Immunomodulatory activity of 4-(Benzyloxy)phenol facilitates intracellular mycobacterial clearance through p53 mediated IL-35 signaling dependent JAK1/STAT3 pathway in human macrophages

Abstract

Mycobacterium tuberculosis (M. tuberculosis), the causative agent of tuberculosis (TB), modulates host immune responses by regulating various cytokines. Precise regulation of these cytokines renders the host pathogen-free, whereas their dysregulation increases the susceptibility to infection. Hence, induction of host protective cytokines using immunomodulators to promote M. tuberculosis clearance has a rewarding impact in the context of TB treatment. This study explored the immunomodulatory activity of 4-(Benzyloxy)phenol (4-BOP) in mycobacteria infected differentiated THP-1 cells through IL-35 (an anti-inflammatory cytokine) production. Initially, we observed an increased mRNA and protein level expression of IL-35 and its cognate receptor upon 4-BOP treatment in mycobacteria-infected dTHP-1 cells. IL-35 receptor activation further led to phosphorylation of JAK1/STAT3, culminating in increased phagosome-lysosome fusion through elevation of intracellular Ca²⁺ level. Blocking IL-35 receptors using siRNA-mediated approach against IL-12Rβ2 and gp130 or the JAK1/STAT3 associated signaling with specific inhibitors like Baricitinib and Stattic promoted the intracellular mycobacterial survival by compromising Ca²⁺-phagosome-lysosome fusion pathway. Further, we identified a direct regulatory role of p53 (known to be activated by 4-BOP) on IL-35 production, and inhibition of p53 using PFT-α surprisingly abrogated the IL-35 mediated signaling axis. Collectively, our results demonstrated a host defensive role of 4-BOP-induced Il-35 signaling in mycobacteria-infected dTHP-1 cells through the JAK1/STAT3 mediated Ca²⁺-phagosome-lysosome fusion pathway. These results suggest that 4-BOP may serve as a potent HDT candidate for regulating inflammation and enhancing host defense in TB infection.

Keywords: 4-BOP; Ca2+; IL-35; JAK1/STAT3; Mycobacteria; Phagosome-lysosome fusion.