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How to analyze and understand the human immune system.

To enhance our understanding of the pathogenesis of diseases, including rheumatic diseases, and to improve disease control, it is essential to attain a thorough understanding of the human immune system, alongside mouse immunology. Historically, the investigation of the human immune system has posed significant challenges due to methodological limitations. Nonetheless, recent advancements in genomic studies of multifactorial diseases have elucidated that numerous risk-associated genetic variants affecting quantitative differences in cell-specific gene expression. In light of these findings, we are currently examining individual genetic variations in both healthy individuals and patients, as well as categorizing cells into distinct subsets in order to construct a comprehensive dataset concerning the human immune system. This is accomplished by combining data on gene expression, factors influencing the expression mechanisms, protein expression, metabolomics, and environmental variables pertinent to immune functionality-such as gut microbiota. These datasets will facilitate the comprehensive characterization of the human immune system. Using these datasets and through the integrative analyses of data related to risk genetic variations and gene expression profiles of each disease and individual, we anticipate uncovering novel insights into the human immune system, the heterogeneity of diseases, immune function mechanisms, and their regulatory strategies that may not be achievable through murine models.

Humans

Insect immune systems: same same but different but still same.

Insects are the most diverse group of animals in nature, occupying nearly every ecological niche and playing central roles as pollinators, pests, and disease vectors. Despite this vast diversity, insects rely on a set of conserved yet evolutionarily adaptable immune pathways to defend against pathogens. Early studies in insect immunity have laid the foundation for human immunology, and recent advances in genomic and transgenic technologies have renewed interest in understanding how immune responses vary across insect orders. Insects are highly diverse in their immune systems; each species has unique immune responses that help fight infections from specific pathogens. Nevertheless, they share multiple aspects of recognition, regulation, and effector mechanisms. This review focuses on current knowledge of the immune systems of major insect lineages to highlight both shared signaling pathways, immune cells, and humoral factors, as well as lineage-specific responses that reflect distinct ecological pressures that have shaped the host-microbe interactions. Comparing different insect species and orders not only provides insights into the evolutionary divergences and convergences of immune system features but also offers complementary knowledge among species within the same order, helping fill existing gaps. Understanding these evolutionary patterns not only deepens our understanding of insect immunity but also informs the development of transgenic strategies to disrupt pathogen transmission in key vector species.

Animals

Systemic immune activation in hereditary cancer predisposition syndromes: a cross-sectional study.

BACKGROUND: Immune surveillance mechanisms contribute to the elimination of precancerous lesions in hereditary cancer predisposition syndromes (HCPSs). METHODS: By combining single-cell transcriptomics, multiparametric mass cytometry and cytokine profiling of the systemic immune environment in 391 individuals among whom 227 are living with HCPSs we investigated phenotypic alterations in cancer-free individuals with HCPS. RESULTS: A decrease in peripheral B cell abundance and their more differentiated phenotype have been confirmed both in breast cancer patients with germline pathogenic variants in BRCA1 (gpath(BRCA1)) and in patients living with Lynch syndrome (LS). Pre-cancer women with gpath(BRCA1) exhibited an activated phenotype of multiple immune cell lineages, similar to those with manifest disease. In LS, B cell phenotypes exhibited the largest changes in response to cancer eradication, while increased peripheral IL-6 levels was detected even in presymptomatic individuals with LS. CONCLUSIONS: HCPS-specific differences in the phenotype of the systemic immune system might be leveraged in future risk-reducing strategies.

Humans

Cell-type-specific defense priming and NHP-dependent systemic immunity against Pectobacterium in Chinese cabbage.

Defense priming is an effective strategy for mounting the defensive capacity of plants. Primed plants undergo minimal changes, enabling rapid, robust responses to subsequent pathogen attack. The cell-type-specific mechanisms underlying priming and systemic immunity remain unclear. Using single-nucleus RNA sequencing (snRNA-seq), we reveal how primed Chinese cabbage coordinates N-hydroxypipecolic acid (NHP)-dependent systemic immunity against Pectobacterium carotovorum. NHP accumulates as a phloem-mobile priming signal. snRNA-seq identified a priming-specific epidermal cell state transition and transcriptional cascade: BrWRKY18-1 activates BrWRKY33-1 expression during priming, initiating NHP-dependent systemic immunity. At post-challenge primed state, pathogenesis-related genes (PRs), such as BrPR3, BrPR4-1, and BrPR4-2, are predominantly expressed in systemic tissues to inhibit infection. Notably, the functionality of these PR genes in immunity necessitates their expression in all cells to effectively enhance defensive resistance. This NHP-transcription factor-PR axis couples mobile signaling to systemic immunity, elucidating cell-type-specific defense priming.

