Human Cytomegalovirus Infection Research Articles

Risk factors for inflammatory bowel disease: an umbrella review

IntroductionInflammatory bowel disease (IBD) represents a cluster of chronic idiopathic inflammatory disorders situated at the nexus of intricate interplays. The primary aim of the present investigation is to perform an umbrella review of metaanalyses, systematically offering a comprehensive overview of the evidence concerning risk factors for IBD.MethodsTo achieve this, we searched reputable databases, including PubMed, Embase, Web of Science, and the Cochrane Database of Systematic Reviews, from inception through April 2023. Two authors independently assessed the methodological quality of each metaanalysis using the AMSTAR tool and adhered to evidence classification criteria.ResultsIn total, we extracted 191 unique risk factors in meta-analyses, including 92 significantly associated risk factors. The top ten risk factors were human cytomegalovirus (HCMV) infection, IBD family history, periodontal disease, poliomyelitis, campylobacter species infection, hidradenitis suppurativa, psoriasis, use of proton pump inhibitors, chronic obstructive pulmonary disease, and western dietary pattern.DiscussionIn conclusion, this umbrella review extracted 62 risk factors and 30 protective factors, most of which were related to underlying diseases, personal lifestyle and environmental factors. The findings in this paper help to develop better prevention and treatment measures to reduce the incidence of IBD, delay its progression, and reduce the burden of IBD-related disease worldwide.Systematic review registrationhttps://www.crd.york.ac.uk/PROSPERO/, identifier CRD42023417175.

Recent HCMV infection in early pregnancy associates with congenital transmission & adverse pregnancy outcome: A prospective cohort study

Background & objectives Human Cytomegalovirus (HCMV) infection, leading to >90 per cent seropositivity in women of reproductive age from India, is the largest cause of congenital infections worldwide. HCMV infection status was prospectively monitored together with congenital transmission (cCMV) and adverse pregnancy outcomes (APO) in a public health setting where maternal or neonatal screening was not in practice. Methods Eighty three pregnant women, with (n=45) and without (n=38) bad obstetric history (BOH), were monitored for HCMV infection by ELISA-(IgM, IgG, IgG avidity) for all TORCH (Toxoplasma, Rubella, HCMV, HSV 1 & 2) pathogens along with HCMV-specific chemiluminescent microparticle immunoassay (CMIA) and nested polymerase chain reaction (PCR). Descriptive statistics were applied on data sets to determine associations between maternal infection status, pregnancy outcome and cCMV in 52 mother-neonate dyads. Results Combined avidity, PCR-based and HCMV IgM screening, compared to the latter alone, was successful in identifying incident infection during early pregnancy. Pregnancy loss was associated strongly with BOH and concurrent HCMV infection. Features associated with APO and cCMV, were high PCR positivity (first trimester) and high rates of HCMV-specific IgM and intermediate IgG avidity (P=0.0211, 0.0455). Also, recent HCMV infection (intermediate IgG avidity), observed mainly in the BOH group, but not recurrent infection (IgM positivity), in first and second trimesters, was associated with neonatal saliva positivity and adverse outcomes, including neonatal death (P=0.0762). Exposure to other TORCH pathogens, while detected, did not include IgM positivity or low/intermediate IgG. Conclusion This study highlights the significance of conducting early, multi-pronged screening for maternal HCMV infection during pregnancy, especially in public health settings with high HCMV seroprevalence.

Study on mechanism of Spatholobi Caulis in the treatment of the hand-foot skin reaction induced by targeted drug therapy based on network pharmacology and molecular docking: An observational study.

