The immunology and immunopathology of COVID-19

Human-genetic variants associated with susceptibility to SARS-CoV-2 infection

SARS-CoV-2, the third major coronavirus of the 21st century, causing COVID-19 disease, profoundly impacts public health and workforces worldwide. Identifying individuals at heightened risk of SARS-CoV-2 infection is crucial for targeted interventions and preparedness. This study investigated 35 SNVs within viral infection-associated genes in SARS-CoV-2 patients and uninfected controls from the Basque Country (March 2020-July 2021). Its primary aim was to uncover genetic markers indicative of SARS-CoV-2 susceptibility and explore genetic predispositions to infection. Association analyses revealed previously unreported associations between SNVs and susceptibility. Haplotype analyses uncovered novel links between haplotypes and susceptibility, surpassing individual SNV associations. Descriptive modelling identified key susceptibility factors, with rs11246068-CC (IFITM3), rs5742933-GG (ORMDL1), rs35337543-CG (IFIH1), and GGGCT (rs2070788, rs2298659, rs17854725, rs12329760, rs3787950) variation in TMPRSS2 emerging as main infection-susceptibility indicators for a COVID-19 pandemic situation. These findings underscore the importance of integrated SNV and haplotype analyses in delineating susceptibility to SARS-CoV-2 and informing proactive prevention strategies. The genetic markers profiled in this study offer valuable insights for future pandemic preparedness.

The hospital and mortality burden of COVID-19 compared with influenza in Denmark: a national observational cohort study, 2022-24

BACKGROUND

The COVID-19 pandemic has been on a downward trend since May, 2022, but it continues to cause substantial numbers of hospital admissions and deaths. We describe this burden in the 2 years since May, 2022, and compare it with the burden of influenza in Denmark.

METHODS

This observational cohort study included residents in Denmark from May 16, 2022, to June 7, 2024. Data were obtained from national registries, including admissions with COVID-19 or influenza (ie, having a positive PCR test for either virus from 14 days before and up to 2 days after the hospital admission date), deaths, sex, age, COVID-19 and influenza vaccination status, comorbidities, and residence in long-term care facilities. Negative binomial regression was used to estimate adjusted incidence rate ratios (aIRRs) to compare rates of hospital admissions between COVID-19 and influenza. To compare the severity of COVID-19 versus influenza among patients admitted to hospital, we used the Kaplan-Meier estimator to produce weighted cumulative incidence curves and adjusted risk ratios (aRRs) of mortality at 30 days between COVID-19 and influenza admissions.

FINDINGS

Among 5 899 170 individuals, COVID-19 admissions (n=24 400) were more frequent than influenza admissions (n=8385; aIRR 2·04 [95% CI 1·38-3·02]), particularly during the first year (May, 2022, to May, 2023) versus the second year (May, 2023, to June, 2024; p=0·0096), in the summer versus the winter (p<0·0001), and among people aged 65 years or older versus younger than 65 years (p<0·0001). The number of deaths was also higher for patients with COVID-19 (n=2361) than patients with influenza (n=489, aIRR 3·19 [95% CI 2·24-4·53]). Among patients admitted in the winter (n=19 286), the risk of mortality from COVID-19 was higher than for influenza (aRR 1·23 [95% CI 1·08-1·37]), particularly among those without COVID-19 and influenza vaccination (1·36 [1·05-1·67]), with comorbidities (1·27 [1·11-1·43]), and who were male (1·36 [1·14-1·59]).

INTERPRETATION

COVID-19 represented a greater disease burden than influenza, with more hospital admissions and deaths, and more severe disease (primarily among non-vaccinated people, those with comorbidities, and male patients). These results highlight the continued need for attention and public health efforts to mitigate the impact of SARS-CoV-2.

FUNDING

Danish Government.

Nerve- and airway-associated interstitial macrophages mitigate SARS-CoV-2 pathogenesis via type I interferon signaling

Despite vaccines, rapidly mutating viruses such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continue to threaten human health due to an impaired immunoregulatory pathway and a hyperactive immune response. Our understanding of the local immune mechanisms used by tissue-resident macrophages to safeguard the host from excessive inflammation during SARS-CoV-2 infection remains limited. Here, we found that nerve- and airway-associated interstitial macrophages (NAMs) are required to control mouse-adapted SARS-CoV-2 (MA-10) infection. Control mice restricted lung viral distribution and survived infection, whereas NAM depletion enhanced viral spread and inflammation and led to 100% mortality. Mechanistically, type I interferon receptor (IFNAR) signaling by NAMs was critical for limiting inflammation and viral spread, and IFNAR deficiency in CD169+ macrophages mirrored NAM-depleted outcomes and abrogated their expansion. These findings highlight the essential protective role of NAMs in regulating viral spread and inflammation, offering insights into SARS-CoV-2 pathogenesis and underscoring the importance of NAMs in mediating host immunity and disease tolerance.

Multi-layered deep immune profiling, SARS-CoV-2 RNAemia and inflammation in unvaccinated COVID-19 individuals with persistent symptoms

BACKGROUND

Long-COVID immunopathogenesis involves diverse factors. We longitudinally characterize hospitalized COVID-19 patients, examining the role of SARS-CoV-2 RNAemia and inflammation in immune dysregulation.

METHODS

Hospitalized patients are evaluated during acute infection (T0), 3 months post-symptom onset (T1), and 3 years if symptoms persisted (T2). Immune profile includes characterization of SARS-CoV-2-specific/non-specific T/B cells (flow cytometry) and antibodies (ELISA, neutralization, ADCC). RNAemia and cytokines are quantified (RT-PCR, cytometric beads array) and correlated.

STATISTICS

non-parametric cross-sectional, longitudinal and correlation analyses.

RESULTS

Here we show 48 hospitalized individuals during acute COVID-19, 38 exhibit early persistent symptoms (EPS+) 3 months post-symptoms onset, 10 do not (EPS-). Groups are comparable for age, sex, co-morbidities. The EPS+ shows fatigue, dyspnoea, anosmia/dysgeusia, diarrhea, chronic pain, mnestic disorders. Over time, they show a reduction of neutralization ability and total SARS-CoV-2-specific CD4 T cells, with increased total CD4 TEMRA, and failure to increase RBD-specific B cells and IgA+ MBCs. EPS+ patients show higher levels of T0-IFN-γ + CD4 TEMRA, T1-IL-2 + CD4 TEM and T1-TNF-α + CD4 cTfh. In EPS+, baseline SARS-CoV-2 RNAemia positively correlates with CD4 TEMRA, follow-up SARS-CoV-2 RNAemia with ADCC. Among 38 EPS+ individuals at T1, 33 are evaluated 3 years after infection, 5 are lost at follow-up. 10/33 EPS+ show long-term symptoms (late persistent symptoms, EPS + LPS+), whereas 23/33 fully recover (EPS + LPS-). Antibodies, RNAemia, and cytokines show no differences between/within groups at any time point.

CONCLUSIONS

Early persistent symptoms are associated with multi-layered SARS-CoV-2-specific/non-SARS-CoV-2-specific immune dysregulation. The shift towards non-Ag-specific TEMRA and ADCC trigger in EPS+ may relate to SARS-CoV-2 RNAemia. Early immune dysregulation does not associate with long-term persistent symptoms. Further research on SARS-CoV-2 RNAemia and early immune dysregulation is needed.

Toll-like receptors polymorphisms and COVID-19: a systematic review

COVID-19 is a disease caused by SARS-CoV-2. It became a health problem affecting the lives of millions of people. Toll-like receptors are responsible for recognizing viral particles and activating the innate immune system. The genetic factors associated with COVID-19 remain unclear. Thus, this study aims to assess the association between the polymorphism in Toll-like receptors and susceptibility to COVID-19. We searched the electronic databases (Science Direct, PUBMED, Web of Science, and Scopus) for studies assessing the association between Toll-like receptor polymorphisms and susceptibility to COVID-19. The quality of the studies was assessed using the Q-Genie tool. Thirteen studies were included in this systematic review. The studies analyzed polymorphisms in TLR2, TLR3, TLR4, TLR7, TLR8 and TLR9. We used SNP2TFBS bioinformatic analysis to identify the variants influencing transcription factor binding sites. The Ensembl Genome Browser was used to assess the allele and genotype frequencies in different populations. The bioinformatic analysis revealed that the variant rs5743836 of TLR9 affects the transcription factor binding sites NFKB1 and RELA. The genotype frequency of the variants rs3775291, rs3853839, rs3764880 were higher in East Asian population compared to the other populations. The frequency of the rs3775290 variant was higher in East and South Asian populations. The rs179008 variant was higher in the European population, and the rs5743836 was higher in the African population. Toll-like receptors play an important role in COVID-19 susceptibility. Further studies in different populations are necessary to elucidate the role of Toll-like receptors polymorphisms in SARS-CoV-2 infection.

Nasal cytological evidence of chronic inflammation in the olfactory cleft in post-viral olfactory dysfunction

PURPOSE

This study investigated nasal cytological alterations in patients with persistent post-viral olfactory dysfunction. The primary objective was to evaluate the role of immune dysregulation and chronic local inflammation within the nasal mucosa in sustaining long-term olfactory impairment.

