The subversion of toll-like receptor signaling by bacterial and viral proteases during the development of infectious diseases

Pharmacological mechanisms of probenecid for SARS-CoV-2 and RSV co-infection: findings of system pharmacology, molecular docking, molecular dynamics simulation, and structure-activity relationship

Background

The clinical consequences of the co-infection with novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and respiratory syncytial virus (RSV) are not optimistic. Nevertheless, there is currently no approved therapeutic regimen specifically targeting SARS-CoV-2/RSV co-infection, with existing monotherapies showing limited efficacy. According to recent studies, probenecid has both anti-SARS-CoV-2 and anti-RSV effects. Therefore, as one probable molecular candidate for the co-infection with SARS-CoV-2 and RSV, probenecid was researched in this exploration.

Methods

Using systems pharmacology and bioinformatics, we characterized the targets associated with probenecid for the treatment of SARS-CoV-2/RSV co-infection, focusing on their biological functions, mechanisms and binding activities. To further validate these findings, we conducted molecular docking, MD simulations, electrostatic potential mapping, and SAR analysis to explore the binding interactions between probenecid and the identified core targets.

Results

We identified 141 targets that overlapped with the co-infection and probenecid, and used these shared targets to construct a protein-protein interaction (PPI) network. Subsequently, we obtained the top 16 hub targets of probenecid for SARS-CoV-2/RSV co-infection, namely, AKT1, ALB, EGFR, CASP3, CTNNB1, SRC, HSP90AA1, and so on. According to the enrichment analysis, probenecid might affect inflammation, immunity, oxidative stress, and virus defenses; Toll-like receptor, TNF, IL-17, NOD-like receptor, cytokine-cytokine receptor, among others. Additionally, based on molecular docking analysis, probenecid is effectively bound to the targets related to the SARS-CoV-2/RSV co-infection. Meanwhile, according to molecular dynamics (MD) simulations and structure-activity relationship (SAR) analysis, we speculated that SRC and HSP90AA1 are more likely to be the target proteins of probenecid than the other proteins.

Conclusion

Our findings from systems pharmacology and bioinformatics analysis indicate that immune and inflammatory responses play a pivotal role in the therapeutic effects of probenecid. Infectious disease-related pathways also contribute significantly to its effectiveness in treating SARS-CoV-2/RSV co-infection. Further validation was conducted through molecular docking, MD simulations, electrostatic potential mapping, and SAR analysis. These analyses suggest that SRC and HSP90AA1 are the potential binding targets of probenecid. This study provides valuable preliminary insights into the molecular mechanisms of probenecid. It establishes a strong foundation for future research to explore its potential as a therapeutic strategy for SARS-CoV-2/RSV co-infection.

Bidirectional Interaction Between Chronic Kidney Disease and Porphyromonas gingivalis Infection Drives Inflammation and Immune Dysfunction

Introduction: Chronic kidney disease (CKD) is characterized by a decline in renal function, increased mortality, and significant impairments in the immune system and function of immune cells. These alterations are often derived by uremic toxins, which, in turn, modify the immune system's response to infections. Our research investigates the progression of Porphyromonas gingivalis (P. gingivalis) infection during CKD and its subsequent impact on kidney failure. Methods: We utilized two infectious models, a chamber model representing short-term local inflammation and alveolar bone loss that mimic chronic infection of periodontium, both in conjunction with a CKD model. Additionally, our in vitro studies employed primary macrophages, osteoclasts, and lymphocytes to characterize the immune responses to P. gingivalis and pathogen-associated molecular patterns (PAMPs) in the presence of uremic toxins. Results and Conclusion: Our findings demonstrate that uremic toxins, such as indoxyl sulfate (IS), alter responses of macrophages and lymphocytes to P. gingivalis. In vivo, CKD significantly enhanced P. gingivalis survival and infection-induced alveolar bone loss. The increased distribution of pathogen within peripheral tissues was associated with altered inflammatory responses, indicating that CKD promotes infection. Moreover, P. gingivalis-infected mice exhibited a marked increase in renal inflammation, suggesting that the relationship between uremia and infection is bidirectional, with infection exacerbating kidney dysfunction. Furthermore, we observed that infected CKD mice exhibit decreased serum immunoglobulin G (IgG) levels compared to infected mice without CKD, implying that uremia is associated with immune dysfunction characterized by immunodepression and impaired B lymphocyte function.

