Endothelial dysfunction and persistent inflammation in severe post-COVID-19 patients: implications for gas exchange.

BACKGROUND: Understanding the enduring respiratory consequences of severe COVID-19 is crucial for comprehensive patient care. This study aims to evaluate the impact of post-COVID conditions on respiratory sequelae of severe acute respiratory distress syndrome (ARDS). METHODS: We examined 88 survivors of COVID-19-associated severe ARDS six months post-intensive care unit (ICU) discharge. Assessments included clinical and functional evaluation as well as plasma biomarkers of endothelial dysfunction, inflammation, and viral response. Additionally, an in vitro model using human umbilical vein endothelial cells (HUVECs) explored the direct impact of post-COVID plasma on endothelial function. RESULTS: Post-COVID patients with impaired gas exchange demonstrated persistent endothelial inflammation marked by elevated ICAM-1, IL-8, CCL-2, and ET-1 plasma levels. Concurrently, systemic inflammation, evidenced by NLRP3 overexpression and elevated levels of IL-6, sCD40-L, and C-reactive protein, was associated with endothelial dysfunction biomarkers and increased in post-COVID patients with impaired gas exchange. T-cell activation, reflected in CD69 expression, and persistently elevated levels of interferon-ß (IFN-ß) further contributed to sustained inflammation. The in vitro model confirmed that patient plasma, with altered levels of sCD40-L and IFN-ß proteins, has the capacity to alter endothelial function. CONCLUSIONS: Six months post-ICU discharge, survivors of COVID-19-associated ARDS exhibited sustained elevation in endothelial dysfunction biomarkers, correlating with the severity of impaired gas exchange. NLRP3 inflammasome activity and persistent T-cell activation indicate on going inflammation contributing to persistent endothelial dysfunction, potentially intensified by sustained viral immune response.

Inflammasome activation mediated by oxidised low-density lipoprotein in patients with sleep apnoea and early subclinical atherosclerosis.

BACKGROUND: Atherosclerosis is a common comorbidity of obstructive sleep apnoea (OSA) patients, caused by the interaction of dyslipidaemia and systemic inflammation. The OSA pro-inflammatory response is mediated by NLRP3 inflammasome activation, which requires a priming signal mediated by intermittent hypoxia (IH) and an activation signal provided by soluble stimulus present in plasma. Our objectives were to study oxidised low-density lipoprotein (oxLDL) expression in OSA patients with or without early subclinical atherosclerosis (eSA) as well as its contribution to NLRP3 activation and tissue factor (TF) release. METHODS: We analysed oxLDL, key components of the NLRP3 inflammasome cascade and TF in plasma and monocytes from OSA patients and non-apnoeic subjects, with or without eSA as determined by increased carotid intima-media thickness without the appearance of atherosclerotic plaques. The oxLDL contribution to NLRP3 inflammasome activation was assessed using in vitro models. RESULTS: High levels of oxLDL were identified in plasma from OSA patients, particularly in those with eSA, as well as an overexpression of NLRP3 cascade components and TF. Furthermore, in vitro models showed that both oxLDL and plasma from OSA patients with eSA act synergistically with IH as a priming and activation signal of NLRP3 that enhances the inflammatory response, pyroptosis and TF release. CONCLUSIONS: OSA patients with eSA exhibit NLRP3 activation by IH and the presence of oxLDL capable of releasing TF, constituting a pathway for the interaction between dyslipidaemia and systemic inflammation in the development of atherosclerotic lesions.

Obstructive sleep apnoea is related to melanoma aggressiveness through paraspeckle protein-1 upregulation.

BACKGROUND: In patients with obstructive sleep apnoea (OSA), intermittent hypoxia induces overexpression of paraspeckle component (PSPC)1, a master modulator of transforming growth factor (TGF)-ß signalling, which promotes cell cancer progression through epithelial-mesenchymal transition (EMT) and acquisition of cancer stem cell (CSC)-like features. However, the persistence of intermittent hypoxia-induced effects on PSPC1, and their consequences in cancer patients are not known. To this effect, circulating PSPC1 levels were compared in patients with cutaneous melanoma with or without OSA, and their relationship with tumour aggressiveness along with the in vitro effects of soluble PSPC1 and intermittent hypoxia on melanoma cell aggressiveness mechanisms were assessed. METHODS: In 292 cutaneous melanoma patients, sleep studies and serum levels of PSPC1 and TGF-ß were evaluated. The effect of PSPC1 on expression of EMT and CSC transcription factors was assessed using melanoma cell lines with patient sera under both normoxia and intermittent hypoxia conditions. RESULTS: PSPC1 levels were higher in patients with moderate-severe OSA compared with mild OSA or non-OSA patients. Serum levels of PSPC1 were associated with several cutaneous melanoma clinical aggressiveness indicators. Both intermittent hypoxia exposures and serum from OSA patients upregulated TGF-ß expression and amplified the expression of transcription factors associated with EMT activation and acquisition of CSC characteristics. CONCLUSION: In cutaneous melanoma patients, OSA severity is associated with higher PSPC1 serum levels, which jointly with intermittent hypoxia would enhance the self-reprogramming capabilities of EMT and CSC feature acquisition of melanoma cells, promoting their intrinsic aggressiveness.