METHODS

An observational case-control study was conducted at the Otorhinolaryngology Department of the University of Rome Tor Vergata. Thirty-six patients with persistent olfactory dysfunction were compared to two control groups: one comprised subjects recovered from SARS-CoV-2 infection without olfactory impairment, and the other included individuals without a history of COVID-19 or olfactory dysfunction. Psychophysical olfactory function was assessed using the TDI (Threshold, Discrimination, and Identification) test. Nasal cytology samples were obtained via nasal brushing at the level of the olfactory cleft and stained using the May-Grunwald-Giemsa technique. Cellular alterations were evaluated using a semiquantitative grading system.

RESULTS

Patients with persistent olfactory dysfunction exhibited increased lymphocytes and neutrophils compared to both control groups, indicating ongoing local inflammation. Ciliocytophthoria was notably present in a significant portion of the olfactory dysfunction group, while absent or minimally present in controls. Eosinophils and mast cells were rare across all groups.

CONCLUSION

Persistent post-viral olfactory dysfunction is associated with sustained immune activation and epithelial damage localized to the olfactory cleft. Elevated lymphocytes, neutrophils, and ciliocytophthoria emphasize the role of chronic inflammation in the pathogenesis of prolonged olfactory deficits. These findings highlight the potential utility of targeted therapies to modulate immune responses and promote olfactory recovery in affected patients.

Coronavirus Disease 2019 Symptoms by Immunity Status and Predominant-Variant Period Among US Blood Donors

Background

Amid changing variant and immunity landscapes since early in the coronavirus disease 2019 (COVID-19) pandemic, common COVID-19 symptoms need better understanding in relation to prior immunity or infecting variant.

Methods

American Red Cross blood donors were surveyed during February-April 2022 about prior COVID-19 vaccinations and symptomatic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections. Donations were tested for anti-nucleocapsid antibodies to inform infection history. Restricting analysis to donors with survey-reported infections during the Omicron BA.1-predominant period (19 December 2021 through 19 March 2022), we used multivariable logistic regression to compare symptoms by existing immunity from prior infection or vaccination. Restricting analysis to those with no existing immunity, we compared symptoms by variant-predominant period of their first reported infection (BA.1 vs before).

Results

Among 9505 donors with a BA.1-predominant period infection, donors with prior infection (n = 1115), vaccination (n = 5888), or both (n = 1738) were less likely than those without prior immunity (n = 764) to report loss of taste or smell, lower respiratory tract, constitutional, or gastrointestinal symptoms and more likely to report upper respiratory tract symptoms. Stronger associations followed recent prior infection, vaccination, or more vaccine doses. Among 8539 donors without prior immunity, those with survey-reported infections during the BA.1-predominant period (n = 764) were less likely to report loss of taste or smell, or lower respiratory tract symptoms than those with infections before this period (n = 7775).

Conclusions

Our data suggest that both prior immunity and Omicron predominance redistributed COVID-19 symptoms toward upper respiratory tract presentations and likely both contributed to a decrease in COVID-19 severity over time. These findings may better inform COVID-19 identification in high-immunity settings and demonstrate additional benefits of vaccination.

The CD38+HLA-DR+ T cells with activation and exhaustion characteristics as predictors of severity and mortality in COVID-19 patients

Background

The COVID-19 pandemic remains a global health challenge. Severe cases often respond poorly to standard treatments, highlighting the necessity for novel therapeutic targets and early predictive biomarkers.

Methods

We utilized flow cytometry to analyze peripheral immune cells from healthy, bacterial pneumonia patients, and COVID-19 patients. The expansion of activated T cells (CD38+HLA-DR+), monocytes, and myeloid-derived suppressor cells (MDSCs) were detected and correlated with clinical outcomes to evaluate prognostic potential. The single-cell RNA sequencing (scRNA-seq) was applied to characterize the critical cell subset associated with prognosis and elucidate its phenotype in COVID-19.

Results

We revealed a significant increase in CD38+HLA-DR+ T cells in non-survivor COVID-19 patients, establishing them as an independent risk factor for 28-day mortality. The scRNA-seq analysis identified the CD38+HLA-DR+ T cell as a terminally differentiated, Treg-like subset exhibiting both activation and exhaustion characteristics. This subset presented the highest IL-6 and IL-10 mRNA levels among all T-cell subsets. Further functional analysis demonstrated its enhanced major histocompatibility complex class II (MHC-II) cross-signaling and correspondingly enriched cytoskeletal rearrangement processes. In addition, there was dysregulated NAD+ metabolism in CD38+HLA-DR+ T cells via scRNA-seq, accompanied by elevated adenosine and decreased NAD+ levels in serums from COVID-19 patients.

Conclusions

We identified the selective expansion of CD38+HLA-DR+ T cells as a novel prognostic indicator for COVID-19 outcomes. These cells' unique activated-exhausted phenotype, along with their impact on NAD+ metabolism, provides new insights into COVID-19 immunopathogenesis.

SARS-CoV-2 Spike Protein and Long COVID-Part 1: Impact of Spike Protein in Pathophysiological Mechanisms of Long COVID Syndrome

SARS-CoV-2 infection has resulted in more than 700 million cases and nearly 7 million deaths worldwide. Although vaccination efforts have effectively reduced mortality and transmission rates, a significant proportion of recovered patients-up to 40%-develop long COVID syndrome (LC) or post-acute sequelae of COVID-19 infection (PASC). LC is characterized by the persistence or emergence of new symptoms following initial SARS-CoV-2 infection, affecting the cardiovascular, neurological, respiratory, gastrointestinal, reproductive, and immune systems. Despite the broad range of clinical symptoms that have been described, the risk factors and pathogenic mechanisms behind LC remain unclear. This review, the first of a two-part series, is distinguished by the discussion of the role of the SARS-CoV-2 spike protein in the primary mechanisms underlying the pathophysiology of LC.

Shengxian decoction alleviates cyclophosphamide-induced immunosuppression via improving B cell-mediated immune responses

Background

Chemotherapy is a prevalent and extensively utilized cancer treatment modality. However, it can result in immunosuppression. Shengxian Decoction (SXD) is a Traditional Chinese Medicine formula that has been demonstrated to improve immunosuppression caused by chemotherapy in clinical settings. Nevertheless, the therapeutic evaluation and mechanism of SXD in regulating immunosuppression remain unclear. The aim of this study was to ascertain the efficacy of SXD in immunocompromised mice and to elucidate the underlying immunological mechanisms.

Methods

The immunosuppression mouse model was generated through the administration of cyclophosphamide for 3 days. After that, the mice were treated by SXD extracts at doses of 0.47 and 0.94 g/kg/day, respectively. The spleen, thymus and blood of mice were collected for evaluation of drug efficacy. The population of B and T cells was detected by flow cytometry. The genes regulated by SXD in spleen were identified by utilizing RNA sequencing. The Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment were used to analyze the signaling pathway modulated by SXD. The protein expression of B cell transcription factors was detected by the immunoblotting. The signaling pathways modulated by SXD were elucidated using transcriptomics analysis complemented by network analysis.

Results

SXD treatment ameliorates decreased splenic and thymic organ indexes, as well as decreased lymphocyte number in the spleen in immunosuppressed mice. ELISA assay and flow cytometry shows that SXD promotes attenuate B-cell-mediated humoral immune responses. The RNA sequencing reveals that SXD primarily upregulates the B cell-mediated immune response and B cell receptor signaling pathway. SXD treatment upregulates the expression of B cell differentiation factors Pax5, Tcf3 and promotes splenic cell proliferation. Furthermore, SXD extract significantly inhibits hypoxia and senescence pathways in the spleen.

Conclusion

SXD exerts a protective effect against CTX-induced immunosuppression by upregulating B cell immunity and inhibiting hypoxia and senescence pathways.

Microbiome dysbiosis in SARS-CoV-2 infection: implication for pathophysiology and management strategies of COVID-19

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the etiological agent of coronavirus disease 2019 (COVID-19), in late 2019 initiated a global health crisis marked by widespread infection, significant mortality, and long-term health implications. While SARS-CoV-2 primarily targets the respiratory system, recent findings indicate that it also significantly disrupts the human microbiome, particularly the gut microbiota, contributing to disease severity, systemic inflammation, immune dysregulation, and increased susceptibility to secondary infections and chronic conditions. Dysbiosis, or microbial imbalance, exacerbates the clinical outcomes of COVID-19 and has been linked to long-COVID, a condition affecting a significant proportion of survivors and manifesting with over 200 symptoms across multiple organ systems. Despite the growing recognition of microbiome alterations in COVID-19, the precise mechanisms by which SARS-CoV-2 interacts with the microbiome and influences disease progression remain poorly understood. This narrative review investigates the impact of SARS-CoV-2 on host-microbiota dynamics and evaluates its implications in disease severity and for developing personalized therapeutic strategies for COVID-19. Furthermore, it highlights the dual role of the microbiome in modulating disease progression, and as a promising target for advancing diagnostic, prognostic, and therapeutic approaches in managing COVID-19.

WITHDRAWN: Comparative metatranscriptome analysis in gut reveals insignificant host or microbiota changes in SARS-related coronavirus naturally infected bats

The publisher regrets that this article has withdrawn. The full Elsevier Policy on Article Withdrawal can be found athttps://www.elsevier.com/about/policies-and-standards/article-withdrawal.