Plant Immunity

Bacterial immune systems as causes and consequences of microbiome structure.

Attacks from molecular parasites such as mobile genetic elements (MGEs) have driven the evolution of defense systems in bacterial genomes. Yet, despite significant advances in understanding the molecular mechanisms of these bacterial immune systems, we have only a rudimentary understanding of their ecology and evolution. Bacteria exist as part of complex microbiomes, but community ecology and microbiome research has yet to characterize the impacts of interactions between MGEs and defense mechanisms upon the structure, dynamics and evolution of microbiomes. This Essay introduces and discusses the interplay between bacterial community dynamics and bacterial immune systems, speculating about how these reciprocal interactions may shape microbial community structure and function.

Bacteria

The ecology and evolution of microbial immune systems: a look on the wild vibrio side.

Natural populations of vibrio beyond the well-studied pandemic strains of Vibrio cholerae, provide a powerful model for investigating the eco-evolutionary dynamics of microbial immune systems. Their genetic diversity, ecological versatility, ease of culturability and the availability of time-series data enable detailed studies of phage-host interactions in natural contexts. This review synthesizes recent advances in vibriophage research, highlighting key findings and emerging tools. High-throughput assays and genomic tools have offered new perspectives on phage specificity, host range and the evolutionary pressures shaping these interactions. Theoretical frameworks, such as arms race and fluctuating selection dynamics, are informed by empirical data from vibrio-phage systems, with time-series sampling providing crucial insights into their temporal and spatial dynamics. A major finding is the role of mobile genetic elements (MGEs) in encoding bacterial defence systems, which shape phage-host coevolution. Discoveries like the phage satellite PICMI illustrate how MGEs facilitate the transfer of antiviral systems, influencing ecological and evolutionary dynamics. The paradox of generalist vibriophages, rare despite their broad host ranges, is also explored. By integrating experimental approaches with field observations, vibriophage research advances microbial ecology and informs sustainable applications in aquaculture and phage therapy, reinforcing vibrios as a versatile model system.This article is part of the discussion meeting issue 'The ecology and evolution of bacterial immune systems'.

Bacteriophages

Admission whole-blood transcriptomic characterization of a neutrophil-predominant systemic immune response in patients with acute traumatic brain injury.

BACKGROUND: Acute traumatic brain injury (TBI) is accompanied by systemic immune responses, but their whole-blood transcriptomic features at hospital arrival remain incompletely characterized. We aimed to characterize these features in patients with acute TBI compared with healthy controls. METHODS: In this single-center prospective observational study, we performed whole-blood RNA sequencing on hospital-arrival samples from 42 patients with acute TBI and 21 healthy controls. Analyses included differential expression (limma-voom; FDR < 0.05, |log2FC| > 0.7), functional enrichment, Ingenuity Pathway Analysis, CIBERSORTx LM22 deconvolution, and per-sample neutrophil degranulation signature scoring. RESULTS: Differential expression analysis identified 996 upregulated and 863 downregulated genes, with marked upregulation of inflammation-, innate immunity-, and neutrophil-related genes including DUSP1, HMGB2, MMP9, and S100A8. Canonical pathways with positive IPA z-scores included Neutrophil degranulation, Neutrophil Extracellular Trap Signaling Pathway, and Toll-like Receptor Signaling; upstream regulators included TNF, IL1B, IFNG, and STAT3. Deconvolution identified 7 of 22 differing subsets (q < 0.05), with relatively higher myeloid and lower lymphoid fractions in TBI. The Neutrophil degranulation signature score correlated with Injury Severity Score within TBI (Spearman &#x3c1; = +0.55; q < 0.001). CONCLUSIONS: Admission whole-blood transcriptomics characterized a neutrophil-predominant systemic transcriptional response in patients with acute TBI. This response was also evident among patients without major extracranial injury and was associated with total ISS. However, because the study lacked an appropriately matched non-TBI trauma comparator, the findings should be interpreted as a descriptive characterization of a systemic injury response accompanying TBI and do not establish a TBI-specific molecular signature or mechanism.

gene expression

Epigenome-wide meta-analysis of PTSD symptom severity in three military cohorts implicates DNA methylation changes in genes involved in immune system and oxidative stress.

