Medical Microbiology and Immunology最新文献

Enterovirus A71 (EV-A71) infection is known to cause hand-foot-mouth disease, which may develop severe symptoms such as encephalitis, herpangina, and paralysis, leading to pulmonary edema and even death in children under five years old. Existing animal models for EV-A71 pathogenesis have limitations, necessitating novel models to study human-relevant disease mechanisms. Using glycoproteomic profiling to identify EV-A71-interacting proteins, we previously discovered human nucleolin (hNCL) as an attachment molecule that enhances viral binding and infection in vitro. Here, we developed human nucleolin transgenic (hNCL-Tg) mice to investigate EV-A71 pathogenesis in vivo. Compared to wild-type (WT) mice, EV-A71-infected hNCL-Tg mice exhibited higher clinical scores, progressive limb paralysis, and increased mortality. Six days post-infection, hNCL-Tg mice showed elevated viral loads in the spinal cord and skeletal muscle, with pronounced EV-A71 VP1 expression in these tissues and the brainstem. Histopathology revealed severe skeletal muscle damage and significant pulmonary edema, characterized by lung congestion, hemorrhage, and erythrocyte infiltration into alveoli. Infected hNCL-Tg mice also displayed elevated levels of encephalitis- and pulmonary edema-associated proinflammatory cytokines (IL-1β, IL-6, IL-13). These findings establish the hNCL-Tg mouse as a robust model for studying EV-A71 pathogenesis and evaluating preclinical therapeutics.

Hepatitis E virus (HEV) has attracted increasing attention in transfusion medicine in recent years. Mandatory testing regimes in Europe have resulted in not only ensuring the safety of blood products, but also providing information on the spread and immunology of HEV infections. We tracked a cohort of 497 donors identified as HEV RNA-positive during blood donation. Several follow-up samples were collected and serologically analyzed for 370 of them, up to five years after the index donation. In addition to the expected increase in immunoglobulins M (IgM) and G (IgG) titers at the beginning and the decrease over the years, we observed a proportion of 7.3% with positive anti-HEV IgM (long-term IgM-positive) and 9.1% with negative anti-HEV IgG (seroreversion) in five-year follow-ups, determined by serological tests from three different manufacturers. Both phenomena have an impact on the assessment of the correlation between incidence and seroprevalence. They are dependent on the sensitivity and specificity of serologic assays used and have a sex bias, which indicates a stronger, longer-lasting humoral immune response in women. These data offer new insights into the long-term development of immunity to HEV and thus complement short-term epidemiological data on the incidence and seroprevalence that have been obtained so far.

With around 2 billion cases each year, infectious gastroenteritis remains a worldwide health problem. A major cause of acute gastroenteritis is infection with enteric viruses, which often leads to hospitalization in children and immunocompromised people. We adapted and validated a gastrointestinal qPCR panel, which simultaneously detects the most common enteric viruses: Norovirus GI and GII, Rotavirus, Adenovirus, Sapovirus, Astrovirus and Enterovirus in stool samples on a fully automated, high-throughput system (Roche cobas5800/6800/8800). Limits of detection (LOD), linear range and precision were determined using dilutions of clinical stool samples, which were quantified by digital droplet PCR. Specificity and sensitivity were evaluated using clinical stool samples from patients with diarrhoea and results were compared with commercial CE-IVD qPCR assays. LODs were below 100 for all targets except for Norovirus GI (3,180 copies/ml), Norovirus GII (299 copies/ml) and Rotavirus (851 copies/ml). The assay showed excellent linearity over 5-6 log steps for all pathogens (r²: 0.992-0.998). For inclusivity External Quality Assessment samples were correctly identified, and no false positives occurred in exclusivity panels containing 26 bacterial isolates and 12 clinical virus samples. Specificity and sensitivity determined by using 243 patient samples ranged between 98.2 and 100.0% and 85.7-100.0%, respectively. In this study we validated a lab-developed syndromic qPCR assay that reliably detects the seven most common enteric viruses in clinical stool samples. Our assay provides a fast, fully automated and easily scalable high-throughput solution for gastrointestinal routine virus testing and screening in high-risk patient groups and outbreaks.

Airway epithelial cells play a pivotal role in the early host response to Mycoplasma pneumoniae colonization. Our previous study has revealed that M. pneumoniae infection induces metabolic reprogramming in bronchial epithelial cells. However, the mechanisms underlying these metabolic shifts and their contribution to the pathogenesis of pneumonia remain unclear. Herein, we demonstrate that M. pneumoniae infection activates signal transducer and activator of transcription 3 (STAT3), which drives citrate accumulation in airway epithelial cells. Citrate is metabolized by adenosine triphosphate-citrate lyase (ACLY) into acetyl coenzyme A, which is further converted to malonyl coenzyme A, promoting post-translational modifications such as histone acetylation and glyceraldehyde-3-phosphate dehydrogenase malonylation (GAPDH). In vivo, pharmacological inhibition of STAT3 or ACLY attenuated pulmonary inflammation and pro-inflammatory cytokine expression yet paradoxically delayed pathogen clearance, as evidenced by increased colonyforming units in bronchoalveolar lavage fluid and lung tissue. These findings demonstrate that targeting the STAT3/ACLY axis exerts antiinflammatory potential without direct antibacterial activity. Our work highlights the dual regulatory roles of citrate metabolism in inflammation and pathogen control and suggests that combined use of STAT3/ACLY inhibitors with conventional antibiotics may be necessary to achieve both immunomodulation and effective bacterial eradication.