A multidisciplinary review of long COVID to address the challenges in diagnosis and updated management guidelines

Long COVID has emerged as a significant challenge since the COVID-19 pandemic, which was declared as an outbreak in March 2020, marked by diverse symptoms and prolonged duration of disease. Defined by the WHO as symptoms persisting or emerging for at least two months post-SARS-CoV-2 infection without an alternative cause, its prevalence varies globally, with estimates of 10-20% in Europe, 7.3% in the USA, and 3.0% in the UK. The condition's etiology remains unclear, involving factors, such as renin-angiotensin system overactivation, persistent viral reservoirs, immune dysregulation, and autoantibodies. Reactivated viruses, like EBV and HSV-6, alongside epigenetic alterations, exacerbate mitochondrial dysfunction and energy imbalance. Emerging evidence links SARS-CoV-2 to chromatin and gut microbiome changes, further influencing long-term health impacts. Diagnosis of long COVID requires detailed systemic evaluation through medical history and physical examination. Management is highly individualized, focusing mainly on the patient's symptoms and affected systems. A multidisciplinary approach is essential, integrating diverse perspectives to address systemic manifestations, underlying mechanisms, and therapeutic strategies. Enhanced understanding of long COVID's pathophysiology and clinical features is critical to improving patient outcomes and quality of life. With a growing number of cases expected globally, advancing research and disseminating knowledge on long COVID remain vital for developing effective diagnostic and management frameworks, ultimately supporting better care for affected individuals.

Long-Term Follow-Up of Neuropsychiatric Symptoms After Sustained Virological Response to Interferon-Free and Interferon-Based Hepatitis C Virus Treatment

Chronic hepatitis C virus (HCV) infection can be associated with neuropsychiatric symptoms like fatigue and cognitive impairment, independent of the liver status. The present study aims to assess changes in the pattern and extent of neuropsychological symptoms after successful treatment with interferon (IFN)-based and IFN-free therapy. HCV-infected patients who underwent neuropsychological assessment in previous studies were invited to a follow-up examination. Patients were grouped according to the treatment status: Sustained virological response (SVR) after IFN treatment (IFN SVR, n = 14) or after therapy with direct acting antivirals (DAA SVR, n = 28) or ongoing HCV infection (HCV RNA+, n = 11). A group of 33 healthy controls served as reference. Patients completed self-report questionnaires addressing health-related quality of life (HRQoL), mood and sleep quality and a neuropsychological test battery including tests of memory and attention (Luria's list of words, PSE test, cancelling "d" test, Word-Figure-Memory Test and computer-based test battery for the assessment of attention [TAP]). At baseline, all three patient groups had worse fatigue, depression, anxiety and HRQoL scores compared to healthy controls. Longitudinal analysis revealed that fatigue and mood slightly improved in all patient groups over time, while HRQoL improved in SVR patients but not in HCV RNA+ patients. Memory test results improved significantly in all patient groups, irrespective of their virological status. In contrast, the attention test results showed no clear change from baseline to follow-up. Our data can be considered as a hint that HCV eradication-independent of therapy regimen-does not substantially ameliorate neuropsychiatric symptoms in HCV-afflicted patients.

Distinct type 1 immune networks underlie the severity of restrictive lung disease after COVID-19

The variable origins of persistent breathlessness after coronavirus disease 2019 (COVID-19) have hindered efforts to decipher the immunopathology of lung sequelae. Here we analyzed hundreds of cellular and molecular features in the context of discrete pulmonary phenotypes to define the systemic immune landscape of post-COVID lung disease. Cluster analysis of lung physiology measures highlighted two phenotypes of restrictive lung disease that differed according to their impaired diffusion and severity of fibrosis. Machine learning revealed marked CCR5+CD95+CD8+ T cell perturbations in milder lung disease but attenuated T cell responses hallmarked by elevated CXCL13 in more severe disease. Distinct sets of cells, mediators and autoantibodies distinguished each restrictive phenotype and differed from those of patients without substantial lung involvement. These differences were reflected in divergent T cell-based type 1 networks according to the severity of lung disease. Our findings, which provide an immunological basis for active lung injury versus advanced disease after COVID-19, might offer new targets for treatment.

Insights into Long COVID: Unraveling Risk Factors, Clinical Features, Radiological Findings, Functional Sequelae and Correlations: A Retrospective Cohort Study

BACKGROUND

The long-term symptomatology of COVID-19 has yet to be comprehensively described. The aim of the study was to describe persistent COVID-19 symptoms in a cohort of hospitalized and home-isolated patients.

METHODS

A retrospective cohort study was conducted on long COVID patients. Long COVID symptoms were identified, and patients were divided into hospitalized (in-patients) and home-isolated (out-patients), as well as according to the number of symptoms. Patients were examined by a multidisciplinary medical team. Blood tests, high resolution chest computed tomography (CT), and physical and infectious examinations were performed. Finally, in-patients were evaluated at 2 time-points: on hospital admission (T0) and 3 months after discharge (Tpost).

RESULTS

There were 364 COVID-19 patients enrolled; 82% of patients reported one or more symptoms. The most reported symptom was fatigue. Chest CT showed alteration in 76% of patients, and pulmonary function alterations were observed in 44.7% of patients. A higher risk of presenting at least one symptom was seen in patients treated with corticosteroid, and a higher risk of presenting chest CT residual lesion was observed in hospitalized patients and in patients that received hydroxychloroquine treatment. Moreover, a higher risk of altered pulmonary function was observed in older patients.

CONCLUSION

Long-term sequelae are present in a remarkable number of long COVID patients and pose a new challenge to the health care system to identify long-lasting effects and improve patients' well-being. Multidisciplinary teams are crucial to develop preventive measures, and clinical management strategies.

Prophylactic vaccination strategies for adult patients with diabetes: a narrative review of safety profiles and clinical effectiveness

This narrative review analyzed roles of several prophylactic vaccinations in adult patients with diabetes, focusing on their safety profiles and clinical effectiveness. Individuals with diabetes mellitus are at increased risk for infections, making vaccination a critical component of their healthcare. The review assessed various vaccines that are particularly relevant for this population, i.e., vaccines for pneumococcus, meningococcus, severe acute respiratory syndrome coronavirus 2, influenza, herpes zoster, human papillomavirus, and dengue. It highlighted the safety profiles and clinical effectiveness of these vaccines in preventing serious infections and improving long-term health outcomes in diabetic patients. Taken together, this review emphasized the importance of prophylactic vaccinations in reducing infection-related morbidity and mortality as well as encouraged fostering greater adoption and advocacy for immunization programs among diabetic adults.

The intersection of microbiome and autoimmunity in long COVID-19: Current insights and future directions

Long COVID-19 affects a significant percentage of patients and is characterized by a wide range of symptoms, including weariness and mental fog as well as emotional symptoms like worry and sadness. COVID-19 is closely linked to the autoimmune disorders that are becoming more prevalent worldwide and are linked to immune system hyperactivation, neutrophil extracellular trap (NET) development, and molecular mimicry pathways. Long-term COVID-related autoimmune responses include a watchful immune system referring to the ability of immune system to constantly monitor the body for signs of infection, disease, or abnormal cells; altered innate and adaptive immune cells, autoantigens secreted by living or dead neutrophils, and high concentrations of autoantibodies directed against different proteins. The microbiome, which consists of billions of bacteria living in the human body, is essential for controlling immune responses and supporting overall health. The microbiome can affect the course of long COVID-associated autoimmunity, including the degree of illness, the rate of recovery, and the onset of autoimmune reactions. Although the precise role of the microbiome in long COVID autoimmunity is still being investigated, new studies indicate that probiotics, prebiotics, and dietary changes-interventions that target the microbiome-may be able to reduce autoimmune reactions and enhance long-term outcomes for COVID-19 survivors. More research is required to precisely understand how the microbiome affects COVID-19-related autoimmunity and to create tailored treatment plans.

Impact of Severe COVID-19 on Accelerating Dementia Onset: Clinical and Epidemiological Insights

Importance

Severe COVID-19 infection has been associated with neurological complications, but its role in accelerating cognitive decline remains unclear.

Objective

To determine whether individuals hospitalized for severe COVID-19 exhibit a higher incidence of new onset cognitive impairment compared to those hospitalized for other conditions.

Design

A retrospective study emulating a target trial using Mass General Brigham electronic health records (March 2020-August 2024). The causal effect of COVID-19 hospitalization was estimated via cumulative incidence functions accounting for the competing risk of death.

Setting

Multicenter hospital-based study across the Mass General Brigham healthcare system.

Participants

A total of 221613 hospitalized patients met the eligibility criteria, including 6454 (2.0%) admitted due to COVID-19 and 215159 (98.0%) for all other conditions. Patients were excluded if they had less than three months of follow-up (due to censoring, cognitive impairment, or death), were younger than 55 years at baseline, or had no prior visit to Mass General Brigham in the year before baseline.

Main Outcomes and Measures

The primary outcome was new-onset cognitive impairment, identified via ICD codes and dementia medication prescriptions. The primary analysis estimated the hazard ratio for cognitive impairment with COVID-19 hospitalization relative to other hospitalizations, along with the risk difference at 4.5 years estimated via cumulative incidence functions. Inverse propensity score weighting was used to balance covariates (age, sex, comorbidities, hospitalization period).

