The innate immune sensor NLRP3 inflammasome overactivation is involved in the pathogenesis of ulcerative colitis. PGAM5 is a mitochondrial phosphatase involved in NLRP3 inflammasome activation in macrophages. However, the role of PGAM5 in ulcerative colitis and the mechanisms underlying PGAM5 regulating NLRP3 activity remain unknown. Here, we show that PGAM5 deficiency ameliorates dextran sodium sulfate (DSS)-induced colitis in mice via suppressing NLRP3 inflammasome activation. By combining APEX2-based proximity labeling focused on PGAM5 with quantitative proteomics, we identify NEK7 as the new binding partner of PGAM5 to promote NLRP3 inflammasome assembly and activation in a PGAM5 phosphatase activity-independent manner upon inflammasome induction. Interfering with PGAM5-NEK7 interaction by punicalagin inhibits the activation of the NLRP3 inflammasome in macrophages and ameliorates DSS-induced colitis in mice. Altogether, our data demonstrate the PGAM5-NEK7 interaction in macrophages for NLRP3 inflammasome activation and further provide a promising therapeutic strategy for ulcerative colitis by blocking the PGAM5-NEK7 interaction.

OBJECTIVE To investigate the effect and possible mechanism of shikonin on neuroinflammation in sepsis- associated encephalopathy （SAE） rats by regulating the cyclic guanosine monophosphate-adenosine monophosphate synthase （cGAS）-stimulator of interferon gene （STING） signaling pathway. METHODS Rats were randomly separated into SAE group， shikonin low-dose， medium-dose and high-dose groups （1.33， 2.66， 5.32 mg/kg）， high dose of shikonin+Roc A group （5.32 mg/kg shikonin+0.67 mg/kg cGAS-STING signaling pathway activator Roc A）， and control group， with 12 rats in each group. Except for the control group， SAE models were constructed in all other groups. After successful modeling， administration began once a day for 14 days. After administration， the Y-maze experiment and open-field experiment were applied to evaluate the learning and memory ability and anxiety state of rats， respectively. The pathological changes of neurons in the dentate gyrus （DG） of the hippocampus were observed. The number of CD86 and CD206 positive cells， the levels of interleukin-1β （IL-1β）， tumor necrosis factor-α （TNF-α）， IL-4 and IL-10， and the protein expressions of cGAS and STING were detected in the brain tissue of the hippocampus DG region. RESULTS Compared with the SAE group， the neuronal damage of rats in shikonin low-dose， medium-dose and high-dose groups were improved； the percentage of activity distance in the “new arm”， the duration of stay in the central area， walking distance， the number of intact neurons and CD206 positive cells in the brain tissue of the hippocampal DG area， and the levels of IL-4 and IL-10 increased/rised/prolonged significantly （P＜0.05）； the number of CD86 positive cells in the brain tissue of the hippocampal DG region， the levels of IL-1β and TNF-α， and protein expressions of cGAS and STING were significantly reduced/decreased/down-regulated （P＜0.05）， and the effect of shikonin was dose-dependent （P＜0.05）. Roc A could significantly reverse the improvement effect of high-dose shikonin on neuroinflammation in SAE rats （P＜0.05）. CONCLUSIONS Shikonin can improve neuroinflammation in SAE rats by inhibiting cGAS-STING signaling pathway.

Objective To obtain alpaca single domain antibody targeting Her2.Methods An alpaca was immunized with human recombination Her2 protein mixed with Freund's adjuvant.Total RNA was extracted from the alpaca's blood and was used to synthesize first strand cDNA.Single domain antibody variable region (VHH) gene of the alpaca was amplified by PCR and cloned into pMES4 vector for library construction.After screening, E.coli BL21 (DE3) was transformed with selected clones and was induced with IPTG for the expression of recombinant proteins.The nanobody was purified by nickel ion affinity chromatography column.The affinity of the nanobodies to Her2 was tested.Results After the second round of screening, two antibody clones were selected, H3 and H5.The affinity of H5 was 8.106×10-10mol/L.Histochemistry results showed that H5 could recognize Her2 antigen in breast tumor tissue.Conclusion An Her2 specific nanobody derived from alpaca is obtained through phage display library screening, which can recognize human Her2 antibody in human breast tumor tissue.