Microbes and Infection最新文献

Mycobacterium avium is a slow-growing non-tuberculous mycobacterium. While its medical importance is increasing, its virulence is only poorly characterized. A highly virulent M. avium strain ATTC25291 (MAA25291) has been shown to cause severe disease in mice by survival and growth in nitric oxide (NO) producing, immune suppressive monocytic-MDSC (M-MDSC). The induction and persistence of MAA25291 in M-MDSC is still unresolved. In the present study, we were interested in the role of M-MDSC in mice infected with MAA25291 at infection doses that led to the manifestation of clinical disease (high dose) or subclinical disease (low dose). Flow cytometry revealed the presence of M-MDSC in both infection groups, however, this infiltration was significantly lower after low dose infection. Histopathology showed lower infiltration of NOS2 expressing cells in spleen and liver correlated with high CD3⁺ T cell numbers after low dose infection, whereas high dose infection of mice led to T cell losses in the tissues. This study highlights that the infection dose significantly affects M-MDSC induction and their immune regulatory roles. Furthermore, it suggests that the induction and persistence of MAA25291 in M-MDSC relies on the amount of NO production.

Background: Cathepsin play a crucial role in the progression of various diseases, including cancer, neurodegenerative disorders, and processes involving inflammation and immune modulation. The global pandemic of COVID-19 has heightened the need for further exploration into the interactions between cathepsin and the virus, and their impact on disease progression.

Methods: This study employed Mendelian randomization to analyze the causal relationships between specific genetically predicted plasma cathepsin and COVID-19 outcomes, both severe and non-severe. Using data from genome-wide association studies, we evaluated the associations of genetically predicted plasma levels of cathepsin B, D, F, and S with susceptibility to and severity of COVID-19.

Results: An increase in genetically predicted circulating cathepsin S levels might be associated with a reduced susceptibility risk to COVID-19 (P < 0.05). Furthermore, while there appears to be a correlation where increased susceptibility to COVID-19 leads to elevated levels of genetically predicted circulating cathepsin F and a reduction in genetically predicted cathepsin S levels (P < 0.05), these associations should be interpreted with caution. There is also suggestive evidence of a causal association between the progression of COVID-19 severity and increased levels of genetically predicted circulating cathepsin F (P < 0.05). However, due to the inherent limitations of the Mendelian randomization approach, further studies are warranted to substantiate these initial findings.

Conclusion: This study highlights the potential role of cathepsin in the pathophysiology of COVID-19 and suggests that modulating the expression or activity of these enzymes could influence susceptibility and disease severity. These findings provide a new perspective on the interaction between genetically predicted plasma cathepsin and COVID-19, suggesting further research is needed to explore the mechanisms behind these findings and the potential efficacy of interventions targeting specific cathepsin in the prevention or treatment of COVID-19.

Pathogenic Leptospira spp. evade the complement system by capturing soluble regulators of the alternative, classical, and lectin pathways - such as factor H, C4BP, and vitronectin - via proteins on their surface. By capturing these regulators, Leptospira can disrupt the complement activation cascade, thereby preventing opsonization by C3b/iC3b and lysis by the membrane attack complex (MAC). The ability of low-passage pathogenic Leptospira strains - LOCaS46 (L. interrogans sv Canicola), LOVe30 (L. interrogans sv Icterohaemorrhagiae), and MOCA45 (L. santarosai sv Tarassovi) - to bind C4BP was evaluated and compared to their corresponding culture-attenuated (LOCaS46, LOVe30, and MOCA45) and to the saprophytic Patoc I strain of Leptospira biflexa sv Patoc. Binding to C4BP was assessed by ELISA and confirmed by Western blot, the expression level of the genes for C4BP-binding proteins was evaluated by RT-qPCR, and the survival of the Leptospira spp. strains in normal human serum (NHS) was estimated to assess complement resistance. Results showed that culture attenuated (CA) strains had a lower capacity for binding to C4BP, and surviving to NHS as compared to low-passage (LP) strains. Also, transcription level of the genes for the C4BP-binding proteins LigA, LigB, LcpA, enolase and Lsa23, was lower in the CA strains than in their corresponding LP strains. This suggest that reduction of the ability to capture C4BP in culture attenuated (CA) strains is due at least in part to lower expression of C4BP-binding proteins, affecting the evasion of classical and lectin pathways of the complement system and therefore the capability of survival in NHS.