Results

Among eligible patients (mean [SD] age, 69.55 [9.42] years, 55% female), those hospitalized for COVID-19 were significantly older and had more comorbidities (p < 0.05). COVID-19 hospitalization was associated with a higher risk of developing cognitive impairment (Hazard Ratio: 1.14 [95% CI: 1.02-1.30], P = 0.018). At 4.5 years, the cumulative incidence of cognitive impairment was 12.5% [95% CI: 11.3-13.5] in the COVID-19 group, compared to 11.6% [95% CI: 11.1-12.1] in the non-COVID-19 group.

Conclusions and Relevance

Severe COVID-19 infection was associated with an elevated risk of developing clinically recognized cognitive impairment. Future studies are needed to validate findings in other health care settings. Early screening and intervention for cognitive decline may help optimize long-term outcomes for COVID-19 patients.

A Review on Long COVID Screening: Challenges and Perspectives Focusing on Exhaled Breath Gas Sensing

Long COVID (LC) is a great global health concern, affecting individuals recovering from SARS-CoV-2 infection. The persistent and varied symptoms across multiple organs complicate diagnosis and management, and an incomplete understanding of the condition hinders advancements in therapeutics. Current diagnostic methods face challenges related to standardization and completeness. To overcome this, new technologies such as sensor-based electronic noses are being explored for LC assessment, offering a noninvasive screening approach via volatile organic compounds (VOC) sensing in exhaled breath. Although specific LC-associated VOCs have not been fully characterized, insights from COVID-19 research suggest their potential as biomarkers. Additionally, AI-driven chemometrics are promising in identifying and predicting outcomes; despite challenges, AI-driven technologies hold the potential to enhance LC evaluation, providing rapid and accurate diagnostics for improved patient care and outcomes. This review underscores the importance of emerging and sensing technologies and comprehensive diagnostic strategies to address screening and treatment challenges in the face of LC.

Role of toll-like receptors in post-COVID-19 associated neurodegenerative disorders?

In the intricate realm of interactions between hosts and pathogens, Toll-like receptors (TLRs), which play a crucial role in the innate immune response, possess the ability to identify specific molecular signatures. This includes components originating from pathogens such as SARS-CoV-2, as well as the resulting damage-associated molecular patterns (DAMPs), the endogenous molecules released after cellular damage. A developing perspective suggests that TLRs play a central role in neuroinflammation, a fundamental factor in neurodegenerative conditions like Alzheimer's and Parkinson's disease (PD). This comprehensive review consolidates current research investigating the potential interplay between TLRs, their signaling mechanisms, and the processes of neurodegeneration following SARS-CoV-2 infection with an aim to elucidate the involvement of TLRs in the long-term neurological complications of COVID-19 and explore the potential of targeting TLRs as a means of implementing intervention strategies for the prevention or treatment of COVID-19-associated long-term brain outcomes.

The effect of inflammatory proteins on COVID-19 is mediated by blood metabolites: A Mendelian randomization study

Several studies have suggested that inflammatory proteins may be associated with Coronavirus disease 2019 (COVID-19). However, the specific causal relationship between the 2 and whether blood metabolites act as mediators remains unclear. Therefore, the purpose of the present study is to investigate the causal relationship between inflammatory proteins and COVID-19 and to identify and quantify the role of blood metabolites as potential mediators. Two-sample Mendelian randomization (MR) and 2-step mediated MR analyses were used to investigate the causal relationships between 91 inflammatory proteins, 486 blood metabolites and COVID-19. A random-effects inverse variance weighted (IVW) approach was used as the primary analytical method, supplemented by weighted medians, MR-Egger and MR multivariate residual sums, and outliers to test MR hypotheses. Our results showed that 2 inflammatory proteins (interleukin-10 and interleukin-18) were positively associated with COVID-19 risk, while 1 inflammatory protein (PD-L1) was negatively associated. Further validation was performed using sensitivity analysis. The results of mediated MR showed that Betaine was a mediator of PD-L1 to COVID-19 with a mediation ratio of 15.92%. Our study suggests a genetic causality between specific inflammatory proteins and COVID-19, highlights the potential mediating role of the blood metabolite betaine, and contributes to a deeper understanding of the mechanism of action of severe COVID-19.

Severely Ill COVID-19 Patients May Exhibit Hypercoagulability Despite Escalated Anticoagulation

Introduction: Severely ill COVID-19 patients receiving prophylactic-dose anticoagulation exhibit high rates of thrombosis and mortality. The escalation of anticoagulation also does not reduce mortality and has an uncertain impact on thrombosis rates. The reasons why escalated doses fail to outperform prophylactic doses in reducing risks of thrombosis and death in severely ill COVID-19 patients remain unclear. We hypothesized that escalated anticoagulation would not effectively prevent hypercoagulability and, consequently, would not reduce the risk of thrombosis and death in some severely ill patients. Methods: We conducted a prospective multicenter study that enrolled 3860 COVID-19 patients, including 1654 severely ill. They received different doses of low-molecular-weight or unfractionated heparin, and their blood coagulation was monitored with activated partial thromboplastin time, D-dimer, and Thrombodynamics. A primary outcome was hypercoagulability detected by Thrombodynamics. Blood samples were collected at the trough level of anticoagulation. Results: We found that escalated anticoagulation did not prevent hypercoagulability in 28.3% of severely ill patients at the trough level of the pharmacological activity. Severely ill patients with such hypercoagulability had higher levels of inflammation markers and better creatinine clearance compared to severely ill patients without it. Hypercoagulability detected by Thrombodynamics was associated with a 1.68-fold higher hazard rate for death and a 3.19-fold higher hazard rate for thrombosis. Elevated D-dimer levels were also associated with higher hazard rates for thrombosis and death, while shortened APTTs were not. The simultaneous use of Thrombodynamics and D-dimer data enhanced the accuracy for predicting thrombotic events and fatal outcomes in severely ill patients. Conclusions: Thrombodynamics reliably detects hypercoagulability in COVID-19 patients and can be used in conjunction with D-dimer to assess the risk of thrombosis and death in severely ill patients. The pharmacological effect of LMWH at the trough level might be too low to prevent thrombosis in some severely ill patients with severe inflammation and better creatinine clearance, even if escalated doses are used.

Delayed viral clearance and altered inflammatory responses affect severity of SARS-CoV-2 infection in aged mice

Epidemiological investigations consistently demonstrate an overrepresentation of the elderly in COVID-19 hospitalizations and fatalities, making the advanced age as a major predictor of disease severity. Despite this, a comprehensive understanding of the cellular and molecular mechanisms explaining how old age represents a major risk factor remain elusive. To investigate this, we compared SARS-CoV-2 infection outcomes in young adults (2 months) and geriatric (15-22 months) mice. Both groups of K18-ACE2 mice were intranasally infected with 500 TCID50 of SARS-CoV-2 Delta variant with analyses performed on days 3, 5, and 7 post-infection (DPI). Analyses included pulmonary cytokines, lung RNA-seq, viral loads, lipidomic profiles, and histological assessments, with a concurrent evaluation of the percentage of mice reaching humane endpoints. The findings unveiled notable differences, with aged mice exhibiting impaired viral clearance, reduced survival, and failure to recover weight loss due to infection. RNA-seq data suggested greater lung damage and reduced respiratory function in infected aged mice. Additionally, elderly-infected mice exhibited a deficient antiviral response characterized by reduced Th1-associated mediators (IFNγ, CCL2, CCL3, CXCL9) and diminished number of macrophages, NK cells, and T cells. Furthermore, mass-spectrometry analysis of the lung lipidome indicated altered expression of several lipids with immunomodulatory and pro-resolution effects in aged mice such as Resolvin, HOTrEs, and NeuroP, but also DiHOMEs-related ARDS. These findings indicate that aging affects antiviral immunity, leading to prolonged infection, greater lung damage, and poorer clinical outcomes. This underscores the potential efficacy of immunomodulatory treatments for elderly subjects experiencing symptoms of severe COVID-19.

Neuropsychiatric Manifestations of Long COVID-19: A Narrative Review of Clinical Aspects and Therapeutic Approaches

The COVID-19 (C-19) pandemic has highlighted the significance of understanding the long-term effects of this disease on the quality of life of those infected. Long COVID-19 (L-C19) presents as persistent symptoms that continue beyond the main illness period, usually lasting weeks to years. One of the lesser-known but significant aspects of L-C19 is its impact on neuropsychiatric manifestations, which can have a profound effect on an individual's quality of life. Research shows that L-C19 creates neuropsychiatric issues such as mental fog, emotional problems, and brain disease symptoms, along with sleep changes, extreme fatigue, severe head pain, tremors with seizures, and pain in nerves. People with cognitive problems plus fatigue and mood disorders experience great difficulty handling everyday activities, personal hygiene, and social interactions. Neuropsychiatric symptoms make people withdraw from social activity and hurt relationships, thus causing feelings of loneliness. The unpredictable state of L-C19 generates heavy psychological pressure through emotional suffering, including depression and anxiety. Neuropsychiatric changes such as cognitive impairment, fatigue, and mood swings make it hard for people to work or study effectively, which decreases their output at school or work and lowers their job contentment. The purpose of this narrative review is to summarize the clinical data present in the literature regarding the neuropsychiatric manifestations of L-C19, to identify current methods of diagnosis and treatment that lead to correct management of the condition, and to highlight the impact of these manifestations on patients' quality of life.