Deep insight into cytokine storm: from pathogenesis to treatment

Cytokine storm (CS) is a severe systemic inflammatory syndrome characterized by the excessive activation of immune cells and a significant increase in circulating levels of cytokines. This pathological process is implicated in the development of life-threatening conditions such as fulminant myocarditis (FM), acute respiratory distress syndrome (ARDS), primary or secondary hemophagocytic lymphohistiocytosis (HLH), cytokine release syndrome (CRS) associated with chimeric antigen receptor-modified T (CAR-T) therapy, and grade III to IV acute graft-versus-host disease following allogeneic hematopoietic stem cell transplantation. The significant involvement of the JAK-STAT pathway, Toll-like receptors, neutrophil extracellular traps, NLRP3 inflammasome, and other signaling pathways has been recognized in the pathogenesis of CS. Therapies targeting these pathways have been developed or are currently being investigated. While novel drugs have demonstrated promising therapeutic efficacy in mitigating CS, the overall mortality rate of CS resulting from underlying diseases remains high. In the clinical setting, the management of CS typically necessitates a multidisciplinary team strategy encompassing the removal of abnormal inflammatory or immune system activation, the preservation of vital organ function, the treatment of the underlying disease, and the provision of life supportive therapy. This review provides a comprehensive overview of the key signaling pathways and associated cytokines implicated in CS, elucidates the impact of dysregulated immune cell activation, and delineates the resultant organ injury associated with CS. In addition, we offer insights and current literature on the management of CS in cases of FM, ARDS, systemic inflammatory response syndrome, treatment-induced CRS, HLH, and other related conditions.

Biomarkers (NLR, PLR, SII) for Frequent COPD Exacerbations: Diagnostic and Clinical Management Implications in a Retrospective Study

Objective

To evaluate the diagnostic and predictive value of the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and systemic immune-inflammation index (SII) for frequent exacerbations of chronic obstructive pulmonary disease (AECOPD), and to develop a risk stratification scoring system to optimize clinical management in resource-limited healthcare settings.

Patients and Methods

This retrospective observational study enrolled 16,849 AECOPD patients, categorized into frequent exacerbators (≥2 exacerbations/year, n=3,488) and non-frequent exacerbators (<2 exacerbations/year, n=13,361). Comparative analyses of clinical characteristics and inflammatory biomarkers (NLR, PLR, SII, CRP, PCT) were conducted. Spearman correlation, receiver operating characteristic (ROC) curve analysis, and binary logistic regression were employed to assess biomarker performance. A risk scoring system was developed using odds ratios (OR) and regression coefficients (β) of NLR and PLR.

Results

The frequent exacerbators group exhibited significantly higher median NLR (6.71 vs 5.10, P < 0.001), mean PLR (239 ± 204 vs 218 ± 195, P < 0.001), and median SII (1,137.48 vs 847.54, P < 0.001). NLR, PLR and SII showed strong positive correlations with CRP and PCT (P < 0.001). ROC analysis identified NLR (specificity = 84.1%) and PLR (sensitivity = 55%) as optimal diagnostic indicators. Regression analysis confirmed NLR and PLR as independent risk factors for frequent exacerbations. The risk stratification system categorized patients into low-risk (<290 points; annual exacerbation rate 17%), intermediate-risk (290-768 points; 19.1%), and high-risk (>768 points; 23.4%) groups.

Conclusion

NLR and PLR serve as cost-effective biomarkers for identifying high-risk frequent exacerbators patients with COPD in primary care settings. The percentile-based scoring system enables management strategies to address clinical needs in resource-constrained healthcare environments.

Targeting Bacteria-Induced Ferroptosis of Bone Marrow Mesenchymal Stem Cells to Promote the Repair of Infected Bone Defects

The specific mechanisms underlying bacteria-triggered cell death and osteogenic dysfunction in host bone marrow mesenchymal stem cells (BMSCs) remain unclear, posing a significant challenge to the repair of infected bone defects. This study identifies ferroptosis as the predominant cause of BMSCs death in the infected bone microenvironment. Mechanistically, the bacteria-induced activation of the innate immune response in BMSCs leads to upregulation and phosphorylation of interferon regulatory factor 7 (IRF7), thus facilitating IRF7-dependent ferroptosis of BMSCs through the transcriptional upregulation of acyl-coenzyme A synthetase long-chain family member 4 (ACSL4). Moreover, it is found that intervening in ferroptosis can partially rescue cell injuries and osteogenic dysfunction. Based on these findings, a hydrogel composite 3D-printed scaffold is designed with reactive oxygen species (ROS)-responsive release of antibacterial quaternized chitosan and sustained delivery of the ferroptosis inhibitor Ferrostatin-1 (Fer-1), capable of eradicating pathogens and promoting bone regeneration in a rat model of infected bone defects. Together, this study suggests that ferroptosis of BMSCs is a promising therapeutic target for infected bone defect repair.

