Vasculitis and the NLRP3 inflammasome

Ultraviolet-treated riboflavin alleviates atopic dermatitis by inhibiting NLRP3 inflammasome activation and M1 macrophage polarization via histone lactylation

Atopic dermatitis (AD) is a chronic inflammatory skin disorder requiring improved therapeutic strategies. This study investigates the potential of ultraviolet (UV)-treated riboflavin in AD treatment. Using a MC903-induced mouse model, we demonstrate that topical UV-treated riboflavin significantly attenuates AD progression. Mechanistically, UV-treated riboflavin suppresses macrophage nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome activation by reducing histone H3 lysine 9 lactylation (H3K9la) on NLRP3 and apoptosis-associated speck-like protein containing a CARD (ASC) promoter, decreasing interleukin-1β (IL-1β) secretion and subsequent keratinocyte-derived thymic stromal lymphopoietin (TSLP) production. It also directly inhibits inflammatory cytokine expression in keratinocytes. NLRP3 activation in vivo partially reverses these effects, confirming the central role of NLRP3 inflammasome inhibition. Our findings reveal a novel epigenetic mechanism of UV-treated riboflavin in modulating immune responses in AD, highlighting its potential as a therapeutic strategy for inflammatory skin disorders.

IL-38 in Behçet's disease: Gene expression in bronchoalveolar lavage from patients having pulmonary involvement

The etiological complexity of Behçet disease (BD), an immune-mediated rare form of vasculitis characterized by multi-organ involvement, is still elusive due to an incomplete understanding of the synergy between genetic susceptibility, environmental triggers, and an abnormal immune response. The diagnosis of BD relies on clinical symptoms. Lung inflammatory disorders are severe conditions of patients with BD, here we focus on the expression of biomarkers in BD patients with pulmonary manifestations. Aiming to identify additional discriminating biomarker patterns, we measured and compared protein and gene expression of IL-38 and a broad panel of selected genes in bronchoalveolar cells of patients suffering from BD with and without pulmonary involvement compared to controls. ELISA and RT-PCR analysis were applied. The first principal analysis highlighted decreased IL-38 level in BD patients compared to Rheumatoid Arthritis (RA) patients and controls: BD patients expressed lower IL-38 levels, particularly in cases with pulmonary involvement. The area under the curve (AUC) of the receiver-operating characteristic curve showed that IL-38 may be an eventual biomarker for BD. Co-cultured recombinant IL-38 and stimulated memory PBMCs of active BD, were able to suppress IL-17 and NLRP3 inflammasome and ameliorate the secretion of IL-10 and TGFβ. Transcription factors of the IL-1 family (IL-1β, IL-18, IL-32, IL-33 and IL-37) along with IFN-γ, IL-17, RORγt, Foxp3, TGFβ, IL-10 and NLRP3 inflammasome were the parameters that are the main contributor to the segregation between BD with and without lung involvement. Our results indicate that IL-38 might be involved in the pathogenesis of BD and the combined gene expression in BAL suggests distinct mechanisms governing the inflammatory disorders in the lung.