Bone marrow derived mast cells injected into the osteoarthritic knee joints of mice induced by sodium monoiodoacetate enhanced spontaneous pain through activation of PAR2 and action of extracellular ATP

Abstract

Conditions that resemble osteoarthritis (OA) were produced by injection of sodium monoiodoacetate (MIA) into the knee joints of mice. Bone marrow derived mast cells (BMMCs) injected into the OA knee joints enhanced spontaneous pain. Since no spontaneous pain was observed when BMMCs were injected into the knee joints of control mice that had not been treated with MIA, BMMCs should be activated within the OA knee joints and release some pain-inducible factors. Protease activated receptor-2 (PAR2) antagonist (FSLLRY-NH2) almost abolished the pain-enhancing effects of BMMCs injected into the OA knee joints, suggesting that tryptase, a mast cell protease that is capable of activating PAR2, should be released from the injected BMMCs and enhance pain through activation of PAR2. When PAR2 agonist (SLIGKV-NH2) instead of BMMCs was injected into the OA knee joints, it was also enhanced pain. Apyrase, an ATP degrading enzyme, injected into the OA knee joints before BMMCs suppressed the pain enhanced by BMMCs. We showed that purinoceptors (P2X4 and P2X7) were expressed in BMMCs and that extracellular ATP stimulated the release of tryptase from BMMCs. These observations suggest that ATP may stimulate degranulation of BMMCs and thereby enhanced pain. BMMCs injected into the OA knee joints stimulated expression of IL-1β, IL-6, TNF-α, CCL2, and MMP9 genes in the infrapatellar fat pads, and PAR2 antagonist suppressed the stimulatory effects of BMMCs. Our study suggests that intermittent pain frequently observed in OA knee joints may be due, at least partly, to mast cells through activation of PAR2 and action of ATP, and that intraarticular injection of BMMCs into the OA knee joints may provide a useful experimental system for investigating molecular mechanisms by which pain is induced in OA knee joints.

Therapeutic application of PPE2 protein of Mycobacterium tuberculosis in inhibiting tissue inflammation

“…These results indicated that inflammatory mediators were reduced in paw tissues of mice treated with rPPE2. To further demonstrate that PPE2 suppresses formalin-induced tissue inflammation specifically through inhibition of mast cells, we 6 of 21 performed a mast cell transplantation experiment, where bone marrow-derived mast cells (BDMCs) were purified (with > 95% purity, Fig 4A) and injected into the paw of rPPE2-treated mice via subplantar route as described elsewhere (Lee et al, 2002;Patel et al, 2016;Habuchi et al, 2021). When the percentage of inflammation in paw tissue was measured, an increased inflammation was observed in rPPE2-treated mice that were injected with bone marrow-derived mast cells when compared to rPPE2-treated mice that did not receive any mast cells (Fig 4B and C).…”

Par2-mediated responses in inflammation and regeneration: choosing between repair and damage

“…This pain was reduced by a Par2 antagonist. When a Par2 agonist was injected instead of mast cells, the painful phenotype was regained, indicating that Par2 activation in the tissue is mediated by Par2 signaling [ 2 ].…”