Inflammasome Activation: A Keystone of Proinflammatory Response in Obstructive Sleep Apnea.

Rationale: As the mechanism that links obstructive sleep apnea (OSA) with the regulation of inflammatory response is not well known, it is important to understand the inflammasome activation, mainly of NLRP3 (nucleotide-binding oligomerization domain-like receptor 3). Objectives: To assess the NLRP3 activity in patients with severe OSA and to identify its role in the systemic inflammatory response of patients with OSA. Methods: We analyzed the NLRP3 activity as well as key components of the inflammasome cascade, such as adaptor molecule apoptosis-associated speck-like protein, caspase-1, Gasdermin D, IL-1ß, IL-18, and tissue factor, in monocytes and plasma from patients with severe OSA and control subjects without sleep apnea. We explored the association of the different key markers with inflammatory comorbidities. Measurements and Main Results: Monocytes from patients with severe OSA presented higher NLRP3 activity than those from control subjects, which directly correlated with the apnea-hypopnea index and hypoxemic indices. NLRP3 overactivity triggered inflammatory cytokines (IL-1ß and IL-18) via caspase-1 and increased Gasdermin D, allowing for tissue factor to be released. In vitro models confirmed that monocytes increase NLRP3 signaling under intermittent hypoxia in a hypoxia-inducible factor-1α-dependent manner, and/or in combination with plasma from patients with OSA. Plasma concentrations of tissue factor were higher in patients with OSA with systemic inflammatory comorbidities than in those without them. Conclusions: In patients with severe OSA, NLRP3 activation might be a linking mechanism between intermittent hypoxia and other OSA-induced immediate changes with the development of systemic inflammatory response.

Medium-Term Disability and Long-Term Functional Impairment Persistence in Survivors of Severe COVID-19 ARDS: Clinical and Physiological Insights.

BACKGROUND: Although the medium- and long-term sequelae of survivor of acute respiratory distress syndrome (ARDS) of any cause have been documented, little is known about the way in which COVID-19-induced ARDS affects functional disability and exercise components. Our aims were to examine the medium-term disability in severe COVID-19-associated ARDS survivors, delineate pathophysiological changes contributing to their exercise intolerance, and explore its utility in predicting long-term functional impairment persistence. METHODS: We studied 108 consecutive subjects with severe COVID-19 ARDS who remained alive 6 months after intensive care unit (ICU) discharge. Lung morphology was assessed with chest non-contrast CT scans and CT angiography. Functional evaluation included spirometry, plethysmography, muscle strength, and diffusion capacity, with assessment of gas exchange components through diffusing capacity of nitric oxide. Disability was assessed through an incremental exercise test, and measurements were repeated 12 and 24 months later in patients with functional impairments. RESULTS: At 6 months after ICU discharge, a notable dissociation between morphological and clinical-functional sequelae was identified. Moderate-severe disability was present in 47% of patients and these subjects had greater limitation of ventilatory mechanics and gas exchange, as well as greater symptomatic perception during exercise and a probable associated cardiac limitation. Female sex, hypothyroidism, reduced membrane diffusion component, lower functional residual capacity, and high-attenuation lung volume were independently associated with the presence of moderate-severe functional disability, which in turn was related to higher frequency and greater intensity of dyspnea and worse quality of life. Out of the 71 patients with reduced lung volumes or diffusion capacity at 6 months post-ICU discharge, only 19 maintained a restrictive disorder associated with gas exchange impairment at 24 months post-discharge. In these patients, 6-month values for diffusion membrane component, maximal oxygen uptake, ventilatory equivalent for CO2, and dead space to tidal volume ratio were identified as independent risk factors for persistence of long-term functional sequelae. CONCLUSIONS: Less than half of survivors of COVID-19 ARDS have moderate-severe disability in the medium term, identifying several risk factors. In turn, diffusion membrane component and exercise tolerance at 6-month ICU discharge are independently associated with the persistence of long-term functional sequelae.