Based on network pharmacology and molecular docking methods, this study explored its active compounds and confirmed its potential mechanism of action against Hand-foot skin reaction induced by tumor-targeted drugs. Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform and UniProt Database were used to obtain the active ingredients and target proteins of Spatholobi Caulis. All hand-foot skin reaction (HFSR)-related targets were obtained with the help of the Human Gene Database, Online Mendelian Inheritance in Humans (OMIM), DisGeNET and DrugBank databases. Cytoscape 3.7.1 software was used to construct the active ingredient-target visualization network of Spatholobi Caulis, and the common target network of Spatholobi Caulis and HFSR. And through the BisoGenet plug-in in Cytoscape, PPI network topology analysis was performed. The Metescape database and online mapping tool platform were used for Gene Ontology (GO) function and Kyoto Encyclopedia of Genes Genomes (KEGG) pathway enrichment analysis to identify the key pathways of Spatholobi Caulis. Finally, Autodock Vina software and PyMol 2.5 software were used for molecular docking verification. There were 24 active components of Spatholobi Caulis and 244 target genes, 1635 disease-related target genes, 51 common target genes of Spatholobi Caulis and Hand-foot skin reaction, and key targets included NTRK1, epidermal growth factor receptor (EGFR), APP, TP53, HSP90AB1, HSP90AA, CUL3, etc. GO functional analysis involved a total of 66 molecular functions, 39 cellular components, and 817 biological processes. KEGG pathway analysis found 154 related signaling pathways, mainly enriched in Pathways in cancer, Human cytomegalovirus infection, Kaposi arcoma-associated herpesvirus infection, panic cancer, EGFR tyrosine kinase inhibitor resistance, P13K-Akt signaling pathway, Proteoglycans in cancer, HIF-1 signaling pathway and Ras signaling pathway, etc. Molecular docking results showed that luteolin, the active component of Spatholobi Caulis, had a high affinity with EGFR. Medicagol, the active components of Spatholobi Caulis, is proved in the Hand-foot skin reaction induced by lung cancer targeted therapy by regulating multiple signaling pathways through EGFR. It is confirmed that the treatment of Hand-foot skin reaction has the characteristics of multi-component, multi-target and multi-pathway regulation.

Infection-induced lysine lactylation enables herpesvirus immune evasion.

Aerobic glycolysis is a hallmark of many viral infections, leading to substantial accumulation of lactate. However, the regulatory roles of lactate during viral infections remain poorly understood. Here, we report that human cytomegalovirus (HCMV) infection leverages lactate to induce widespread protein lactylation and promote viral spread. We establish that lactyllysine is enriched in intrinsically disordered regions, regulating viral protein condensates and immune signaling transduction. Dynamic lactylation of immune factors suppresses immunity, a feature we show to be shared for HCMV and herpes simplex virus 1 infections, through regulation of RNA binding protein 14 and interferon-γ-inducible protein 16 (IFI16). K90 lactylation of the viral DNA sensor IFI16 inhibits recruitment of the DNA damage response kinase DNA-PK, preventing IFI16-driven virus gene repression and cytokine induction. Together, we characterize global protein lactylation dynamics during virus infection, finding that virus-induced lactate contributes to its immune evasion through direct inhibition of immune signaling pathways.

HCMV infection downregulates GPX4 and stimulates lipid peroxidation but does not induce ferroptosis.

Human cytomegalovirus (HCMV) infection is intimately linked with countless host cell pathways that are modulated in a coordinated fashion to facilitate infection. Here, we describe HCMV-induced regulation of lipid peroxidation, a precursor of the iron-regulated cell death pathway known as ferroptosis, during human cytomegalovirus infection. These studies reveal hitherto unidentified changes in metabolism mediated by HCMV that decrease sensitivity to ferroptosis, despite increases in lipid peroxidation and transient increases in intracellular iron levels in infected cells.

Complex roles for proliferating cell nuclear antigen in restricting human cytomegalovirus replication.

DNA viruses at once elicit and commandeer host pathways, including DNA repair pathways for virus replication. Despite encoding its own DNA polymerase and processivity factor, human cytomegalovirus (HCMV) recruits the cellular processivity factor, proliferating cell nuclear antigen (PCNA) and specialized host DNA polymerases involved in translesion synthesis (TLS) to replication compartments (RCs) where viral DNA (vDNA) is synthesized. While the recruitment of TLS polymerases is important for viral genome stability, the role of PCNA is poorly understood. PCNA function in DNA repair is regulated by monoubiquitination (mUb) or SUMOylation of PCNA at lysine 164 (K164). We find that mUb-PCNA increases over the course of infection, and modification of K164 is required for PCNA-mediated restriction of virus replication. mUb-PCNA plays important known roles in recruiting TLS polymerases to DNA, which we have shown are important for viral genome integrity and diversity, represented by novel junctions and single nucleotide variants (SNVs), respectively. We find that PCNA drives SNVs on vDNA similar to Y-family TLS polymerases, but that this did not require modification at K164. Unlike TLS polymerases, PCNA was dispensable for preventing large scale rearrangements on vDNA. These striking results suggest separable PCNA-dependent and - independent functions of TLS polymerases on vDNA. By extension, these results imply roles for TLS polymerase beyond their canonical function in TLS in host biology. These findings highlight PCNA as a complex restriction factor for HCMV infection, likely with multiple distinct roles, and provides new insights into the PCNA-mediated regulation of DNA synthesis and repair in viral infection.

