Introduction: Cystic fibrosis (CF) is an inherited disease caused by mutations in the CF transmembrane conductance regulator gene (CFTR). It is characterized by progressive decline in lung function, often driven by chronic respiratory infections, particularly with Staphylococcus aureus and Pseudomonas aeruginosa. MicroRNAs (miRNAs), small noncoding regulatory RNAs that negatively regulate protein expression by binding to mRNA, are altered in people with CF and potentially contribute to the pulmonary manifestations of CF. The management of CF lung infections is further complicated by the formation of bacterial biofilms and the emergence of antimicrobial resistance which renders conventional treatments ineffective.
Methods: In silico analysis identified hsa-miR.101.3p as a promising miRNA with potential targets including genes associated with beta-lactam resistance and biofilm formation in P. aeruginosa, as well as genes involved in the overall growth of S. aureus. To facilitate delivery, miRNA mimic DNA oligonucleotides were conjugated to DNA tetrahedrons (DNAtds). The structural integrity of the DNAtd-miRNA complexes was confirmed via transmission electron microscopy, characterized by nanoparticle tracking analysis, and successful bacterial uptake was verified using fluorescence microscopy.
Results: DNAtd-miR.101.3p significantly reduced the viability of both S. aureus and P. aeruginosa. Furthermore, DNAtd-miR.101-3p enhanced the activity of the beta-lactam antibiotic cefotaxime against both non-mucoid and mucoid planktonic and biofilm-forming P. aeruginosa. The mechanisms involve DNAtd-miR.101.3p targeting of ampC, fleN, and pslK.
Conclusion: DNAtd-miR.101.3p displays unique inhibition properties against P. aeruginosa and S. aureus in the exponential phase of bacterial growth in vitro and increases the rate of the bactericidal activity of cefotaxime against P. aeruginosa.
.Introduction: The alternative pathway of complement activation is consistently active, keeping the complement system primed for immediate response. This constant "tick-over" mechanism is regulated by the factor H (FH) protein family, which encompasses seven highly related proteins: FH, FHL-1, and five FH-related (FHR-1 to -5) proteins. The current model is that the FHRs compete with FH and FHL-1 to fine-tune their activities. Genetic studies of this complex locus have revealed distinct haplotypes associating with a wide array of human diseases, underscoring its significant role in complement regulation. Nevertheless, a comprehensive analysis of systemic concentrations of all FH protein family members, accounting for known genetic variability within the population, is still lacking.
Methods: Systemic levels of each member of the FH protein family were quantified with the use of recently developed target specific ELISAs. Next, a genetic analysis focused on the chromosome 1q31.3 region was performed using next generation sequencing and multiplex ligase probe-dependent amplification.
Results: We report systemic protein levels of each member of the FH protein family found in vivo and demonstrate common haplotypes within the CFH locus give rise to classifiable protein expression patterns, establishing distinct ratios between FH, FHL-1, and the FHRs.
Conclusions: The established reference intervals and identified genetic effects provide a benchmark for further research and emphasize the importance of including all family members when studying their role in both health and disease.
Introduction: In severe COVID-19, excessive cytokine release may be driven by SARS-CoV-2. We investigated the modulatory effect of probiotics taking into consideration direct interaction with the immune gut cells.
Methods: Fifty-five patients with confirmed COVID-19 infection were classified by the presence of acute respiratory distress syndrome (ARDS) or not. Peripheral blood mononuclear cells (PBMCs) were isolated and stimulated with lipopolysaccharide (LPS), a preparation of four probiotics (LactoLevure® containing Saccharomyces boulardii, Bifidobacterium lactis BB-12, Lactobacillus acidophilus LA-5, and L. plantarum) and/or recombinant human interferon-gamma (rhIFNγ) and tocilizumab. Cytokine concentrations were measured in cell supernatants. Gene expression of Toll-like receptors 2 (TLR2) and 4 (TLR4) was performed by quantitative real-time polymerase chain reaction (RT-PCR). Results were associated with the level of viremia.
Results: Probiotics decreased tumor necrosis factor-alpha (TNFα) production by the PBMCs of both ARDS and non-ARDS patients. LPS stimulated the production of interleukin (IL)-1β, IL-6 in non-ARDS patients. IL-6 production was maintained in the presence of probiotics. rhIFNγ enhanced LPS-stimulated cytokine production by PBMCs; this was not the case when PBMCs were stimulated by probiotics. Probiotics upregulated TLR2 and LPS downregulated TLR4 in the PBMCs of patients with ARDS. PBMCs from patients with viremia had more cytokine production by probiotic stimulation.
Conclusion: Probiotics interact with the immune system of COVID-19 patients by modulating the production of TNFα, IL-1β, and IL-6 in an IFNγ-independent mechanism.
Introduction: Toll-like receptor (TLR) engagement on macrophages can improve responsiveness to infection. TNF is upregulated following TLR2 or TLR4 stimulation. We sought to determine whether and how the two bioactive forms of TNF, soluble (sTNF) and transmembrane (tmTNF), may be contributing to macrophage priming, which improved responsiveness to subsequent Staphylococcus aureus infection.
Methods: RNA sequencing and cytokine quantification assays identified differentially upregulated cytokines in response to TLR2 stimulation. Immortalized and primary bone marrow-derived macrophages (BMDMs) coupled with receptor blocking and cytokine supplementation were used to investigate whether/how prior TLR-primed macrophages improved S. aureus clearance.
Results: TLR2 or TLR4 stimulated TNF-/- BMDMs failed to efficiently clear a subsequent S. aureus infection compared to TLR-stimulated wild-type (WT) BMDMs. Depletion of sTNF from TLR-stimulated WT BMDMs retained their improved S. aureus clearance. Exogenous sTNF supplementation to TNF-/- BMDMs did not rescue improved S. aureus clearance. Cell density assays showed cell-to-cell contact was important for TLR-induced improvement of S. aureus clearance. Conversely, blocking TNFR2 reduced BMDM clearance of S. aureus, despite TLR2 stimulation.
Conclusions: Our results demonstrated that TNF produced in response to TLR stimulated BMDMs was required for improved clearance of a subsequent S. aureus infection. We found that sTNF did not contribute to this priming, which suggested that tmTNF may be critical for BMDM priming which leads to improved S. aureus clearance.
Introduction: COVID-19 is highly heterogeneous, ranging from cases with mild disease with an almost asymptomatic carrier to severe cases, in which the disease evolves rapidly. A better understanding of monocyte response during SARS-CoV-2 infection would highlight potential biomarkers and establish other possible approaches for severe cases.
Methods: The study group consisted of 32 COVID-19 patients and 18 health controls from June 2023 to March 2024. The COVID-19 patients were further classified as mild and severe illnesses based on World Health Organization (WHO) criteria. For flow cytometric analysis, 50 µL of peripheral blood and 1 µL of specific monoclonal antibodies were added to each cytometric tube for surface marker detection.
Results: Here, the promising finding was that the blood non-classical/classical monocyte (NC/CL) subset was skewed toward NChighCLlow and NClowCLhigh clusters among the severe COVID-19 patients. The NChighCLlow cluster in severe COVID-19 displayed a distinct clinical phenotype, implying a higher 7-day disease progression rate (p = 0.019) and a worse 28-day survival (p = 0.026). Moreover, the secretion of IL-1β and IFN-γ was primarily attributed to CL subset in monocytes, while IL-6 was secreted mainly by NC subset.
Conclusion: As supported, regarding cytokine profile in context of SARS-CoV-2 infection, it was identified that circulating NC cells are proinflammatory cells most related to regulatory cells, while CL subset displayed an effective capacity to virus. These findings have implications toward optimizing evaluation in severe COVID-19, and developing strategies that target altered balance of NC/CL cell subsets.
Introduction: Streptococcus pyogenes (group A streptococcus, GAS) is an exclusively human pathogen. It causes a wide spectrum of diseases, ranging from mild infections such as pharyngitis to severe life-threatening conditions such as streptococcal toxic shock syndrome (STSS). Thrombocytopenia is a common feature of STSS and is associated with severe outcome. GAS produce a plethora of virulence factors, including streptolysin S (SLS), which has lytic as well as immunomodulatory properties. However, its role in platelet activation remains unclear.
Methods: Washed human platelets were infected with GAS wild-type and SLS-deficient mutant (ΔsagA) strains. Platelet activation was assessed by measuring degranulation (CD62P expression). The role of calcium influx and the involvement of purinergic type 2 receptors (P2R) in platelet activation by GAS were assessed using chemical antagonists and calcium chelators.
Results: GAS activate human platelets via SLS-mediated calcium influx, marked by increased surface expression of CD62P. IVIG treatment improved platelet viability in wild-type infections but failed to prevent SLS-mediated activation. Blocking of P2 receptors via suramin or NF449 as well as the use of calcium chelators reduced SLS-mediated platelet activation.
Conclusion: This study identified SLS as an M-protein and consequently a serotype-independent activator of human platelets. While IVIG partially improved platelet viability in GAS infections, its inability to prevent excessive platelet activation underscores the need for additional treatment options in severe GAS infections.
Introduction: Streptococcus pyogenes (group A streptococcus, GAS) is an exclusively human pathogen. It causes a wide spectrum of diseases, ranging from mild infections such as pharyngitis to severe life-threatening conditions such as streptococcal toxic shock syndrome (STSS). Thrombocytopenia is a common feature of STSS and is associated with severe outcome. GAS produce a plethora of virulence factors, including streptolysin S (SLS), which has lytic as well as immunomodulatory properties. However, its role in platelet activation remains unclear.
Methods: Washed human platelets were infected with GAS wild-type and SLS-deficient mutant (ΔsagA) strains. Platelet activation was assessed by measuring degranulation (CD62P expression). The role of calcium influx and the involvement of purinergic type 2 receptors (P2R) in platelet activation by GAS were assessed using chemical antagonists and calcium chelators.