NLRP3 Inflammasome Overactivation in Patients with Aneurysmal Subarachnoid Hemorrhage.

Aneurysmal subarachnoid hemorrhage (aSAH) is an uncommon and severe subtype of stroke leading to the loss of many years of productive life. We analyzed NLRP3 activity as well as key components of the inflammasome cascade in monocytes and plasma from 28 patients with aSAH and 14 normal controls using flow cytometry, western blot, ELISA, and qPCR technologies. Our data reveal that monocytes from patients with aSAH present an overactivation of the NLRP3 inflammasome, which results in the presence of high plasma levels of interleukin (IL)-1ß, IL-18, gasdermin D, and tissue factor. Although further research is needed, we propose that serum tissue factor concentration might be a useful prognosis biomarker for clinical outcome, and for Tako-Tsubo cardiomyopathy and cerebral vasospasm prediction. Remarkably, MCC-950 inhibitor effectively blocks NLRP3 activation in aSAH monocyte culture and supresses tissue factor release to the extracellular space. Finally, our findings suggest that NLRP3 activation could be due to the release of erythrocyte breakdown products to the subarachnoid space during aSAH event. These data define NLRP3 activation in monocytes from aSAH patients, indicating systemic inflammation that results in serum TF upregulation which in turns correlates with aSAH severity and might serve as a prognosis biomarker for aSAH clinical outcome and for cerebral vasospasm and Tako-Tsubo cardiomyopathy prediction.

Upregulated Proteasome Subunits in COVID-19 Patients: A Link with Hypoxemia, Lymphopenia and Inflammation.

Severe COVID-19 disease leads to hypoxemia, inflammation and lymphopenia. Viral infection induces cellular stress and causes the activation of the innate immune response. The ubiquitin-proteasome system (UPS) is highly implicated in viral immune response regulation. The main function of the proteasome is protein degradation in its active form, which recognises and binds to ubiquitylated proteins. Some proteasome subunits have been reported to be upregulated under hypoxic and hyperinflammatory conditions. Here, we conducted a prospective cohort study of COVID-19 patients (n = 44) and age-and sex-matched controls (n = 20). In this study, we suggested that hypoxia could induce the overexpression of certain genes encoding for subunits from the α and ß core of the 20S proteasome and from regulatory particles (19S and 11S) in COVID-19 patients. Furthermore, the gene expression of proteasome subunits was associated with lymphocyte count reduction and positively correlated with inflammatory molecular and clinical markers. Given the importance of the proteasome in maintaining cellular homeostasis, including the regulation of the apoptotic and pyroptotic pathways, these results provide a potential link between COVID-19 complications and proteasome gene expression.

Impaired Kallikrein-Kinin System in COVID-19 Patients' Severity.

COVID-19 has emerged as a devastating disease in the last 2 years. Many authors appointed to the importance of kallikrein-kinin system (KKS) in COVID-19 pathophysiology as it is involved in inflammation, vascular homeostasis, and coagulation. We aim to study the bradykinin cascade and its involvement in severity of patients with COVID-19. This is an observational cohort study involving 63 consecutive patients with severe COVID-19 pneumonia and 27 healthy subjects as control group. Clinical laboratory findings and plasma protein concentration of KKS peptides [bradykinin (BK), BK1-8], KKS proteins [high-molecular weight kininogen (HK)], and KKS enzymes [carboxypeptidase N subunit 1 (CPN1), kallikrein B1 (KLKB1), angiotensin converting enzyme 2 (ACE2), and C1 esterase inhibitor (C1INH)] were analyzed. We detected dysregulated KKS in patients with COVID-19, characterized by an accumulation of BK1-8 in combination with decreased levels of BK. Accumulated BK1-8 was related to severity of patients with COVID-19. A multivariate logistic regression model retained BK1-8, BK, and D-dimer as independent predictor factors to intensive care unit (ICU) admission. A Youden's optimal cutoff value of -0.352 was found for the multivariate model score with an accuracy of 92.9%. Multivariate model score-high group presented an odds ratio for ICU admission of 260.0. BK1-8 was related to inflammation, coagulation, and lymphopenia. Our data suggest that BK1-8/BK plasma concentration in combination with D-dimer levels might be retained as independent predictors for ICU admission in patients with COVID-19. Moreover, we reported KKS dysregulation in patients with COVID-19, which was related to disease severity by means of inflammation, hypercoagulation, and lymphopenia.