Epigenetic factors modify the effects of environmental factors on biological outcomes. Identification of epigenetic changes that associate with PTSD is therefore a crucial step in deciphering mechanisms of risk and resilience. In this study, our goal is to identify epigenetic signatures associated with PTSD symptom severity (PTSS) and changes in PTSS over time, using whole blood DNA methylation (DNAm) data (MethylationEPIC BeadChip) of military personnel prior to and following combat deployment. A total of 429 subjects (858 samples across 2 time points) from three male military cohorts were included in the analyses. We conducted two different meta-analyses to answer two different scientific questions: one to identify a DNAm profile of PTSS using a random effects model including both time points for each subject, and the other to identify a DNAm profile of change in PTSS conditioned on pre-deployment DNAm. Four CpGs near four genes (F2R, CNPY2, BAIAP2L1, and TBXAS1) and 88 differentially methylated regions (DMRs) were associated with PTSS. Change in PTSS after deployment was associated with 15 DMRs, of those 2 DMRs near OTUD5 and ELF4 were also associated with PTSS. Notably, three PTSS-associated CpGs near F2R, BAIAP2L1 and TBXAS1 also showed nominal evidence of association with change in PTSS. This study, which identifies PTSD-associated changes in genes involved in oxidative stress and immune system, provides novel evidence that epigenetic differences are associated with PTSS.

Adaptor Proteins, Signal Transducing

EBV reactivation priming of the peripheral immune system in multiple sclerosis relapse.

Despite decades of research, the cellular and molecular events preceding multiple sclerosis (MS) relapse remain incompletely understood. Here, in this observational study of longitudinal blood samples from patients with relapsing-remitting MS, we used single-cell RNA sequencing, bulk transcriptomics, multiparameter flow cytometry and targeted viral reverse transcription quantitative polymerase chain reaction (RT-qPCR) to construct a time-resolved atlas of immune perturbations surrounding relapse. A reproducible pre-relapse signature in monocytes and B cells, emerging up to 3&#x2009;months before clinical onset, was enriched for host genes responsive to Epstein-Barr virus (EBV) lytic reactivation factors. RT-qPCR confirmed elevated EBV LMP-1 transcripts in pre-relapse B cells, and flow cytometry demonstrated expansion of CD11c+ atypical B cell populations displaying EBV surface protein gp350. Pre-relapse transcriptional modules overlapped with MS genome-wide association study (GWAS) risk loci and EBNA-2-bound enhancers, suggesting that inherited MS susceptibility and EBV-responsive programs operate through shared regulatory elements. How this peripheral activation relates to central nervous system lesion formation remains to be established. These findings nonetheless suggest that EBV reactivation, when occurring within a genetically predisposed peripheral immune environment, is a proximal precursor of MS relapse.

Journal Article

Widespread Molecular Imprints in the Serum Proteome of COVID-19 Convalescents Uncovering Immune System Sequelae.

Post-COVID-19 sequelae have become an emerging global health issue, but the mechanisms for the sustained susceptibility of convalescents to the sequelae remain poorly understood. Here we report the use of a restricted open-search approach to explore the molecular imprints of SARS-CoV-2 infection left on the proteome of 412 COVID-19 patients and convalescences. A total of 827 non-standard amino acid variations, chemically modified residues as well as post-translational modifications, termed non-coded amino acids (ncAAs), are found spreading over 29,814 sites in patient's serum proteins. Markedly, widespread ncAAs are induced and sustainedly imprinted on the serum proteome predominately perturbing the immunoglobulin-mediated immune response, complement activation and coagulation regulation even 12 months after recovery. Sustained amino acid variations and chemical modifications are found in the complementary&#x2011;determining regions (CDRs) of the variable region of immunoglobulin contributing to the interactions between the emerging antibody and antigens; durable chemical amino acid modifications found in the hyper ncAA-modified regions of the constant region of immunoglobulin important for the interaction with the complement and regulatory receptors. In the complement system, inducible ncAAs are memorized in the components essential for the complement activation, amplification cascades and membrane attack processes. Thus, the workflow described in this study can be used to identify the molecular imprints of viral infection at the proteomic scale, particularly the specific antibodies and the immune targets left in COVID-19 patients and convalescents.

