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 effects of IL-28B in a mouse model of dextran sulfate sodium (DSS)-induced colitis and to analyze the possible mechanism.Methods:Thirty-five male C57BL/6 mice were randomly divided into the following groups with seven mice in each group: control group, DSS group and three IL-28B groups (1.25 μg, 2.5 μg and 5 μg). The mice in the DSS group and IL-28B groups were fed with 2.5% DSS solution and from day 3, the IL-28B groups were given intraperitoneal injection of corresponding IL-28B every day and the DSS group was treated with PBS. During the experiment, the disease activity index (DAI) was evaluated daily. On day 8, the mice were sacrificed and peripheral blood, spleen, mesenteric lymph node and colon samples were collected. The colon samples were observed, measured in length and stained with HE, and histopathological scores were calculated based on HE staining. Changes of immune cells in different samples were detected by flow cytometry. ELISA was used to detect the expression of IL-12, IL-10, IL-1β, IL-6, IL-4 and IL-13 in serum and colon tissues.Results:Compared with the DSS group, the IL-28B group (2.5 μg) had lower DAI scores [(9.40±1.67) vs (3.50±1.73), P<0.01], less shortening of the colon [(5.16±0.61) cm vs (6.91±0.60) cm, P<0.01] and significantly lower histopathological scores [(7.33±0.58) vs (4.33±0.58), P<0.01]. Moreover, compared with the DSS group, the IL-28B group (2.5 μg) showed decreased macrophages in the peripheral blood [(21.39±3.21)% vs (15.63±2.98)%, P<0.05] and spleen [(3.03±0.28)% vs (2.05±0.48)%, P<0.05], and significantly increased mean fluorescence intensity of M2 macrophages in the colon [(1 361.00±293.40) vs (2 074.00±87.61), P<0.05]. IL-12 expression in colon tissues and IL-1β expression in serum were reduced, and IL-10, IL-4 and IL-13 expression in colon tissues was significantly increased in the IL-28B group (2.5 μg) as compared with those in the DSS group [IL-12: (31.72±6.92) pg/mg vs (5.41±3.41) pg/mg; IL-1β: (48.01±16.13) pg/ml vs (12.27±6.26) pg/ml; IL-10: (184.70±46.82) pg/mg vs (444.30±157.80) pg/mg; IL-4: (2.23±0.27) pg/mg vs (3.64±0.80) pg/mg; IL-13: (11.79±0.99) pg/mg vs (22.59±1.92) pg/mg; all P<0.05]. Conclusions:IL-28B might alleviate the severity of acute enteritis in mice by increasing the secretion of IL-4 and IL-13, regulating macrophage differentiation and modulating the expression of inflammatory factors.

Myeloid-derived suppressor cells (MDSCs) have strong immunosuppressive activity and are morphologically similar to conventional monocytes and granulocytes. The development and classification of these cells have, however, been controversial. The activation network of MDSCs is relatively complex, and their mechanism of action is poorly understood, creating an avenue for further research. In recent years, MDSCs have been found to play an important role in immune regulation and in effectively inhibiting the activity of effector lymphocytes.Under certain conditions, particularly in the case of tissue damage or inflammation, MDSCs play a leading role in the immune response of the central nervous system. In cancer, however, this can lead to tumor immune evasion and the development of related diseases. Under cancerous conditions, tumors often alter bone marrow formation, thus affecting progenitor cell differentiation, and ultimately, MDSC accumulation. MDSCs are important contributors to tumor progression and play a key role in promoting tumor growth and metastasis, and even reduce the efficacy of immunotherapy. Currently, a number of studies have demonstrated that MDSCs play a key regulatory role in many clinical diseases. In light of these studies, this review discusses the origin of MDSCs, the mechanisms underlying their activation, their role in a variety of clinical diseases, and their function in immune response regulation.

Myeloid-derived suppressor cells (MDSCs) have strong immunosuppressive activity and are morphologically similar to conventional monocytes and granulocytes. The development and classification of these cells have, however, been controversial. The activation network of MDSCs is relatively complex, and their mechanism of action is poorly understood, creating an avenue for further research. In recent years, MDSCs have been found to play an important role in immune regulation and in effectively inhibiting the activity of effector lymphocytes.Under certain conditions, particularly in the case of tissue damage or inflammation, MDSCs play a leading role in the immune response of the central nervous system. In cancer, however, this can lead to tumor immune evasion and the development of related diseases. Under cancerous conditions, tumors often alter bone marrow formation, thus affecting progenitor cell differentiation, and ultimately, MDSC accumulation. MDSCs are important contributors to tumor progression and play a key role in promoting tumor growth and metastasis, and even reduce the efficacy of immunotherapy. Currently, a number of studies have demonstrated that MDSCs play a key regulatory role in many clinical diseases. In light of these studies, this review discusses the origin of MDSCs, the mechanisms underlying their activation, their role in a variety of clinical diseases, and their function in immune response regulation.

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.