LNP-RNA-mediated antigen presentation leverages SARS-CoV-2-specific immunity for cancer treatment

Lipid nanoparticle (LNP)-mRNA vaccines have demonstrated protective capability in combating SARS-CoV-2. Their extensive deployment across the global population leads to the broad presence of T-cell immunity against the SARS-CoV-2 spike protein, presenting an opportunity to harness this immunological response as a universal antigen target for cancer treatment. Herein, we design and synthesize a series of amino alcohol- or amino acid-derived ionizable lipids (AA lipids) and develop an LNP-RNA-based antigen presentation platform to redirect spike-specific T-cell immunity against cancer in mouse models. First, in a prime-boost regimen, AA2 LNP encapsulating spike mRNA elicit stronger T-cell immunity against the spike epitopes compared to FDA-approved LNPs (ALC-0315 and SM-102), highlighting the superior delivery efficiency of AA2 LNP. Next, AA15V LNP efficiently delivers self-amplifying RNAs (saRNAs) encoding spike epitope-loaded single-chain trimer (sSE-SCT) MHC I molecules into tumor tissues, thereby inducing the presentation of spike epitopes. Our results show that a single intratumoral (i.t.) treatment of AA15V LNP-sSE-SCTs suppresses tumor growth and extends the survival of B16F10 melanoma and A20 lymphoma tumor-bearing mice vaccinated with AA2 LNP-spike mRNA. Additionally, AA15V LNP-sSE-SCTs enable SE-SCT expression in ex vivo human glioblastoma and lung cancer samples, suggesting its potential in clinical translation.

Single-cell transcriptome-wide Mendelian randomization and colocalization reveals immune-mediated regulatory mechanisms and drug targets for COVID-19

BACKGROUND

COVID-19 continues to show long-term impacts on our health. Limited effective immune-mediated antiviral drugs have been launched.

METHODS

We conducted a Mendelian randomization (MR) and colocalization analysis using 26,597 single-cell expression quantitative trait loci (sc-eQTL) to proxy effects of expressions of 16,597 genes in 14 peripheral blood immune cells and tested them against four COVID-19 outcomes from COVID-19 Genetic Housing Initiative GWAS meta-analysis Round 7. We also carried out additional validations including colocalization, linkage disequilibrium check and host-pathogen interactome predictions. We integrated MR findings with clinical trial evidence from several drug gene related databases to identify drugs with repurposing potential. Finally, we developed a tier system and identified immune-cell-based prioritized drug targets for COVID-19.

FINDINGS

We identified 132 putative causal genes in 14 immune cells (343 MR associations) for COVID-19, with 58 genes that were not reported previously. 145 (73%) gene-COVID-19 pairs showed effects on COVID-19 in only one immune cell type, which implied widespread immune-cell specific effects. For pathway analyses, we found the putative causal genes were enriched in natural killer (NK) recruiting cells but de-enriched in NK cells. Using a deep learning model, we found 107 (81%) of the putative causal genes (41 novel genes) were predicted to interact with SARS-COV-2 proteins. Integrating the above evidence with drug trial information, we developed a tier system and prioritized 37 drug targets for COVID-19.

INTERPRETATION

Our study showcased the central role of immune-mediated regulatory mechanisms for COVID-19 and prioritized drug targets that might inform interventions for viral infectious diseases.

FUNDING

This work was supported by grants from the National Key Research and Development Program of China (2022YFC2505203).

Neutropenia and SARS-CoV-2 infection, A review of the literature

According to reports, coronavirus disease 2019 (COVID-19) is associated with various complications, including hematological abnormalities. Lymphopenia and thrombocytopenia have been recognized as common hematological abnormalities. Moreover, some reports have shown cases of neutropenia occurring during or after infection with SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2). Neutropenia is a condition characterized by a decrease in the absolute neutrophil count (ANC) to less than 1500/µ. Although neutropenia has been considered a rare complication of SARS-Cov-2 infection, it is important to closely monitor patients and thoroughly investigate all laboratory findings, particularly in those with severe COVID-19. This will allow for effective therapeutic intervention and appropriate disease management in challenging conditions. In this study, our aim was to conduct a comprehensive review of the current literature on neutropenia during or after SARS-CoV2 infection. Furthermore, we assessed whether there have been any documented cases of immune-mediated neutropenia following COVID-19 and if the appropriate laboratory investigations have been carried out in these patients.

Demographic, epidemiological and clinical profile of patients with post-COVID syndrome followed at a teaching hospital in Brazil

INTRODUCTION

Post-COVID Syndrome (PCS), occurs several weeks after Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-2 infection), has a frequency of 10 %‒35 % of cases, presents a wide range of symptoms that can persist for months or years and markedly reduces the quality of life of patients.

OBJECTIVE

To describe clinical, epidemiological and evolutionary aspects of a cohort of patients diagnosed with PCS followed on an outpatient basis.

METHODOLOGY

Individuals of both sexes, > 18-years old who presented symptoms suggestive of PCS and had previously confirmed SARS-CoV-2 infection were included. Clinical evaluation was carried out monthly by a multidisciplinary team, and if necessary laboratorial exams were performed.

RESULTS

From June 2021 to June 2022, 92 cases of PCS were diagnosed, of which 60 (65.2 %) were female and the average age was 49.1 years. In 61 (66.3 %) of the cases, SARS-CoV-2 infection occurred between January and November 2021. In 55 (59.7 %) of the cases the symptoms were mild, while 31 (36.0 %) were moderate or severe cases. Most cases of PCS occurred in individuals with the mild form of COVID-19. The predominant symptoms were chronic fatigue in 59 (68.6 %) cases, brain fog in 68 (73.4 %), myalgias and arthralgias in 44 (47.8 %), cramps and paresthesia's in 40 (46.5 %). The main comorbidities observed were high blood pressure, obesity and diabetes mellitus. The persistence of symptoms was greater in those cases who presented severe forms of COVID-19. Most patients experienced gradual and progressive improvement over the months.

DISCUSSION

The profile of patients with PCS in this cohort is similar to other reports. A great number of symptoms is remarkable with variable presentation and evolution and their frequency exceeds that previously described in a large meta-analysis. Inflammatory phenomena mediated by the virus, autoimmunity and direct organic damage have been implicated in the genesis of this syndrome.

Serum Lactate Dehydrogenase Levels Reflect the Lung Injury Extension in COVID-19 Patients at Hospital Admission

BACKGROUND

Several hematological and biochemical parameters have been related to the COVID-19 infection severity and outcomes. However, less is known about clinical indicators reflecting lung involvement of COVID-19 patients at hospital admission. Computed tomography (CT) represents an established imaging tool for the detection of lung injury, and the quantitative analysis software CALIPER has been used to assess lung involvement in COVID-19 patients. Herein, the relationship between the lung involvement expressed by CALIPER interstitial lung disease (ILD) percentage and a set of blood parameters related to tissue oxygenation and damage in COVID-19 patients at hospital admission was evaluated.

METHODS

We performed a retrospective and a prospective study involving 321 and 75, respectively, COVID-19-positive patients recruited from Pisa University Hospital. The association between CALIPER ILD percentages and selected blood parameters was investigated by a regression tree approach, after multiple imputations of the dataset missing values.

RESULTS

High serum lactate dehydrogenase (LDH) values appeared to be predictive of high CALIPER ILD percentages at hospital admission in both retrospective and prospective datasets, even if the predictive performance of the algorithm was not optimal.

CONCLUSIONS

LDH levels could be evaluated as a tool for early identification of COVID-19 patients at risk of extensive lung injury, as well as in fast screening procedures before hospitalization.

Anti-inflammatory effect of nestorone in a lipopolysaccharide-induced acute lung injury model through regulation of the TLR-4/Myd88/NF-κB signaling pathway

Progesterone plays a crucial and indispensable role in regulating immunity and attenuating inflammation. Nestorone® (NES, segesterone acetate) is a steroidal progestin and a 19-norprogesterone derivative with no -CH3 group radical at the 6-position. Here, we showed that NES enhanced the viability of lipopolysaccharide (LPS)-stimulated THP-1 cell-derived macrophages, potently inhibiting both arms of the Toll-like receptor 4 (TLR-4) signaling cascade triggered by LPS, especially the TLR-4/MyD88/NF-κB pathway. In addition, NES exerted an anti-inflammatory effect by significantly decreasing the secretion of inflammatory cytokines and chemokines in type II alveolar epithelial A549 cells and THP-1 cell-derived macrophages stimulated by LPS. Furthermore, we evaluated the potential of NES pre-treatment, administered 2 h prior to LPS exposure, to mitigate acute lung injury induced by LPS, using an LPS-induced acute lung injury (ALI) mouse model. In this study, NES alleviated lung inflammation and damage by reducing leukocyte infiltration and inflammatory cytokines in the bronchoalveolar lavage fluid (BALF) and lung tissues of mice. Interestingly, our findings indicate that NES at a dosage of 1 mg/kg (91.67%) was more effective than at dosages of 0.1 mg/kg (70.83%) or 10 mg/kg (87.50%), as well as more effective than dexamethasone (DEX, 5 mg/kg, 83.34%), in extending survival in mice subjected to lethal LPS-induced injury. Additionally, this dosage was more successful in reducing acute lung inflammation and alleviating diffuse alveolar damage in the lungs of C57 mice. Our study indicates that concentration is a critical determinant of the anti-inflammatory efficacy of NES. Consequently, NES emerges as a potentially promising therapeutic agent for the treatment of pulmonary inflammatory conditions through the modulation of TLR-4 signaling pathways.