Humans

Association of time-averaged systemic immune-inflammation indices with in-hospital mortality after intracerebral hemorrhage: a retrospective study.

BACKGROUND: Systemic inflammation plays a central role in secondary brain injury following intracerebral hemorrhage (ICH). Although inflammatory indices such as the neutrophil-to-lymphocyte ratio (NLR), systemic immune-inflammation index (SII), and systemic inflammation response index (SIRI) are linked to poor outcomes, their associations with mortality are commonly assumed to be linear, potentially overlooking nonlinear patterns where mortality risk rises steeply at higher levels. METHODS: We conducted a retrospective study using the MIMIC-IV database, including 440 patients with non-traumatic ICH who were alive and remained in the ICU for at least 72&#xa0;h after admission. Mean NLR, SII, and SIRI were calculated from measurements obtained during this period. Multivariable logistic regression and restricted cubic spline (RCS) analyses were applied to assess their independent and nonlinear associations with in-hospital mortality. Model discrimination and calibration were internally validated using 1,000 bootstrap resamples. RESULTS: The in-hospital mortality rate was 26.1%. After multivariable adjustment, NLR and SIRI remained independently associated with mortality. Patients in the highest SIRI quartile had the highest risk of death (aOR&#xa0;=&#xa0;5.12; 95% CI: 2.57-12.24; p&#xa0;<&#xa0;0.001). RCS analysis revealed a significant nonlinear association between SIRI and mortality (p-nonlinearity&#xa0;<&#xa0;0.05), showing a steep risk increase at higher SIRI levels. Adding SIRI to the base model provided a modest improvement in discrimination (AUC 0.762 to 0.785, p&#xa0;=&#xa0;0.045) and significantly improved risk reclassification (cNRI&#xa0;=&#xa0;0.4778, p&#xa0;<&#xa0;0.001; IDI&#xa0;=&#xa0;0.0240, p&#xa0;=&#xa0;0.0151). CONCLUSIONS: Among patients with ICH who met the 72-hour eligibility criterion, higher 72-hour average SIRI was independently associated with in-hospital mortality. As a time-averaged measure, SIRI should be interpreted as a dynamic marker integrating the initial inflammatory state and the early clinical course rather than as a purely baseline prognostic factor. Although adding SIRI to the base model modestly improved discrimination and risk reclassification, it should be considered a candidate prognostic marker requiring external validation before clinical application.

Humans

An atlas of ferroptosis-induced secretomes.

Cells undergoing regulated necrosis systemically communicate with the immune system via the release of protein and non-protein secretomes. Ferroptosis is a recently described iron-dependent type of regulated necrosis driven by massive lipid peroxidation. While membrane rupture occurs during ferroptosis, a comprehensive appraisal of ferroptotic secretomes and their potential biological activity has been lacking. Here, we apply a multi-omics approach to provide an atlas of ferroptosis-induced secretomes and reveal a novel function in macrophage priming. Proteins with assigned DAMP and innate immune system function, such as MIF, heat shock proteins (HSPs), and chaperones, were released from ferroptotic cells. Non-protein secretomes with assigned inflammatory function contained oxylipins as well as TCA- and methionine-cycle metabolites. Interestingly, incubation of bone marrow-derived macrophages (BMDMs) with ferroptotic supernatants induced transcriptional reprogramming consistent with priming. Indeed, exposure to ferroptotic supernatants enhanced LPS-induced cytokine production. These results define a catalog of ferroptosis-induced secretomes and identify a biological activity in macrophage priming with important implications for the fine-tuning of inflammatory processes.

Ferroptosis

IgStrand: A universal residue numbering scheme for the immunoglobulin-fold (Ig-fold) to study Ig-proteomes and Ig-interactomes.

