OBJECTIVE: To observe the effect of "Zhibian" (BL54)-toward-"Shuidao" (ST28) needling technique on the relative protein expression of the signaling pathway of nucleotide-binding oligomerization domain-containing protein 1 (NOD1)/ receptor-interacting protein 2 (RIP2)/nuclear factor kappa-B (NF-κB) and the expression of proinflammatory cytokines in the rats with primary dysmenorrhea (PD), so as to explore the underlying mechanism of this acupuncture technique for pain alleviation in PD. METHODS: Thirty female SD rats of SPF grade with normal estrous cycle were randomized into a blank group, a model group and an acupuncture group, 10 rats in each one. Using the intraperitoneal injection with estradiol benzoate combined with oxytocin, PD model was prepared in the model group and the acupuncture group. In the acupuncture group, during model preparation, the intervention with "Zhibian" (BL54)-toward-"Shuidao" (ST28) needling technique was delivered simultaneously, 20 min each time, once daily for consecutive 10 days. On day 11, within 30 min after the intraperitoneal injection with oxytocin, the writhing reaction (latency, frequency and score) was recorded; the morphology of uterine tissue was observed with HE staining, the contents of prostaglandin E₂ (PGE₂), prostaglandin F_2α (PGF_2α), interleukin (IL)-1β, IL-18, cyclooxygenase-2 (COX-2), and tumor necrosis factor-α(TNF-α) in the serum were detected using ELISA method; the relative protein expression of NOD1, RIP2, NF-κB p65, phosphorylation-NF-κB p65 (p-NF-κB p65) was detected in the uterine tissue using Western blot method; and the mRNA expression of NOD1, RIP2 and NF-κB p65 was detected with the quantitative real-time PCR employed. RESULTS: Compared with the blank group, in the model group, the writhing latency was prolonged (P<0.01), the writhing frequency and score increased (P<0.01) in the rats; the endometrial epithelial cells showed massive degeneration and necrosis, with severe endometrial edema and widespread shedding, combined with neutrophil infiltration; the serum PGE₂ content was dropped (P<0.01), while those of PGF_2α, IL-1β, IL-18, COX-2, and TNF-α elevated (P<0.01); the protein expression of NOD1, RIP2, NF-κB p65 and p-NF-κB p65, and the mRNA expression of NOD1, RIP2 and NF-κB p65 in uterine tissue increased (P<0.01). In comparison with the model group, in the acupuncture group, the writhing latency was prolonged (P<0.01), the writhing frequency and score were reduced (P<0.01) in the rats; there was less degeneration and necrosis of endometrial epithelial cells, with mild endometrial edema and very little neutrophil infiltration; the serum PGE₂ content increased (P<0.01), while those of PGF_2α, IL-1β, IL-18, COX-2, and TNF-α decreased (P<0.01); the protein expression of NOD1, RIP2, NF-κB p65 and p-NF-κB p65 and the mRNA expression of NOD1, RIP2 and NF-κB p65 in uterine tissue were dropped (P<0.05, P<0.01). CONCLUSION "Zhibian" (BL54)-toward-"Shuidao" (ST28) needling technique can alleviate the pain symptom of PD rats, and its action mechanism may be related to inhibiting the active expression of NOD1/RIP2/NF-κB signaling pathway in the uterine tissue, thereby reducing the inflammatory response.
Animals ; Female ; Rats, Sprague-Dawley ; Rats ; Signal Transduction ; Dysmenorrhea/metabolism* ; NF-kappa B/metabolism* ; Acupuncture Points ; Humans ; Acupuncture Analgesia ; Nod1 Signaling Adaptor Protein/metabolism* ; Receptor-Interacting Protein Serine-Threonine Kinase 2/metabolism* ; Acupuncture Therapy

The innate immune system is critical for clearing infection, and is tightly regulated to avert excessive tissue damage. Nod1/2-Rip2 signaling, which is essential for initiating the innate immune response to bacterial infection and ER stress, is subject to many regulatory mechanisms. In this study, we found that LRRK2, encoded by a gene implicated in Crohn's disease, leprosy and familial Parkinson's disease, modulates the strength of Nod1/2-Rip2 signaling by enhancing Rip2 phosphorylation. LRRK2 deficiency markedly reduces cytokine production in macrophages upon Nod2 activation by muramyl dipeptide (MDP), Nod1 activation by D-gamma-Glu-meso-diaminopimelic acid (iE-DAP) or ER stress. Our biochemical study shows that the presence of LRRK2 is necessary for optimal phosphorylation of Rip2 upon Nod2 activation. Therefore, this study reveals that LRRK2 is a new positive regulator of Rip2 and promotes inflammatory cytokine induction through the Nod1/2-Rip2 pathway.
Animals ; Cytokines ; genetics ; immunology ; HEK293 Cells ; Humans ; Immunity, Innate ; genetics ; Inflammation ; genetics ; immunology ; Leucine-Rich Repeat Serine-Threonine Protein Kinase-2 ; genetics ; immunology ; Mice ; Mice, Knockout ; Nod1 Signaling Adaptor Protein ; genetics ; immunology ; Nod2 Signaling Adaptor Protein ; genetics ; immunology ; Phosphorylation ; genetics ; immunology ; Receptor-Interacting Protein Serine-Threonine Kinase 2 ; genetics ; immunology ; Receptor-Interacting Protein Serine-Threonine Kinases ; genetics ; immunology ; Signal Transduction ; genetics ; immunology