ROCK2 signaling is required to induce a subset of T follicular helper cells through opposing effects on STATs in autoimmune settings

Abstract

Rho-associated kinase 2 (ROCK2) determines the balance between human T helper 17 (TH17) cells and regulatory T (Treg) cells. We investigated its role in the generation of T follicular helper (TFH) cellswhich provide help necessary to generate antibody-producing B cells in normal and autoimmune conditionsWe found that targeting ROCK2 in normal human T cells or peripheral blood mononuclear cells (PBMCs) from patients with active systemic lupus erythematosus (SLE) decreased the number and function of Tfh cells induced by activation ex vivo. Moreover, inhibition of ROCK2 activity concomitantly decreased the abundance of the transcriptional regulator Bcl6 and increased that of Blimp1 by xxx concurrent regulation of the binding of signal transducer and activator of transcription 3 (STAT3) and STAT5 to the promoters of the genes Bcl6 and PRDM1, respectively. In the MRL/lpr murine model of SLE, oral administration of the selective ROCK2 inhibitor KD025 resulted in a two-fold reduction in the numbers of Tfh cells and antibody-producing plasma cells in the spleen, as well as a decrease in the size of splenic germinal centers, sites of interaction between TFH cells and B cells. KD025-treated mice showed a substantial improvement in both histological and clinical scores compared to those of untreated mice, and had reduced amounts of Bcl6 and phosphorylated STAT3, as well as increased STAT5 phosphorylation. Together, these data suggest that ROCK2 signaling plays a critical role in controlling the development of Tfh cells induced by autoimmune conditions through reciprocal regulation of STAT3 and STAT5 activation.

Cutting Edge: Selective Oral ROCK2 Inhibitor Reduces Clinical Scores in Patients with Psoriasis Vulgaris and Normalizes Skin Pathology via Concurrent Regulation of IL-17 and IL-10

“…In agreement with previous findings in animal models and Th17-skewing in vitro culture of human T cells (15)(16)(17), this study further confirmed the potential of selective ROCK2 inhibition to downregulate autoimmune-driven pathology via shifting the balance between proinflammatory and anti-inflammatory immune cell responses. Although the clinical improvement achieved in the same time span by treatment with KD025 was not as robust as the response seen with other oral treatments, such as methotrexate, JAK inhibitors, and apremilast, or newer biologics neutralizing cytokines in the Th17 pathway, future randomized trials of KD025 carried out for a longer time period (to account for a different molecular mechanism of action) in a larger population of psoriatic patients are required to further validate the therapeutic potential and risk-benefit profile of targeted ROCK2 inhibition in psoriasis.…”

“…ROCK2 is induced during Th17-skewing conditions and regulates IL-17 secretion via a STAT3/IRF4/RORgtdependent mechanism in mice and humans (13,(15)(16)(17). Histological assessment revealed that baseline pSTAT3, IRF4, RORgt, and ROCK2 staining were greater, whereas ROCK1 expression was diminished in lesional skin in comparison with nonlesional skin (Fig.…”

“…Previous findings demonstrated that oral administration of a selective ROCK2 inhibitor (KD025) in healthy subjects decreases IL-17 and IL-21 secretion induced by ex vivo stimulation (15 immunosuppressive T cell subsets via concurrent regulation of STAT3/STAT5 phosphorylation (16)(17)(18). Thus, we have hypothesized that targeting of ROCK2 may restore disrupted immune homeostasis and could have a role in the treatment of Th17-mediated inflammatory disorders such as psoriasis.…”

Targeting the RhoA-ROCK pathway to reverse T-cell dysfunction in SLE

“…In line with prior observations demonstrating that the selective ROCK2 inhibitor, KD025, can downregulate the production of IL-17 and IL-21 by RA T cells, KD025 decreased the production of these cytokines by SLE T cells, although the production of IFNγ appears to be ROCK2 dependent in RA but not in SLE T cells 18. The ability of KD025 to target IL-17A and IL-21 production in our study was, however, not accompanied by decreases in Stat3 phosphorylation or IRF4 expression,18 36 possibly due to the later timing of addition of the ROCK2 inhibitor to the cultures, which may have enabled the initial wave of signalling events to be protected from the inhibitory effects of KD025.…”

An activated Th17-prone T cell subset involved in chronic graft-versus-host disease sensitive to pharmacological inhibition

“…Dual RORγt or STAT3 pathway inhibitors have been developed, such as the small GTPase, ρ-associated coiled-coil containing protein kinase 2 (Rock2) inhibitor, KD025. We recently showed that KD025 was efficient in suppressing murine and human cGvHD through inhibition of RORγt and STAT3, leading to reduced IL-17 and IL-21 cytokine production and T follicular helper (TFH) cells that can support pathogenic antibody production during cGvHD (31,37). Via its effects on STAT5, Treg production also is facilitated (31,38).…”