Role of ROCK2 in CD4⁺ cells in allergic airways responses in mice

Abstract

Background Rho kinases (ROCKs) contribute to allergic airways disease. ROCKs also play a role in lymphocyte proliferation and migration. Objective To determine the role of ROCK2 acting within CD4+ cells in allergic airways responses. Methods ROCK2 haploinsufficient (ROCK2+/-) and wildtype mice were sensitized with ovalbumin (OVA). ROCK2+/- mice then received either CD4+ cells from ROCK2 sufficient OVA TCR transgenic (OT-II) mice or saline i.v. 48 hours before challenge with aerosolized OVA. Wildtype mice received saline before challenge. Allergic airway responses were measured 48 hours after the last challenge. Allergic airways responses were also assessed in mice lacking ROCK2 only in CD4+ cells (ROCK2CD4Cre mice) versus control (CD4-Cre and ROCK2flox/flox) mice. Results OVA-induced increases in bronchoalveolar lavage lymphocytes, eosinophils, IL-13, IL-5, and eotaxin were reduced in ROCK2+/- versus wildtype mice, as were airway hyperresponsiveness and mucous hypersecretion. In ROCK2+/- mice, adoptive transfer with CD4+ cells from OT-II mice restored effects of OVA on lymphocytes, eosinophils, IL-13, IL-5, and mucous hypersecretion to wildtype levels, whereas eotaxin and airway hyperrresponsiveness were not affected. ROCK2 inhibitors reduced IL-13-induced release of eotaxin from airway smooth muscle (ASM), similar to effects of these inhibitors on ASM contractility. Despite the ability of adoptive transfer to restore allergic airways inflammation in ROCK2 insufficient mice, allergic inflammation was not different in ROCK2CD4Cre versus control mice. Conclusion ROCK2 contributes to allergic airways responses likely via effects within ASM cells and within non lymphocyte cells involved in lymphocyte activation and migration into the airways.

Instillation of hyaluronan reverses acid instillation injury to the mammalian blood gas barrier

“…Moreover, ROCK2 ϩ/Ϫ mice showed reduced AHR via effects within airway smooth muscle cells in murine asthma model (28). In addition, airway smooth muscle cells and activation of RhoA and ROCKs enhance methacholine-induced contraction via retention of myosin light chain in a phosphorylated state, which favors contraction (28,31). We found a significant increase in RhoA and ROCK2 activity after HCl instillation, which was ameliorated through blockade of L-HA signaling, either through competitive inhibition by H-HA or by genetic deficiency of HA receptor CD44.…”

“…It is thus likely that sustained production of L-HA is achieved through neutrophil influx, which sustains the inflammatory response, barrier disruption and, AHR development. Recent studies showed that L-HA increases vascular permeability by activating small GTPases (such as RhoA), which in turn induce actin cytoskeletal reorganization; inhibit endothelial cell-cell contacts (36),; activate ROCK, their downstream kinases (28), and Ca 2ϩ channels (such as TRPC); and increase Ca 2ϩ influx from the extracellular milieu to the cytoplasm (46). Moreover, ROCK2 ϩ/Ϫ mice showed reduced AHR via effects within airway smooth muscle cells in murine asthma model (28).…”

“…Recent studies showed that L-HA increases vascular permeability by activating small GTPases (such as RhoA), which in turn induce actin cytoskeletal reorganization; inhibit endothelial cell-cell contacts (36),; activate ROCK, their downstream kinases (28), and Ca 2ϩ channels (such as TRPC); and increase Ca 2ϩ influx from the extracellular milieu to the cytoplasm (46). Moreover, ROCK2 ϩ/Ϫ mice showed reduced AHR via effects within airway smooth muscle cells in murine asthma model (28). In addition, airway smooth muscle cells and activation of RhoA and ROCKs enhance methacholine-induced contraction via retention of myosin light chain in a phosphorylated state, which favors contraction (28,31).…”

Rho signaling research: history, current status and future directions

“…These effects of Y‐27632 may well be due to the suppression of enhanced calcium sensitization of airway smooth muscle contraction induced by allergen‐sensitization , and effects of ROCK inhibition on chemotaxis of inflammatory cells. Studies using ROCK hetero‐deficient mice indicate that both ROCK1 and ROCK2 in lymphocytes and nonlymphocyte cells are involved in these processes .…”