This study aims to compare the clinical, laboratory, and therapeutic outcomes between acute and subacute/chronic phases of brucellosis and to identify independent predictors of a favorable treatment response. This retrospective observational and analytic study included 171 patients with brucellosis, categorized as acute (n = 146) or subacute/chronic (n = 25). A therapeutic response was defined as the complete resolution of initial symptoms with no relapse during a 12-month follow-up. A serological response was defined as a ≥4-fold decrease in the serum tube agglutination (STA) titer post-treatment. Outcomes were compared using appropriate statistical tests (p < 0.05), and logistic regression was used to identify predictors of response. Compared to the subacute/chronic group, patients with acute brucellosis had a significantly higher frequency of leukopenia (21.2 % vs. 0 %; p < 0.01), elevated C reactive protein (CRP) (76.7 % vs. 52.0 %; p = 0.01), and elevated transaminases (43.8 % vs. 20.0 %; p = 0.025). A significantly higher therapeutic response rate was observed in acute cases (93.2 %) compared to subacute/chronic cases (0.76 %) (p = 0.01). Multivariate analysis identified elevated baseline CRP (OR: 4.00; p = 0.02) and a post-treatment decrease in STA titer (OR: 5.84; p = 0.007) as independent predictors of a favorable therapeutic response. In conclusion, acute brucellosis presents with a more pronounced inflammatory profile than subacute/chronic forms. While patients with acute brucellosis demonstrated a significantly higher therapeutic response rate, the serological response was also more pronounced in this group. Elevated CRP at diagnosis and a significant decrease in STA titer post-treatment are strong, independent predictors of successful outcomes, highlighting their value in patient monitoring.

Severe fever with thrombocytopenia syndrome (SFTS) is a life-threatening tick-borne viral infection with a high mortality rate and limited treatment options. While gastrointestinal symptoms are common, the contribution of gut microbiome disruption to disease progression remains unclear. Previous studies have noted taxonomic shifts in SFTS-associated microbiota, but their functional and metabolic consequences have not been systematically characterized. We conducted an integrated metagenomic and metabolomic analysis of fecal samples from 20 SFTS patients and 20 healthy controls. At the time of admission, patients with SFTS exhibited acute-stage infection, characterized by symptoms such as fever, thrombocytopenia, and gastrointestinal disturbances. Metagenomic sequencing was used to assess the microbial gene content, taxonomic composition, and functional potential. Untargeted metabolomics analysis using liquid chromatography-tandem mass spectrometry (LC-MS/MS) was performed to profile fecal metabolites. The SFTS patients showed a significantly reduced microbial gene richness, alpha diversity, and compositional stability. Short-chain fatty acid (SCFA)-producing genera (e.g., Faecalibacterium and Roseburia) were depleted, while mucin-degrading and opportunistic taxa (e.g., Pseudomonas and Akkermansia) were enriched. Functionally, biosynthetic and homeostatic pathways were suppressed; while stress-adaptive, biofilm-forming, and virulence-associated pathways were elevated. Metabolomic profiling revealed depletion of anti-inflammatory metabolites (e.g., bile acids and curcumin sulfate) and enrichment of proinflammatory compounds (e.g., porphyrins and beta-tyvelose). Multi-omic correlation highlighted strong links between microbial disruption and altered metabolite production. In conclusion, SFTS is associated with significant alterations in the gut microbiome and its metabolic profile, which is characterized by the loss of beneficial microbial taxa and functions, alongside the emergence of virulence factors and stress-related signatures. These findings underscore the role of microbiome dysfunction in SFTS and suggest that microbiota-targeted strategies may offer supportive benefits, particularly in alleviating SFTS-associated gastrointestinal disturbances and secondary microbial imbalance.

Background: Toxoplasmosis, caused by the protozoan Toxoplasma gondii, is a public health problem, especially in congenital infections. Current treatments, with spiramycin or pyrimethamine and sulfadiazine, are highly toxic, prompting the search for effective and safe natural alternatives.

Objective: This study evaluated the in vitro effect of caffeic acid (CA) on human extravillous trophoblast cells (HTR8/SVneo) infected by T. gondii.

Methods: The microbicidal and metabolic activity of CA against free tachyzoites was analyzed, in addition to its immunological and anti-Toxoplasma action in infected trophoblast cells.

Results: The compound was able to reduce the viability of tachyzoites (IC₅₀ 5 μg/mL) without any toxicity to the trophoblast cells (CC₅₀ 1950 μg/mL); in addition, it reduced the proliferation and infection by tachyzoites at all concentrations tested (5-50 μg/mL). CA also induced changes to the parasite's morphology, including mitochondrial integrity loss, increased production of reactive oxygen species, nitric oxide, exposure to phosphatidylserine and loss of plasmatic membrane integrity, characterizing an apoptosis-like process. Furthermore, there was an increase in interleukins interleukin-1 beta (IL-1β), macrophage migration inhibitory factor (MIF) and transforming growth factor beta (TGF-β) in the T. gondii infected HTR8/SVneo cells.