Human Cytomegalovirus Infection Induces Long-Term Changes in the Cytokine Milieu of Kidney Transplant Recipients.

The impact of human cytomegalovirus (HCMV) infection on the mid- and long-term balance between pro-inflammatory and anti-inflammatory cytokines among kidney transplant recipients (KTRs) remains unclear. We measured plasma levels of 12 Th1/Th2-type cytokines (granulocyte-macrophage colony-stimulating factor, interferon-γ, interleukin [IL]-1β, IL-2, IL-4, IL-5, IL-6, IL-10, IL-12p70, IL-13, IL-18 and tumor necrosis factor-α) in a cohort of 290 KTRs at four time points through month 12 after transplantation. Cytokine levels at each point were compared according to the previous documentation of HCMV replication by two approaches: "cumulative exposure" from the time of transplantation and "recent exposure" within the 2-3 months preceding cytokine assessment. Significance levels were Bonferroni-corrected for multiple pairwise comparisons. Plasma levels of IL-6, IL-10, and IL-12p70 at month 1 were significantly increased in KTRs that had experienced HCMV infection during the first 30 days. By month 3, IL-6 and IL-10 remained increased in KTRs with cumulative exposure through day 90. Cumulative exposure to HCMV replication through day 180 was also associated to increased IL-10 levels at month 6. In addition, KTRs with recent HCMV exposure had increased IL-10 levels at months 3 and 6. After multivariable adjustment, cumulative exposure to HCMV infection and/or the area under curve of HCMV DNAemia during the corresponding period were associated to IL-10 levels within the highest quartile at months 1, 3, and 6. Preceding HCMV infection induces sustained changes in the plasma cytokine milieu of KTRs, with elevated IL-6 and IL-10 levels throughout the first 6 months after transplantation.

An epigenetic human cytomegalovirus infection score predicts viremia risk in seropositive lung transplant recipients

ABSTRACT Cytomegalovirus (CMV) infection and reactivation in solid organ transplant (SOT) recipients increases the risk of viremia, graft failure and death. Clinical studies of CMV serostatus indicate that donor positive recipient negative (D+/R−) patients have greater viremia risk than D−/R−. The majority of patients are R+ having intermediate serologic risk. To characterize the long-term impact of CMV infection and assess viremia risk, we sought to measure the effects of CMV on the recipient immune epigenome. Specifically, we profiled DNA methylation in 156 individuals before lung or kidney transplant. We found that the methylome of CMV positive SOT recipients is hyper-methylated at loci associated with neural development and Polycomb group (PcG) protein binding, and hypo-methylated at regions critical for the maturation of lymphocytes. In addition, we developed a machine learning-based model to predict the recipient CMV serostatus after correcting for cell type composition and ancestry. This CMV episcore measured at baseline in R+ individual stratifies viremia risk accurately in the lung transplant cohort, and along with serostatus the CMV episcore could be a potential biomarker for identifying R+ patients at high viremia risk.

Increased Cytotoxic CD4+ T Cells with Reduced Cytotoxic Gene Profile Expression in Cytomegalovirus Reactivated Kidney Transplant Patients