Role of CD39 in COVID-19 Severity: Dysregulation of Purinergic Signaling and Thromboinflammation.

CD39/NTPDase1 has emerged as an important molecule that contributes to maintain inflammatory and coagulatory homeostasis. Various studies have hypothesized the possible role of CD39 in COVID-19 pathophysiology since no confirmatory data shed light in this regard. Therefore, we aimed to quantify CD39 expression on COVID-19 patients exploring its association with severity clinical parameters and ICU admission, while unraveling the role of purinergic signaling on thromboinflammation in COVID-19 patients. We selected a prospective cohort of patients hospitalized due to severe COVID-19 pneumonia (n=75), a historical cohort of Influenza A pneumonia patients (n=18) and sex/age-matched healthy controls (n=30). CD39 was overexpressed in COVID-19 patients' plasma and immune cell subsets and related to hypoxemia. Plasma soluble form of CD39 (sCD39) was related to length of hospital stay and independently associated with intensive care unit admission (adjusted odds ratio 1.04, 95%CI 1.0-1.08, p=0.038), with a net reclassification index of 0.229 (0.118-0.287; p=0.036). COVID-19 patients showed extracellular accumulation of adenosine nucleotides (ATP and ADP), resulting in systemic inflammation and pro-coagulant state, as a consequence of purinergic pathway dysregulation. Interestingly, we found that COVID-19 plasma caused platelet activation, which was successfully blocked by the P2Y12 receptor inhibitor, ticagrelor. Therefore, sCD39 is suggested as a promising biomarker for COVID-19 severity. As a conclusion, our study indicates that CD39 overexpression in COVID-19 patients could be indicating purinergic signaling dysregulation, which might be at the basis of COVID-19 thromboinflammation disorder.

Intermittent Hypoxia Mediates Paraspeckle Protein-1 Upregulation in Sleep Apnea.

As some evidence suggests that hypoxia might be an inducer of nuclear paraspeckle formation, we explore whether intermittent hypoxia (IH)-mediated paraspeckle protein-1 (PSPC1) overexpression might contribute to the activation of tumor growth factor (TGF)ß-SMAD pathway in patients with obstructive sleep apnea (OSA). This activation would promote changes in intracellular signaling that would explain the increased cancer aggressiveness reported in these patients. Here, we show that patients with OSA exhibit elevated PSPC1 levels both in plasma and in monocytes. Our data suggest that PSPC1 is ultimately delivered to the plasma through its cleavage from OSA monocytes by matrix metalloproteinase-2 (MMP2). In addition, IH promotes PSPC1, TGFß, and MMP2 expression in monocytes through the hypoxia-inducible factor. Lastly, both PSPC1 and TGFß induce increased expression of genes that drive the epithelial-to-mesenchymal transition. Our study details the mechanism by which hypoxemia upmodulates the extracellular release of PSPC1 by means of MMP2, such that plasma PSPC1 together with TGFß activation signaling further promotes tumor metastasis and supports cancer aggressiveness in patients with OSA.

SMAD4 Overexpression in Patients with Sleep Apnoea May Be Associated with Cardiometabolic Comorbidities.

Obstructive sleep apnoea (OSA) is associated with several diseases related to metabolic and cardiovascular risk. Although the mechanisms involved in the development of these disorders may vary, OSA patients frequently present an increase in transforming growth factor beta (TGFß), the activity of which is higher still in patients with hypertension, diabetes or cardiovascular morbidity. Smad4 is a member of the small mother against decapentaplegic homologue (Smad) family of signal transducers and acts as a central mediator of TGFß signalling pathways. In this study, we evaluate Smad4 protein and mRNA expression from 52 newly diagnosed OSA patients, with an apnoea-hypopnoea index (AHI) ≥30 and 26 healthy volunteers. These analyses reveal that OSA patients exhibit high levels of SMAD4 which correlates with variation in HIF1α, mTOR and circadian genes. Moreover, we associated high concentrations of Smad4 plasma protein with the presence of diabetes, dyslipidaemia and hypertension in these patients. Results suggest that increased levels of SMAD4, mediated by intermittent hypoxaemia and circadian rhythm deregulation, may be associated with cardiometabolic comorbidities in patients with sleep apnoea.