Objective To investigate the development, role, and regulatory mechanism of macrophage efferocytosis in the liver of hosts infected with Schistosoma japonicum. Methods The expression of efferocytosis-related gene like efferocytosis receptors, efferocytosis-related bridging molecules,“eat me” signal and “don’t eat me” signal was detected in the livers of patients and mice infected with S. japonicum in the Gene Expression Omnibus (GEO) database. Ten wild-type (WT) male mice (6 ~ 8 weeks old, weighing 20 ~ 25 g) were randomly divided into a Schistosoma japonicum infection (SJ) group and a normal control (NC) group, with 5 mice in each group. The efferocytosis of neutrophils and T cells by liver macrophages was detected in mice from SJ group and NC group using flow cytometry and immunofluorescence assay, respectively. The expression of efferocytosis-related Mer receptor tyrosine kinase (MerTK) and Axl receptor tyrosine kinase (Axl) proteins was determined in mouse liver tissues using Western blotting assay, and the proportion of MerTK⁺ macrophages and the average fluorescence intensity of macrophage MerTK were detected in mouse livers using flow cytometry. Changes in liver granulomas and fibrosis were observed in mice infected with S. japonicum following injection of efferocytosis inhibitors, and S. japonicum-infected mice without injection of efferocytosis inhibitors served as controls. Bone marrow-derived macrophages (BMDMs) were isolated from macrophage scavenger receptor class A (SR-A) conditional knockout (CKO) and wild-type (WT) mice, and changes in apoptotic neutrophils were detected in SR-A CKO mouse macrophages in vitro using flow cytometry. Then, BMDMs was divided into the WT mono-culture group, the WT and apoptotic neutrophils co-culture group, the SR-A CKO mono-culture group, and the SR-A CKO and neutrophils co-culture group, and the expression of MerTK and Axl was quantified in vitro using Western blotting and real-time quantitative PCR (RT-qPCR) assays during neutrophil efferocytosis. The efferocytosis of neutrophils and T cells by mouse liver macrophages was detected in the SR-A CKO SJ group and the WT SJ group using flow cytometry and immunofluorescence assay, and the expression of MerTK and Axl proteins was determined in mouse liver tissues in both groups using Western blotting. In addition, the proportion of MerTK⁺ macrophages and the average fluorescence intensity of macrophage MerTK were detected in mouse livers in both groups using flow cytometry. Results Data from the GEO database showed that the expression of some efferocytosis receptors and efferocytosis-related bridging molecules, and “eat me” and “don’t eat me” signals all appeared a tendency towards a rise in livers of patients and mice in the SJ group relative to the NC group, suggesting that S. japonicum infection-induced liver diseases may be associated with efferocytosis. Flow cytometry detected higher proportions of Ly6G⁺ cells [(13.13 ± 0.45)% vs. (6.48 ± 0.25)%; t = 22.30, P < 0.05] and CD3⁺ cells [(7.60 ± 0.33)% vs. (3.30 ± 0.42)%; t = 13.98, P < 0.05] in mouse liver macrophages in the SJ group than in the NJ group, and the expression of MerTK protein [(2.30 ± 0.14) vs. (1.14 ± 0.46); t = 4.19, P < 0.05], the mean fluorescence intensity of macrophages [(160.67 ± 15.28) vs. (94.50 ± 19.61); t = 4.81, P < 0.05], and the proportion of MerTK⁺ macrophages [(20.78 ± 4.17)% vs. (6.85 ± 0.39)%; t = 6.57, P < 0.05] were significantly higher in mouse liver tissues in the SJ group than in the NC group. The Axl expression was lower in mouse liver tissues in the SJ group than in the NC group [(1.25 ± 0.08) vs. (1.93 ± 0.37); t = 2.79, P < 0.05], and the area of granulomas around single eggs [(9.18 ± 1.81) × 10⁴μm² vs. (5.24 ± 1.35) × 10⁴ μm²; t = 3.03, P < 0.05] and proportion of collagen fibers [(25.27 ± 3.99)% vs. (15.14 ± 4.02)%; t = 3.10, P < 0.05] were significantly greater in livers of S. japonicum-infected mice with injection of efferocytosis inhibitors than in mice without injection of efferocytosis inhibitors. The in vitro efferocytosis