Conclusion: CA is a potential candidate for further research aimed at the development of novel therapies for congenital toxoplasmosis.

Bovine viral diarrhea virus (BVDV) is a major pathogen in cattle, causing significant economic losses and frequently contaminating cell cultures through fetal calf serum, which can compromise biological products. Gene editing technologies, such as CRISPR/Cas9, offer promising tools for developing disease-resistant models. CD46, the primary cellular receptor for BVDV, has an incompletely understood role in viral infection. This study aimed to: (i) characterize and compare CD46 between bovine cell lines resistant (CRIB) and susceptible (MDBK); (ii) edit the BVDV-binding region of MDBK-CD46; and (iii) evaluate the susceptibility of CD46-edited MDBK cells to BVDV infection. CD46 was sequenced in BVDV-sensitive MDBK cells, BVDV-resistant CRIB cells, and bovine fibroblasts. CRISPR/Cas9 was used to delete exon 1 of CD46, which encodes the viral attachment platform. Two guide RNAs were cloned into px458 plasmids expressing GFP and co-transfected into MDBK cells. Genomic DNA was PCR-amplified, cloned, and sequenced. Results showed that CRIB cells express a wild-type CD46 protein, suggesting that CD46 is not responsible for their resistance to BVDV. This resistance is likely due to the truncated ADAM17 in CRIB cells, which may alter membrane composition and endocytic pathways, affecting viral entry. Three edited MDBK cell lines were generated: two with homozygous deletions (A and B), and one with a heteroallelic edit (C). The edited lines A and B exhibited over 90 % resistance to BVDV. These findings support the use of gene editing to generate BVDV-resistant models and to further explore alternative viral receptors and entry pathways.

This study characterizes the alterations in peripheral blood lymphocyte subsets and cytokine levels in patients with respiratory syncytial virus (RSV) infection and evaluates their clinical relevance. We collected clinical data from 215 RSV-positive inpatients. Patients were stratified into distinct groups according to different criteria; within-group comparisons were performed. In the RSV-infected group, absolute counts of all peripheral blood lymphocyte subsets were significantly lower than in controls and showed a negative correlation with disease severity. Conversely, all measured cytokines were markedly elevated in the infected group and positively correlated with the severity of RSV infection. Within the infected group, elderly patients (≥65 years) showed significantly different lymphocyte-subset counts and cytokine profiles compared with non-elderly patients. Similarly, individuals with high-risk diseases exhibited significant differences in these parameters relative to those without such diseases. RSV infection induces abnormalities in peripheral blood lymphocyte subsets and cytokine levels. The magnitude of these immune changes is linked to disease severity, patient age, and selected comorbidities, suggesting their potential utility as adjunct biomarkers for clinical assessment.

Campylobacter jejuni is the major bacterial cause of foodborne gastroenteritis worldwide. How this pathogen interacts with the host defence machinery of human intestinal epithelial cells (IECs) and is involved in pathogenesis remains elusive. Bacterial pathogens utilise strategies to gain access to the eukaryotic cell machinery that can involve subversion of biological processes in host. Unfolded protein response (UPR) is a highly conserved host cell stress response to the accumulation of misfolded proteins in the endoplasmic reticulum (ER) and is a conserved evolutionary response against invading pathogens. Several bacterial pathogens can induce the UPR for their own survival and thus design a dual scenario where UPR can both protect and facilitate pathogen evasion. Herein, we investigated whether UPR represents a virulence mechanism exploited by C. jejuni during bacterial invasion in human IECs. Our data show that following C. jejuni infection, we observe consistent upregulation of protein kinase R-like ER kinase (PERK), inositol-requiring enzyme 1α and (IRE1α), with activating transcription factor 6 (ATF6) activation occurring in a strain- and cell line-dependent manner. Chemical induction of UPR by thapsigargin in host cells reduced intracellular survival of C. jejuni while conversely pretreatment with UPR inhibitors increased intracellular survival of C. jejuni and attenuated IL-8 release. Finally, we show using C. jejuni mutants that the capsular polysaccharide and flagella contribute to UPR activation in IECs. Collectively, these findings provide observational insights into UPR activation during infections and how C. jejuni infection leads to UPR activation and inflammation, potentially contributing to downstream C. jejuni-mediated damage.