GRK2 inhibits Flt-1+ macrophage infiltration and its proangiogenic properties in rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease with a complex etiology. Monocyte-derived macrophages (MDMs) infiltration are associated with RA severity. We have reported the deletion of G-protein-coupled receptor kinase 2 (GRK2) reprograms macrophages toward an anti-inflammatory phenotype by recovering G-protein-coupled receptor signaling. However, as more GRK2-interacting proteins were discovered, the GRK2 interactome mechanisms in RA have been understudied. Thus, in the collagen-induced arthritis mouse model, we performed genetic GRK2 deletion using GRK2f/fLyz2-Cre+/- mice. Synovial inflammation and M1 polarization were improved in GRK2f/fLyz2-Cre+/- mice. Supporting experiments with RNA-seq and dual-luciferase reporter assays identified peroxisome proliferator-activated receptor γ (PPARγ) as a new GRK2-interacting protein. We further confirmed that fms-related tyrosine kinase 1 (Flt-1), which promoted macrophage migration to induce angiogenesis, was inhibited by GRK2-PPARγ signaling. Mechanistically, excess GRK2 membrane recruitment in CIA MDMs reduced the activation of PPARγ ligand-binding domain and enhanced Flt-1 transcription. Furthermore, the treatment of mice with GRK2 activity inhibitor resulted in significantly diminished CIA pathology, Flt-1+ macrophages induced-synovial inflammation, and angiogenesis. Altogether, we anticipate to facilitate the elucidation of previously unappreciated details of GRK2-specific intracellular signaling. Targeting GRK2 activity is a viable strategy to inhibit MDMs infiltration, affording a distinct way to control joint inflammation and angiogenesis of RA.

Effect of paeoniflorin-6'-O benzene sulfonate on JAK1/STAT3 signaling pathway in rat macrophages with collagen-induced arthritis through regulating G protein coupled receptor kinase 2 / 中国药理学通报

Aim To investigate the inhibitory effect of peonia-6'-o benzene sulfonate (CP-25) on the JAK1/STAT3 signaling pathway in collagen-induced arthritis (CIA) rats macrophages through regulating G protein coupled receptor kinase 2 (GRK2). Methods SD rats were randomly divided into four groups; normal group, model group, CP-25 (50 mg · kg

Paeoniflorin besylate relieves mice with antigen-induced experimental Sjogren's syndrome by regulating GRK2-JAK1-STAT1/2 signaling pathway / 中国药理学通报

Aim To observe the effect of CP-25 on the ESS mouse model and establish whether its effect is through regulating the binding of GRK2 to JAK1 and inhibiting the JAK1-STAT1/2-CXCL13 signaling pathway. Method We established ESS mouse model induced by SG protein, established into normal group, model group, CP-25 group with concentration of 35 mg • kg"1, 70 mg • kg"1, and HCQ group with concentration of 80 mg • kg"1. Mouse saliva flow was measured. The infiltration of lymphocyte in SG was observed by HE staining. The expression of p-JAKl, p- STAT1 and p-STAT2 in submandibular gland tissue was detected by Western blot. The level of CXCL13 in SG of mice was tested by IHC. GRK2 and JAK1 binding was determined by immunofluorescence and CO- IP. Results Compared with normal group, the saliva flow rate of ESS mice was low and lymphocytes were significantly infiltrated in the submandibular gland pathological sections. The CXCL13 protein level was highly expressed, which activated the JAK1-STAT1/2 signal. CP-25 significantly increased the salivary flow rate in ESS mice, reduced lymphocyte infiltration, improved pathological abnormalities, and inhibited the expression of JAK1-STAT 1/2 signaling and CXCL13. CP-25 significantly promoted the binding of GRK2 to JAK1. Conclusions CP-25 may inhibit the binding of GRK2 to JAK1, and then inhibit the activation of JAK1-STAT1/2-CXCL13 signaling pathway, improve the abnormal pathological manifestations of lymphocyte infiltration in submandibular gland, and improve the rate of saliva flow. CP-25 plays a therapeutic role in ESS mice.

Inhibition of MicroRNA-15a/16 Expression Alleviates Neuropathic Pain Development through Upregulation of G Protein-Coupled Receptor Kinase 2

There is accumulating evidence that microRNAs are emerging as pivotal regulators in the development and progression of neuropathic pain. MicroRNA-15a/16 (miR-15a/16) have been reported to play an important role in various diseases and inflammation response processes. However, whether miR-15a/16 participates in the regulation of neuroinflammation and neuropathic pain development remains unknown. In this study, we established a mouse model of neuropathic pain by chronic constriction injury (CCI) of the sciatic nerves. Our results showed that both miR-15a and miR-16 expression was significantly upregulated in the spinal cord of CCI rats. Downregulation of the expression of miR-15a and miR-16 by intrathecal injection of a specific inhibitor significantly attenuated the mechanical allodynia and thermal hyperalgesia of CCI rats. Furthermore, inhibition of miR-15a and miR-16 downregulated the expression of interleukin-1β and tumor-necrosis factor-α in the spinal cord of CCI rats. Bioinformatic analysis predicted that G protein-coupled receptor kinase 2 (GRK2), an important regulator in neuropathic pain and inflammation, was a potential target gene of miR-15a and miR-16. Inhibition of miR-15a and miR-16 markedly increased the expression of GRK2 while downregulating the activation of p38 mitogen-activated protein kinase and NF-κB in CCI rats. Notably, the silencing of GRK2 significantly reversed the inhibitory effects of miR-15a/16 inhibition in neuropathic pain. In conclusion, our results suggest that inhibition of miR-15a/16 expression alleviates neuropathic pain development by targeting GRK2. These findings provide novel insights into the molecular pathogenesis of neuropathic pain and suggest potential therapeutic targets for preventing neuropathic pain development.