Microbiology and Immunology最新文献

The extensive and indiscriminate use of antibiotics, which are intended to halt bacterial growth or eliminate them, has unintentionally given rise to antimicrobial resistance (AMR), which is a critical threat to global health. In the pursuit of alternative solutions, researchers have focused on type II toxin-antitoxin systems prevalent within the bacterial domain. One such promising example is the MazF toxin, which has been demonstrated to cleave RNA at specific sequences. MazF toxins are now recognized as present in a diverse range of bacterial species and exhibit varying cleavage sequence specificities. This diversity offers the potential for controlling bacterial growth by silencing the expression of hundreds of essential genes. In this study, a preliminary screening of five MazF homologs from distinct taxonomic groups was conducted to identify a MazF candidate that can effectively suppress bacterial proliferation. MazFne1, an endoribonuclease toxin originating from Nitrosomonas europaea that specifically targets UGG sequences, emerged as a promising candidate. Building upon this discovery, a phagemid system was engineered to deliver mazFne1 and express it in two distinct Escherichia coli strains. This approach successfully inhibited E. coli growth, suggesting a potential strategy for developing therapeutic interventions to combat antibiotic-resistant bacterial infections.

Cover photograph: Photograph of a 96-well plate onto which each strain was cultured with rabbit red blood cells for 1 h and the supernatant was transferred after centrifugation. Microbiol Immunol: 70:57-67. Article link here

Psoriasis is a common immune-mediated skin disorder. miR-34a, as a significant regulatory component, has been involved in the regulation of immune-inflammatory responses. Previous studies have shown that miR-34a is abnormally expressed in psoriasis cell models. However, the role of miR-34a in psoriasis remains unvalidated by any existing studies. We co-stimulated HaCaT cells with IL-17A, IL-22, TNF-α, IL-1α, and M5 to establish an in vitro model of psoriasis. qPCR was used to detect the expression of miR-34a; ELISA was performed to measure the secretion levels of pro-inflammatory cytokines IL-1β, IL-6, IL-17, and IL-23 in HaCaT cells; CCK-8 and EdU staining assays were used to assess cell growth and proliferation; Western blot analysis was employed to assess the expression levels of relevant proteins, including SIRT1, NLRP3, ASC, pro-Caspase-1, and Caspase-1; dual-luciferase reporter gene assays and RNA immunoprecipitation (RIP) were conducted to investigate the interaction between miR-34a and SIRT1. Additionally, a mouse psoriasis model was induced by imiquimod (IMQ) to validate the role of miR-34a in vivo. qPCR results found that miR-34a was upregulated in HaCaT cells. ELISA results indicated that the levels of IL-1β, IL-6, IL-17, and IL-23 were significantly elevated in the M5-treated group. CCK-8 and EdU staining assays revealed that M5 treatment notably increased the proliferation and viability of HaCaT cells. After treatment with the miR-34a inhibitor, the levels of cytokines and cell proliferation were significantly reduced. Western blot analysis showed that M5 treatment resulted in a significant decrease in SIRT1 protein levels, while the expression levels of NLRP3, ASC, pro-Caspase-1, and Caspase-1 were increased. In contrast, miR-34a-inhibitor treatment showed the opposite results. Dual-luciferase reporter and RIP assays indicated a negative feedback interaction between miR-34a and SIRT1. Rescue experiments showed that overexpression of SIRT1 effectively inhibited NLRP3 expression, significantly reduced IL-23/IL-17 immune-inflammatory responses, and suppressed HaCaT cell proliferation, while overexpression of NLRP3 had the opposite effects. In the IMQ-induced mouse psoriasis model, the IMQ group showed severe psoriasis-like phenotypes, obvious skin pathological changes, upregulated miR-34a expression, and increased skin cytokine levels; all these abnormalities were alleviated by miR-34a inhibitor treatment. miR-34a mediates the IL-23/IL-17 immune-inflammatory response and promotes HaCaT cell proliferation by regulating the SIRT1/NLRP3 pathway.