Cytotoxic CD4+ T cells eliminate human cytomegalovirus (HCMV)-infected cells through direct cytotoxic granules exocytosis. We aimed to evaluate the functional cytotoxic gene profile of CD4+ T cells alongside the frequency of the cytotoxic phenotype in renal transplant recipients with cytomegalovirus reactivation. Blood samples were collected from twenty renal recipients with and without HCMV reactivation (HCMV+ and HCMV- groups) and ten healthy adults (control group). CD4+ T cells were isolated to assess the frequency of cytotoxic CD4+ T cells via CD107a surface staining using flow cytometry and to evaluate gene expression of perforin, granzyme B, Runt-related transcription factor 3 (RUNX3), and Eomesodermin (Eomes) by quantitative PCR. The frequency of CD4+ CD107a+ T cells was higher in the HCMV+ group compared to the HCMV- group and significantly higher than in the control group (22.69 ± 3.47 vs 16.41 ± 2.24 and 11.60 ± 1.17, respectively). Perforin gene levels were reduced in the HCMV+ group compared to the other two groups, while granzyme B gene levels were similar between HCMV+ and HCMV- groups but lower than in the control group (0.63 ± 1.24 vs 0.67 ± 2.27 and 1.00 ± 0.00, respectively). This study demonstrated an increased frequency of cytotoxic CD4+ T cells with potentially reduced functionality in kidney transplant patients with HCMV infection. It also suggests that these cells might employ other mechanisms, such as death receptor-mediated killing, or the production of other granules.

Mapping the Protein Phosphatase 1 Interactome in Human Cytomegalovirus Infection.

Protein phosphorylation is a crucial regulatory mechanism in cellular homeostasis. The human cytomegalovirus (HCMV) incorporates protein phosphatase 1 (PP1) into its tegument, yet the biological relevance and mechanisms of this incorporation remain unclear. Our study offers the first characterization of the PP1 interactome during HCMV infection and its alterations. Using co-immunoprecipitation, mass spectrometry, and quantitative proteomics, we identified 159 high-confidence interacting proteins (HCIPs) in the PP1 interactome, consisting of 126 human and 33 viral proteins. We observed significant temporal changes in the PP1 interactome following HCMV infection, including the altered interactions of PP1 regulatory subunits. Further analysis highlighted the central roles of these PP1 interacting proteins in intracellular trafficking, with particular emphasis on the trafficking protein particle complex and Rab GTPases, which are crucial for the virus's manipulation of host cellular processes in virion assembly and egress. Additionally, our study on the noncatalytic PP1 inhibitor 1E7-03 revealed a decrease in PP1's interaction with key HCMV proteins, supporting its potential as an antiviral agent. Our findings suggest that PP1 docking motifs are critical in viral-host interactions and offer new insights for antiviral strategies.

Alzheimer's disease-associated CD83(+) microglia are linked with increased immunoglobulin G4 and human cytomegalovirus in the gut, vagal nerve, and brain.

While there may be microbial contributions to Alzheimer's disease (AD), findings have been inconclusive. We recently reported an AD-associated CD83(+) microglia subtype associated with increased immunoglobulin G4 (IgG4) in the transverse colon (TC). We used immunohistochemistry (IHC), IgG4 repertoire profiling, and brain organoid experiments to explore this association. CD83(+) microglia in the superior frontal gyrus (SFG) are associated with elevated IgG4 and human cytomegalovirus (HCMV) in the TC, anti-HCMV IgG4 in cerebrospinal fluid, and both HCMV and IgG4 in the SFG and vagal nerve. This association was replicated in an independent AD cohort. HCMV-infected cerebral organoids showed accelerated AD pathophysiological features (Aβ42 and pTau-212) and neuronal death. Findings indicate complex, cross-tissue interactions between HCMV and the adaptive immune response associated with CD83(+) microglia in persons with AD. This may indicate an opportunity for antiviral therapy in persons with AD and biomarker evidence of HCMV, IgG4, or CD83(+) microglia. Cross-tissue interaction between HCMV and the adaptive immune response in a subset of persons with AD. Presence of CD83(+) microglial associated with IgG4 and HCMV in the gut. CD83(+) microglia are also associated presence of HCMV and IgG4 in the cortex and vagal nerve. Replication of key association in an independent cohort of AD subjects. HCMV infection of cerebral organoids accelerates the production of AD neuropathological features.

Susceptibility of Mouse Brain to MCMV Infection and Neuroinflammation During Ontogeny.

Human cytomegalovirus (HCMV) rarely infects the brain following infection of adult individuals. However, the virus readily infects the brain during congenital HCMV (cHCMV) infection, frequently causing severe neurodevelopmental and neurological sequelae. Interestingly, although the incidence of cHCMV infection is 0.5-1%, the proportion of congenitally infected individuals in which the virus manages to gain access to the brain is unknown. In this study, we used infection of mice with mouse cytomegalovirus (MCMV), the most commonly used experimental system for modeling HCMV disease in humans, to determine the impact of age on the susceptibility of the brain to cytomegalovirus infection and infection-mediated neuroinflammation. We demonstrate that infection of mice during various stages of neonatal development can lead to CMV neuroinvasion and inflammation. In contrast, MCMV infection does not result in MCMV neuroinvasion and neuroinflammation in weanling and adult mice. The obtained results establish a basis for elucidating the mechanisms of CMV neuroinvasion and the deleterious inflammatory response during ontogeny.

Increased EBNA1-specific antibody response in primary-progressive multiple sclerosis

Background and objectivesThe impact of viral infections on disease susceptibility and progression has predominantly been studied in patients with relapse-onset MS (RMS). Here, we determined immune responses to ubiquitous viruses in patients with primary progressive MS (PPMS).MethodsAntibody responses to Epstein–Barr virus (EBV), specifically to the latent EBV nuclear antigen 1 and the lytic viral capsid antigen VCA, human herpesvirus 6 (HHV-6), human cytomegalovirus (HCMV), and measles virus were determined in a cohort of 68 PPMS patients with a mean follow-up of 8 years and compared with 66 healthy controls matched for sex and age.ResultsCompared with controls, PPMS patients showed increased humoral immune responses to the EBV-encoded nuclear antigen-1 (EBNA1), but not to the lytic EBV capsid antigen (VCA) or to other viral antigens. Seroprevalence rates for HCMV were significantly higher in PPMS. Antiviral immune responses at baseline did not correlate with disability progression over time.DiscussionElevated immune responses toward EBNA1 are selectively increased in people with primary progressive disease, indicating a link between EBNA1-targeting immune responses and the development of both RMS and PPMS. Our data also suggest that chronic HCMV infection is associated with progressive MS.

Viral microRNA regulation of Akt is necessary for reactivation of Human Cytomegalovirus from latency in CD34+ hematopoietic progenitor cells and humanized mice.

Human cytomegalovirus (HCMV) actively manipulates cellular signaling pathways to benefit viral replication. Phosphatidyl-inositol 3-kinase (PI3K)/Akt signaling is an important negative regulator of HCMV replication, and during lytic infection the virus utilizes pUL38 to limit Akt phosphorylation and activity. During latency, PI3K/Akt signaling also limits virus replication, but how this is overcome at the time of reactivation is unknown. Virally encoded microRNAs (miRNAs) are a key component of the virus arsenal used to alter signaling during latency and reactivation. In the present study we show that three HCMV miRNAs (miR-UL36, miR-UL112 and miR-UL148D) downregulate Akt expression and attenuate downstream signaling, resulting in the activation of FOXO3a and enhanced internal promoter-driven IE transcription. A virus lacking expression of all three miRNAs is unable to reactivate from latency both in CD34+ hematopoietic progenitor cells and in a humanized mouse model of HCMV infection, however downregulating Akt restores the ability of the mutant virus to replicate. These findings highlight the negative role Akt signaling plays in HCMV replication in lytic and latent infection and how the virus has evolved miRNA-mediated countermeasures to promote successful reactivation.

Third intracellular loop of HCMV US28 is necessary for signaling and viral reactivation.

The human cytomegalovirus (HCMV) encoded chemokine receptor US28 plays a critical role in viral pathogenesis, mediating several processes such as cellular migration, differentiation, transformation, and viral latency and reactivation. Despite significant research examining the signal transduction pathways utilized by US28, the precise mechanism by which US28 activates these pathways remains unclear. We performed a mutational analysis of US28 to identify signaling domains that are critical for functional activities. Our results indicate that specific residues within the third intracellular loop (ICL3) of US28 are major determinants of G-protein coupling and downstream signaling activity. Alanine substitutions at positions S218, K223, and R225 attenuated US28-mediated activation of MAPK and RhoA signal transduction pathways. Furthermore, we show that mutations at positions S218, K223, or R225 result in impaired coupling to multiple Gα isoforms. However, these substitutions did not affect US28 plasma membrane localization or the receptor internalization rate. Utilizing CD34+ HPC models, we demonstrate that attenuation of US28 signaling via mutation of residues within the ICL3 region results in an inability of the virus to efficiently reactivate from latency. These results were recapitulated in vivo, utilizing a humanized mouse model of HCMV infection. Together, our results provide new insights into the mechanism by which US28 manipulates host signaling networks to mediate viral latency and reactivation. The results reported here will guide the development of targeted therapies to prevent HCMV-associated disease.IMPORTANCEHuman cytomegalovirus (HCMV) is a β-herpesvirus that infects between 44% and 100% of the world population. Primary infection is typically asymptomatic and results in the establishment of latent infection within CD34+hematopoietic progenitor cells (HPCs). However, reactivation from latent infection remains a significant cause of morbidity and mortality in immunocompromised individuals. The viral chemokine receptor US28 influences various cellular processes crucial for viral latency and reactivation, yet the precise mechanism by which US28 functions remains unclear. Through mutational analysis, we identified key residues within the third intracellular loop (ICL3) of US28 that govern G-protein coupling, downstream signaling, and viral reactivation in vitro and in vivo. These findings offer novel insights into how US28 manipulates host signaling networks to regulate HCMV latency and reactivation and expand our understanding of HCMV pathogenesis.

Human Cytomegalovirus Replication Enhanced By Placental MicroRNAs

ABSTRACTPlacental trophoblasts constitute the interface between the fetal and maternal environments and physically prevent maternal–fetal viral transmission. However, congenital human cytomegalovirus (HCMV) infection in the early stages of pregnancy results in severe symptoms in the fetus. HCMV is the most common causative agent of intrauterine infection. To clarify the etiology of congenital HCMV infection, we focused on how the placental environment affects HCMV infection. We investigated the role of microRNAs (miRNAs), which are highly and specifically expressed in placental trophoblasts. The transfection of trophoblast‐specific C19MC miRNAs, encoded by the chromosome 19 miRNA cluster, markedly enhanced HCMV Immediate Early (IE) gene expression and subsequent viral production. However, the expression of the herpes simplex virus type‐1 IE gene was not changed by C19MC‐BAC transfection. From among 46427 mapped genes, we identified that the expression of RAC2, a Rac family small GTPase, was markedly suppressed with an independent genetic hierarchical cluster by C19MC‐BAC transfection. The suppression of RAC2 expression enhanced HCMV IE gene expression. Here, we propose the hypothesis that the placental environment contributes to HCMV‐specific replication via the trophoblast‐specific miRNA‐mediated downregulation of RAC2 expression.

Decoding the Ferroptosis-Related Gene Signatures and Immune Infiltration Patterns in Ovarian Cancer: Bioinformatic Prediction Integrated with Experimental Validation.

Ovarian cancer is a type of gynecological cancer with extremely high fatality rate. Ferroptosis, an iron-dependent regulated cell death, inhibits the immune infiltration of tumor cells. Therefore, it is worthwhile to explore the effects of ferroptosis-related gene signatures and immune infiltration patterns on the clinical prognosis of ovarian cancer. In this study, we used the mRNA expression matrix and related medical information of those who suffer from ovarian cancer in the TCGA database. After that, we established a ferroptosis-related gene signature based on LASSO Cox regression model, and employed several specific enrichment analyses to explore the bioinformatics functions of differentially expressed genes (DEGs). Additionally, we analyzed the link between ferroptosis and immune cells by single-sample gene set enrichment analysis (ssGSEA) to create a heatmap of gene-immune cell correlation. We then examined the expression of immune checkpoints and verified the gene expression in ovarian cancer tissues by qPCR assays. Finally, we induced ferroptosis in ovarian cancer cells using drugs and analyzed their migration, invasion and gene expression. According to LASSO Cox regression analysis, 9 prognostic DEGs were in association with overall survival (OS), which was utilized to construct a 9-gene signature for patients. Patients were divided into two groups, in which high-risk group's OS was markedly shorter than that of low-risk group (Log-rank p<0.001). KEGG enrichment analysis showed that these DEGs were linked to human cytomegalovirus (HCMV) infection. The ssGSEA analysis revealed significant differences in immune cell type and expression between ALOX12 and GLRX5 groups (p<0.05). Heatmap showed high correlation of prognostic genes with various immune cells. qPCR assay confirmed the 9 gene expression signature in ovarian cancer tissues. The ovarian cancer cell invasion and migration were significantly inhibited after induction of ferroptosis. We decoded the ferroptosis-related gene signatures and immune infiltration patterns that can be used to predict the prognosis of ovarian cancer patients.

Association Between NK Cell Genetic Variants and the Development of Long COVID Associated- and Prepandemic Small Fiber Neuropathy.

Long coronavirus disease 2019 (COVID) (LC) symptoms including pain and autonomic dysfunction are in some patients associated with small-fiber neuropathy (SFN). The pathomechanisms underlying SFN are mostly unclear. Natural killer (NK) cells play a crucial role in immune regulation, viral clearance and nerve metabolism. The aim of this study was to identify associations between development of small-fiber dysfunction dependent and independent of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, and human genetic markers associated with specific NK cell functions. The genetic markers assessed in all cohorts included: FCGR3A, IGHG1, HLA-E, NKG2C, and rs9916629. Genotyping was performed using TaqMan assays, Sanger sequencing and touchdown polymerase chain reaction. We assessed human cytomegalovirus (HCMV) IgG serostatus in all participants, and screened for anti-neuronal, anti-glial and anti-ganglioside autoantibodies in both patient cohorts. We included 50 LC patients with newly-emerged symptoms of small-fiber dysfunction after SARS-CoV-2 infection, 27 prepandemic SFN patients and 320 control persons. Markers associated with low NKG2C response, that is, deletion of the NKG2C gene and lack of prior HCMV infection (IgG seronegativity), occurred significantly more frequently in prepandemic SFN patients compared to LC patients and controls (p = 0.0109 and 0.0005, respectively). In conclusion, markers of impaired NKG2C pathways are associated with prepandemic SFN, but not with Long COVID-associated small-fiber dysfunction.

Modulation of Monocyte Effector Functions and Gene Expression by Human Cytomegalovirus Infection.

Monocytes are crucial players in innate immunity. The human cytomegalovirus (CMV) infection has significant impacts on monocyte effector functions and gene expression. CMV, a β-herpesvirus, disrupts key monocyte roles, including phagocytosis, antigen presentation, cytokine production, and migration, impairing their ability to combat pathogens and activate adaptive immune responses. CMV modulates monocyte gene expression, decreasing their capacity for antigen presentation and phagocytosis while increasing pro-inflammatory cytokine production, which can contribute to tissue damage and chronic inflammation. CMV also alters monocyte migration to sites of infection while promoting trans-endothelial migration, thus aiding viral dissemination. Additionally, the virus affects reactive oxygen species (ROS) production, thereby contributing to end-organ disease associated with CMV infection. Overall, these changes enhance viral persistence during acute infection and facilitate immune evasion during latency. We highlight the clinical significance of these disruptions, particularly in immunocompromised patients such as transplant recipients, where the modulation of monocyte function by CMV exacerbates risks for infection, inflammation, and graft rejection. An understanding of these mechanisms will inform therapeutic strategies to mitigate CMV-related complications in vulnerable populations.

Glucose-independent human cytomegalovirus replication is supported by metabolites that feed upper glycolytic branches

Viruses with broad tissue distribution and cell tropism successfully replicate in various nutrient environments in the body. Several viruses reprogram metabolism for viral replication. However, many studies focus on metabolic reprogramming in nutrient-rich conditions that do not recapitulate physiological environments in the body. Here, we investigated how viruses may replicate when a metabolite thought to be essential for replication is limited. We use human cytomegalovirus infection in glucose-free conditions as a model to determine how glucose supports virus replication and how physiologically relevant nutrients contribute to glucose-independent virus production. We find that glucose supports viral genome synthesis, viral protein production and glycosylation, and infectious virus production. Notably, supplement of glucose-free cultures with uridine, ribose, or UDP-GlcNAc-metabolites that feed upper glycolytic branches like the pentose phosphate pathway-results in partially restored virus replication, including low levels of infectious virus production. Supplementing lower glycolysis in glucose-free cultures using pyruvate fails to restore virus replication. These results indicate that nutrients can compensate for glucose via feeding upper glycolytic branches to sustain low levels of virus production. More broadly, our findings suggest that viruses may successfully replicate in diverse metabolic niches, including those in the body with low glucose levels, through alternative nutrient usage.