The Immunoglobulin fold (Ig-fold) is found in proteins from all domains of life and represents the most populous fold in the human genome, with current estimates ranging from 2 to 3% of protein coding regions. That proportion is much higher in the surfaceome where Ig and Ig-like domains orchestrate cell-cell recognition, adhesion and signaling. The ability of Ig-domains to reliably fold and self-assemble through highly specific interfaces represents a remarkable property of these domains, making them key elements of molecular interaction systems: the immune system, the nervous system, the vascular system and the muscular system. We define a universal residue numbering scheme, common to all domains sharing the Ig-fold in order to study the wide spectrum of Ig-domain variants constituting the Ig-proteome and Ig-Ig interactomes at the heart of these systems. The "IgStrand numbering scheme" enables the identification of Ig structural proteomes and interactomes in and between any species, and comparative structural, functional, and evolutionary analyses. We review how Ig-domains are classified today as topological and structural variants and highlight the "Ig-fold irreducible structural signature" shared by all of them. The IgStrand numbering scheme lays the foundation for the systematic annotation of structural proteomes by detecting and accurately labeling Ig-, Ig-like and Ig-extended domains in proteins, which are poorly annotated in current databases and opens the door to accurate machine learning. Importantly, it sheds light on the robust Ig protein folding algorithm used by nature to form beta sandwich supersecondary structures. The numbering scheme powers an algorithm implemented in the interactive structural analysis software iCn3D to systematically recognize Ig-domains, annotate them and perform detailed analyses comparing any domain sharing the Ig-fold in sequence, topology and structure, regardless of their diverse topologies or origin. The scheme provides a robust fold detection and labeling mechanism that reveals unsuspected structural homologies among protein structures beyond currently identified Ig- and Ig-like domain variants. Indeed, multiple folds classified independently contain a common structural signature, in particular jelly-rolls. Examples of folds that harbor an "Ig-extended" architecture are given. Applications in protein engineering around the Ig-architecture are straightforward based on the universal numbering.

Humans

In vivo vitamin D target genes interconnect key signaling pathways of innate immunity.

The vitamin D3 metabolite 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), its nuclear receptor VDR (vitamin D receptor) and hundreds of their target genes are not only key regulators of calcium homeostasis, but also important modulators of the immune system. Innate immune cells like monocytes use VDR for efficient differentiation and are very responsive to vitamin D. So far, most information on the gene regulatory function of vitamin D and its physiological impact had been obtained from in vitro studies using supraphysiological doses of 1,25(OH)2D3. Therefore, medical experiments like the study VitDHiD (NCT03537027), where 25 healthy individuals were supplemented once with a vitamin D3 bolus (80,000 IU), provide important insight into the response to vitamin D under in vivo conditions. In this study, we inspected 452 in vivo vitamin D target genes from peripheral blood mononuclear cells (PBMCs) detected in VitDHiD and found 61 of them involved in eight major KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways of innate immunity. Under in vivo conditions in healthy individuals vitamin D either silences five pathways of innate immunity, stabilizes two and increases one, so that acute inflammation is suppressed and the release of cytokines is kept under control. A ranking of the 61 target genes by inducibility, basal expression and multiple involvements in the pathways highlighted the genes NFKBIA (NF&#x3ba;B inhibitor alpha), NFKBIZ, FOSL2 (FOS like 2, AP1 transcription factor subunit), JDP2 (Jun dimerization protein 2), PIK3R1 (phosphoinositide-3-kinase regulatory subunit 1), CLEC7A (C-type lectin domain containing 7A), DUSP6 (dual specificity phosphatase 6), NCF2 (neutrophil cytosolic factor 2), PLCB1 (phospholipase C beta 1), PLCG2 and TNFAIP3 (TNF alpha induced protein 3). In conclusion, vitamin D's in vivo effect on innate immunity in healthy adults is mediated by the interconnection of the pathways of neutrophil extracellular trap formation, Toll-like receptor, chemokine and phagosome signaling, NOD-like receptor, C-type lectin receptor, apoptosis and interleukin 17 through a limited set of proteins encoded by key target genes.

Humans

Multi-level aggregation analysis of microbiome composition and host gene expression reveals associations with systemic and local immunity.

The human gut microbiome plays a critical role in immune regulation, yet the molecular links between microbiome composition and host gene expression remain incompletely understood. We analyzed associations between host gene expression and microbiome composition in a cohort of 315 healthy individuals, integrating microarray-based gene expression data from three intestinal sites (ileum, transverse colon, and rectum) and six immune cell types with microbiome sequencing data. Using a hierarchical feature aggregation strategy combining principal component analysis, clustering, and covariate correction, we discovered significant associations primarily related to immunity. While microbial profiles were similar across the three intestinal sites, the transverse colon yielded the most "microbiome-host gene expression" associations. Among the immune cell types, CD8+ cells showed the highest number of associations. The first principal component of microbiome composition, reflecting a gradient from commensals (e.g., Ruminococcaceae and Christensenellaceae) to proinflammatory taxa ([Ruminococcus] gnavus and Lachnoclostridium), correlated with the expression of TNF-&#x3b1;-linked genes (HMOX1, CPI17, HSD3B2, and SLC5A1). Among individual genera, Catenibacterium abundance was associated with gene expression in both intestinal and immune cells, including negative associations with MRPS21 (related to mitochondrial function) in the transverse colon and with CD8+ gene programs related to T cell differentiation. These findings align with emerging evidence implicating mitochondrial dysfunction in intestinal inflammation. Our results identify multi-level associations between the gut microbiome and host gene expression, suggesting potential mechanisms by which microbiota shape local and systemic immunity and vice versa. The implicated genes and taxa represent candidates for experimental validation to improve understanding of host-microbiome homeostasis and its disruption in disease.IMPORTANCEThe gut microbiome and immune system are engaged in a complex interplay throughout human life. While most associative studies focus on case-control comparisons-typically examining patients with conditions such as inflammatory bowel disease or metabolic diseases-less is known about the molecular links between the microbiome and immune system in healthy individuals. In this study of a large cohort of healthy individuals, we addressed this gap by applying multiscale modeling to tackle the high dimensionality of host-microbiome data. We identified multi-level associations between microbiome composition and host gene expression in both intestinal tissues and immune cells. These findings offer a valuable reference for understanding baseline host-microbiome communication and highlight molecular candidates-such as TNF-&#x3b1;-related genes and mitochondrial pathways-for future experimental validation.

Humans

Comparison of the predictive performance of systemic immune-inflammation index and neutrophil-to-lymphocyte ratio for three-month poor functional outcome in ischemic stroke: a systematic review and meta-analysis.

INTRODUCTION: Ischemic stroke (IS) is a leading cause of global mortality and disability. Early and accurate prognosis is crucial for patient management. The neutrophil-to-lymphocyte ratio (NLR) and systemic immune-inflammation index (SII) are emerging inflammatory biomarkers; however, their relative predictive value for three-month poor functional outcome (modified Rankin Scale [mRS]&#x2009;>&#x2009;2) remains uncertain. METHODS: We systematically searched PubMed, Embase, Web of Science, and the Cochrane Library up to 20 July 2025, adhering to PRISMA guidelines. Observational studies reporting the association of SII or NLR with three-month poor outcome were included. Study quality was evaluated using the Newcastle-Ottawa Scale. Area under the curve (AUC), odds ratios (OR), and standardized mean differences (SMD) were pooled using random-effects models in Stata 16.0. RESULTS: Twenty-one studies involving 7520 IS patients were analysed. NLR demonstrated marginally superior discriminative ability compared to SII (AUC 0.71, 95% CI: 0.67-0.76 vs. 0.68, 95% CI: 0.64-0.71), though this difference was not statistically significant. Elevated NLR was significantly associated with poor outcome (OR = 1.26, 95% CI: 1.17-1.37, p&#x2009;<&#x2009;.001), whereas SII was not (OR = 1.00, 95% CI: 1.00-1.00, p&#x2009;=&#x2009;.384). Both markers showed moderate effect sizes (SMD: NLR = 0.69, SII = 0.72; p&#x2009;<&#x2009;.001). NLR performed better in non-intervention and Chinese subgroups, while SII exhibited consistent AUC values across treatment and ethnic subgroups. CONCLUSION: NLR and SII are accessible prognostic markers in IS. NLR demonstrates superior accuracy and a significant association with poor outcome, while SII shows greater stability across patient subgroups. Both may assist in risk stratification, in resource-limited settings.

Humans

Clinical and Multiorgan Proteomics Characteristics of the Diverse Fatal Phase in Super Elderly Patients With SARS-CoV-2 Infection: A Descriptive Study.

