BACKGROUND: Timely resolution of innate immune responses activated by surgical intervention is crucial for patient recovery. While cytokines and innate immune cells are critical in inflammation resolution, the specific role of IL-18 in these processes remains controversial and underexplored. METHODS: We investigate determinants of successful recovery using peripheral blood samples from orthopedic surgery (ORT) patients (n = 33) at T0 (before surgery), T1 (24 h after surgery) and T2 (3 days after surgery). Monocytes from ORT patients underwent immunophenotyping together with bulk transcriptomic analysis. We found that IL-18 strongly defines the recovery immune signature. These results were further validated in vitro by comparing IL-18 and TNF-α effects on monocytes, and in 3D human intestine organoids together with single cell (sc)-RNAseq analysis. RESULTS: Transcriptomics of ORT monocytes revealed upregulation of ITG family integrins, namely ITGB3 and ITGB5, CXCL family chemokines, notably CXCL1-3, CXCL5, and SCL/TAL1 factor controlling differentiation and migration, but not pro-inflammatory genes. Similar changes were observed in IL-18 stimulated healthy donor monocytes in vitro, including an increase in CD11b, CD64, and CD86 levels, accompanied by increased phosphorylation of Akt but not NFκB. These changes were attenuated in the presence of TNF-α, thus showing a unique role of IL-18 when acting alone without its most frequent paired cytokine TNF-α. We further confirmed that IL-18 induces monocyte-macrophage transition and migration using human intestinal organoids. Finally, TNF-α/IL-18 ratio showed a high predictive value of clinical severity in septic patients. CONCLUSIONS: We propose a novel role of IL-18 on monocyte migration and macrophage transition characterizing successful orthopedic surgery recovery, as well as the ratio of IL-18/TNF-α as a novel marker of inflammation resolution, with potential implications for patient monitoring and therapeutic strategies.

• Keywords
• Cytokine profiling, IL-18, Inflammation resolution, Monocyte macrophage transition, Recovery, Sepsis,
• MeSH
• Interleukin-18 * metabolism   MeSH
• Middle Aged MeSH
• Humans MeSH
• Monocytes metabolism   drug effects   MeSH
• Organoids drug effects   MeSH
• Aged MeSH
• Sepsis * blood   genetics   MeSH
• Tumor Necrosis Factor-alpha pharmacology   MeSH
• Inflammation * pathology   blood   MeSH
• Check Tag
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Interleukin-18 * MeSH
• Tumor Necrosis Factor-alpha MeSH

The Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) infection is not limited to the respiratory tract as receptors, including the angiotensin-converting enzyme 2 (ACE2), are expressed across many tissues. This study employed a new conditional mouse model, Rosa26creERT2/chACE2, which expresses human ACE2 (hACE2) across multiple organs, to investigate the effects of SARS-CoV-2 infection beyond the respiratory system. This strain demonstrated susceptibility to SARS-CoV-2 infection in a dose and sex-dependent manner, showing that infected male mice exhibited more severe disease outcomes, including significant weight loss, pronounced lung pathology and dysfunction, and increased mortality, compared to females. In contrast to intratracheal infection, intranasal virus administration facilitated viral spread to the brain, thereby underscoring the nasal route's role in the pathogenesis of neurological manifestations. Intranasal infection also led to increased innate immune system activation as compared to intratracheal virus administration, even though both routes activated the adaptive immune response. This model provides a valuable tool to study SARS-CoV-2 in individual tissues or use a multisystemic approach, and it also advances possibilities for preclinical evaluation of antiviral therapies and vaccine strategies.

• Keywords
• Conditional mouse model, Infection, SARS-CoV-2, hACE2,
• MeSH
• Angiotensin-Converting Enzyme 2 * genetics   metabolism   MeSH
• COVID-19 * pathology   virology   immunology   genetics   MeSH
• Respiratory System virology   pathology   MeSH
• Humans MeSH
• Disease Models, Animal MeSH
• Mice, Transgenic MeSH
• Mice MeSH
• Lung virology   pathology   MeSH
• Immunity, Innate MeSH
• SARS-CoV-2 * pathogenicity   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Male MeSH
• Mice MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• ACE2 protein, human MeSH Browser
• Angiotensin-Converting Enzyme 2 * MeSH

