Monocytes and Macrophages in COVID-19

Identification and validation of programmed cell death related biomarkers for the treatment and prevention COVID-19

PURPOSE

Programmed cell death (PCD) plays a key role in the progression of coronavirus disease 2019 (COVID-19). However, PCD-relevant biomarkers have not been fully discovered. The aim of this study was to explore the PCD-relevant biomarkers for the treatment and prevention of COVID-19.

METHODS

Bioinformatic analyses were performed to explore the clinical relevant PCD genes with differential expression (DE) in COVID-19 compared with matched controls. PPI network was used for hub genes screening and machine learning methods were employed for filtering feature genes. The biomarker genes were screened by Venn diagram. The correlations between biomarkers with clinical features and immune microenvironment were further explored. Biomarker validation was performed in clinical samples by real-time reverse transcriptase-polymerase chain reaction (RT-qPCR).

RESULTS

In total, 118 clinically relevant and PCD associated differential expressed genes (DEGs) were screened, which were mainly related with apoptosis related pathways, among which six biomarkers (Cyclin B1 (CCNB1), cyclin-dependent kinase 1 (CDK1), interferon regulatory factor 4 (IRF4), lipoteichoic acid (LTA), matrix metallopeptidase 9 (MMP9) and Oncostatin M (OSM)) were identified. The excellent or good diagnostic performance of biomarkers was determined by receiver operating characteristic (ROC) curve analysis. The biomarkers showed diverse correlations with clinical indicators, such as age, sex and Intensive Care Unit (ICU) admission. Total 14 types of immune cells exerted differential infiltration between COVID-19 and controls. Biomarkers were correlated with immune cells at varying levels. COVID-19 was classified in three clusters, which showed differential expression of biomarker genes and significant associations with clinical information, such as sex, age and ICU admission. The DEGs of biomarkers were determined in COVID-19 patients relative to controls.

CONCLUSION

The six biomarkers (CCNB1, CDK1, IRF4, LTA, MMP9 and OSM) can be served as the biomarkers for the treatment and prevention of COVID-19.

Diagnostic biomarkers and immune infiltration profiles common to COVID-19, acute myocardial infarction and acute ischaemic stroke using bioinformatics methods and machine learning

BACKGROUND

COVID-19 is a disease that affects people globally. Beyond affecting the respiratory system, COVID-19 patients are at an elevated risk for both venous and arterial thrombosis. This heightened risk contributes to an increased probability of acute complications, including acute myocardial infarction (AMI) and acute ischemic stroke (AIS). Given the unclear relationship between COVID-19, AMI, and AIS, it is crucial to gain a deeper understanding of their associations and potential molecular mechanisms. This study aims to utilize bioinformatics to analyze gene expression data, identify potential therapeutic targets and biomarkers, and explore the role of immune cells in the disease.

METHODS

This study employed three Gene Expression Omnibus (GEO) datasets for analysis, which included data on COVID-19, AMI and AIS. We performed enrichment analysis on the co-DEGs for these three diseases to clarify gene pathways and functions, and also examined the relationship between co-DEGs and immune infiltration. Machine learning techniques and protein-protein interaction networks (PPI) were used to identify hub genes within the co-DEGs. Finally, we employed a dual validation strategy integrating independent GEO datasets and in vitro experiments with human blood samples to comprehensively assess the reliability of our experimental findings.

RESULTS

We identified 88 co-DEGs associated with COVID-19, AMI and AIS. Enrichment analysis results indicated that co-DEGs were significantly enriched in immune inflammatory responses related to leukocytes and neutrophils. Immune infiltration analysis revealed significant differences in immune cell populations between the disease group and the normal group. Finally, genes selected through machine learning methods included: CLEC4E, S100A12, and IL1R2. Based on the PPI network, the top ten most influential DEGs were identified as MMP9, TLR2, TLR4, ITGAM, S100A12, FCGR1A, CD163, FCER1G, FPR2, and CLEC4D. The integration of the protein-protein interaction (PPI) network with machine learning techniques facilitated the identification of S100A12 as a potential common biomarker for early diagnosis and a therapeutic target for all three diseases. Ultimately, validation of S100A12 showed that it was consistent with our experimental results, confirming its reliability as a biomarker. Moreover, it demonstrated good diagnostic performance for the three diseases.

CONCLUSION

We employed bioinformatics methods and machine learning to investigate common diagnostic biomarkers and immune infiltration characteristics of COVID-19, AMI and AIS. Functional and pathway analyses indicated that the co-DEGs were primarily enriched in immune inflammatory responses related to leukocytes and neutrophils. Through two machine learning approaches and the PPI network, and subsequent validation and evaluation, we identified S100A12 as a potential common therapeutic target and biomarker related to immune response that may influence these three diseases.

Longitudinal Changes in Peripheral and Alveolar Monocyte and Inflammatory Biomarkers are Distinct in Hypercapnia Patients Following Pulmonary Sepsis-Induced ARDS

Background

Hypercapnia, an Acute Respiratory Distress Syndrome (ARDS) complication after pulmonary sepsis, remains enigmatic in terms of its immunological mechanisms. Our study was designed to compare initial values and longitudinal changes in cellular composition and inflammatory biomarkers between pneumonia sepsis-induced ARDS patients without hypercapnia and hypercapnia patients.

Methods

Between Dec 2022-Apr 2023, we prospectively studied 61 severe pneumonia patients. Eleven non-sepsis pneumonia patients were controls; 50 patients with pulmonary sepsis met ARDS criteria, 26 among them developed hypercapnia. We collected clinical data, respiratory parameters, peripheral blood mononuclear cells (PBMCs), and bronchoalveolar lavage fluid (BALF) at Day 1 and Day 7 post-intubation. Single-cell RNA sequencing (ScRNA-seq) was performed between selected hypercapnia and non-hypercapnia patients to characterize immune and cellular profiles. Specimens were analyzed via flow cytometry and cytokine panel.

Results

By compiling clinical data and specimens, we found that hypercapnia patients with ARDS had poorer outcomes and higher mortality. At day 1, ScRNA-seq and cytometric analysis revealed increase in monocytes and activation of cytokine storm genes with elevated interleukin (IL) -1β, IL-12p40, and IL-23 in peripheral blood. In hypercapnia patients, percentage of CD14+CD16- classical monocyte and concentrations of IL-12p40 and IL-23 increased from day 1 to day 7 in both circulation and airways. However, these alterations of cellular phenotype and cytokine decreased during seven-treatment period in non-hypercapnia patients.

Conclusion

We offer novel perspectives on monocyte-centered clusters and associated biomarkers, which play a pivotal role in driving hypercapnia after pulmonary sepsis-induced ARDS. Our study provides fresh insights into the immunological mechanisms underlying hypercapnia in ARDS, laying the foundation for useful therapeutic targets to improve patient outcomes.

Blood Transcriptome Profiling Highlights the Role of Intestinal Bacterial Translocation in Severe COVID-19

COVID-19 has caused millions of deaths globally; however, the characterization of molecular biomarkers of severe disease remains of great scientific importance. The aim of this study was to capture the transcriptional differences of the whole blood gene expression between COVID-19 patients with mild and severe disease, using Next Generation Sequencing technologies, on admission and after 7 days. The genes which were differentially expressed in severe compared to mild patients were used for Gene Ontology (GO) enrichment analysis. Gene expression data were used to estimate the cell abundance of 22 immune cell types via digital cytometry. GO terms related to the response to molecules of bacterial origin, such as intestine-derived lipopolysaccharide (LPS), were enriched, among other dysregulated pathways, which are well described as paramount mechanisms of severe manifestations of COVID-19. The neutrophil population increased in patients with severe disease, whereas the monocyte, CD8+ T cell, and activated Natural Killer (NK) cell populations were depleted. These cell population dynamics are also indicative of severe COVID-19 and intestinal bacterial translocation. This study elucidates the molecular basis of severe COVID-19 and highlights intestinal bacterial translocation as a potential driver of severe disease.

LPS-induced extracellular AREG triggers macrophage pyroptosis through the EGFR/TLR4 signaling pathway

Amphiregulin (AREG), a member of the EGF family, exists as a transmembrane protein anchored to the cell surface. In response to external stimuli, its extracellular domain is released into the extracellular matrix through paracrine or autocrine signaling. However, its role in septic macrophage pyroptosis remains poorly understood. This study aims to investigate the role of extracellular AREG in septic macrophages, mice, and patients. We found that high expression of extracellular AREG was regulated by RPLP1 at the translation level, which increased the expression of IL-6, CCL2, and CCL3 protein, as well as Caspase 1, IL-1β, and Nlrp3 mRNA expression, resulting in macrophage pyroptosis. Mechanistically, macrophage pyroptosis was aggravated by extracellular AREG pretreatment, which was triggered by extracellular AREG and ATP (adenosine 5'-triphosphate). The AREG-neutralizing antibody reduced LPS-induced epidermal growth factor receptor (EGFR) activation, TLR4 expression, and pyroptosis. Extracellular AREG-induced macrophage pyroptosis decreased with EGFR and NF-κB inhibition, as well as TLR4 and Myd88 knockout. Additionally, DTT-pretreated extracellular AREG suppressed macrophage pyroptosis. In vivo, extracellular AREG attenuates systemic inflammation infiltration and delays survival in a septic mouse model. Furthermore, extracellular AREG mediates sepsis in humans, and genes involved in the AREG-mediated pyroptosis signaling pathway were highly expressed in patients with severe sepsis compared with those with general or moderate sepsis. Overall, LPS-induced extracellular AREG aggravated or triggered macrophage pyroptosis through the EGFR/TLR4/Myd88/NF-κB signaling pathway, providing promising treatment strategies for sepsis.

The relationship between ferroptosis and respiratory infectious diseases: a novel landscape for therapeutic approach

Respiratory infectious diseases, particularly those caused by respiratory viruses, have the potential to lead to global pandemics, thereby posing significant threats to public and human health. Historically, the primary treatment for respiratory bacterial infections has been antibiotic therapy, while severe cases of respiratory viral infections have predominantly been managed by controlling inflammatory cytokine storms. Ferroptosis is a novel form of programmed cell death that is distinct from apoptosis and autophagy. In recent years, Recent studies have demonstrated that ferroptosis plays a significant regulatory role in various respiratory infectious diseases, indicating that targeting ferroptosis may represent a novel approach for the treatment of these conditions. This article summarized the toxic mechanisms underlying ferroptosis, its relationship with respiratory infectious diseases, the mechanisms of action, and current treatment strategies. Particular attentions were given to the interplay between ferroptosis and Mycobacterium tuberculosis, Epstein-Barr virus, severe acute respiratory syndrome coronavirus-2, Pseudomonas aeruginosa, dengue virus, influenza virus and herpes simplex virus type1infection. A deeper understanding of the regulatory mechanisms of ferroptosis in respiratory infections will not only advance our knowledge of infection-related pathophysiology but also provide a theoretical foundation for the development of novel therapeutic strategies. Targeting ferroptosis pathways represents a promising therapeutic approach for respiratory infections, with significant clinical and translational implications.

Identifying influencing factors and constructing a prediction model for long COVID-19 in hemodialysis patients

PURPOSE

This study aimed to identify the potential influencing factors and construct a prediction model for long COVID in hemodialysis patients.

METHODS

We retrospectively reviewed 115 patients undergoing hemodialysis in a tertiary hospital between December 2022 and January 2023. Both univariate and multivariate logistic regression models were applied to identify potential influencing factors, and the prediction model was constructed using an ROC curve.

RESULTS

Of the 115 included patients, 60 experienced long COVID, with a prevalence of 52.2%. The univariate analysis found that a three-dose COVID-19 vaccination was associated with a reduced risk of long COVID (OR: 0.10; 95%CI: 0.01-0.86; P = 0.036). However, severe COVID (OR: 9.49; 95%CI: 1.14-78.90; P = 0.037), undergoing CT examination (OR: 3.01; 95%CI: 1.34-6.78; P = 0.008), and abnormal neutrophil (OR: 5.95; 95%CI: 1.26-28.19; P = 0.025), and platelet (OR: 2.39; 95%CI: 1.11-5.13; P = 0.025) counts were associated with a higher risk of long COVID. After adjusting for potential confounding factors, undergoing CT examination (OR: 2.60; 95%CI: 1.02-6.64; P = 0.046) and having abnormal neutrophil (OR: 8.16; 95%CI: 1.57-42.38; P = 0.013) and monocyte (OR: 17.77; 95%CI: 1.30-242.29; P = 0.031) counts were associated with a higher risk of long COVID. The prediction model constructed based on these factors showed a relatively better predictive value (AUC: 0.738; 95%CI: 0.648-0.828; P < 0.001).

CONCLUSIONS

The risk of long COVID-19 in hemodialysis patients was significantly related to undergoing CT examination and having abnormal neutrophil and monocyte counts, and the prediction model constructed using these factors showed a moderate predictive value.

Immune dysregulation in COVID-19 induced ARDS in kidney transplant recipients revealed by single-cell RNA sequencing

BACKGROUND

Since the emergence of COVID-19 at the end of 2019, the disease has led to widespread acute respiratory distress syndrome (ARDS), particularly among kidney transplant recipients (KTRs), who are at increased risk due to long-term immunosuppressive therapy. This study aims to explore the differences in immune responses between kidney transplant recipients and non-kidney transplant recipients in COVID-19-induced ARDS to identify potential therapeutic targets for improving outcomes. Single-cell RNA sequencing was performed on 108,320 cells derived from peripheral blood samples to construct a global single-cell map of COVID-19 induced ARDS in kidney transplant recipients(ARDSKT), COVID-19 induced ARDS in non transplant recipients(ARDSNKT), and healthy controls. Subsequently, using cellular clustering analysis, we obtained single-cell maps of different cell types. We employed enrichment analysis to determine the pathways involved in different subpopulations and focused on the role of key immune cells such as monocytes, megakaryocytes, B cells, and CD8+ T cells in the pathogenesis of ARDS. Significant immune differences were observed between ARDSKT and ARDSNKT. In ARDSKT, the S100A9+ MK subpopulation, which activates the NF-κB signaling pathway, was elevated, promoting inflammation. In contrast, the S100A12+ monocyte subpopulation that activates the chemokine signaling pathway was more abundant in ARDSNKT, reflecting a stronger inflammatory response, while its abundance was reduced in ARDSKT due to immunosuppression. The CXCR4+ B subpopulation, crucial for adaptive immunity, was significantly reduced in ARDSKT. Additionally, the XAF1+ Teff subpopulation, associated with apoptosis, was more abundant in ARDSKT, potentially impairing immune recovery. This study highlights the immune differences between ARDSKT and ARDSNKT, revealing the impact of immunosuppression on immune dysregulation. These findings suggest that targeting specific immune pathways can improve therapeutic strategies for ARDSKT.

IL-1β-driven NF-κB transcription of ACE2 as a Mechanism of Macrophage Infection by SARS-CoV-2

Coronavirus disease 2019 (COVID-19), caused by infection with the enveloped RNA betacoronavirus, SARS-CoV-2, led to a global pandemic involving over 7 million deaths. Macrophage inflammatory responses impact COVID-19 severity; however, it is unclear whether macrophages are infected by SARS-CoV-2. We sought to identify mechanisms regulating macrophage expression of ACE2, the primary receptor for SARS-CoV-2, and to determine if macrophages are susceptible to productive infection. We developed a humanized ACE2 (hACE2) mouse whereby hACE2 cDNA was cloned into the mouse ACE2 locus under control of the native promoter. We validated the susceptibility of hACE2 mice to SARS-CoV-2 infection relative to wild-type mice and an established K18-hACE2 model of acute fulminating disease. Intranasal exposure to SARS-CoV-2 led to pulmonary consolidations with cellular infiltrate, edema, and hemorrhage, consistent with pneumonia, yet unlike the K18-hACE2 model, hACE2 mice survived and maintained stable weight. Infected hACE2 mice also exhibited a unique plasma chemokine, cytokine, and growth factor inflammatory signature relative to K18-hACE2 mice. Infected hACE2 mice demonstrated evidence of viral replication in infiltrating lung macrophages, and infection of macrophages in vitro revealed a transcriptional profile indicative of altered RNA and ribosomal processing machinery as well as activated cellular antiviral defense. Macrophage IL-1β-driven NF-κB transcription of ACE2 was an important mechanism of dynamic ACE2 upregulation, promoting macrophage susceptibility to infection. Experimental models of COVID-19 that make use of native hACE2 expression will allow for mechanistic insight into factors that can either promote host resilience or increase susceptibility to worsening severity of infection.

Immunologic and inflammatory consequences of SARS-CoV-2 infection and its implications in renal disease

The emergence of the COVID-19 pandemic made it critical to understand the immune and inflammatory responses to the SARS-CoV-2 virus. It became increasingly recognized that the immune response was a key mediator of illness severity and that its mechanisms needed to be better understood. Early infection of both tissue and immune cells, such as macrophages, leading to pyroptosis-mediated inflammasome production in an organ system critical for systemic oxygenation likely plays a central role in the morbidity wrought by SARS-CoV-2. Delayed transcription of Type I and Type III interferons by SARS-CoV-2 may lead to early disinhibition of viral replication. Cytokines such as interleukin-1 (IL-1), IL-6, IL-12, and tumor necrosis factor α (TNFα), some of which may be produced through mechanisms involving nuclear factor kappa B (NF-κB), likely contribute to the hyperinflammatory state in patients with severe COVID-19. Lymphopenia, more apparent among natural killer (NK) cells, CD8+ T-cells, and B-cells, can contribute to disease severity and may reflect direct cytopathic effects of SARS-CoV-2 or end-organ sequestration. Direct infection and immune activation of endothelial cells by SARS-CoV-2 may be a critical mechanism through which end-organ systems are impacted. In this context, endovascular neutrophil extracellular trap (NET) formation and microthrombi development can be seen in the lungs and other critical organs throughout the body, such as the heart, gut, and brain. The kidney may be among the most impacted extrapulmonary organ by SARS-CoV-2 infection owing to a high concentration of ACE2 and exposure to systemic SARS-CoV-2. In the kidney, acute tubular injury, early myofibroblast activation, and collapsing glomerulopathy in select populations likely account for COVID-19-related AKI and CKD development. The development of COVID-19-associated nephropathy (COVAN), in particular, may be mediated through IL-6 and signal transducer and activator of transcription 3 (STAT3) signaling, suggesting a direct connection between the COVID-19-related immune response and the development of chronic disease. Chronic manifestations of COVID-19 also include systemic conditions like Multisystem Inflammatory Syndrome in Children (MIS-C) and Adults (MIS-A) and post-acute sequelae of COVID-19 (PASC), which may reflect a spectrum of clinical presentations of persistent immune dysregulation. The lessons learned and those undergoing continued study likely have broad implications for understanding viral infections' immunologic and inflammatory consequences beyond coronaviruses.

Vascular endothelial growth factor A: friend or foe in the pathogenesis of HIV and SARS-CoV-2 infections?