This study aims to identify the risk factors associated with clinical outcomes and the proteomic changes in organs related to fatal SARS-CoV-2 infection within the super-elderly population. This retrospective analysis included all elderly individuals with COVID-19 admitted to the Second Medical Center of PLA General Hospital from December 2022 to January 2023. The follow-up period ended on March 30, 2023. During this time, epidemiological, demographic, laboratory, and outcome data were analyzed descriptively. Proteomic sequencing was performed on super-elderly patients who died from COVID-19 at different stages of the disease. A total of 352 elderly COVID-19 patients, with a mean age of 89.84&#x2009;&#xb1;&#x2009;8.54 years, were included in this study. During a median follow-up period of 98 days, 79 patients died. Deceased patients were older and more likely to have cardiovascular and cerebrovascular diseases, with a lower prevalence of lipid-lowering therapy. The number of deaths in the acute and post-acute phases were 34 and 45, respectively. Proteomics data suggest that the immune systems of patients who died in the acute phase underwent a more rapid and severe onslaught. Patients in the post-acute phase showed higher levels of viral genome replication and a more robust immune response. However, the over-activation of the immune system led to systemic organ dysfunction. Effective management of comorbidities may improve the prognosis of COVID-19 in super-elderly patients. The continuous replication of the SARS-CoV-2 virus and its subsequent impact on the immune system are critical determinants of survival time in this demographic.

Humans

Optimization of a niosomal formulation for Quercetin delivery: Comparative effects on growth performance, antioxidant and immune responses, and disease resistance against Streptococcus iniae in rainbow trout (Oncorhynchus mykiss).

Quercetin (QUR) is a flavonoid with antibacterial and antioxidant properties that has been studied for its effects on fish health and the immune system. Due to the low bioavailability of QUR, the present study was primarily aimed at developing a niosomal formulation of QUR to enhance its bioavailability and therapeutic properties. The performance of niosomal QUR was then compared with that of its free form by evaluating their effects on the growth and immune system of rainbow trout, Oncorhynchus mykiss. For this purpose, an optimal QUR-containing niosome was formulated by testing different proportions of cholesterol, surfactant, and stabilizer, and the niosomes were then added to the fish diet. A QUR-free diet and a diet containing QUR-free niosomes (QFN) were considered control groups. Niosomes prepared at low hydrophilic-lipophilic balance (HLB) values showed higher QUR entrapment efficiency (QUR-EE%) (P&#x202f;<&#x202f;0.01). An increase in the molar ratio of cholesterol to surfactant significantly reduced QUR-EE% (P&#x202f;<&#x202f;0.05). A surfactant/cholesterol/stabilizer ratio of 1:1:0.1 increased QUR-EE% (P&#x202f;<&#x202f;0.05). The particle size of the niosomes was also affected by HLB and the surfactant/cholesterol/stabilizer ratio. Low HLB values resulted in smaller particle sizes (P&#x202f;<&#x202f;0.01). Furthermore, a surfactant/cholesterol/stabilizer ratio of 1:1:0.1 resulted in the smallest niosomal particle size (P&#x202f;<&#x202f;0.05). The presence of diacetyl phosphate as the stabilizer in the formulation improved the niosomal zeta potential to -40.55&#x202f;mV. The optimal niosomal formulation (HLB&#x202f;=&#x202f;6.6; surfactant/cholesterol/stabilizer ratio of 1:1:0.1) remained stable at 2&#x202f;&#xb0;C over 10 days of storage, as the niosomal QUR content and size did not show significant changes during this period (P&#x202f;>&#x202f;0.01). After preparation of the diets containing the optimal niosomal QUR, fish were fed the experimental diets for two months. QUR, in both niosomal and free forms, resulted in better growth performance than the QUR-free diets (P&#x202f;<&#x202f;0.01). There were no significant differences in growth performance between the free and niosomal forms of QUR; however, 500&#x202f;mg/kg QUR showed significantly better growth performance than 250&#x202f;mg/kg QUR (P&#x202f;<&#x202f;0.01). Although both the niosomal and free forms of QUR enhanced immune and antioxidant components in the fish, the effects of the niosomal form were more significant (P&#x202f;<&#x202f;0.01). In addition, QUR in both free and niosomal forms reduced fish mortality after challenge with Streptococcus iniae. In conclusion, the results of this study suggest that the niosomal form of QUR has strong potential for improving the immune system of fish and increasing resistance to S. iniae infection.

Animals