Neutrophil extracellular traps and macrophage activation contibute to thrombosis and post-covid syndrome in SARS-CoV-2 infection

Background

SARS-CoV-2 infection activates macrophages and induces the release of neutrophil extracellular traps (NETs). Excess NETs is linked to inflammatory and thrombotic complications observed in COVID-19.

Aim

To explore the impact of NETs and macrophage activation on SARS-CoV-2-infected patients who developed complications.

Methods

We included 30 patients from the first (March 2020) and 30 from the second wave (July 2021), collecting two plasma samples at diagnosis and seven days later. Data on demographics, comorbidities, and basic analytical data were compiled. NETs markers (myeloperoxidase (MPO), neutrophil elastase (NE), p-selectin (P-SEL) and S100A8/S100A9 heterodimer (MRP)) and macrophage activation markers (Chitotriosidase activity (ChT), CCL18/PARC and YKL-40) were measured.

Results

The first wave had higher incidences of post-COVID syndrome, ICU admissions, and mortality. Patients of each wave showed elevated blood cells, liver enzymes, and coagulation markers at the time of diagnosis, with fibrinogen and D-Dimer differing between waves. NET and macrophage markers, NE, MPO, MRP, DNAse, ChT, and CCL18 were elevated, while P-SEL, cfDNA, and YKL-40 were decreased if compared to controls. A decrease in NE and DNAse is a link to lower levels of these two markers in complications versus without complications.

Conclusions

This study emonstrates alterations in NETs and macrophage activation markers in COVID-19 patients, indicating an imbalance in inflammatory response regulation.

COVID-19 patient serum-derived extracellular vesicles deliver miR-20b-5p induces neutrophil extracellular traps

BACKGROUND

Severe cases of COVID-19 are characterized by an excessive presence of neutrophils. Neutrophil extracellular traps (NETs), released by activated neutrophils due to SARS-CoV-2 infection, contribute to lung epithelial cell death and are key drivers in COVID-19-associated immunothrombosis. However, the mechanism underlying NET formation in COVID-19 remain unclear.

METHODS

Extracellular vesicles (EVs) were isolated from the serum of COVID-19 patients and healthy volunteers, while neutrophils were isolated from blood samples of healthy volunteers. Neutrophils were treated with EVs, and the formation of NETs was observed. To identify the components responsible for the COVID-19-EVs-induced NET formation, we analyzed the expression profiles of microRNA (miRNAs) in COVID-19-EVs. We identified eight highly expressed miRNAs in COVID-19-EVs and explored their potential roles in COVID-19-EVs-mediated NET formation. Additionally, we explored the role of miR-20b-5p in COVID-19-EVs-induced NET formation.

RESULTS

In this study, we demonstrate that patients with COVID-19 have a higher concentration of serum EVs (COVID-19-EVs) than healthy controls (Normal-EVs). We also found that COVID-19-EVs are internalized by neutrophils to induced NET formation. Through comprehensive miRNA profiling of COVID-19-EVs versus Normal-EVs, we identified 78 differentially expressed miRNAs, with 27 of these being upregulated and 51 being downregulated. Subsequently, we discovered that COVID-19-EVs that were highly abundant with certain miRNAs promote NET formation. Specifically, miR-20b-5p was found to be the strongest inducer of NET formation of the identified miRNAs. Inhibition of miR-20b-5p resulted in a significant decrease in COVID-19-EVs-mediated induction of NET formation.

CONCLUSION

Herein, we reveal a previously unknown role of COVID-19-EVs in NET formation, which contributes to COVID-19 progression. This study suggests that miR-20b-5p may serve as a potential therapeutic target for COVID-19 treatment.

Treatment with the CCR5 antagonist OB-002 reduces lung pathology, but does not prevent disease in a Syrian hamster model of SARS-CoV-2 infection

Since the emergence of SARS-CoV-2 and the COVID-19 pandemic, a wide range of treatment options have been evaluated in preclinical studies and clinical trials, with several being approved for use in humans. Immunomodulatory drugs have shown success in dampening the deleterious inflammatory response seen in severe COVID-19 patients, but there remains an urgent need for development of additional therapeutic options for COVID-19 treatment. A potential drug target is the CCR5-CCL5 axis, and blocking this pathway may protect against severe disease. Here we evaluated whether OB-002, an analog of human CCL5 and a potent antagonist of CCR5, provides therapeutic benefit in SARS-CoV-2 infected Syrian hamsters. Daily treatment with OB-002 altered immune gene transcription in the lungs, and reduced pathology following infection, but did not prevent weight loss or viral replication in the lungs of infected animals, even in combination with the antiviral drug remdesivir. Our data suggest that targeting the CCR5-CCL5 pathway in SARS-CoV-2 infection in hamsters is insufficient to significantly impact disease development in this model.

Blood CD45+/CD3+ lymphocyte-released extracellular vesicles and mortality in hospitalized patients with coronavirus disease 2019

BACKGROUND

The global pandemic of coronavirus disease 2019 (COVID-19) represented a major public health concern. Growing evidence shows that plasma of COVID-19 patients contains large numbers of circulating extracellular vesicles (cEVs) that correlate with disease severity and recovery. In this study, we sought to characterize the longitudinal cEV signature in critically ill COVID-19 patients during hospitalization and its relation to mortality risk.

METHODS

cEVs were quantitatively and phenotypically analysed in hospitalized non-surviving COVID-19 patients at baseline (n = 42) and before exitus (n = 40) and in 40 healthy volunteers as a reference group by high sensitivity nano flow cytometry using specific markers for parental cell sources and activation.

RESULTS

Levels of cEV subtypes differed between patients with severe COVID-19 and healthy subjects, specifically those from platelets and endothelial, inflammatory and viral infected cells, which associate to high mortality risk. In the longitudinal analysis from baseline to the time point immediately preceding death, no changes were found for platelet, pan-leukocyte, and lung epithelial cell-shed cEVs, while endothelial cell releases of EVs (eEVs) significantly differed. Vascular endothelial growth factor receptor 2-positive eEVs were significantly increased before death compared to admission whereas endoglin and E-selectin-containing eEVs did not change. Conversely, lymphocyte (ℓEV), monocyte, macrophage, pericyte and progenitor cell-derived cEVs displayed significant reductions before exitus. Noteworthy, levels of CD45+/CD3+-ℓEVs were significantly associated to the patient's survival time.

CONCLUSIONS

An evolving cEV profile able to discriminate prompt risk of death during hospitalization has been defined suggesting a role for circulating and vascular cell-derived EVs in COVID-19 pathogenesis.

Purinergic signaling in the battlefield of viral infections

Purinergic signaling has been associated with immune defenses against pathogens such as bacteria, protozoa, fungi, and viruses, acting as a sentinel system that signals to the cells when a threat is present. This review focuses on the roles of purinergic signaling and its therapeutic potential for viral infections. In this context, the purinergic system may play potent antiviral roles by boosting interferon signaling. In other cases, though, it can contribute to a hyperinflammatory response and disease severity, resulting in poor outcomes, such as during flu and potentially COVID-19. Lastly, a third situation may occur since viruses are obligatory intracellular parasites that hijack the host cell machinery for their infection and replication. Viruses such as HIV-1 use the purinergic system to favor their infection and persistence within the host cell. Therefore, understanding the particular nuances of purinergic signaling in each viral infection may contribute to designing proper therapeutic strategies to treat viral diseases.

Airway Basal Stem Cells Inflammatory Alterations in COVID-19 and Mitigation by Mesenchymal Stem Cells

SARS-CoV-2 infection and the resultant COVID-19 pneumonia cause significant damage to the airway and lung epithelium. This damage manifests as mucus hypersecretion, pulmonary inflammation and fibrosis, which often lead to long-term complications collectively referred to as long COVID or post-acute sequelae of COVID-19 (PASC). The airway epithelium, as the first line of defence against respiratory pathogens, depends on airway basal stem cells (BSCs) for regeneration. Alterations in BSCs are associated with impaired epithelial repair and may contribute to the respiratory complications observed in PASC. Given the critical role of BSCs in maintaining epithelial integrity, understanding their alterations in COVID-19 is essential for developing effective therapeutic strategies. This study investigates the intrinsic properties of BSCs derived from COVID-19 patients and evaluates the modulatory effects of mesenchymal stem cells (MSCs). Through a combination of functional assessments and transcriptomic profiling, we identified key phenotypic and molecular deviations in COVID-19 patient-derived BSCs, including goblet cell hyperplasia, inflammation and fibrosis, which may underlie their contribution to PASC. Notably, MSC co-culture significantly mitigated these adverse effects, potentially through modulation of the interferon signalling pathway. This is the first study to isolate BSCs from COVID-19 patients in the Chinese population and establish a COVID-19 BSC-based xenograft model. Our findings reveal critical insights into the role of BSCs in epithelial repair and their inflammatory alterations in COVID-19 pathology, with potential relevance to PASC and virus-induced respiratory sequelae. Additionally, our study highlights MSC-based therapies as a promising strategy to address respiratory sequelae and persistent symptoms.

Endocan as a marker of endotheliitis in COVID-19 patients: modulation by veno-venous extracorporeal membrane oxygenation, arterial hypertension and previous treatment with renin-angiotensin-aldosterone system inhibitors

BACKGROUND AND AIMS

Endocan has been scarcely explored in COVID-19, especially regarding its modulation by veno-venous extracorporeal membrane oxygenation (VV-ECMO), hypertension or previous renin-angiotensin-aldosterone system (RAAS) inhibitors treatment. We compared endocan and other endotheliitis markers in hospitalized COVID-19 patients and assessed their modulation by VV-ECMO, hypertension and previous RAAS inhibitors treatment.

MATERIAL AND METHODS

Serum endocan, intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and E-selectin were measured in "severe" (n = 27), "critically ill" (n = 17) and "critically ill on VV-ECMO" (n = 17) COVID-19 patients at admission, days 3-4, 5-8 and weekly thereafter, and in controls (n = 23) at a single time point.

RESULTS

Admission endocan and VCAM-1 were increased in all patients, but "critically ill on VV-ECMO" patients had higher endocan and E-Selectin. Endocan remained elevated throughout hospitalization in all groups. "Severe" and "critically ill" hypertensive patients or previously treated with RAAS inhibitors had higher endocan and/or VCAM-1, but in VV-ECMO patients the raised endocan values seemed unrelated with these factors. Among all COVID-19 hypertensive patients, those with previous RAAS inhibitors treatment had higher endocan.

CONCLUSIONS

In our study, endocan stands out as the best marker of endotheliitis in hospitalized COVID-19 patients, being upregulated by VV-ECMO support, hypertension and previous RAAS inhibitor treatment.

Selective phosphodiesterase 4 inhibitor roflumilast reduces inflammation and lung injury in models of betacoronavirus infection in mice

OBJECTIVE

We aimed to understand the potential therapeutic and anti-inflammatory effects of the phosphodiesterase-4 (PDE4) inhibitor roflumilast in models of pulmonary infection caused by betacoronaviruses.

METHODS

Mice were infected intranasally with murine hepatitis virus (MHV-3) or severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Roflumilast was given to MHV-3-infected mice therapeutically at doses of 1 mg/kg or 10 mg/kg, or prophylactically at 10 mg/kg. In SARS-CoV-2-infected mice, roflumilast was given therapeutically at a dose of 10 mg/kg. Lung histopathology, chemokines (CXCL-1 and CCL2), cytokines (IL-1β, IL-6, TNF, IFN-γ, IL-10 and TGFβ), neutrophil immunohistochemical staining (Ly6G+ cells), macrophage immunofluorescence staining (F4/80+ cells), viral titration plaque assay, real-time PCR virus detection, and blood cell counts were examined.

RESULTS

Therapeutic treatment with roflumilast at 10 mg/kg reduced lung injury in SARS-CoV-2 or MHV-3-infected mice without compromising viral clearance. In MHV-3-infected mice, reduced lung injury was associated with decreased chemokines levels, prevention of neutrophil aggregates and reduced macrophage accumulation in the lung tissue. However, the prophylactic treatment strategy with roflumilast increased lung injury in MHV-3-infected mice.

CONCLUSION

Our findings indicate that therapeutic treatment with roflumilast reduced lung injury in MHV-3 and SARS-CoV-2 lung infections. Given the protection induced by roflumilast in inflammation, PDE4 targeting could be a promising therapeutic avenue worth exploring following severe viral infections of the lung.

Therapeutic plasma exchange accelerates immune cell recovery in severe COVID-19

Background

Immunological disturbances (anti-type I IFN auto-antibody production, cytokine storm, lymphopenia, T-cell hyperactivation and exhaustion) are responsible for disease exacerbation during severe COVID-19 infections.

Methods

In this study, we set up a prospective, randomised clinical trial (ClinicalTrials.gov ID: NCT04751643) and performed therapeutic plasma exchange (TPE) in severe COVID-19 patients in order to decrease excess cytokines and auto-antibodies and to assess whether adding TPE to the standard treatment (ST, including corticosteroids plus high-flow rate oxygen) could help restore immune parameters and limit the progression of acute respiratory distress syndrome (ARDS).

Results

As expected, performing TPE decreased the amount of anti-type I IFN auto-antibodies and improved the elimination or limited the production of certain inflammatory mediators (IL-18, IL-7, CCL2, CCL3, etc.) circulating in the blood of COVID-19 patients, compared to ST controls. Interestingly, while TPE did not influence changes in ARDS parameters throughout the protocol, it proved more effective than ST in reversing lymphopenia, preventing T-cell hyperactivation and reducing T-cell exhaustion, notably in a fraction of TPE patients who had an early favourable respiratory outcome. TPE also restored appropriate numbers of CD4+ and CD8+ T-cell memory populations and increased the number of circulating virus-specific T cells in these patients.

Conclusion

Our results therefore indicate that the addition of TPE sessions to the standard treatment accelerates immune cell recovery and contributes to the development of appropriate antiviral T-cell responses in some patients with severe COVID-19 disease.

Immune-Boosting and Antiviral Effects of Antioxidants in COVID-19 Pneumonia: A Therapeutic Perspective

The COVID-19 pandemic caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has profoundly impacted global health, with pneumonia emerging as a major complication in severe cases. The pathogenesis of COVID-19 is marked by the overproduction of reactive oxygen species (ROS) and an excessive inflammatory response, resulting in oxidative stress and significant tissue damage, particularly in the respiratory system. Antioxidants have garnered considerable attention for their potential role in managing COVID-19 pneumonia by mitigating oxidative stress and modulating immune responses. This review provides a comprehensive overview of the literature on the use of antioxidants in hospitalized patients with mild-to-moderate COVID-19. Studies exploring antioxidants, including vitamins, trace elements, nitric oxide (NO), ozone (O3), glutathione (GSH), L-carnitine, melatonin, bromelain, N-acetylcysteine (NAC), and numerous polyphenols, have yielded promising outcomes. Through their ROS-scavenging properties, these molecules support endothelial function, reduce the thrombosis risk, and may help mitigate the effects of the cytokine storm, a key contributor to COVID-19 morbidity and mortality. Clinical evidence suggests that antioxidant supplementation may improve patient outcomes by decreasing inflammation, supporting immune cell function, and potentially shortening recovery times. Furthermore, these molecules may mitigate the symptoms of COVID-19 by exerting direct antiviral effects that inhibit the infection process and genomic replication of SARS-CoV-2 in host cells. Moreover, antioxidants may work synergistically with standard antiviral treatments to reduce viral-induced oxidative damage. By integrating findings from the literature with real-world data from our clinical experience, we gain a more profound understanding of the role of antioxidants in managing COVID-19 pneumonia. Further research combining comprehensive literature reviews with real-world data analysis is crucial to validate the efficacy of antioxidants and establish evidence-based guidelines for their use in clinical practice.

Neutrophil adhesion to vessel walls impairs pulmonary circulation in COVID-19 pathology

Microthrombus formation is associated with COVID-19 severity; however, the detailed mechanism remains unclear. In this study, we investigated mouse models with severe pneumonia caused by SARS-CoV-2 infection by using our in vivo two-photon imaging system. In the lungs of SARS-CoV-2-infected mice, increased expression of adhesion molecules in intravascular neutrophils prolonged adhesion time to the vessel wall, resulting in platelet aggregation and impaired lung perfusion. Re-analysis of scRNA-seq data from peripheral blood mononuclear cells from COVID-19 cases revealed increased expression levels of CD44 and SELL in neutrophils in severe COVID-19 cases compared to a healthy group, consistent with our observations in the mouse model. These findings suggest that pulmonary perfusion defects caused by neutrophil adhesion to pulmonary vessels contribute to COVID-19 severity.

Sparse Bernoulli mixture modeling with negative-unlabeled data: an approach to identify and characterize long COVID

SARS-CoV-2-infected individuals have reported a diverse collection of persistent and often debilitating symptoms commonly referred to as long COVID or post-acute sequelae of SARS-CoV-2 (PASC). Identifying PASC and its subphenotypes is challenging because available data are "negative-unlabeled" as uninfected individuals must be PASC negative, but those with prior infection have unknown PASC status. Moreover, feature selection among many potentially informative characteristics can facilitate reaching a concise and easily interpretable PASC definition. Therefore, to characterize PASC and the spectrum of PASC subphenotypes while identifying a minimal set of features, we propose a Bernoulli mixture model with novel parameterization to accommodate negative-unlabeled data and Bayesian priors to induce sparsity. We present an efficient expectation-maximization algorithm for estimation, and a grid search procedure to select the number of clusters and level of sparsity. We evaluate the proposed method with a simulation study and an analysis of data on self-reported symptoms from the ongoing Researching COVID to Enhance Recovery-Adult Cohort study.

An emerging double‑edged sword role of ferroptosis in cardiovascular disease (Review)

The pathophysiology of cardiovascular disease (CVD) is complex and presents a serious threat to human health. Cardiomyocyte loss serves a pivotal role in both the onset and progression of CVD. Among various forms of programmed cell death, ferroptosis, along with apoptosis, autophagy and pyroptosis, is closely linked to the advancement of CVD. Ferroptosis, a mechanism of cell death, is driven by the buildup of oxidized lipids and excess iron. This pathway is modulated by lipid, amino acid and iron metabolism. Key characteristics of ferroptosis include disrupted iron homeostasis, increased peroxidation of polyunsaturated fatty acids due to reactive oxygen species, decreased glutathione levels and inactivation of glutathione peroxidase 4. Treatments targeting ferroptosis could potentially prevent or alleviate CVD by inhibiting the ferroptosis pathway. Ferroptosis is integral to the pathogenesis of several types of CVD and inhibiting its occurrence in cardiomyocytes could be a promising therapeutic strategy for the future treatment of CVD. The present review provided an in‑depth analysis of advancements in understanding the mechanisms underlying ferroptosis. The present manuscript summarized the interplay between ferroptosis and CVDs, highlighting its dual roles in these conditions. Additionally, potential therapeutic targets within the ferroptosis pathway were discussed, alongside the current limitations and future directions of these novel treatment strategies. The present review may offer novel insights into preventive and therapeutic approaches for CVDs.

Clinical Comparison of Post-intensive Care Syndrome and Long Coronavirus Disease

Post-intensive care syndrome (PICS) encompasses persistent physical, psychological, and cognitive impairments. The coronavirus disease of 2019 (COVID-19) pandemic highlighted parallels between PICS and "long COVID". There is an overlap between the 2 in risk factors, symptoms, and pathophysiology. Physical impairments in both include weakness and fatigue. Cognitive impairments include executive dysfunction in PICS and "brain fog" in long COVID. Mental health issues consist of depression, anxiety, and posttraumatic stress disorder in both disease states. Long COVID and PICS impact families, with multifaceted effects on physical health, mental well-being, and socioeconomic stability. Understanding these syndromes is crucial for comprehensive patient care and family support.

Exploring the Relationship Between Humoral and Cellular T Cell Responses Against SARS-CoV-2 in Exposed Individuals From Emilia Romagna Region and COVID-19 Severity

COVID-19 remains a significant global health problem with uncertain long-term consequences for convalescents. We investigated the relationships between anti-N protein antibody levels, severe acute respiratory syndrome (SARS)-CoV-2-associated TCR repertoire parameters, HLA type and epidemiological information from three cohorts of 524 SARS-CoV-2-infected subjects subgrouped in acute phase, seronegative and seropositive convalescents from the Emilia Romagna region. Epidemiological information and anti-N antibody index were associated with TCR repertoire data. HLA type was inferred from TCR repertoire using the HLA3 tool and its association with clonal breadth (CB) and clonal depth (CD) was assessed. Age above 58 years, male and COVID-19 hospitalisation were significantly and independently associated with seropositivity (p = 0.004; p = 0.004; p = 0.04), suggesting an association between high antibody titres and symptoms' severity. As for the TCR repertoire analysis, we found no difference in CB among the cohorts, while CD was higher in seronegative than acute (p = 0.04). However, clustering analysis supported that seronegative patients are endowed with broader CB and deeper CD indicating a compensatory mechanism without effective seroconversion. The CD calculated on the TCRs associated with the single SARS-CoV-2 ORFs in convalescents is higher when compared to the acute. Lastly, we identified and reported on novel HLAs significantly associated with increased risk of hospitalisation such as HLA-C*07:02 carriers (OR = 3.9, CI = 1.1-13.4, p = 0.03) and on HLAs that associate significantly with lower or higher TCR repertoire parameters in a population exposed for the first time to SARS-CoV-2.

Multidisciplinary Center Care for Long COVID Syndrome-A Retrospective Cohort Study

BACKGROUND

Persistent multi-organ symptoms after coronavirus disease 2019 (COVID-19) have been termed "long COVID" or "post-acute sequelae of SARS-CoV-2 infection." The complexity of these clinical manifestations posed challenges early in the pandemic as different ambulatory models formed out of necessity to manage the influx of patients. Little is known about the characteristics and outcomes of patients seeking care at multidisciplinary post-COVID centers.

METHODS

We performed a retrospective cohort study of patients evaluated at our multidisciplinary comprehensive COVID-19 center in Chicago, Ill, between May 2020 and February 2022. We analyzed specialty clinic utilization and clinical test results according to severity of acute COVID-19.

RESULTS

We evaluated 1802 patients a median of 8 months from acute COVID-19 onset, including 350 post-hospitalization and 1452 non-hospitalized patients. Patients were seen in 2361 initial visits in 12 specialty clinics, with 1151 (48.8%) in neurology, 591 (25%) in pulmonology, and 284 (12%) in cardiology. Among the patients tested, 742/916 (81%) reported decreased quality of life, 284/553 (51%) had cognitive impairment, 195/434 (44.9%) had alteration of lung function, 249/299 (83.3%) had abnormal computed tomography chest scans, and 14/116 (12.1%) had elevated heart rate on rhythm monitoring. Frequency of cognitive impairment and pulmonary dysfunction was associated with severity of acute COVID-19. Non-hospitalized patients with positive SARS-CoV-2 testing had findings similar to those with negative or no test results.

CONCLUSIONS

The experience at our multidisciplinary comprehensive COVID-19 center shows common utilization of multiple specialists by long COVID patients, who harbor frequent neurologic, pulmonary, and cardiologic abnormalities. Differences in post-hospitalization and non-hospitalized groups suggest distinct pathogenic mechanisms of long COVID in these populations.

Neurological, psychological, psychosocial complications of long-COVID and their management

Since it first appeared, Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has had a significant and lasting negative impact on the health and economies of millions of individuals all over the globe. At the level of individual health too, many patients are not recovering fully and experiencing a long-term condition now commonly termed 'long-COVID'. Long-COVID is a collection of symptoms which must last more than 12 weeks following initial COVID infection, and which cannot be adequately explained by alternate diagnoses. The neurological and psychosocial impact of long-COVID is itself now a global health crisis and therefore preventing, diagnosing, and managing these patients is of paramount importance. This review focuses primarily on: neurological functioning deficits; mental health impacts; long-term mood problems; and associated psychosocial issues, among patients suffering from long-COVID with an eye towards the neurological basis of these symptoms. A concise account of the clinical relevance of the neurological and psychosocial impacts of long-COVID, the effects on long-term morbidity, and varied approaches in managing patients with significant chronic neurological symptoms and conditions was extracted from the literature, analysed and reported. A comprehensive account of plausible pathophysiological mechanisms involved in the development of long-COVID, its management, and future research needs have been discussed.

Sustained Vascular Inflammatory Effects of SARS-CoV-2 Spike Protein on Human Endothelial Cells

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has been associated with systemic inflammation and vascular injury, which contribute to the development of acute respiratory syndrome (ARDS) and the mortality of COVID-19 infection. Moreover, multiorgan complications due to persistent endothelial dysfunction have been suspected as the cause of post-acute sequelae of SARS-CoV-2 infection. Therefore, elucidation of the vascular inflammatory effect of SARS-CoV-2 will increase our understanding of how endothelial cells (ECs) contribute to the short- and long-term consequences of SARS-CoV-2 infection. Here, we investigated the interaction of SARS-CoV-2 spike protein with human ECs from aortic (HAoEC) and pulmonary microvascular (HPMC) origins, cultured under physiological flow conditions. We showed that the SARS-CoV-2 spike protein triggers prolonged expression of cell adhesion markers in both ECs, similar to the effect of TNF-α. SARS-CoV-2 spike treatment also led to the release of various cytokines and chemokines observed in severe COVID-19 patients. Moreover, increased binding of leucocytes to the endothelial surface and a procoagulant state of the endothelium were observed. Transcriptomic profiles of SARS-CoV-2 spike-activated HPMC and HAoEC showed prolonged upregulation of genes and pathways associated with responses to virus, cytokine-mediated signaling, pattern recognition, as well as complement and coagulation pathways. Our findings support experimental and clinical observations of the vascular consequences of SARS-CoV-2 infection and highlight the importance of EC protection as one of the strategies to mitigate the severe effects as well as the possible post-acute complications of COVID-19 disease.

Antibodies to the RBD of SARS-CoV-2 spike mediate productive infection of primary human macrophages

The role of myeloid cells in the pathogenesis of SARS-CoV-2 is well established, in particular as drivers of cytokine production and systemic inflammation characteristic of severe COVID-19. However, the potential for myeloid cells to act as bona fide targets of productive SARS-CoV-2 infection, and the specifics of entry, remain unclear. Using a panel of anti-SARS-CoV-2 monoclonal antibodies (mAbs) we performed a detailed assessment of antibody-mediated infection of monocytes/macrophages. mAbs with the most consistent potential to mediate infection were those targeting a conserved region of the receptor binding domain (RBD; group 1/class 4). Infection was closely related to the neutralising concentration of the mAbs, with peak infection occurring below the IC50, while pre-treating cells with remdesivir or FcγRI-blocking antibodies inhibited infection. Studies performed in primary macrophages demonstrated high-level and productive infection, with infected macrophages appearing multinucleated and syncytial. Infection was not seen in the absence of antibody with the same quantity of virus. Addition of ruxolitinib significantly increased infection, indicating restraint of infection through innate immune mechanisms rather than entry. High-level production of pro-inflammatory cytokines directly correlated with macrophage infection levels. We hypothesise that infection via antibody-FcR interactions could contribute to pathogenesis in primary infection, systemic virus spread or persistent infection.