Severe COVID-19 Shares a Common Neutrophil Activation Signature with Other Acute Inflammatory States.

Severe COVID-19 patients present a clinical and laboratory overlap with other hyperinflammatory conditions such as hemophagocytic lymphohistiocytosis (HLH). However, the underlying mechanisms of these conditions remain to be explored. Here, we investigated the transcriptome of 1596 individuals, including patients with COVID-19 in comparison to healthy controls, other acute inflammatory states (HLH, multisystem inflammatory syndrome in children [MIS-C], Kawasaki disease [KD]), and different respiratory infections (seasonal coronavirus, influenza, bacterial pneumonia). We observed that COVID-19 and HLH share immunological pathways (cytokine/chemokine signaling and neutrophil-mediated immune responses), including gene signatures that stratify COVID-19 patients admitted to the intensive care unit (ICU) and COVID-19_nonICU patients. Of note, among the common differentially expressed genes (DEG), there is a cluster of neutrophil-associated genes that reflects a generalized hyperinflammatory state since it is also dysregulated in patients with KD and bacterial pneumonia. These genes are dysregulated at the protein level across several COVID-19 studies and form an interconnected network with differentially expressed plasma proteins that point to neutrophil hyperactivation in COVID-19 patients admitted to the intensive care unit. scRNAseq analysis indicated that these genes are specifically upregulated across different leukocyte populations, including lymphocyte subsets and immature neutrophils. Artificial intelligence modeling confirmed the strong association of these genes with COVID-19 severity. Thus, our work indicates putative therapeutic pathways for intervention.

HO-1 is located in liver mitochondria and modulates mitochondrial heme content and metabolism.

This study investigated whether inducible heme oxygenase-1[corrected] (HO-1) [corrected] is targeted to mitochondria and its putative effects on oxidative metabolism in rat liver. Western blot and immune-electron microscopy in whole purified and fractionated organelles showed basal expression of HO-1 protein in both microsomes and mitochondria (inner membrane), accompanied by a parallel HO activity. Inducers of HO-1 increased HO-1 targeting to the inner mitochondrial membrane, which also contained biliverdin reductase, supporting that both enzymes are in the same compartmentalization. Induction of mitochondrial HO-1 was associated with a decrease of mitochondrial heme content and selective reduction of protein expression of cytochrome oxidase (COX) subunit I, which is coded by the mitochondrial genome and synthesized in the mitochondria depending on heme availability; these changes resulted in decreased COX spectrum and activity. Mitochondrial HO-1 induction was also associated with down-regulation of mitochondrial-targeted NO synthase expression and activity, resulting in a reduction of NO-dependent mitochondrial oxidant yield; inhibition of HO-1 activity reverted these effects. In conclusion, we demonstrated for the first time localization of HO-1 protein in mitochondria. It is surmised that mitochondrial HO-1 has important biological roles in regulating mitochondrial heme protein turnover and in protecting against conditions such as hypoxia, neurodegenerative diseases, or sepsis, in which substantially increased mitochondrial NO and oxidant production have been implicated.

[Adhesion molecules. Their role in cardiovascular physiopathology]. / Moléculas de adhesión. Su papel en la fisiopatología cardiovascular.

Adhesion molecules are membrane receptors that mediate several functions related to cell traffic, cell-cell interactions, and cell-matrix contact. There are three important groups associated to cardiovascular disease: integrins, selectins, and the immunoglobulin superfamily. They are involved in the endothelial disfunction and activation processes, and are related to the pathogenesis of coronary artery disease, reperfusion injury, allograft vasculopathy, myocarditis, hypertrophic myocardiopathy, etc. Also, they are related to the mechanism of action of statins. Serologic titer of these molecules has diagnostic and predictive value on diverse cardiovascular diseases. This review focuses on the functions of adhesins and discusses various therapeutic possibilities based on their recognition.

Mitochondrial nitric oxide synthase drives redox signals for proliferation and quiescence in rat liver development.

Mitochondrial nitric oxide synthase (mtNOS) is a fine regulator of oxygen uptake and reactive oxygen species that eventually modulates the activity of regulatory proteins and cell cycle progression. From this perspective, we examined liver mtNOS modulation and mitochondrial redox changes in developing rats from embryonic days 17-19 and postnatal day 2 (proliferating hepatocyte phenotype) through postnatal days 15-90 (quiescent phenotype). mtNOS expression and activity were almost undetectable in fetal liver, and progressively increased after birth by tenfold up to adult stage. NO-dependent mitochondrial hydrogen peroxide (H(2)O(2)) production and Mn-superoxide dismutase followed the developmental modulation of mtNOS and contributed to parallel variations of cytosolic H(2)O(2) concentration ([H(2)O(2)](ss)) and cell fluorescence. mtNOS-dependent [H(2)O(2)](ss) was a good predictor of extracellular signal-regulated kinase (ERK)/p38 activity ratio, cyclin D1, and tissue proliferation. At low 10(-11)-10(-12) M [H(2)O(2)](ss), proliferating phenotypes had high cyclin D1 and phospho-ERK1/2 and low phospho-p38 mitogen-activated protein kinase, while at 10(-9) M [H(2)O(2)](ss), quiescent phenotypes had the opposite pattern. Accordingly, leading postnatal day 2-isolated hepatocytes to embryo or adult redox conditions with H(2)O(2) or NO-H(2)O(2) scavengers, or with ERK inhibitor U0126, p38 inhibitor SB202190 or p38 activator anisomycin resulted in correlative changes of ERK/p38 activity ratio, cyclin D1 expression, and [(3)H] thymidine incorporation in the cells. Accordingly, p38 inhibitor SB202190 or N-acetyl-cysteine prevented H(2)O(2) inhibitory effects on proliferation. In conclusion, the results suggest that a synchronized increase of mtNOS and derived H(2)O(2) operate on hepatocyte signaling pathways to support the liver developmental transition from proliferation to quiescence.