Severe acute pancreatitis (SAP) is a critical abdominal emergency, with inflammatory response being the core pathogenic mechanism. This study aims to explore the role of miR-711 in SAP and its underlying mechanisms. This study enrolled 121 MAP patients and 109 SAP patients, collecting their clinical data. qRT-PCR measured miR-711 expression in serum and cells. Cell viability was tested with CCK-8, inflammatory factors via ELISA kits, and oxidative stress using SOD and MDA kits. The dual-luciferase assay confirmed miR-711 and KRT8 binding. Compared to the mild acute pancreatitis (MAP) group, the expression level of miR-711 in the serum of patients in the SAP group was significantly upregulated and positively correlated with relevant indicators. The ROC curve demonstrated its potential diagnostic value for SAP. In vitro, the miR-711 inhibitor effectively enhances the viability of Caerulein-induced AR42J cells and alleviates their inflammation and oxidative damage. Furthermore, the study confirmed that KRT8 is a downstream target gene of miR-711, and there is a negative correlation between their expressions. KRT8 may reverse the protective effect of miR-711 inhibitor on Cerulein-induced AR42J cells by regulating the NF-κB and p38 MAPK signaling pathways. The serum level of miR-711 in SAP patients is significantly upregulated and negatively correlated with SAP disease-related indicators. In vitro models demonstrate that inhibition of miR-711 effectively alleviates cerulein-induced cellular damage. Overexpression of KRT8 can reverse the cellular damage caused by miR-711 overexpression.

Parahenipaviruses (genus Parahenipavirus) are nonsegmented negative-strand RNA viruses belonging to the family Paramyxoviridae of the order Mononegavirales. Parahenipaviruses have been detected in shrews and rodents, some of which have been reported to be associated with human diseases. Although many parahenipaviruses have been identified thus far, there still exist large phylogenetic gaps in parahenipaviruses, suggesting the existence of yet-to-be-identified parahenipaviruses. In this study, we analyzed public RNA-seq data and identified a novel parahenipavirus from northern short-tailed shrews (Blarina brevicauda [Say, 1823]), tentatively named Blarina brevicauda virus (BbV). Based on sequence comparisons between BbV and its most closely related viruses, BbV meets the International Committee on Taxonomy of Viruses species demarcation criteria, and therefore we propose that BbV is a novel species of virus in the genus Parahenipavirus. Furthermore, mapping analysis using RNA-seq data derived from multiple tissues of northern short-tailed shrews suggested a possible kidney tropism of BbV. This study provides novel insights into the diversity of parahenipaviruses, which would contribute to a deeper understanding of their evolution and control of infectious diseases.

Influenza pneumonia is characterized by excessive inflammatory responses that contribute to severe lung injury and mortality. Supersulfides, endogenously produced cysteine-derived persulfides and polysulfides, exert potent antioxidant, anti-ferroptotic, and anti-inflammatory activities; however, their therapeutic potential after disease onset remains unclear. Here, we investigated the efficacy of N-acetylcysteine tetrasulfide (NAC-S2), a highly water-soluble and cell-permeable supersulfide donor, in a mouse model of influenza A virus (IAV)-induced pneumonia. Subcutaneous administration of NAC-S2 rapidly elevated systemic levels of cysteine- and glutathione-derived supersulfides. In therapeutic treatment starting 2 days post-infection, when body weight loss and clinical signs had already developed, NAC-S2 significantly improved survival and mitigated body weight loss compared with vehicle and oxidized NAC controls. Metabolomic analysis revealed that influenza virus infection depleted lung glutathione persulfide (GSSH), while NAC-S2 effectively restored tissue GSSH levels. NAC-S2 treatment markedly reduced pulmonary interleukin (IL)-1β and IL-6 production without affecting viral load or Type-I interferon responses. Furthermore, NAC-S2 suppressed NLRP3 inflammasome activation and gasdermin D expression, leading to decreased infiltration of CD3⁺ T cells and myeloperoxidase-positive neutrophils. Histopathological analyses confirmed that NAC-S2 ameliorated epithelial injury, interstitial edema, and hemorrhage in infected lungs. Collectively, our findings demonstrate that NAC-S2 exerts therapeutic benefit even after the onset of severe influenza pneumonia, primarily by replenishing supersulfides and alleviating excessive inflammatory responses. Supersulfide donors represent a promising class of adjunctive therapeutics for severe viral pneumonia.

This study compared bacterial counts and composition in plastic-bottled green tea beverages immediately after direct drinking and after storage at 37°C for 1 day. Immediately after drinking, (1.9 ± 1.6) × 10³ and (4.5 ± 3.9) × 10³ colony forming units (CFU)/mL were recovered from standard green tea and strong green tea, respectively. After 1 day of storage, (1.3 ± 1.5) × 10⁴ and (1.6 ± 3.1) × 10³ CFU/mL were recovered from standard green tea and strong green tea, respectively. Following storage, Lacticaseibacillus spp., Streptococcus, and Veillonella were isolated from both beverages.

