treatment revealed 42 DEPs. They were mostly associated with bone metabolism and inflammation response pathways. Significant enrichment was also found in LXR/RXR activation but not the coagulation function-related pathways. Upstream regulator analysis suggested that most regulators also significantly functioned under usage of ADA. Precisely, seven proteins were abnormally expressed in AS and restored after ADA treatment. Retinol-binding protein 4 (RBP4), one of the seven proteins, was validated that its baseline levels were inversely correlated with improvements in Ankylosing Spondylitis Disease Activity Score-C-reactive protein (ASDAS-CRP). Likewise, percentage changes in RBP4 levels were inversely correlated with changes in ASDAS-CRP score.

Conclusion

A dysregulated serum protein profile existed in AS. ADA exerted a considerable but not entire alteration toward the dysregulation. RBP4 could be a biomarker for predicting and monitoring ADA treatment response.

P2X7 receptor restrains pathogenic Tfh cell generation in systemic lupus erythematosus

T follicular helper cells promote the generation of protective antibodies, but can also foster pathogenic antibodies. The ATP-gated P2X7 receptor selectively limits the expansion of Tfh cells that amplify self-reactive antibodies in systemic lupus erythematosus.

Altered control of T follicular helper (Tfh) cells can lead to generation of autoantibodies and autoimmune manifestations. Signaling pathways that selectively limit pathogenic responses without affecting the protective function of Tfh cells are unknown. Here we show that the ATP-gated ionotropic P2X7 receptor restricts the expansion of aberrant Tfh cells and the generation of self-reactive antibodies in experimental murine lupus, but its activity is dispensable for the expansion of antigen-specific Tfh cells during vaccination. P2X7 stimulation promotes caspase-mediated pyroptosis of Tfh cells and controls the development of pathogenic ICOS⁺ IFN-γ–secreting cells. Circulating Tfh cells from patients with systemic lupus erythematosus (SLE) but not primary antiphospholipid syndrome (PAPS), a nonlupus systemic autoimmune disease, were hyporesponsive to P2X7 stimulation and resistant to P2X7-mediated inhibition of cytokine-driven expansion. These data point to the P2X7 receptor as a checkpoint regulator of Tfh cells; thus, restoring P2X7 activity in SLE patients could selectively limit the progressive amplification of pathogenic autoantibodies, which deteriorate patients’ conditions.

Current perspective on rituximab in rheumatic diseases

The steadily increasing knowledge regarding pathogenetic mechanisms in autoimmune rheumatic diseases has paved the way to different therapeutic approaches. In particular, the market entry of biologics has dramatically modified the natural history of rheumatic chronic inflammatory diseases with a meaningful impact on patients’ quality of life. Among the wide spectrum of available biological treatments, rituximab (RTX), first used in the treatment of non-Hodgkin’s lymphoma, was later approved for rheumatoid arthritis and anti-neutrophil cytoplasmic antibodies-associated vasculitis. Nowadays, in rheumatology, RTX is also used with off-label indications in patients with systemic sclerosis, Sjögren’s syndrome and systemic lupus erythematosus. RTX is a monoclonal antibody directed to CD20 molecules expressed on the surfaces of pre-B and mature B lymphocytes. It acts by causing apoptosis of these cells with antibody- and complement-dependent cytotoxicity. As inflammatory responses to cell-associated immune complexes are key elements in the pathogenesis of several autoimmune rheumatic diseases, such an approach might be effective in these patients. In fact, RTX, by promoting the rapid and long-term depletion of circulating and lymphoid tissue-associated B cells, leads to a lower recruitment of these effector cells at sites of immune complex deposition, thus reducing inflammation and tissue damage. RTX is of the most interest to rheumatologists as it represents an important additional therapeutic approach. Thus, the advent in clinical practice of approved RTX biosimilars, such as CT-P10, may be of help in improving treatment access as well as in reducing costs.

Update on juvenile systemic sclerosis

Juvenile systemic sclerosis is an orphan disease of the macro- and microvasculature with an unknown etiology. Although pediatric and adult classification systems have been developed, neither has been validated yet. Recent publications have shown a shift in the subset pattern in juvenile-onset adult patients, with a better outcome in these patients as compared with young adult patients. As a first step in assessing activity, damage, and severity, a pediatric severity score--a modification of the adult Medsger scale--was proposed but has not been validated. An activity score also has been developed but has not yet been published. Currently, treatment approaches are based only on adult data, and problems exist in extrapolating these data to a pediatric population.