Proteomics analysis of PK-15 cells infected with porcine parvovirus and the effect of PCBP1 on PPV replication

Porcine parvovirus (PPV) is one of the most important pathogens that cause reproductive failure in pigs. However, the pathogenesis of PPV infection remains unclear. Proteomics is a powerful tool to understand the interaction between virus and host cells. In the present study, we analyzed the proteomics of PPV-infected PK-15 cells. A total of 32 and 345 proteins were differentially expressed at the early and replication stages, respectively. Subsequent gene ontology annotation and Kyoto Encyclopedia of Genes and Genomes enrichment analysis showed these differentially expressed proteins were significantly enriched in pathways including toll-like receptor signaling pathway, tumor necrosis factor signaling pathway, and viral carcinogenesis. The expression of poly (rC) binding protein 1 (PCBP1) was observed to decrease after PPV infection. Overexpressed or silenced PCBP1 expression inhibited or promoted PPV infection. Our studies established a foundation for further exploration of the multiplication mechanism of PPV.

IMPORTANCE

Porcine parvovirus (PPV) is a cause of reproductive failure in the swine industry. Our knowledge of PPV remains limited, and there is no effective treatment for PPV infection. Proteomics of PPV-infected PK-15 cells was conducted to identify differentially expressed proteins at 6 hours post-infection (hpi) and 36 hpi. Gene ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analysis showed that various pathways participate in PPV infection. Poly (rC) binding protein 1 was confirmed to inhibit PPV replication, which provided potential targets for anti-PPV infection. Our findings improve the understanding of PPV infection and pave the way for future research in this area.

TRIF-dependent signaling and its role in liver diseases

TIR domain-containing adaptor inducing IFN-β (TRIF) is a crucial adaptor molecule downstream of toll-like receptors 3 (TLR3) and 4 (TLR4). TRIF directly binds to TLR3 through its TIR domain, while it associates with TLR4 indirectly through the bridge adaptor molecule TRIF-related adaptor molecule (TRAM). TRIF plays a pivotal role in regulating interferon beta 1 (IFN-β) response, nuclear factor kappa B (NF-κB) signaling, apoptosis, and necroptosis signaling mediated by TLR3 and TLR4. It accomplishes these by recruiting and activating various kinases or transcription factors via its distinct domains. In this review, we comprehensively summarize the TRIF-dependent signaling pathways mediated by TLR3 and TLR4, elucidating key target molecules and downstream pathways. Furthermore, we provide an overview of TRIF's impact on several liver disorders, including drug-induced liver injury, ischemia-reperfusion liver injury, autoimmune hepatitis, viral hepatitis, alcohol-associated liver disease (ALD), metabolic dysfunction-associated steatotic liver disease (MASLD) and metabolic dysfunction-associated steatohepatitis (MASH). We also explore its effects on liver steatosis, inflammation, fibrosis, and carcinogenesis. A comprehensive understanding of the TRIF-dependent signaling pathways, as well as the intricate relationship between TRIF and liver diseases, can facilitate the identification of potential drug targets and the development of novel and effective therapeutics against hepatic disorders.

Neutrophil-to-Lymphocyte Ratio (NLR), Platelet-to-Lymphocyte Ratio (PLR) and Monocyte-to-Lymphocyte Ratio (MLR) as Biomarkers in Diagnosis Evaluation of Acute Exacerbation of Chronic Obstructive Pulmonary Disease: A Retrospective, Observational Study

PURPOSE

Hierarchical management is advocated in China to effectively manage chronic obstructive pulmonary disease (COPD) patients and reduce the incidence and mortality of acute exacerbation of COPD (AE-COPD). However, primary and community hospitals often have limited access to advanced equipment and technology. Complete blood count (CBC), which is commonly used in these hospitals, offers the advantages of being cost-effective and easily accessible. This study aims to evaluate the significance of routine blood indicators in aiding of diagnosing AE-COPD.