efficiency of BMDMs [(32.83 ± 3.17)% vs. (45.43 ± 2.34)%; t = 5.54, P < 0.05], and the proportions of Ly6G⁺ [(9.37 ± 0.48)% vs. (13.13 ± 0.72)%; t = 7.50, P < 0.05] and CD3⁺ cells [(4.95 ± 0.17)% vs. (7.64 ± 0.50)%; t = 8.87, P < 0.05] in liver macrophages post-infection with S. japonicum were significantly lower in SR-A CKO mice than in WT mice, and the expression of MerTK protein [(0.65 ± 0.25) vs. (1.96 ± 0.69); t = 3.10, P < 0.05], the average fluorescence intensity of macrophages [(138.33 ± 8.39) vs. (160.67 ± 15.28); t = 3.03, P < 0.05] and the proportion of MerTK⁺ macrophages [(13.17 ± 5.01)% vs. (22.63 ± 2.06)%; t = 3.56, P < 0.05] were significantly lower in mouse liver tissues in the SR-A CKO SJ group than in the WT group. Western blotting detected no significant difference in the Axl protein expression in mouse liver tissues between the SR-A CKO SJ group and the WT SJ group [(0.48 ± 0.07) vs. (0.68 ± 0.30); t = 1.09, P > 0.05]. There were significant differences in the relative MerTK mRNA and protein expression during efferocytosis of BMDMs among the WT monoculture group, the WT and apoptotic neutrophils co-culture group, the SR-A CKO mono-culture group, and the SR-A CKO and neutrophils co-culture group (F = 9.41 and 40.68, both P values < 0.05). In addition, there was a significant difference in the relative Axl mRNA expression during efferocytosis of BMDMs among the four groups (F = 13.62, P < 0.05); however, no significant difference was seen in the relative Axl protein expression (F = 1.27, P > 0.05). Conclusions Efferocytosis of liver macrophages is seen in mice infected with S. japonicum and inhibits liver fibrosis. SR-A may up-regulate the efficiency of macrophage efferocytosis through regulating the expression of efferocytosis receptors.

Emergence of the colistin resistance gene,mcr-1,has attracted worldwide attention.Despite the prevalence of mcr-1-positive Escherichia coli(MCRPEC)strains in human carriage showing a significant decrease between 2016 and 2019,genetic differences in MCRPEC strains remain largely unknown.We therefore conducted a comparative genomic study on MCRPEC strains from fecal samples of healthy human subjects in 2016 and 2019.We identified three major differences in MCRPEC strains between these two time points.First,the insertion sequenceISApll1 was often deleted and the percentage of mcr-1-carrying IncI2 plasmids was increased in MCRPEC strains in 2019.Second,the antibiotic resistance genes(ARGs),aac(3)-Ⅳa and blaCTX-M-1,emerged and coexisted with mcr-1 in 2019.Third,MCRPEC strains in 2019 contained more viru-lence genes,resulting in an increased proportion of extraintestinal pathogenic E.coli(ExPEC)strains(36.1％)in MCRPEC strains in 2019 compared to that in 2016(10.5％),implying that these strains could occupy intestinal ecological niches by competing with other commensal bacteria.Our results suggest that despite the significant reduction in the prevalence of MCRPEC strains in humans from 2016 to 2019,MCRPEC exhibits increased resistance to other clinically important ARGs and contains more virulence genes,which may pose a potential public health threat.

Objective: Our aim was to study the role of telomerase activation in the course of cervical carcinogenesis and progression.Methods:Telomeric repeat amplification protocol(TRAP) assay was used to measure telomerase activity in tissue samples with various cervical conditions:40 with cervical cancer, 50 with cervical intraepithelial neoplasia(CIN), 20 with normal cervice. Results:The positive rate of telomerase activity was 95.0%,44.0%, and 10.0% in cervical cancer, CIN, and normal cervices, respectively, which was significantly higher in cervical cancer than that in CIN and normal cervices, so was that in CIN than that in normal cervices (P<0.01) . The positive rate was 22.2%, 37.5%, and 75.0% in CINⅠ,Ⅱ, and Ⅲ, respectively, which was significantly higher in CINⅢ than that in CIN Ⅱand CINⅠ (P<0.01).Conclusion:Telomerase activation may relate to cervical carcinogenesis, which correlates well with the grade of cervical lesions.