Mitochondrial extracellular signal-regulated kinases 1/2 (ERK1/2) are modulated during brain development.

Intracellular activation and trafficking of extracellular signal-regulated protein kinases (ERK) play a significant role in cell cycle progression, contributing to developmental brain activities. Additionally, mitochondria participate in cell signalling through energy-linked functions, redox metabolism and activation of pro- or anti-apoptotic proteins. The purpose of the present study was to analyze the presence of ERK1/2 in mitochondria during rat brain development. Immunoblotting, immune electron microscopy and activity assays demonstrated that ERK1/2 are present in fully active brain mitochondria at the outer membrane/intermembrane space fraction. Besides, it was observed that ERK1/2 translocation to brain mitochondria follows a developmental pattern which is maximal between E19-P2 stages and afterwards declines at P3, just before maximal translocation to nucleus, and up to adulthood. Most of mitochondrial ERK1/2 were active; upstream phospho-MAPK/ERK kinases (MEK1/2) were also detected in the brain organelles. Mitochondrial phospho-ERK1/2 increased at 1 microm hydrogen peroxide (H(2)O(2)) concentration, but it decreased at higher 50-100 microm H(2)O(2), almost disappearing after the organelles were maximally stimulated to produce H(2)O(2) with antimycin. Our results suggest that developmental mitochondrial activation of ERK1/2 cascade contributes to its nuclear translocation effects, providing information about mitochondrial energetic and redox status to the proliferating/differentiating nuclear pathways.

Moleculas de adhesion: su papel en la fisiopatologia cardiovascular / Adhesion molecules: their role in cardiovascular physiopathology

Las moléculas de adhesión son receptores de menbrana que participan en diversas funciones vinculadas al tráfico celular, a las interacciones célula-célula y célula-matriz extracelular. Tres grupos destas moléculas, conocidas como "adhesinas", están relacionados con la enfermedad cadiovascular: integrinas, selectinas y superfamilia de inminoglobulinas. Intervienen en los fenómenos de activación y desifunción endotelial y se vinculan a la patogenia de la enfermedad coronaria, la injuria por reperfusión, el rechazo del corazón transplantado, la miocarditis, la miocardiopatía hipertrófica, etc. Se asocian también con el mecanismo de acción de las estatinas. El dosaje de los niveles séricos de las moléculas de adhesión tiene valor diagnóstico y predictivo de diversas enfermedades cardiovasculares. Esta revisión enfoca las variadas funciones de las adhesinas y se orienta sobre diversas posibilidades terapéuticas derivadas de su conocimiento.

Moléculas de adhesión. Su papel en la fisiopatología cardiovascular. / [Adhesion molecules. Their role in cardiovascular physiopathology]

Adhesion molecules are membrane receptors that mediate several functions related to cell traffic, cell-cell interactions, and cell-matrix contact. There are three important groups associated to cardiovascular disease: integrins, selectins, and the immunoglobulin superfamily. They are involved in the endothelial disfunction and activation processes, and are related to the pathogenesis of coronary artery disease, reperfusion injury, allograft vasculopathy, myocarditis, hypertrophic myocardiopathy, etc. Also, they are related to the mechanism of action of statins. Serologic titer of these molecules has diagnostic and predictive value on diverse cardiovascular diseases. This review focuses on the functions of adhesins and discusses various therapeutic possibilities based on their recognition.

Moleculas de adhesion: su papel en la fisiopatologia cardiovascular / Adhesion molecules: their role in cardiovascular physiopathology

Las moléculas de adhesión son receptores de menbrana que participan en diversas funciones vinculadas al tráfico celular, a las interacciones célula-célula y célula-matriz extracelular. Tres grupos destas moléculas, conocidas como "adhesinas", están relacionados con la enfermedad cadiovascular: integrinas, selectinas y superfamilia de inminoglobulinas. Intervienen en los fenómenos de activación y desifunción endotelial y se vinculan a la patogenia de la enfermedad coronaria, la injuria por reperfusión, el rechazo del corazón transplantado, la miocarditis, la miocardiopatía hipertrófica, etc. Se asocian también con el mecanismo de acción de las estatinas. El dosaje de los niveles séricos de las moléculas de adhesión tiene valor diagnóstico y predictivo de diversas enfermedades cardiovasculares. Esta revisión enfoca las variadas funciones de las adhesinas y se orienta sobre diversas posibilidades terapéuticas derivadas de su conocimiento. (AU)