This review article discusses the role of vascular endothelial growth factor A (VEGF-A) in the pathogenesis of SARS-CoV-2 and HIV infection, both conditions being renowned for their impact on the vascular endothelium. The processes involved in vascular homeostasis and angiogenesis are reviewed briefly before exploring the interplay between hypoxia, VEGF-A, neuropilin-1 (NRP-1), and inflammatory pathways. We then focus on SARS-CoV-2 infection and show how the binding of the viral pathogen to the angiotensin-converting enzyme 2 receptor, as well as to NRP-1, leads to elevated levels of VEGF-A and consequences such as coagulation, vascular dysfunction, and inflammation. HIV infection augments angiogenesis via several mechanisms, most prominently, by the trans-activator of transcription (tat) protein mimicking VEGF-A by binding to its receptor, VEGFR-2, as well as upregulation of NRP-1, which enhances the interaction between VEGF-A and VEGFR-2. We propose that the elevated levels of VEGF-A observed during HIV/SARS-CoV-2 co-infection originate predominantly from activated immune cells due to the upregulation of HIF-1α by damaged endothelial cells. In this context, a few clinical trials have described a diminished requirement for oxygen therapy during anti-VEGF treatment of SARS-CoV-2 infection. The currently available anti-VEGF therapy strategies target the binding of VEGF-A to both VEGFR-1 and VEGFR-2. The blocking of both receptors could, however, lead to a negative outcome, inhibiting not only pathological, but also physiological angiogenesis. Based on the examination of published studies, this review suggests that treatment targeting selective inhibition of VEGFR-1 may be beneficial in the context of SARS-CoV-2 infection.

Metabolomics Profiling Reveals Critical Roles of Indoxyl Sulfate in the Regulation of Innate Monocytes in COVID-19

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is intricately related to the reprogramming of host metabolism. However, existing studies have mainly focused on peripheral blood samples and barely identified specific metabolites that are critically involved in the pathology of coronavirus disease 2019 (COVID-19). In the current small-scale study, we performed metabolic profiling in plasma (n = 61) and paired bronchoalveolar lavage fluid (BALF) samples (n = 20) using parallel two-dimensional liquid chromatography-mass spectrometry (2DLC-MS). In addition, we studied how an identified metabolite regulates the immunopathogenesis of COVID-19. The results unveiled distinct metabolome changes between healthy donors, and moderate and severe patients in both plasma and BALF, indicating that locations and disease severity play critical roles in COVID-19 metabolic alteration. Notably, a vital metabolite, indoxyl sulfate, was found to be elevated in both the plasma and BALF of severe COVID-19 patients. Indoxyl sulfate selectively induced TNF-α production, reduced co-stimulatory signals, and enhanced apoptosis in human monocytes. Moreover, its levels negatively correlated with the strength of co-stimulatory signals and antigen presentation capability in monocytes of COVID-19 patients. Collectively, our findings suggest that the levels of indoxyl sulfate could potentially serve as a functional biomarker to monitor COVID-19 disease progression and guide more individualized treatment for COVID-19 patients.

Cyclophilin-CD147 interaction enables SARS-CoV-2 infection of human monocytes and their activation via Toll-like receptors 7 and 8

Monocytes and macrophages, as important constituents of the innate immune system, are equipped with multiple Toll-like-receptors (TLRs) to recognize invading pathogens, such as SARS-CoV-2, and mount an antiviral response. Nevertheless, their uncontrolled activation can lead to hyperinflammation seen in severe COVID-19. Surprisingly, we observed that recombinant SARS-CoV-2 Spike (S) and Nucleocapsid (N) proteins triggered only a weak proinflammatory response in human peripheral blood monocytes. By employing THP-1 and Jurkat NF-κB::eGFP reporter cell lines expressing specific TLRs, various TLR ligands and blocking antibodies, we determined that surface TLRs, including TLR2/1, TLR2/6 and TLR4 do not play a major role in SARS-CoV-2 sensing. However, monocytes are potently activated by the replication-competent SARS-CoV-2, and the response correlates with the viral uptake that is observed only in monocytes, but not in lymphocytes. We show that monocyte activation involves two distinct steps. Firstly, SARS-CoV-2 infects monocytes in a process independent of the S protein and the prime SARS-CoV-2 receptor angiotensin-converting enzyme 2. Instead, the alternative SARS-CoV-2 receptor CD147, which is highly expressed on monocytes, recognizes its well-known interaction partners cyclophilins A and B that are incorporated into SARS-CoV-2 virions. Secondly, upon viral uptake via the cyclophilin-CD147 interaction, that can be inhibited by specific CD147 blocking antibodies or competition with recombinant human cyclophilin A and B, SARS-CoV-2 RNA is recognized by TLR7/8 in endosomes, leading to upregulation of tumor necrosis factor (TNF), interleukin (IL)-1β and IL-6, comprising the core hyperinflammatory signature. Taken together, our data reveal a novel mechanism how human monocytes sense SARS-CoV-2 and suggest that targeting the cyclophilin-CD147 axis might be beneficial to alleviate overt myeloid-driven inflammation triggered by SARS-CoV-2 infection.

Expression of the mucin-like glycoprotein CD24 and its ligand siglec-10 in placentas with acute and post SARS-CoV-2 infection

CD24 is a mucin-like glycoprotein expressed on trophoblast cells and endothelial tissue of first and third trimester placentas. As an immune suppressor, CD24 may contribute to maternal immune tolerance to the growing fetus. CD24 is known to interact with the sialic acid-binding immunoglobulin-type lectins (Siglecs), specifically siglec-10. The aim of this study was to investigate the expression of both, CD24 and siglec-10 on placental tissue slides from acute covid patients, patients who survived a covid-19 infection and normal term controls. For the evaluation of CD24 & siglec-10 we used a total of 60 placentas, 10 acute covid-19 female, 10 acute covid-19 male, 10 post-covid-19 female, 10 post-covid-19 male, 10 female term controls and 10 male term controls. Immunohistochemical staining against CD24 and siglec-10 was performed and the expression of both markers was done with an immunoreactive score (IRS). Identity of CD24- or siglec-10 expressing cells was analyzed by double immune fluorescence analyses. The expression of CD24 is significantly downregulated on the extravillous trophoblast and on Hofbauer cells of female acute covid placentas. In the contrary, CD24 is significantly upregulated on male post-covid-19 Hofbauer cells. The CD24-ligand siglec-10 is significantly downregulated in post-covid-19 Hofbauer cells independently of fetal sex, whereas it shows significant higher expression in control female Hofbauer cells. CD24 and its ligand siglec-10 are differentially expressed in placentas of patients who survived a covid-19 infection. Surprisingly this effect is related to the fetal gender. Further investigation is necessary to analyze especially the imprinting effect of this infection.

Analysis of the immune response in COVID-19

The COVID-19 pandemic, instigated by the novel coronavirus SARS-CoV-2, has emerged as a significant global health challenge, demanding a profound grasp of the immune response. The innate immune system, a multifaceted network encompassing pattern recognition receptors (PRRs) and effector cells, assumes a pivotal function in detecting and countering this viral assailant. Toll-like receptors (TLRs), situated on immune cell surfaces and within endosomes, play a central role in recognizing SARS-CoV-2. TLR-2 and TLR-4 discern specific viral constituents, such as the spike (S) protein, setting off inflammatory signaling cascades and catalyzing the generation of type I interferons. Intracellular PRRs, including the RIG-I-like receptors (RLRs), RIG-I and MDA5, detect viral RNA within the cytoplasm of infected cells, provoking antiviral responses by initiating the synthesis of type I interferons. The equilibrium between interferons and pro-inflammatory cytokines dictates the outcomes of the disease. Interferons play an indispensable role in governing viral replication, while unregulated cytokine production can result in tissue harm and inflammation. This intricate dynamic underpins therapeutic strategies aimed at regulating immune responses in individuals grappling with COVID-19. Natural killer (NK) cells, with their capacity to recognize infected cells through the "missing self" phenomenon and activating receptors, make significant contributions to the defense against SARS-CoV-2. NK cells play a pivotal role in eliminating infected cells and boosting immune responses through antibody-dependent cell-mediated cytotoxicity (ADCC). In conclusion, comprehending the interplay among PRRs, interferons, and NK cells within innate immunity is paramount for discerning and combatting SARS-CoV-2. This comprehension illuminates therapeutic interventions and vaccine development, casting light on our endeavors to confront this worldwide health crisis.

Molecular imaging of viral pathogenesis and opportunities for the future

Molecular imaging is used in clinical and research settings. Since tools to study viral pathogenesis longitudinally and systemically are limited, molecular imaging is an attractive and largely unexplored tool. This review discusses molecular imaging probes and techniques for studying viruses, particularly those currently used in oncology that are applicable to virology. Expanding the repertoire of probes to better detect viral disease may make imaging even more valuable in (pre-)clinical settings.

A randomized, placebo-controlled trial of the BTK inhibitor zanubrutinib in hospitalized patients with COVID-19 respiratory distress: immune biomarker and clinical findings

Background

Cytokine release triggered by a hyperactive immune response is thought to contribute to severe acute respiratory syndrome coronavirus 2019 (SARS-CoV-2)-related respiratory failure. Bruton tyrosine kinase (BTK) is involved in innate immunity, and BTK inhibitors block cytokine release. We assessed the next-generation BTK inhibitor zanubrutinib in SARS-CoV-2-infected patients with respiratory distress.

Method

Cohort 1 had a prospective, randomized, double-blind, placebo-controlled design; cohort 2 had a single-arm design. Adults with SARS-CoV-2 requiring hospitalization (without mechanical ventilation) were randomized in cohort 1. Those on mechanical ventilation ≤24 hours were enrolled in cohort 2. Patients were randomized 1:1 to zanubrutinib 320 mg once daily or placebo (cohort 1), or received zanubrutinib 320 mg once daily (cohort 2). Co-primary endpoints were respiratory failure-free survival rate and time to return to breathing room air at 28 days. Corollary studies to assess zanubrutinib's impact on immune response were performed.

Results

Sixty-three patients in cohort 1 received zanubrutinib (n=30) or placebo (n=33), with median treatment duration of 8.5 and 7.0 days, respectively. The median treatment duration in cohort 2 (n=4) was 13 days; all discontinued treatment early. In cohort 1, respiratory failure-free survival and the estimated rates of not returning to breathing room air by day 28 were not significantly different between treatments. Importantly, serological response to coronavirus disease 2019 (COVID-19) was not impacted by zanubrutinib. Lower levels of granulocyte colony-stimulating factor, interleukin (IL)-10, monocyte chemoattractant protein-1, IL-4, and IL-13 were observed in zanubrutinib-treated patients. Moreover, single-cell transcriptome analysis showed significant downregulation of inflammatory mediators (IL-6, IL-8, macrophage colony-stimulating factor, macrophage inflammatory protein-1α, IL-1β) and signaling pathways (JAK1, STAT3, TYK2), and activation of gamma-delta T cells in zanubrutinib-treated patients.

Conclusions

Marked reduction in inflammatory signaling with preserved SARS-CoV-2 serological response was observed in hospitalized patients with COVID-19 respiratory distress receiving zanubrutinib. Despite these immunological findings, zanubrutinib did not show improvement over placebo in clinical recovery from respiratory distress. Concurrent administration of steroids and antiviral therapy to most patients may have contributed to these results. Investigation of zanubrutinib may be warranted in other settings where cytokine release and immune cell exhaustion are important.

Clinical Trial Registration

https://www.clinicaltrials.gov/study/NCT04382586, identifier NCT04382586.

Pathogenesis of influenza and SARS-CoV-2 co-infection at the extremes of age: decipher the ominous tales of immune vulnerability

The co-circulation of influenza and SARS-CoV-2 has led to co-infection events, primarily affecting children and older adults, who are at higher risk for severe disease. Although co-infection prevalence is relatively low, it is associated with worse outcomes compared to mono-infections. Previous studies have shown that the outcomes of co-infection depend on multiple factors, including viral interference, virus-host interaction and host response. Children and the elderly exhibit distinct patterns of antiviral response, which involve airway epithelium, mucociliary clearance, innate and adaptive immune cells, and inflammatory mediators. This review explores the pathogeneses of SARS-CoV-2 and influenza co-infection, focusing on the antiviral responses in children and the elderly. By comparing immature immunity in children and immune senescence in older adults, we aim to provide insights for the clinical management of severe co-infection cases.

Passive infusion of an S2-Stem broadly neutralizing antibody protects against SARS-CoV-2 infection and lower airway inflammation in rhesus macaques

The continued evolution of SARS-CoV-2 variants capable of subverting vaccine and infection-induced immunity suggests the advantage of a broadly protective vaccine against betacoronaviruses (β-CoVs). Recent studies have isolated monoclonal antibodies (mAbs) from SARS-CoV-2 recovered-vaccinated donors capable of neutralizing many variants of SARS-CoV-2 and other β-CoVs. Many of these mAbs target the conserved S2 stem region of the SARS-CoV-2 spike protein, rather than the receptor binding domain contained within S1 primarily targeted by current SARS-CoV-2 vaccines. One of these S2-directed mAbs, CC40.8, has demonstrated protective efficacy in small animal models against SARS-CoV-2 challenge. As the next step in the pre-clinical testing of S2-directed antibodies as a strategy to protect from SARS-CoV-2 infection, we evaluated the in vivo efficacy of CC40.8 in a clinically relevant non-human primate model by conducting passive antibody transfer to rhesus macaques (RM) followed by SARS-CoV-2 challenge. CC40.8 mAb was intravenously infused at 10mg/kg, 1mg/kg, or 0.1 mg/kg into groups (n = 6) of RM, alongside one group that received a control antibody (PGT121). Viral loads in the lower airway were significantly reduced in animals receiving higher doses of CC40.8. We observed a significant reduction in inflammatory cytokines and macrophages within the lower airway of animals infused with 10mg/kg and 1mg/kg doses of CC40.8. Viral genome sequencing demonstrated a lack of escape mutations in the CC40.8 epitope. Collectively, these data demonstrate the protective efficiency of broadly neutralizing S2-targeting antibodies against SARS-CoV-2 infection within the lower airway while providing critical preclinical work necessary for the development of pan-β-CoV vaccines.

Clinical characteristics and distinguishing factors of patients with COVID-19 complicated with active pulmonary tuberculosis

The current study was conducted aimed at exploring the clinical characteristics and distinguishing factors of patients with the novel coronavirus pneumonia (COVID-19) complicated with active pulmonary tuberculosis. A total of 354 patients with COVID-19 in our hospital from November 2022 to February 2023 were included in the present study, of whom 87 patients were also combined with active pulmonary tuberculosis. Significant differences were found in fever, fatigue, nasal congestion, nasal discharge, sore throat, expectoration, and weight loss between the two groups (p < 0.05). There were significant differences in the levels of leukocyte, neutrophil, lymphocyte count, monocyte, hemoglobin, C-reactive protein, and CD4/CD8 between the two groups (p < 0.05). There were significant differences in pulmonary consolidation, multifocal ground-glass opacities in both lungs and infiltrating shadows, "cavity" by CT imaging between the two groups (p < 0.05). The independent variables were set as the indicators with different results of clinical characteristics and CT imaging, including fever, fatigue, nasal congestion, nasal discharge, sore throat, expectoration, weight loss, leukocytes, count neutrophils and lymphocytes, monocytes, hemoglobin, C-reactive protein, CD4/CD8, pulmonary consolidation, multifocal ground-glass opacities in both lungs and infiltration shadows. Our findings have revealed that fever, fatigue, expectoration, leukocytes, neutrophils, monocytes, hemoglobin, C-reactive protein, lymphocytes, CD4/CD8, pulmonary consolidation, multifocal ground-glass opacities in both lungs, and infiltration shadows were the risk factors responsible for the patients with COVID-19 complicated with active pulmonary tuberculosis.

A comprehensive examination and analysis of the effectiveness and safety of finerenone for the treatment of diabetic kidney disease: a systematic review and meta-analysis

Objectives

The study will evaluate the effectiveness and safety of finerenone in patients diagnosed with diabetic kidney disease (DKD).

Methods

Various databases including PubMed, Sinomed, Web of Science, Embase, Clinical Trials, and Cochrane Library were systematically reviewed for pertinent studies published from the beginning to February 2024.This meta-analysis utilized RevMan 5.3 and Stata 15.1.

Results

The analysis of 4 randomized controlled trials involving 13,943 participants found that finerenone treatment significantly decreased the urine albumin-to-creatinine ratio compared to placebo. Additionally, the risk of COVID-19, cardiovascular events, and estimated glomerular filtration rate(eGFR) reduction of at least 40% were all significantly lower in the finerenone treatment group. However, the finerenone group did experience higher baseline increases in serum potassium levels. The meta-analysis revealed that there was no variation in the likelihood of general negative outcomes (RR 1.00, 95% CI 0.98, 1.01, I2 = 0%) and the occurrence of cancers (RR 0.99, 95% CI 0.83, 1.18,I2 = 0%) among the two categories.

Conclusion

Our study demonstrates that finerenone has the potential to lower the chances of end-stage kidney disease, renal failure and cardiovascular mortality in individuals with diabetic kidney disease. It is important to monitor for hyperkalemia risk. The administration of finelidone among individuals with diabetic kidney disease may potentially mitigate the susceptibility to contracting COVID-19.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42024536612.

A biomathematical model of SARS-CoV-2 in Syrian hamsters

When infected with SARS-CoV-2, Syrian hamsters (Mesocricetus auratus) develop moderate disease severity presenting key features of human COVID-19. We here develop a biomathematical model of the disease course by translating known biological mechanisms of virus-host interactions and immune responses into ordinary differential equations. We explicitly describe the dynamics of virus population, affected alveolar epithelial cells, and involved relevant immune cells comprising for example CD4+ T cells, CD8+ T cells, macrophages, natural killer cells and B cells. We also describe the humoral response dynamics of neutralising antibodies and major regulatory cytokines including CCL8 and CXCL10. The model is developed and parametrized based on experimental data collected at days 2, 3, 5, and 14 post infection. Pulmonary cell composition and their transcriptional profiles were obtained by lung single-cell RNA (scRNA) sequencing analysis. Parametrization of the model resulted in a good agreement of model and data. The model can be used to predict, for example, the time course of the virus population, immune cell dynamics, antibody production and regeneration of alveolar cells for different therapy scenarios or after multiple-infection events. We aim to translate this model to the human situation in the future.

Widespread gene-environment interactions shape the immune response to SARS-CoV-2 infection in hospitalized COVID-19 patients

Genome-wide association studies performed in patients with coronavirus disease 2019 (COVID-19) have uncovered various loci significantly associated with susceptibility to SARS-CoV-2 infection and COVID-19 disease severity. However, the underlying cis-regulatory genetic factors that contribute to heterogeneity in the response to SARS-CoV-2 infection and their impact on clinical phenotypes remain enigmatic. Here, we used single-cell RNA-sequencing to quantify genetic contributions to cis-regulatory variation in 361,119 peripheral blood mononuclear cells across 63 COVID-19 patients during acute infection, 39 samples collected in the convalescent phase, and 106 healthy controls. Expression quantitative trait loci (eQTL) mapping across cell types within each disease state group revealed thousands of cis-associated variants, of which hundreds were detected exclusively in immune cells derived from acute COVID-19 patients. Patient-specific genetic effects dissipated as infection resolved, suggesting that distinct gene regulatory networks are at play in the active infection state. Further, 17.2% of tested loci demonstrated significant cell state interactions with genotype, with pathways related to interferon responses and oxidative phosphorylation showing pronounced cell state-dependent variation, predominantly in CD14+ monocytes. Overall, we estimate that 25.6% of tested genes exhibit gene-environment interaction effects, highlighting the importance of environmental modifiers in the transcriptional regulation of the immune response to SARS-CoV-2. Our findings underscore the importance of expanding the study of regulatory variation to relevant cell types and disease contexts and argue for the existence of extensive gene-environment effects among patients responding to an infection.

Red blood cell distribution width-to-monocyte ratio for predicting 90-day mortality of COVID-19 in patients with chronic kidney disease during the Omicron period: a prospective single-center study

We aimed to test whether red blood cell distribution width (RDW) to monocyte percentage ratio (RMR) was associated with the acute-phase prognosis of coronavirus disease 2019 (COVID-19) in chronic kidney disease (CKD) patients. Prospective enrollment and 90-day follow-up of CKD patients with COVID-19 were conducted from December 1, 2022 to January 31, 2023. Demographics, clinical data, and laboratory and radiographic findings were collected, and multiple logistic regression, subgroup analysis, and receiver operating characteristic (ROC) curve analysis were performed. A total of 218 patients were enrolled, with a mean age of 59 years and 69.7% being male. The 90-day mortality rate was 24.8%. The lnRMR level was 5.18 (4.91-5.43) and emerged as an independent risk factor (OR: 3.01, 95% CI: 1.72-5.85). The lnRMR-mortality association was consistent across sex, age, CKD stage, COVID-19 vaccination, and comorbidity subgroups. The area under the ROC curve of lnRMR was 0.737 (95% CI: 0.655-0.819). Our findings indicate that lnRMR is a simple and practical predictor for identifying high-risk CKD patients during the acute phase of COVID-19.

SARS-CoV-2 hijacks host CD55, CD59 and factor H to impair antibody-dependent complement-mediated lysis

The complement system is a vital anti-microbial defence mechanism against circulating pathogens. Excessive complement activation can have deleterious outcomes for the host and is consequently tightly modulated by a set of membrane-associated and fluid-phase regulators of complement activation (RCAs). Here, we demonstrate that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) hijacks host cellular RCA members CD55 and CD59 and serum-derived Factor H (FH) to resist antibody-dependent complement-mediated lysis triggered by immunized human sera. Blockage of the biological functions of virion-associated CD55 and CD59 and competition of FH recruitment with functionally inactive recombinant FH-derived short consensus repeats SCR18-20 restore SARS-CoV-2 complement sensitivity in a synergistic manner. Moreover, complement-mediated virolysis is dependent on classical pathway activation and does not occur in the absence of virus-specific antibodies. Altogether, our findings present an intriguing immune escape mechanism that provides novel insights into the immunopathology observed in severe coronavirus disease 2019 (COVID-19).

NK Cell and Monocyte Dysfunction in Multisystem Inflammatory Syndrome in Children

Multisystem inflammatory syndrome in children (MIS-C) is a severe complication of SARS-CoV-2 infection characterized by multiorgan involvement and inflammation. Testing of cellular function ex vivo to understand the aberrant immune response in MIS-C is limited. Despite strong Ab production in MIS-C, SARS-CoV-2 nucleic acid testing can remain positive for 4-6 wk postinfection. Therefore, we hypothesized that dysfunctional cell-mediated Ab responses downstream of Ab production may be responsible for delayed clearance of viral products in MIS-C. In MIS-C, monocytes were hyperfunctional for phagocytosis and cytokine production, whereas NK cells were hypofunctional for both killing and cytokine production. The decreased NK cell cytotoxicity correlated with an NK exhaustion marker signature and systemic IL-6 levels. Potentially providing a therapeutic option, cellular engagers of CD16 and SARS-CoV-2 proteins were found to rescue NK cell function in vitro. Taken together, our results reveal dysregulation in Ab-mediated cellular responses of myeloid and NK cells that likely contribute to the immune pathology of this disease.

The role of viral infection in implantation failure: direct and indirect effects

Implantation is the key initial complex stage of pregnancy. Several factors are involved in implantation, but acute and controlled inflammation has been shown to play as a key role. On the other hand, the role of viral infections in directly infecting blastocyst and trophoblast and inducing chronic and uncontrolled inflammation and disrupting microRNAs expression can make this review strongly attractive and practical. We aim to provide an overview of viral infections as the potential etiology of unsuccessful implantation pathophysiology through alteration of the cellular and molecular endometrial microenvironment. Based on our search, this is the first review to discuss the role of inflammation associated with viral infection in implantation failure.

Pro-inflammatory macrophages suppress HIV replication in humanized mice and ex vivo co-cultures

Introduction

Very little is known about the role of macrophages as immune mediators during natural HIV infection. Humanized mice are an extremely valuable in vivo model for studying HIV pathogenesis. However, the presence of murine mononuclear phagocytes in these models represents a significant limitation for studying their human counterpart. Therefore, we have developed a novel humanized mouse model that allows selective depletion of human myeloid cells at a time point of our choosing.

Methods

We genetically engineered human hematopoietic stem and progenitor cells (HSPCs) to express an inducible caspase-9 (iCas9) suicide system under a synthetic myeloid promoter. Using these HSPCs, we generated humanized mice. iCasp9 induction in vivo resulted in selective human myeloid cell death in this inducible human myeloid depletion (iHMD) mouse model. In addition, we co-cultured monocyte-derived macrophages with ex vivo HIV-infected PBMCs to further mechanistically investigate the effect of macrophages on HIV replication using flow cytometry, cytokine analysis, and RNA sequencing of both macrophages and CD4+ T cells.

Results

HIV infection induced a pro-inflammatory phenotype in HIV-infected humanized NSG mice during the early and late stages of HIV infection. Myeloid cell depletion in HIV-infected iHMD-NSG mice resulted in a rapid increase in HIV RNA replication, which was accompanied by a loss of pro-inflammatory cytokines. Co-culture of macrophages with ex vivo HIV-infected PBMCs reproduced their anti-HIV effects observed in vivo. Transcriptomic data showed macrophages upregulate antiviral cytokines and chemokines in co-culture, while inducing CD4+ T cells to upregulate HIV restriction factors and downregulate pathways involved in protein expression and cell replication.

Discussion

This study describes a novel role of macrophages as effector cells, both ex vivo and in vivo, acting against HIV replication and limiting disease progression.

A spatially resolved single-cell lung atlas integrated with clinical and blood signatures distinguishes COVID-19 disease trajectories

COVID-19 is characterized by a broad range of symptoms and disease trajectories. Understanding the correlation between clinical biomarkers and lung pathology during acute COVID-19 is necessary to understand its diverse pathogenesis and inform more effective treatments. Here, we present an integrated analysis of longitudinal clinical parameters, peripheral blood markers, and lung pathology in 142 Brazilian patients hospitalized with COVID-19. We identified core clinical and peripheral blood signatures differentiating disease progression between patients who recovered from severe disease compared with those who succumbed to the disease. Signatures were heterogeneous among fatal cases yet clustered into two patient groups: "early death" (<15 days until death) and "late death" (>15 days). Progression to early death was characterized systemically and in lung histopathological samples by rapid endothelial and myeloid activation and the presence of thrombi associated with SARS-CoV-2+ macrophages. In contrast, progression to late death was associated with fibrosis, apoptosis, and SARS-CoV-2+ epithelial cells in postmortem lung tissue. In late death cases, cytotoxicity, interferon, and T helper 17 (TH17) signatures were only detectable in the peripheral blood after 2 weeks of hospitalization. Progression to recovery was associated with higher lymphocyte counts, TH2 responses, and anti-inflammatory-mediated responses. By integrating antemortem longitudinal blood signatures and spatial single-cell lung signatures from postmortem lung samples, we defined clinical parameters that could be used to help predict COVID-19 outcomes.

Monocyte Production of C1q Potentiates CD8+ T-Cell Function Following Respiratory Viral Infection

Respiratory viral infections remain a leading cause of morbidity and mortality. Using a murine model of human metapneumovirus, we identified recruitment of a C1q-expressing inflammatory monocyte population concomitant with viral clearance by adaptive immune cells. Genetic ablation of C1q led to reduced CD8+ T-cell function. Production of C1q by a myeloid lineage was necessary to enhance CD8+ T-cell function. Activated and dividing CD8+ T cells expressed a C1q receptor, gC1qR. Perturbation of gC1qR signaling led to altered CD8+ T-cell IFN-γ production, metabolic capacity, and cell proliferation. Autopsy specimens from fatal respiratory viral infections in children exhibited diffuse production of C1q by an interstitial population. Humans with severe coronavirus disease (COVID-19) infection also exhibited upregulation of gC1qR on activated and rapidly dividing CD8+ T cells. Collectively, these studies implicate C1q production from monocytes as a critical regulator of CD8+ T-cell function following respiratory viral infection.

Characterization of the SARS-CoV-2 Genome 3'-Untranslated Region Interactions with Host MicroRNAs

The 2019 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has marked the spread of a novel human coronavirus. SARS-CoV-2 has exhibited increased disease severity and immune evasion across its variants, and the molecular mechanisms behind these phenomena remain largely unknown. Conserved elements of the viral genome, such as secondary structures within the 3'-untranslated region (UTR), could prove crucial in furthering our understanding of the host-virus interface. Analysis of the SARS-CoV-2 viral genome 3'-UTR revealed the potential for host microRNA (miR) binding sites, allowing for sequence-specific interactions. In this study, we demonstrate that the SARS-CoV-2 genome 3'-UTR binds the host cellular miRs miR-34a-5p, miR-34b-5p, and miR-760-3p in vitro. Native gel electrophoresis and steady-state fluorescence spectroscopy were utilized to biophysically characterize the binding of these miRs to their predicted sites within the SARS-CoV-2 genome 3'-UTR. Additionally, we investigated 2'-fluoro-d-arabinonucleic acid (FANA) analogs as competitive binding inhibitors for these interactions. These miRs modulate the translation of granulin (GRN), interleukin-6 (IL-6), and the IL-6 receptor (IL-6R), all of which are key modulators and activators of JAK/STAT3 signaling and are implicated in regulation of the immune response. Thus, we propose that hijacking of these miRs by SARS-CoV-2 could identify a mechanism of host immune modulation by the virus. The mechanisms detailed in this study have the potential to drive the development of antiviral treatments for SARS-CoV-2, through direct targeting of the virus-host interface.

Yinqin Qingfei granules alleviate Mycoplasma pneumoniae pneumonia via inhibiting NLRP3 inflammasome-mediated macrophage pyroptosis

BACKGROUND

Mycoplasma pneumoniae pneumonia (MPP) is a prevalent respiratory infectious disease in children. Given the increasing resistance of M. pneumoniae (MP) to macrolide antibiotics, the identification of new therapeutic agents is critical. Yinqin Qingfei granules (YQQFG), a Chinese patent medicine formulated specifically for pediatric MPP, lacks a clear explanation of its mechanism.

METHODS

The primary components of YQQFG were identified using LC-MS/MS. In vitro, RAW264.7 cells infected with MP underwent morphological examination via scanning electron microscopy. Drug-containing serum was prepared, and its intervention concentration was determined using the CCK-8 assay. The active components of YQQFG were molecularly docked with NLRP3 protein using Autodock Vina software. A RAW264.7 cell line overexpressing NLRP3 was created using lentivirus to pinpoint the target of YQQFG. In vivo, MPP model mice were established via nasal instillation of MP. Lung damage was assessed by lung index and H&E staining. Pyroptosis-associated protein levels in cells and lung tissue were measured by western blot, while interleukin (IL)-1β and IL-18 levels in cell supernatants and mouse serum were quantified using ELISA. Immunofluorescence double staining of lung tissue sections was conducted to assess the correlation between NLRP3 protein expression and macrophages. The expression of the community-acquired respiratory distress syndrome toxin (CARDS TX) was evaluated by qPCR.

RESULTS

25 effective components with favorable oral bioavailability were identified in YQQFG. Both in vitro and in vivo studies demonstrated that YQQFG substantially reduced the expression of the NLRP3/Caspase-1/GSDMD pathway, decreasing the release of IL-1β and IL-18, and inhibited MP exotoxin. Molecular docking indicated strong affinity between most YQQFG components and NLRP3 protein. Lentivirus transfection and immunofluorescence double staining confirmed that YQQFG significantly suppressed NLRP3 expression in macrophages, outperforming azithromycin (AZM). The combination of YQQFG and AZM yielded the optimal therapeutic effect for MPP.

CONCLUSION

YQQFG mitigates inflammatory responses by suppressing NLRP3 inflammasome-mediated macrophage pyroptosis, thereby ameliorating MP-induced acute lung injury. YQQFG serves as an effective adjunct and alternative medication for pediatric MPP treatment.

A New Case of Paediatric Systemic Lupus Erythematosus with Onset after SARS-CoV-2 and Epstein-Barr Infection-A Case Report and Literature Review

Viral infections caused by exposure to viruses such as Epstein-Barr, cytomegalovirus, or Parvovirus B19 have always been considered predisposing environmental factors for the onset of autoimmune diseases. More recently, autoimmune mechanisms such as molecular mimicry, T-cell activation, transient immunosuppression and inflammation have also been observed in cases of SARS-CoV-2 infection. Several newly diagnosed autoimmune disorders have been reported post-COVID-19, such as COVID-19-associated multisystemic inflammatory syndrome in children (MIS-C), type 1 diabetes mellitus, systemic lupus erythematosus, or rheumatoid arthritis. In this article, we present a new case of paediatric systemic lupus erythematosus (SLE) with haematological (macrophage activation syndrome), renal (stage 2), cutaneous (urticarial vasculitis) and digestive involvement, onset three and a half months post-COVID-19. In the dynamics, de novo infection generated by Epstein-Barr exposure was associated. The diagnosis was confirmed based on EULAR/ACR 2019 criteria. The aim of the article is to present a possible correlation between SARS-CoV-2 and Epstein-Barr as extrinsic factors in triggering or activating paediatric systemic lupus erythematosus. Keywords: paediatric systemic lupus erythematosus; post-COVID-19; Epstein-Barr; SARS- CoV-2; case report; paediatric patient.

Passive infusion of an S2-Stem broadly neutralizing antibody protects against SARS-CoV-2 infection and lower airway inflammation in rhesus macaques

The continued evolution of SARS-CoV-2 variants capable of subverting vaccine and infection-induced immunity suggests the advantage of a broadly protective vaccine against betacoronaviruses (β-CoVs). Recent studies have isolated monoclonal antibodies (mAbs) from SARS-CoV-2 recovered-vaccinated donors capable of neutralizing many variants of SARS-CoV-2 and other β-CoVs. Many of these mAbs target the conserved S2 stem region of the SARS-CoV-2 spike protein, rather the receptor binding domain contained within S1 primarily targeted by current SARS-CoV-2 vaccines. One of these S2-directed mAbs, CC40.8, has demonstrated protective efficacy in small animal models against SARS-CoV-2 challenge. As the next step in the pre-clinical testing of S2-directed antibodies as a strategy to protect from SARS-CoV-2 infection, we evaluated the in vivo efficacy of CC40.8 in a clinically relevant non-human primate model by conducting passive antibody transfer to rhesus macaques (RM) followed by SARS-CoV-2 challenge. CC40.8 mAb was intravenously infused at 10mg/kg, 1mg/kg, or 0.1 mg/kg into groups (n=6) of RM, alongside one group that received a control antibody (PGT121). Viral loads in the lower airway were significantly reduced in animals receiving higher doses of CC40.8. We observed a significant reduction in inflammatory cytokines and macrophages within the lower airway of animals infused with 10mg/kg and 1mg/kg doses of CC40.8. Viral genome sequencing demonstrated a lack of escape mutations in the CC40.8 epitope. Collectively, these data demonstrate the protective efficiency of broadly neutralizing S2-targeting antibodies against SARS-CoV-2 infection within the lower airway while providing critical preclinical work necessary for the development of pan-β-CoV vaccines.

Cytotoxic Lymphocyte-Monocyte Complex Reflects the Dynamics of Coronavirus Disease 2019 Systemic Immune Response

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection causes a variety of clinical manifestations, many of which originate from altered immune responses, either locally or systemically. Immune cell cross-talk occurs mainly in lymphoid organs. However, systemic cell interaction specific to coronavirus disease 2019 has not been well characterized. Here, by employing single-cell RNA sequencing and imaging flow cytometry analysis, we unraveled, in peripheral blood, a heterogeneous group of cell complexes formed by the adherence of CD14+ monocytes to different cytotoxic lymphocytes, including SARS-CoV-2-specific CD8+ T cells, γδ T cells, and natural killer T cells. These lymphocytes attached to CD14+ monocytes that showed enhanced inflammasome activation and pyroptosis-induced cell death in progression stage; in contrast, in the convalescent phase, CD14+ monocytes with elevated antigen presentation potential were targeted by cytotoxic lymphocytes, thereby restricting the excessive immune activation. Collectively, our study reports previously unrecognized cell-cell interplay in the SARS-CoV-2-specific immune response, providing new insight into the intricacy of dynamic immune cell interaction representing antiviral defense.

Single-cell-resolved interspecies comparison shows a shared inflammatory axis and a dominant neutrophil-endothelial program in severe COVID-19

A key issue for research on COVID-19 pathogenesis is the lack of biopsies from patients and of samples at the onset of infection. To overcome these hurdles, hamsters were shown to be useful models for studying this disease. Here, we further leverage the model to molecularly survey the disease progression from time-resolved single-cell RNA sequencing data collected from healthy and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected Syrian and Roborovski hamster lungs. We compare our data to human COVID-19 studies, including bronchoalveolar lavage, nasal swab, and postmortem lung tissue, and identify a shared axis of inflammation dominated by macrophages, neutrophils, and endothelial cells, which we show to be transient in Syrian and terminal in Roborovski hamsters. Our data suggest that, following SARS-CoV-2 infection, commitment to a type 1- or type 3-biased immunity determines moderate versus severe COVID-19 outcomes, respectively.

Association between polymorphisms in TLR3, TICAM1 and IFNA1 genes and covid-19 severity in Southern Brazil

BACKGROUND

A distinct phenotype in Coronavirus disease 2019 (Covid-19) was observed in severe patients, consisting of a highly impaired interferon (IFN) type I response, an exacerbated inflammatory response.

OBJECTIVE

The aim of the present study was to investigate a possible association of single nucleotide polymorphisms (SNPs), in five genes related to the immune response, rs3775291 in TLR3; rs2292151 in TICAM1; rs1758566 in IFNA1; rs1800629 in TNF, and rs1800795 in IL6 with the severity of Covid-19.

METHODS

A cross-sectional study was performed, with non-severe and severe/critical patients diagnosed with Covid-19, by two public hospitals in Brazil. In total, 300 patients were genotyped for the SNPs, 150 with the non-severe form of the disease and 150 with severe/critical form.

RESULTS

The T/T genotype of TLR3 in recessive model shows 58% of protection against severe/critical Covid-19; as well as the genotypes G/A+A/A of TICAM1 in dominant model with 60% of protection, and in a codominant model G/A with 57% and A/A with 71% of protection against severe/critical Covid-19. Comparing severe and critical cases, the T/C genotype of IFNA1 in the codominant model and TC+C/C in the dominant model showed twice the risk of critical Covid-19.

CONCLUSION

We can conclude that rs3775291, rs2292151 and rs1758566 can influence the COVID-19 severity.

Copper homeostasis dysregulation in respiratory diseases: a review of current knowledge

Cu is an essential micronutrient for various physiological processes in almost all human cell types. Given the critical role of Cu in a wide range of cellular processes, the local concentrations of Cu and the cellular distribution of Cu transporter proteins in the lung are essential for maintaining a steady-state internal environment. Dysfunctional Cu metabolism or regulatory pathways can lead to an imbalance in Cu homeostasis in the lungs, affecting both acute and chronic pathological processes. Recent studies have identified a new form of Cu-dependent cell death called cuproptosis, which has generated renewed interest in the role of Cu homeostasis in diseases. Cuproptosis differs from other known cell death pathways. This occurs through the direct binding of Cu ions to lipoylated components of the tricarboxylic acid cycle during mitochondrial respiration, leading to the aggregation of lipoylated proteins and the subsequent downregulation of Fe-S cluster proteins, which causes toxic stress to the proteins and ultimately leads to cell death. Here, we discuss the impact of dysregulated Cu homeostasis on the pathogenesis of various respiratory diseases, including asthma, chronic obstructive pulmonary disease, idiopathic interstitial fibrosis, and lung cancer. We also discuss the therapeutic potential of targeting Cu. This study highlights the intricate interplay between copper, cellular processes, and respiratory health. Copper, while essential, must be carefully regulated to maintain the delicate balance between necessity and toxicity in living organisms. This review highlights the need to further investigate the precise mechanisms of copper interactions with infections and immune inflammation in the context of respiratory diseases and explore the potential of therapeutic strategies for copper, cuproptosis, and other related effects.

Study of Macrophage Activity in Cats with FIP and Naturally FCoV-Shedding Healthy Cats

Coronavirus frequently infects humans and animals, showing the ability to recombine and cross over to different species. Cats can be considered a model for studying coronavirus infection, in which feline coronavirus (FCoV) represents a major enteric pathogen related to gastroenteric disease. In this animal, the virus can acquire tropism for macrophage cells, leading to a deadly disease called feline infectious peritonitis (FIP). In this study, monocyte-derived macrophages were isolated by CD14-positive selection in venous whole blood from 26 cats with FIP and 32 FCoV-positive healthy cats. Phagocytosis and respiratory burst activities were investigated and compared between the groups. This is the first study comparing macrophage activity in cats affected by FIP and healthy cats positive for FCoV infection. Our results showed that in cats with FIP, the phagocytic and respiratory burst activities were significantly lower. Our results support the possible role of host immunity in Coronaviridae pathogenesis in cats, supporting future research on the immune defense against this systemic disease.

Impact of Chronic HIV Infection on Acute Immune Responses to SARS-CoV-2

ABSTRACT

There is mounting evidence that HIV infection is a risk factor for severe presentations of COVID-19. We hypothesized that the persistent immune activation associated with chronic HIV infection contributes to worsened outcomes during acute COVID-19. The goals of this study were to provide an in-depth analysis of immune response to acute COVID-19 and investigate relationships between immune responses and clinical outcomes in an unvaccinated, sex- and race-matched cohort of people with HIV (PWH, n = 20) and people without HIV (PWOH, n = 41). We performed flow cytometric analyses on peripheral blood mononuclear cells from PWH and PWOH experiencing acute COVID-19 (≤21-day postsymptom onset). PWH were younger (median 52 vs 65 years) and had milder COVID-19 (40% vs 88% hospitalized) compared with PWOH. Flow cytometry panels included surface markers for immune cell populations, activation and exhaustion surface markers (with and without SARS-CoV-2-specific antigen stimulation), and intracellular cytokine staining. We observed that PWH had increased expression of activation (eg, CD137 and OX40) and exhaustion (eg, PD1 and TIGIT) markers as compared to PWOH during acute COVID-19. When analyzing the impact of COVID-19 severity, we found that hospitalized PWH had lower nonclassical (CD16 + ) monocyte frequencies, decreased expression of TIM3 on CD4 + T cells, and increased expression of PDL1 and CD69 on CD8 + T cells. Our findings demonstrate that PWH have increased immune activation and exhaustion as compared to a cohort of predominately older, hospitalized PWOH and raises questions on how chronic immune activation affects acute disease and the development of postacute sequelae.

Immunohistochemical and Morphometric Analysis of Lung Tissue in Fatal COVID-19

The primary targets of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the lungs are type I pneumocytes, macrophages, and endothelial cells. We aimed to identify lung cells targeted by SARS-CoV-2 using viral nucleocapsid protein staining and morphometric features on patients with fatal COVID-19. We conducted a retrospective analysis of fifty-one autopsy cases of individuals who tested positive for SARS-CoV-2. Demographic and clinical information were collected from forensic reports, and lung tissue was examined for microscopic lesions and the presence of specific cell types. Half of the evaluated cohort were older than 71 years, and the majority were male (74.5%). In total, 24 patients presented diffuse alveolar damage (DAD), and 50.9% had comorbidities (56.9% obesity, 33.3% hypertension, 15.7% diabetes mellitus). Immunohistochemical analysis showed a similar pattern of infected macrophages, infected type I pneumocytes, and endothelial cells, regardless of the presence of DAD (p > 0.5). The immunohistochemical reactivity score (IRS) was predominantly moderate but without significant differences between patients with and without DAD (p = 0.633 IRS for type I pneumocytes, p = 0.773 IRS for macrophage, and p = 0.737 for IRS endothelium). The nucleus/cytoplasm ratio shows lower values in patients with DAD (median: 0.29 vs. 0.35), but the difference only reaches a tendency for statistical significance (p = 0.083). Our study confirms the presence of infected macrophages, type I pneumocytes, and endothelial cells with a similar pattern in patients with and without diffuse alveolar damage.

Mast cell degranulation-triggered by SARS-CoV-2 induces tracheal-bronchial epithelial inflammation and injury

SARS-CoV-2 infection-induced hyper-inflammation is a key pathogenic factor of COVID-19. Our research, along with others', has demonstrated that mast cells (MCs) play a vital role in the initiation of hyper-inflammation caused by SARS-CoV-2. In previous study, we observed that SARS-CoV-2 infection induced the accumulation of MCs in the peri-bronchus and bronchioalveolar-duct junction in humanized mice. Additionally, we found that MC degranulation triggered by the spike protein resulted in inflammation in alveolar epithelial cells and capillary endothelial cells, leading to subsequent lung injury. The trachea and bronchus are the routes for SARS-CoV-2 transmission after virus inhalation, and inflammation in these regions could promote viral spread. MCs are widely distributed throughout the respiratory tract. Thus, in this study, we investigated the role of MCs and their degranulation in the development of inflammation in tracheal-bronchial epithelium. Histological analyses showed the accumulation and degranulation of MCs in the peri-trachea of humanized mice infected with SARS-CoV-2. MC degranulation caused lesions in trachea, and the formation of papillary hyperplasia was observed. Through transcriptome analysis in bronchial epithelial cells, we found that MC degranulation significantly altered multiple cellular signaling, particularly, leading to upregulated immune responses and inflammation. The administration of ebastine or loratadine effectively suppressed the induction of inflammatory factors in bronchial epithelial cells and alleviated tracheal injury in mice. Taken together, our findings confirm the essential role of MC degranulation in SARS-CoV-2-induced hyper-inflammation and the subsequent tissue lesions. Furthermore, our results support the use of ebastine or loratadine to inhibit SARS-CoV-2-triggered degranulation, thereby preventing tissue damage caused by hyper-inflammation.

Integrating single-cell RNA sequencing data to genome-wide association analysis data identifies significant cell types in influenza A virus infection and COVID-19

With the global pandemic of COVID-19, the research on influenza virus has entered a new stage, but it is difficult to elucidate the pathogenesis of influenza disease. Genome-wide association studies (GWASs) have greatly shed light on the role of host genetic background in influenza pathogenesis and prognosis, whereas single-cell RNA sequencing (scRNA-seq) has enabled unprecedented resolution of cellular diversity and in vivo following influenza disease. Here, we performed a comprehensive analysis of influenza GWAS and scRNA-seq data to reveal cell types associated with influenza disease and provide clues to understanding pathogenesis. We downloaded two GWAS summary data, two scRNA-seq data on influenza disease. After defining cell types for each scRNA-seq data, we used RolyPoly and LDSC-cts to integrate GWAS and scRNA-seq. Furthermore, we analyzed scRNA-seq data from the peripheral blood mononuclear cells (PBMCs) of a healthy population to validate and compare our results. After processing the scRNA-seq data, we obtained approximately 70 000 cells and identified up to 13 cell types. For the European population analysis, we determined an association between neutrophils and influenza disease. For the East Asian population analysis, we identified an association between monocytes and influenza disease. In addition, we also identified monocytes as a significantly related cell type in a dataset of healthy human PBMCs. In this comprehensive analysis, we identified neutrophils and monocytes as influenza disease-associated cell types. More attention and validation should be given in future studies.

Do chemokine/chemokine receptor axes play paramount parts in trafficking and oriented locomotion of monocytes/macrophages toward the lungs of COVID-19 infected patients? A systematic review

The COVID-19 (coronavirus disease 2019) is a well-defined viral infection, resulting from SARS-CoV-2 (severe acute respiratory syndrome- coronavirus-2). The innate immune system serves as the first line of defense to limit viral spreading and subsequently stimulate adaptive immune responses by the prominent aids of its cellular and molecular arms. Monocytes are defined as the most prominent innate immune cells (IICs) that are reactive against invading pathogens. These cells support host protection against the virus that is mediated by several non-specific mechanisms such as phagocytosis, producing antiviral enzymes, and recruitment of immune cells toward and into the infected tissues. They have the ability to egress from blood and migrate to the SARS-CoV-2 infected regions by the aid of some defense-related functions like chemotaxis, which is mediated by chemical compounds, e.g., chemokines. Chemokines, in addition to their related ligands are categorized within the most important and deserved agents involved in oriented trafficking of monocytes/macrophages towards and within the lung parenchyma in both steady state and pathological circumstances, including COVID-19-raised infection. However, the overexpression of chemokines could have deleterious effects on various organs through the induction of cytokine storm and may be the most important leading mechanisms in the pathogenesis of COVID-19. Authors have aimed the current review article to describe present knowledge about the interplay between monocytes/macrophages and SARS-CoV-2 with a focus on the ability of IICs to migrate and home into the lung of COVID-19 patients through various chemokine-chemokine receptor axes to promote our understanding regarding this disease.

Aryl hydrocarbon receptor activation alters immune cell populations in the lung and bone marrow during coronavirus infection

Respiratory viral infections are one of the major causes of illness and death worldwide. Symptoms associated with respiratory infections can range from mild to severe, and there is limited understanding of why there is large variation in severity. Environmental exposures are a potential causative factor. The aryl hydrocarbon receptor (AHR) is an environment-sensing molecule expressed in all immune cells. Although there is considerable evidence that AHR signaling influences immune responses to other immune challenges, including respiratory pathogens, less is known about the impact of AHR signaling on immune responses during coronavirus (CoV) infection. In this study, we report that AHR activation significantly altered immune cells in the lungs and bone marrow of mice infected with a mouse CoV. AHR activation transiently reduced the frequency of multiple cells in the mononuclear phagocyte system, including monocytes, interstitial macrophages, and dendritic cells in the lung. In the bone marrow, AHR activation altered myelopoiesis, as evidenced by a reduction in granulocyte-monocyte progenitor cells and an increased frequency of myeloid-biased progenitor cells. Moreover, AHR activation significantly affected multiple stages of the megakaryocyte lineage. Overall, these findings indicate that AHR activation modulates multiple aspects of the immune response to a CoV infection. Given the significant burden of respiratory viruses on human health, understanding how environmental exposures shape immune responses to infection advances our knowledge of factors that contribute to variability in disease severity and provides insight into novel approaches to prevent or treat disease.NEW & NOTEWORTHY Our study reveals a multifaceted role for aryl hydrocarbon receptor (AHR) signaling in the immune response to coronavirus (CoV) infection. Sustained AHR activation during in vivo mouse CoV infection altered the frequency of mature immune cells in the lung and modulated emergency hematopoiesis, specifically myelopoiesis and megakaryopoiesis, in bone marrow. This provides new insight into immunoregulation by the AHR and extends our understanding of how environmental exposures can impact host responses to respiratory viral infections.

Comprehensive bioinformatics analysis and systems biology approaches to identify the interplay between COVID-19 and pericarditis

Background

Increasing evidence indicating that coronavirus disease 2019 (COVID-19) increased the incidence and related risks of pericarditis and whether COVID-19 vaccine is related to pericarditis has triggered research and discussion. However, mechanisms behind the link between COVID-19 and pericarditis are still unknown. The objective of this study was to further elucidate the molecular mechanisms of COVID-19 with pericarditis at the gene level using bioinformatics analysis.

Methods

Genes associated with COVID-19 and pericarditis were collected from databases using limited screening criteria and intersected to identify the common genes of COVID-19 and pericarditis. Subsequently, gene ontology, pathway enrichment, protein-protein interaction, and immune infiltration analyses were conducted. Finally, TF-gene, gene-miRNA, gene-disease, protein-chemical, and protein-drug interaction networks were constructed based on hub gene identification.

Results

A total of 313 common genes were selected, and enrichment analyses were performed to determine their biological functions and signaling pathways. Eight hub genes (IL-1β, CD8A, IL-10, CD4, IL-6, TLR4, CCL2, and PTPRC) were identified using the protein-protein interaction network, and immune infiltration analysis was then carried out to examine the functional relationship between the eight hub genes and immune cells as well as changes in immune cells in disease. Transcription factors, miRNAs, diseases, chemicals, and drugs with high correlation with hub genes were predicted using bioinformatics analysis.

Conclusions

This study revealed a common gene interaction network between COVID-19 and pericarditis. The screened functional pathways, hub genes, potential compounds, and drugs provided new insights for further research on COVID-19 associated with pericarditis.

Pharmacological targeting of the hyper-inflammatory response to SARS-CoV-2-infected K18-hACE2 mice using a cluster of differentiation 36 receptor modulator

The scientific and medical community faced an unprecedented global health hazard that led to nearly 7 million deaths attributable to the rapid spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In spite of the development of efficient vaccines against SARS-CoV-2, many people remain at risk of developing severe symptoms as the virus continues to spread without beneficial patient therapy. The hyper-inflammatory response to SARS-CoV-2 infection progressing to acute respiratory distress syndrome remains an unmet medical need for improving patient care. The viral infection stimulates alveolar macrophages to adopt an inflammatory phenotype regulated, at least in part, by the cluster of differentiation 36 receptor (CD36) to produce unrestrained inflammatory cytokine secretions. We suggest herein that the modulation of the macrophage response using the synthetic CD36 ligand hexarelin offers potential as therapy for halting respiratory failure in SARS-CoV-2-infected patients.

The new era of cardiovascular research: revolutionizing cardiovascular research with 3D models in a dish

Cardiovascular research has heavily relied on studies using patient samples and animal models. However, patient studies often miss the data from the crucial early stage of cardiovascular diseases, as obtaining primary tissues at this stage is impracticable. Transgenic animal models can offer some insights into disease mechanisms, although they usually do not fully recapitulate the phenotype of cardiovascular diseases and their progression. In recent years, a promising breakthrough has emerged in the form of in vitro three-dimensional (3D) cardiovascular models utilizing human pluripotent stem cells. These innovative models recreate the intricate 3D structure of the human heart and vessels within a controlled environment. This advancement is pivotal as it addresses the existing gaps in cardiovascular research, allowing scientists to study different stages of cardiovascular diseases and specific drug responses using human-origin models. In this review, we first outline various approaches employed to generate these models. We then comprehensively discuss their applications in studying cardiovascular diseases by providing insights into molecular and cellular changes associated with cardiovascular conditions. Moreover, we highlight the potential of these 3D models serving as a platform for drug testing to assess drug efficacy and safety. Despite their immense potential, challenges persist, particularly in maintaining the complex structure of 3D heart and vessel models and ensuring their function is comparable to real organs. However, overcoming these challenges could revolutionize cardiovascular research. It has the potential to offer comprehensive mechanistic insights into human-specific disease processes, ultimately expediting the development of personalized therapies.

Infection of PRRSV inhibits CSFV C-strain replication by inducing macrophages polarization to M1

It is a common sense that porcine reproductive and respiratory syndrome virus (PRRSV) infection could cause immune failure of classical swine fever (CSF) vaccine, and porcine alveolar macrophages (PAMs) are the target cells of both. To elucidate the role of macrophage polarization in PRRSV infection induced CSF vaccine failure, an immortal porcine alveolar macrophage line PAM39 cell line was used to investigate the effect of PRRSV or/and CSFV C-strain (CSFV-C) infection on macrophage polarization in vitro. Interestingly, PRRSV single infection or PRRSV co-infection with CSFV-C promoted PAM39 cells to M1, while CSFV-C single infection induced PAM39 cells to M2. After the construction of M1 and M2 PAM39 cells polarization models, M1 polarized PAM39 cells were found to inhibit the replication of CSFV-C, and Chinese medicine such as matrine, ginsenosides and astragalus polysaccharides could alleviate the polarization of PAM39 cells and the replication of CSFV-C. Furthermore, interferon (IFN)-γ and lipopolysaccharide (LPS) co-stimulation induced NF-κB activation while matrine treatment blocked M1 polarization-induced NF-κB pathway activation. These findings provided a theoretical basis for designing a new strategy to improve the immune effect of CSFV-C based on porcine alveolar macrophage polarization subtypes.

Classical monocytes-low expressing HLA-DR is associated with higher mortality rate in SARS-CoV-2+ young patients with severe pneumonia

Aims

This study aimed to investigate whether monocyte dysregulation and hyperinflammation serve as predictive markers for mortality in young patients with SARS-CoV-2 severe pneumonia.

Methods

A prospective cohort study was conducted in a tertiary-level public University Hospital in Colombia. Forty young adults (18-50 years of age) with severe pneumonia and SARS-CoV-2 infection confirmed by qPCR, were enrroled. Serum cytokines and the monocyte phenotype profile, including PDL1/HLA-DR expression, were determined during the first 24 h of hospitalization. Routine laboratory parameters were measured throughout patient follow-up until either death or hospital discharge. We also included a cohort of twenty-five healthy control subjects.

Key findings

Elevated levels of IL-10, IL-8, and IL-6 cytokines emerged as robust predictors of mortality in young adults with severe pneumonia due to SARS-CoV-2 infected. A descriptive analysis revealed a cumulative mortality rate of 30 % in unvaccinated and ICU-admitted patients. Patients who died had significantly lower expression of HLA-DR on their classical monocytes subsets (CD14+CD16-) than survivors and healthy controls. Lower expression of HLA-DR was associated with greater clinical severity (APACHE≥12) and bacterial coinfection (relative risk 2.5 95%CI [1.18-5.74]). Notably, the expression of HLA-DR in 27.5 % of CD14+/CD16- monocytes was associated with a significantly lower probability of survival.

Significance

The early reduction in HLA-DR expression within classical monocytes emerged as an independent predictor of mortality, irrespective of comorbidities. Together with PD-L1 expression and cytokine alterations, these findings support the notion that monocyte immunosuppression plays a fundamental role in the pathogenesis and mortality of young patients infected with SARS-CoV-2. These findings hold significant implications for risk assessment and therapeutic strategies in managing critically ill young adults with SARS-CoV-2 infection.