Results: GAS activate human platelets via SLS-mediated calcium influx, marked by increased surface expression of CD62P. IVIG treatment improved platelet viability in wild-type infections but failed to prevent SLS-mediated activation. Blocking of P2 receptors via suramin or NF449 as well as the use of calcium chelators
Introduction: Hepatitis B virus (HBV)-related liver diseases, including hepatitis, cirrhosis, and liver failure, seriously threaten human lives and health worldwide. Innate and adaptive immune cells are all thought to participate in HBV-related diseases. However, there is a lack of information on the comprehensive landscape of the immune microenvironment.
Methods: In this study, single-cell ribonucleic acid sequencing was performed on liver samples obtained from patients diagnosed with hepatitis, cirrhosis, and acute-on-chronic liver failure, which were caused by HBV. Trajectory analysis was performed to analyze the evolution of cell subsets, and branch expression analysis modeling was applied to visualize the changes in gene expression during evolution.
Results: Finally, there was a significant increase in adaptive immune cells in the hepatitis and cirrhosis groups, whereas more innate immune cells were observed in the liver failure group. Furthermore, we found that monocytes underwent remarkable transcriptomic changes into FABP5+ macrophages, promoting the degranulation and chemotaxis of neutrophils through RESISTIN signaling, and LGMN+ macrophages, with the sequential activation of antigen presentation and defense to pathogens through SPP1 signaling.
Conclusion: Macrophages were revealed as central to the progression of acute-on-chronic liver failure as they regulated the activation or inhibition of other immune cells, which could help in developing an effective novel therapy.
Introduction: Neutrophils are key players in the hyperinflammatory response during SARS-CoV-2 infection. The cytosolic proliferating cell nuclear antigen (PCNA) is a scaffolding protein highly dependent on the microenvironment status and known to interact with numerous proteins that regulate neutrophil functions. This study aimed to examine the cytosolic protein content and PCNA interactome in neutrophils from COVID-19 patients.
Methods: Proteomic analyses were performed on neutrophil cytosols from healthy donors and patients with severe or critical COVID-19. In vitro approaches were used to explore the biological significance of the COVID-19-specific PCNA interactome.
Results: Neutrophil cytosol analysis revealed a strong interferon (IFN) protein signature, with variations according to disease severity. Interactome analysis identified associations of PCNA with proteins involved in interferon signaling, cytoskeletal organization, and neutrophil extracellular trap (NET) formation, such as protein arginine deiminase type-4 (PADI4) and histone H3, particularly in critical patients. Functional studies of interferon signaling showed that T2AA, a PCNA scaffold inhibitor, downregulated IFN-related genes, including STAT1, MX1, IFIT1, and IFIT2 in neutrophils. Additionally, T2AA specifically inhibited the secretion of CXCL10, an IFN-dependent cytokine. PCNA was also found to interact with key effector proteins implicated in NET formation, such as histone H3, especially in critical COVID-19 cases.
Conclusion: The analysis of the PCNA interactome has unveiled new protein partners that enhance the interferon pathway, thereby modulating immune responses and contributing to hyperinflammation in COVID-19. These findings provide valuable insights into interferon dysregulation in other immune-related conditions.
Introduction: Neutrophils are key players in the hyperinflammatory response during SARS-CoV-2 infection. The cytosolic proliferating cell nuclear antigen (PCNA) is a scaffolding protein highly dependent on the microenvironment status and known to interact with numerous proteins that regulate neutrophil functions. This study aimed to examine the cytosolic protein content and PCNA interactome in neutrophils from COVID-19 patients.
Methods: Proteomic analyses were performed on neutrophil cytosols from healthy donors and patients with severe or critical COVID-19. In vitro approaches were used to explore the biological significance of the COVID-19-specific PCNA interactome.
Results: Neutrophil cytosol analysis revealed a strong interferon (IFN) protein signature, with variations according to disease severity. Interactome analysis identified associations of PCNA with proteins involved in interferon signaling, cytoskeletal organization, and neutrophil extracellular trap (NET) formation, such as protein argi
Introduction: Species of the ananassae subgroup of Drosophilidae are highly resistant to parasitoid wasp infections. We have previously shown that the genes encoding cytolethal distending toxin B (CdtB) and the apoptosis inducing protein of 56 kDa (AIP56) were horizontally transferred to these fly species from prokaryotes and are now instrumental in the anti-parasitoid immune defense of Drosophila ananassae. Here we describe a new family of genes, which encode proteins with hemolysin E domains, heretofore only identified in prokaryotes. Hemolysin E proteins are pore-forming toxins, important virulence factors of bacteria.
Methods: Bioinformatical, transcriptional, and protein expressional studies were used.
Results: The hemolysin E-like genes have a scattered distribution among the genomes of species belonging to several different monophyletic lineages in the family Drosophilidae. We detected structural homology with the bacterial Hemolysin E toxins and showed that the origin of the D. ananassae hemolysin E-like genes (hl1-38) is consistent with prokaryotic horizontal gene transfer. These genes encode humoral factors, secreted into the hemolymph by the fat body and hemocytes. Their expression is induced solely by parasitoid infection and the proteins bind to the developing parasitoids.
Conclusions: Hemolysin E-like proteins acquired by horizontal gene transfer and expressed by the primary immune organs may contribute to the elimination of parasitoids, as novel humoral factors in Drosophila innate immunity.
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