Bacterial superantigens are potent immune activators that trigger T cell proliferation and intensive release of cytokines, leading to toxic shock syndrome. Also, they impair host immune responses, increasing bacterial carriage and transmission. Several studies proposed that superantigens can induce regulatory T (Treg) cells, which may suppress immune responses against bacterial infection. However, the mechanism of Treg cell induction by superantigens is still elusive. We here demonstrated that streptococcal pyrogenic exotoxin A (SPEA) promoted human CD4⁺CD25⁺Foxp3⁺ T cell induction in a dose- and time-dependent manner and the induction required antigen-presenting cells (APCs). SPEA-induced CD4⁺CD25⁺ T cells could suppress allogeneic T cell proliferation and IL-2 secretion. Flow cytometric analyses demonstrated high expression of TNFR2 on SPEA-induced CD4⁺CD25⁺Foxp3⁺ T cells. Blocking the interaction between TNF-⍺ and TNFR2 reduced SPEA-induced CD25⁺Foxp3⁺ Treg cells. Our present study suggests a mechanism that the TNF-⍺ and TNFR2 axis is required for the induction of human CD4⁺CD25⁺Foxp3⁺ Treg cells by SPEA, which implicates a potential strategy to enhance the clearance of Group A streptococcus infection through reducing Treg cell induction by the inhibition of TNFR2 signaling.

Toll-like receptor (TLR) 9 ligand has been reported to induce the formation of intrahepatic myeloid-cell aggregates for T cell population expansion (iMATEs), which enhances responses of cytotoxic T lymphocytes (CTLs). However, little is known about how the formation of iMATEs is regulated. Previously, various studies have demonstrated that regulatory T cells (Tregs) can suppress CTL responses through soluble cytokines or co-inhibitory molecules. It's unclear whether and how Tregs regulate the formation of iMATEs. In this study, we investigated whether Tregs are involved in regulating TLR9-induced iMATEs formation and the mechanisms behind it by using different gene knockout mice and blocking antibodies. We observed that intravenous injection of TLR9 ligand CpG induced significant iMATEs formation, accompanied by a marked increase in the number of Tregs infiltrating the liver as well as upregulation of IL-10 in both peripheral blood and liver. Importantly, depletion of Tregs either by anti-CD4, anti-CD25 blocking antibodies or diphtheria toxin (DT) in DEREG transgenic mice resulted in enhanced CpG-induced iMATEs formation. Conversely, knocking out IL-10 led to increased intrahepatic Treg infiltration and decreased CpG ODN-induced iMATEs formation. Consistently, depleting Kupffer cells (KCs), one of the main source of IL-10, also resulted in reduced formation of iMATEs. In conclusion, our results suggest that IL-10 suppresses Treg infiltration in the liver and thus promote CpG ODN-induced iMATEs formation. These results fill the gap in our understanding of the intrahepatic regulation mechanism of iMATEs formation.

The pathological basis of many visual disorders involves the abnormal viability and migration of retinal pigment epithelium (RPE) cells. Complement response disorder is a significant pathogenic factor causing some autoimmune and inflammation diseases. The complement activation product anaphylatoxin C5a signaling pathway may be associated with RPE cell dysfunction. This study aimed to analyze the molecular mechanisms by which C5a affects RPE cell viability and migration. Recombinant human complement component C5a protein stimulated RPE cells. Cell biological behavior, including cell viability, invasion, and migration were analyzed with Cell Counting Kit-8 and transwell methods. Bioinformatics analysis identified the differentially expressed genes (DEGs) involved in C5a-treated RPE cells based on RNA sequencing. SLC38A1 was knocked down or overexpressed by vector transfection to investigate its involvement in C5a-stimulated RPE cells. C5a promotes RPE cell viability and migration. C5a-induced DEGs are enriched in migration-associated pathways. C5a increased SLC38A1, and SLC38A1 knockdown or overexpression inhibited or promoted RPE cell viability and migration. Glutaminase inhibition abrogated the promoting effect of C5a and SLC38A1 on cell biological behaviors. METTL3-HNRNPC-mediated m6A modification mediated C5a-induced SLC38A1. C5a, METTL3, and SLC38A1 constituted a signaling axis in regulating cell biological behaviors of C5a-treated RPE cells. C5a promotes RPE cell viability and migration, and SLC38A1-mediated improved glutamine metabolism is the downstream signal pathway of the C5a complement pathway. The C5a complement system may target the SLC38A1 to promote RPE cell migration.

IgG antibodies against terminal galactose-α-1,3-galactose (anti-αGal antibodies) are naturally occurring in humans, but their origins remain poorly understood. These antibodies target various microorganisms including Staphylococcus aureus, a common nasal commensal and the major cause of skin abscesses. This study investigates the impact of S. aureus colonization and abscess events on plasma anti-αGal antibody levels. We measured plasma anti-αGal antibody levels using a quantitative immunoassay in: (i) 101 pairs of healthy individuals with and without nasal S. aureus colonization, (ii) 106 healthy individuals before and after abscess formation, and (iii) 43 patients with recurrent skin abscesses compared with 75 patient controls and 60 healthy controls. We observed a 35% reduction (95%CI: 7-54%) in anti-αGal antibody levels in nasal S. aureus carriers. Conversely, we found a 30% increase (95%CI: 4-66%) in individuals within 187 days post-skin abscess, and patients with recurrent skin abscesses exhibited 81% higher (95%CI: 14-190%) levels than patient controls, and 110% higher (95%CI: 39-230%) than healthy controls. This study suggests that skin abscesses lead to elevated plasma anti-αGal antibody levels and that these antibodies might convey or correlate with mucosal immunity to S. aureus.