INTRODUCTION: Major clinically relevant inflammatory events such as septic shock and severe COVID-19 trigger dynamic changes in the host immune system, presenting promising candidates for new biomarkers to improve precision diagnostics and patient stratification. Hepcidin, a master regulator of iron metabolism, has been intensively studied in many pathologies associated with immune system activation, however these data have never been compared to other clinical settings. Thus, we aimed to reveal the dynamics of iron regulation in various clinical settings and to determine the suitability of hepcidin and/or ferritin levels as biomarkers of inflammatory disease severity. COHORTS: To investigate the overall predictive ability of hepcidin and ferritin, we enrolled the patients suffering with three different diagnoses - in detail 40 patients with COVID-19, 29 patients in septic shock and eight orthopedic patients who were compared to nine healthy donors and all cohorts to each other. RESULTS: We showed that increased hepcidin levels reflect overall immune cell activation driven by intrinsic stimuli, without requiring direct involvement of infection vectors. Contrary to hepcidin, ferritin levels were more strongly boosted by pathogen-induced inflammation - in septic shock more than four-fold and in COVID-19 six-fold in comparison to sterile inflammation. We also defined the predictive capacity of hepcidin-to-ferritin ratio with AUC=0.79 and P = 0.03. DISCUSSION: Our findings confirm that hepcidin is a potent marker of septic shock and other acute inflammation-associated pathologies and demonstrate the utility of the hepcidin-to-ferritin ratio as a predictor of mortality in septic shock, but not in COVID-19.

• Keywords
• COVID-19, ferritin, hepcidin, inflammation, sepsis, septic shock,
• MeSH
• Biomarkers MeSH
• COVID-19 * MeSH
• Ferritins MeSH
• Hepcidins metabolism   MeSH
• Humans MeSH
• Shock, Septic * MeSH
• Inflammation MeSH
• Iron metabolism   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Biomarkers MeSH
• Ferritins MeSH
• Hepcidins MeSH
• Iron MeSH

Around half of people with severe COVID-19 requiring intensive care unit (ICU) treatment will survive, but it is unclear how the immune response to SARS-CoV-2 differs between ICU patients that recover and those that do not. We conducted whole-blood immunophenotyping of COVID-19 patients upon admission to ICU and during their treatment and uncovered marked differences in their circulating immune cell subsets. At admission, patients who later succumbed to COVID-19 had significantly lower frequencies of all memory CD8+ T cell subsets, resulting in increased CD4-to-CD8 T cell and neutrophil-to-CD8 T cell ratios. ROC and Kaplan-Meier analyses demonstrated that both CD4-to-CD8 and neutrophil-to-CD8 ratios at admission were strong predictors of in-ICU mortality. Therefore, we propose the use of the CD4-to-CD8 T cell ratio as a marker for the early identification of those individuals likely to require enhanced monitoring and/or pro-active intervention in ICU.

• Keywords
• CD4-to-CD8 ratio, COVID-19, Intensive care unit, SARS-CoV-2, T cells, TEMRA,
• MeSH
• CD4-Positive T-Lymphocytes immunology   MeSH
• CD8-Positive T-Lymphocytes immunology   MeSH
• COVID-19 immunology   MeSH
• Immunophenotyping methods   MeSH
• Intensive Care Units MeSH
• Middle Aged MeSH
• Humans MeSH
• Lymphocyte Count methods   MeSH
• CD4-CD8 Ratio methods   MeSH
• Prospective Studies MeSH
• SARS-CoV-2 immunology   MeSH
• Aged MeSH
• Check Tag
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Observational Study MeSH

Sepsis and septic shock remain leading causes of morbidity and mortality for patients in the intensive care unit. During the early phase, immune cells produce various cytokines leading to prompt activation of the immune system. Polymorphonuclear leukocytes (PMNs) respond to different signals producing inflammatory factors and executing their antimicrobial mechanisms, resulting in the engulfment and elimination of invading pathogens. However, excessive activation caused by various inflammatory signals produced during sepsis progression can lead to the alteration of PMN signaling and subsequent defects in their functionality. Here, we analyzed samples from 34 patients in septic shock, focusing on PMNs gene expression and proteome changes associated with septic shock. We revealed that, compared to those patients who survived longer than five days, PMNs from patients who had fulminant sepsis were characterized by a dysfunctional hyper-activation, show altered metabolism, and recent exit from the cell cycle and signs of cellular lifespan. We believe that this multi-omics approach, although limited, pinpoints the alterations in PMNs' functionality, which may be rescued by targeted treatments.

• Keywords
• dysfunctionality, polymorphonuclears, proteomics, sepsis, septic shock, transcriptomics,
• MeSH
• Intensive Care Units MeSH
• Cohort Studies MeSH
• Middle Aged MeSH
• Humans MeSH
• Neutrophils immunology   pathology   MeSH
• Prospective Studies MeSH
• Aged, 80 and over MeSH
• Aged MeSH
• Sepsis immunology   pathology   MeSH
• Check Tag
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Aged, 80 and over MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH