Biology subjects

Putrino, D.

Publications and source records attributed to Putrino, D..

3 recordsLinked to original sources

bioRxiv2026

Persistently activated virus-specific CD8 T cells indicate antigen-driven immune aberrations in long COVID

Long COVID (LC) affects millions of people worldwide, yet its driving mechanisms remain incompletely defined and no treatment has been approved. Persistence of SARS-CoV-2 and reactivation of herpesviruses have been implicated in LC, but direct detection of these viral antigens in blood and tissues has been challenging. T cells are exquisitely sensitive to viral antigens, survey organs throughout the body, and can be readily sampled in peripheral blood. Using high-dimensional spectral flow cytometry and single-cell sequencing approaches with multiplexed peptide/HLA tetramers, we profiled virus-specific T cells from hundreds of people with LC and recovered controls. We identified a subset of people with LC that maintained elevated activation of CD8 T cells targeting SARS-CoV-2 spike and/or lytic antigens from Epstein-Barr virus, but not other viral specificities. Spike-specific cells in LC expressed genes linked to TCR stimulation, terminal effector differentiation, and exhaustion and demonstrated reduced functionality upon cognate peptide stimulation ex vivo. Thus, T cells from a subset of people with LC are likely chronically stimulated by persistent SARS-CoV-2 antigens. These findings establish the use of T cells as biosensors of persisting antigen in LC and other disease settings and may help develop new therapeutic strategies for LC.

immunology↗

bioRxiv2026

Persistent SARS-CoV-2 Spike is Associated with Localized Immune Dysregulation in Long COVID Gut Biopsies

SARS-CoV-2 persistence is a proposed driver of Long COVID (LC), but the in-situ relationship between residual viral antigen and immune dysregulation remains poorly defined. To address this critical gap, we employed a high-resolution, multi-modal approach--combining RNAscope, GeoMx Digital Spatial Profiling (DSP), spatial transcriptomics, and multiplex immunofluorescence--on 25 terminal ileum and left colon biopsies from a clinical cohort of 8 LC participants and 5 healthy controls. We confirmed the persistence of SARS-CoV-2 Spike transcript and protein in the gut tissue of all LC cases and controls tested. Yet, comparison of Spike-positive (Spike+) regions in LC versus healthy control colon tissues revealed a differential, symptomatic state-associated signature, with 57 differentially expressed genes (DEGs) (26 upregulated, 31 downregulated), revealing genes that disrupt the immune response in LC subjects. LC colon Spike+ regions demonstrated increased expression of AQP8 and other absorptive-related genes (SLC26A3, SLC26A2, and CLCA4) which are involved with Chrons disease along with transcripts involved in tumorigenesis (GUCA2A, S100P, TSPAN1). Simultaneous downregulation of key homeostatic chemokines (CXCL13, CCL19, CCL21), and other transcripts reported to exhibit low expression in colorectal cancers (TMEM88B, NIBAN3, DMBT1), suggesting a paradox of epithelial tissue stress yet dysfunctional immune trafficking. Further analysis comparing Spike+ versus Spike-regions within LC colon tissue demonstrated an active, localized, antigen-driven immune microenvironment, identifying 122 DEGs (82 upregulated, 40 downregulated), including tumorigenesis genes. Cellular deconvolution of Spike+ regions revealed a statistically significant focal enrichment of myeloid-derived cells (macrophages, non-classical/intermediate monocytes), plasma cells, and regulatory T cells, coupled with significant enrichment in T-cell-related pathways, including "Antigen processing and presentation," and "Th1/Th2/Th17 cell differentiation." The ileum displayed a similar, though less pronounced, signature, demonstrating these statistically significant findings are specific to the colon of LC subjects. In contrast, corresponding Spike+ vs. Spike-analysis in healthy control colon tissues showed a more modest transcriptional response with 38 DEGs. Our data provide robust evidence that persistent SARS-CoV-2 Spike protein detection in the gut is not immunologically inert. Instead, it is actively associated with distinct, immune cell composition shifts and a dysfunctional pro-inflammatory transcriptional profile, supporting the hypothesis that retained viral antigen drives chronic immune dysregulation in tissue of Long COVID subjects.

genomics↗

bioRxiv2022

Mild respiratory SARS-CoV-2 infection can cause multi-lineage cellular dysregulation and myelin loss in the brain

Survivors of Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) infection frequently experience lingering neurological symptoms, including impairment in attention, concentration, speed of information processing and memory. This long-COVID cognitive syndrome shares many features with the syndrome of cancer therapy-related cognitive impairment (CRCI). Neuroinflammation, particularly microglial reactivity and consequent dysregulation of hippocampal neurogenesis and oligodendrocyte lineage cells, is central to CRCI. We hypothesized that similar cellular mechanisms may contribute to the persistent neurological symptoms associated with even mild SARS-CoV-2 respiratory infection. Here, we explored neuroinflammation caused by mild respiratory SARS-CoV-2 infection - without neuroinvasion - and effects on hippocampal neurogenesis and the oligodendroglial lineage. Using a mouse model of mild respiratory SARS-CoV-2 infection induced by intranasal SARS-CoV-2 delivery, we found white matter-selective microglial reactivity, a pattern observed in CRCI. Human brain tissue from 9 individuals with COVID-19 or SARS-CoV-2 infection exhibits the same pattern of prominent white matter-selective microglial reactivity. In mice, pro-inflammatory CSF cytokines/chemokines were elevated for at least 7-weeks post-infection; among the chemokines demonstrating persistent elevation is CCL11, which is associated with impairments in neurogenesis and cognitive function. Humans experiencing long-COVID with cognitive symptoms (48 subjects) similarly demonstrate elevated CCL11 levels compared to those with long-COVID who lack cognitive symptoms (15 subjects). Impaired hippocampal neurogenesis, decreased oligodendrocytes and myelin loss in subcortical white matter were evident at 1 week, and persisted until at least 7 weeks, following mild respiratory SARS-CoV-2 infection in mice. Taken together, the findings presented here illustrate striking similarities between neuropathophysiology after cancer therapy and after SARS-CoV-2 infection, and elucidate cellular deficits that may contribute to lasting neurological symptoms following even mild SARS-CoV-2 infection.

neuroscience↗