PATIENTS AND METHODS

In this research, we enrolled a total of 112 patients diagnosed with AE-COPD, 92 patients with stable COPD, and a control group comprising 60 healthy individuals. Clinical characteristics, CBC parameters, and serum CRP levels were collected within two hours. To assess the associations between NLR/PLR/MLR and CRP by Spearman correlation test. The diagnostic accuracy of NLR, PLR and MLR in AE-COPD was assessed using Receiver Operating Characteristic Curve (ROC) and the area under the curve (AUC). Binary Logistic Regression analysis was conducted for the indicators of NLR, PLR and MLR.

RESULTS

We found that patients with AE-COPD had significantly higher levels of NLR, PLR and MLR in contrast to patients with stable COPD. Additionally, the study revealed a noteworthy correlation between CRP and NLR (rs=0.5319, P<0.001), PLR (rs=0.4424, P<0.001), and MLR (rs=0.4628, P<0.001). By utilizing specific cut-off values, the amalgamation of NLR, PLR and MLR augmented diagnostic sensitivity. Binary logistic regression analysis demonstrated that heightened NLR and MLR act as risk factors for the progression of AE-COPD.

CONCLUSION

The increasing levels of NLR, PLR and MLR could function as biomarkers, akin to CRP, for diagnosis and assessment of acute exacerbations among COPD patients. Further research is required to validate this concept.

Bispecific antibodies tethering innate receptors induce human tolerant-dendritic cells and regulatory T cells

There is an urgent need for alternative therapies targeting human dendritic cells (DCs) that could reverse inflammatory syndromes in many autoimmune and inflammatory diseases and organ transplantations. Here, we describe a bispecific antibody (bsAb) strategy tethering two pathogen-recognition receptors at the surface of human DCs. This cross-linking switches DCs into a tolerant profile able to induce regulatory T-cell differentiation. The bsAbs, not parental Abs, induced interleukin 10 and transforming growth factor β1 secretion in monocyte-derived DCs and human peripheral blood mononuclear cells. In addition, they induced interleukin 10 secretion by synovial fluid cells in rheumatoid arthritis and gout patients. This concept of bsAb-induced tethering of surface pathogen-recognition receptors switching cell properties opens a new therapeutic avenue for controlling inflammation and restoring immune tolerance.

The Application of Cinnamon Twig Extract as an Inhibitor of Listeriolysin O against Listeria monocytogenes Infection

As a major virulence factor of Listeria monocytogenes (L. monocytogenes), listeriolysin O (LLO) can assist in the immune escape of L. monocytogenes, which is critical for the pathogen to evade host immune recognition, leading to various infectious diseases. Cinnamon twig (CT), as a traditional medicine, has been widely used in clinics for multiple functions and it has exhibited excellent safety, efficacy and stability. There are few reports on the effects of the extracts of traditional medicine on bacterial virulence factors. CT has not been reported to be effective in the treatment of L. monocytogenes infection. Therefore, this study aims to explore the preventive effect of CT against L. monocytogenes infection in vivo and in vitro by targeting LLO. Firstly, a hemolysis assay and a cell viability determination are used to detect the effect of CT extract on the inhibition of the cytolytic activity of LLO. The potential mechanism through which CT extract inhibits LLO activity is predicted through network pharmacology, molecular docking assay, real-time polymerase chain reaction (RT-PCR), Western blotting and circular dichroism (CD) analysis. The experimental therapeutic effect of CT extract is examined in a mouse model infected with L. monocytogenes. Then, the ingredients are identified through a high-performance liquid chromatography (HPLC) and thin layer chromatography (TLC) analysis. Here we find that CT extract, containing mainly cinnamic acid, cinnamaldehyde, β-sitosterol, taxifolin, catechin and epicatechin, shows a potential inhibition of LLO-mediated hemolysis without any antimicrobial activity. The results of the mechanism research show that CT extract treatment can simultaneously inhibit LLO expression and oligomerization. Furthermore, the addition of CT extract led to a remarkable alleviation of LLO-induced cytotoxicity. After treatment with CT extract, the mortality, bacterial load, pathological damage and inflammatory responses of infected mice are significantly reduced when compared with the untreated group. This study suggests that CT extract can be a novel and multicomponent inhibitor of LLO with multiple strategies against L. monocytogenes infection, which could be further developed into a novel treatment for infections caused by L. monocytogenes.