Bovine leukemia virus (BLV) is widespread globally and causes economic losses in the cattle industry. Shandong Province plays a significant role in China's livestock industry, with an increasing importance in food of Holstein and Angus cattle. However, BLV prevalence in Holstein and Angus breeds in Shandong Province remains unclear. In particular, there are no reports of BLV prevalence of Angus cattle in field surveys worldwide. In this study, 613 samples from six large-scale farms (> 1000 heads per farm) in Binzhou and Weifang cities were screened for BLV antibodies (gp51) using an enzyme-linked immunosorbent assay. The samples included 303 Angus (beef) and 310 Holstein (dairy) cattle. All Angus breeding samples from the three farms were BLV-negative at both the animal- and herd-level prevalences. In contrast, 62 of 310 Holstein cattle (20.0%) from three dairy farms were positive for BLV antibodies. For example, 35/110 (31.8%), 19/100 (19.0%), and 8/100 (8.0%) samples from the D, E, and F farms, respectively, were BLV-positive. Notably, the animal- and herd-level prevalences for Holstein cattle exhibited 20% and 100% positivity, respectively. These findings offer significant insights into the BLV status of Holstein and Angus cattle in Shandong Province, China.

Among the three prion strains of bovine spongiform encephalopathy (BSE), classical BSE (C-BSE) prions are known causative agents of variant Creutzfeldt-Jakob disease. By contrast, human infections with L-type (L-) or H-type (H-) BSE prions have not been reported. Nonetheless, the zoonotic potential of L-BSE prions is supported by their successful primary transmission from cattle to cynomolgus macaque (Macaca fascicularis) monkeys via intracranial challenge. To assess whether the defining strain traits of L-BSE prions remain stable following secondary intraspecies transmission, we prepared brain homogenates from a diseased macaque that had previously undergone primary transmission of L-BSE prions, and intracranially administered them into two naïve macaques. Both animals succumbed to the disease within humane endpoints comparable to those observed in the primary transmission. Histopathological and immunohistochemical analyses of brain tissues showed no significant changes relative to primary transmission, including severe vacuolation and fine synaptic distribution of disease-associated forms of prion protein (PrP^Sc) in the cerebrum, and sparse PrP^Sc plaques in the cerebellum. In bioassays using C57BL/6 J mice, cattle-derived L-BSE prions and those passaged once or twice in macaques failed to transmit to mice, whereas cattle-derived C-BSE prions and their macaque-passaged counterparts were transmissible. These findings refine our understanding of L-BSE pathogenesis and confirm the stability of L-BSE prions following intracranial transmission in a nonhuman primate model.

Enterococci are commensal bacteria in humans that are found in the intestine, pharynx and oral cavity and sometimes cause opportunistic infections such as intra-abdominal infections and bacteraemia. Several enterococcal species, especially E. faecium and E. faecalis, have become clinical problems as drug-resistant bacteria, including vancomycin-resistant Enterococci (VRE). Therefore, new antibacterial agents against enterococcal infections are needed. Because several fatty acids (FAs) have been reported to possess antibacterial activity, in this study, the effects of 3 unsaturated fatty acids on enterococci were evaluated using clinically isolated strains. Among the 3 fatty acids we tested, linoleic acid (LA) and palmitoleic acid (POA) exhibited antibacterial activity against E. faecalis and E. faecium. Next, we evaluated the antibacterial activities of the two FAs against 126 enterococcal clinical strains, including five different species. The minimum inhibitory concentration (MIC) of LA varied among bacterial species and strains (ranging from 37.5 to 1200 μM), while the MIC of POA was similar (ranging from 37.5 to 150 μM). Among species, E. faecium strains presented higher MICs than E. faecalis, E. avium and E. casseliflavus strains. In 6 VRE strains, the MICs of LA showed variable (150-1200 μM), whereas MICs of POA were constant at 75 μM. We subsequently investigated the combined effects of LA and POA with several antibiotics and found that LA had synergistic effects with β-lactam, gentamicin, ciprofloxacin and vancomycin against E. faecalis and E. faecium strains, including VRE, whereas POA did not have a significant effect. Our results indicate the potential application of FAs for enterococcal infection.