IncHI plasmids could be divided into five different subgroups IncHI1-5. In this study, the complete nucleotide sequences of seven bla IMP- or bla VIM-carrying IncHI5 plasmids from Klebsiella pneumoniae, K. quasipneumoniae, and K. variicola were determined and compared in detail with all the other four available sequenced IncHI5 plasmids. These plasmids carried conserved IncHI5 backbones composed of repHI5B and a repFIB-like gene (replication), parABC (partition), and tra1 (conjugal transfer). Integration of a number of accessory modules, through horizontal gene transfer, at various sites of IncHI5 backbones resulted in various deletions of surrounding backbone regions and thus considerable diversification of IncHI5 backbones. Among the accessory modules were three kinds of resistance accessory modules, namely Tn10 and two antibiotic resistance islands designated ARI-A and ARI-B. These two islands, inserted at two different fixed sites (one island was at one site and the other was at a different site) of IncHI5 backbones, were derived from the prototype Tn3-family transposons Tn1696 and Tn6535, respectively, and could be further discriminated as various intact transposons and transposon-like structures. The ARI-A or ARI-B islands from different IncHI5 plasmids carried distinct profiles of antimicrobial resistance markers and associated mobile elements, and complex events of transposition and homologous recombination accounted for assembly of these islands. The carbapenemase genes bla IMP-4, bla IMP-38 and bla VIM-1 were identified within various class 1 integrons from ARI-A or ARI-B of the seven plasmids sequenced in this study. Data presented here would provide a deeper insight into diversification and evolution history of IncHI5 plasmids.

A novel avian-origin influenza A (H7N9) virus emerged in China in 2013 and has caused zoonotic disease in over 1123 persons with an overall mortality around 30%. Amino acid changes at the residues 591, 627 and 701 of polymerase basic protein 2 (PB2) have been found frequently in the human H7N9 isolates but not in viruses isolated from avian species. We have recently identified a cluster of H7N9 viruses in ducks which circulated in China prior to the first recognition of zoonotic disease in 2013. These duck viruses have genetic background distinct from the zoonotic H7N9 lineage. We found that the introduction of PB2 mutation with K at 627 but not K at 591 or N at 701 to the duck H7N9 virus led to increased pathogenicity in mice. We also found that the induction of pro-inflammatory cytokines including TNF-α, IP-10, MCP-1 and MIP-1α were associated with increased severity of infection. We conclude that introduction of the mammalian adaptation mutations into the PB2 gene of duck H7N9 viruses, which are genetically unrelated to the zoonotic H7N9 lineage, can also enhance pathogenicity in mice.

Atherosclerosis is the major cause of cardiovascular diseases. Current evidences indicate that inflammation is involved in the pathogenesis of atherosclerosis. Human gingiva-derived mesenchymal stem cells (GMSC) have shown anti-inflammatory and immunomodulatory effects on autoimmune and inflammatory diseases. However, the function of GMSC in controlling atherosclerosis is far from clear. The present study is aimed to elucidate the role of GMSC in atherosclerosis, examining the inhibition of GMSC on macrophage foam cell formation, and further determining whether GMSC could affect the polarization and activation of macrophages under different conditions. The results show that infusion of GMSC to AopE-/- mice significantly reduced the frequency of inflammatory monocytes/macrophages and decreased the plaque size and lipid deposition. Additionally, GMSC treatment markedly inhibited macrophage foam cell formation and reduced inflammatory macrophage activation, converting inflammatory macrophages to anti-inflammatory macrophages in vitro. Thus, our study has revealed a significant role of GMSC on modulating inflammatory monocytes/macrophages and alleviating atherosclerosis.

Acute respiratory infections (ARI) cause considerable morbidity and mortality worldwide, especially in children. Unfortunately, there are limited multi-center data on common viral respiratory infections in south China.

Hyperhomocysteinemia (HHcy) has been shown to promote vascular inflammation and atherosclerosis, but the underlying mechanisms remain largely unknown. The NLRP3 inflammasome has been identified as the cellular machinery responsible for activation of inflammatory processes. In this study, we hypothesized that the activation of NLRP3 inflammasomes contributes to HHcy-induced inflammation and atherosclerosis. ApoE-/- mice were fed regular chow, high-fat (HF) diet, or HF plus high methionine diet to induce HHcy. To assess the role of NLRP3 inflammasomes in HHcy-aggravated atherosclerosis, NLRP3 shRNA viral suspension was injected via tail vein to knock down the NLRP3 gene. Increased plasma levels of IL-1β and IL-18, aggravated macrophage infiltration into atherosclerotic lesions, and accelerated development of atherosclerosis were detected in HHcy mice as compared with control mice, and were associated with the activation of NLRP3 inflammasomes. Silencing the NLRP3 gene significantly suppressed NLRP3 inflammasome activation, reduced plasma levels of proinflammatory cytokines, attenuated macrophage infiltration and improved HHcy-induced atherosclerosis. We also examined the effect of homocysteine (Hcy) on NLRP3 inflammasome activation in THP-1-differentiated macrophages in the presence or absence of NLRP3 siRNA or the caspase-1 inhibitor Z-WEHD-FMK. We found that Hcy activated NLRP3 inflammasomes and promoted subsequent production of IL-1β and IL-18 in macrophages, which were blocked by NLRP3 gene silencing or Z-WEHD-FMK. As reactive oxygen species (ROS) may have a central role in NLRP3 inflammasome activation, we next investigated whether antioxidant N-acetyl-l-cysteine (NAC) prevented Hcy-induced NLRP3 inflammasome activation in macrophages. We found Hcy-induced NLRP3 inflammasome activation was abolished by NAC. Treatment with NAC in HHcy mice also suppressed NLRP3 inflammasome activation and improved HHcy-induced atherosclerosis. These data suggest that the activation of NLRP3 inflammasomes contributes to HHcy-aggravated inflammation and atherosclerosis in apoE-/- mice. Hcy activates NLRP3 inflammasomes in ROS-dependent pathway in macrophages. These results may have implication for the treatment of HHcy-associated cardiovascular diseases.