Drug-based therapeutic strategies for COVID-19-infected patients and their challenges

Emerging epidemic-prone diseases have introduced numerous health and economic challenges in recent years. Given current knowledge of COVID-19, herd immunity through vaccines alone is unlikely. In addition, vaccination of the global population is an ongoing challenge. Besides, the questions regarding the prevalence and the timing of immunization are still under investigation. Therefore, medical treatment remains essential in the management of COVID-19. Herein, recent advances from beginning observations of COVID-19 outbreak to an understanding of the essential factors contributing to the spread and transmission of COVID-19 and its treatment are reviewed. Furthermore, an in-depth discussion on the epidemiological aspects, clinical symptoms and most efficient medical treatment strategies to mitigate the mortality and spread rates of COVID-19 is presented

Aspects of Complement Activation in Thrombocytopenic Disorders

The complement system is an essential effector of both innate and acquired immune responses. Due to its destructive potential, tight regulation is required. The contribution of complement has been associated with the pathogeneses in a wide range of diseases. In this thesis, aspects of complement activation were investigated in disorders characterized by thrombocytopenia.In papers I and II, clinical characteristics, complement analyses, and genetic screening for rare variants encoding complement proteins were retrospectively investigated in a cohort suspected to suffer from atypical hemolytic uremic syndrome. In paper I, a population (n = 134) was identified whose phenotypes indicated the possibility of a diagnosis of complement-mediated atypical hemolytic uremic syndrome. In conclusion, laboratory complement analyses and clinical data were consistent with a possible underdiagnosis at the time of discharge. In paper II, recruited patients (n = 20) were subjected to follow-up investigations. Clinical outcomes and the phenotypical relevance of identified genetic variants were assessed. A diagnostic scheme compliant with the American College of Medical Genetics and Genomics guidelines was presented. In addition to identifying several previously described genetic variants, a novel likely disease-contributing missense variant in the complement factor H gene (c.3450A>G, p.I1150M) was identified. In conclusion, the study illustrated the risk of misdiagnosis and the importance of a comprehensive assessment to reach a diagnosis.In paper III, complement and platelet activation biomarkers were prospectively investigated in thrombocytopenic patients (n = 43) receiving prophylactic platelet transfusions during inpatient care in the hematological department. Neither complement nor platelet activation was shown to correlate with the corrected count increment. In conclusion, complement and platelet activation were not demonstrated contributing to a poor post-transfusion platelet response.In summary, this thesis has contributed to the growing knowledge of diseases potentially affected by complement activation

Longitudinal evaluation of post-COVID-19 conditions

Depuis l'émergence de la pandémie de SARS-CoV-2 en décembre 2019, plus de 675 millions de cas confirmés ont été signalés dans le monde, dont 4,6 millions de cas au Canada uniquement. Bien que la plupart des individus récupèrent sans séquelles, 10 à 20 % des survivants signalent des symptômes persistants au-delà de quatre semaines après une infection par le SARS-CoV-2, tels que la fatigue, les altérations cognitives, la toux, l'anxiété, la dépression, la douleur thoracique et autres, connus sous le nom de COVID longue ou de condition post-SARS-CoV-2 (PCC). Par conséquent, la physiopathologie, le diagnostic et la prise en charge de la PCC sont devenus un axe de recherche majeur. Pour contribuer à la compréhension de la PCC, nous avons mené le projet IPCO (Institut de Recherches cliniques de Montréal (IRCM) Post-COVID-19 Research Clinic), en posant comme hypothèses 1 que les personnes infectés par le SARS-CoV-2 au Québec présenteraient des signes et symptômes fréquents et variés post-phase aiguë, affectant différents systèmes d'organes, et 2 Les niveaux élevés de D-dimères dans PCC ne sont pas pertinents pour les événements thromboemboliques 3 que Chez les individus atteints de la PCC, la vaccination contre la COVID-19 réduirait les symptômes de la PCC en diminuant l'inflammation. Pour évaluer ces hypothèses, nous avons recruté des participants âgés de plus de 18 ans, un à 18 mois après l'infection aiguë, présentant au moins un symptôme persistant, et programmé des visites de base et de suivi à 3-6 mois, 1 an et 2 ans post-infection aiguë. Chaque visite comprenait des évaluations cliniques, des prélèvements, des évaluations en laboratoire, des questionnaires sur l'alimentation et le bien-être, ainsi que des évaluations de la physiologie pulmonaire et cardiaque. Sur la base d'une étude allemande qui a catégorisé les symptômes du PCC et les individuals en trois groupes de sévérité, nous avons classé nos participants en trois niveaux de sévérité : non/légère (score du PCC 26,25). Cette thèse présente les résultats de trois sous-études IPCO. Dans l'étude descriptive, nous avons observé que la fatigue, les problèmes de mémoire et les maux de tête étaient les symptômes de PCC les plus courants, la majorité de nos participants étant des femmes et ayant été traités en ambulatoire pendant la phase aiguë. Dans l'étude transversale, nous avons constaté des différences significatives dans les mesures de santé et de bien-être à tous les moments, mais aucune différence significative dans les résultats des tests physiologiques entre les groupes PCC non/léger, modéré et sévère. Dans l'étude longitudinale, les marqueurs de l'inflammation se sont améliorés au fil du temps, mais le taux métabolique basal et la masse grasse ont augmenté. Dans la deuxième étude, nous avons observé une forte prévalence de participants ayant des niveaux de D-dimères, qui n'étaient pas associés à des événements thromboemboliques, et aucune corrélation entre le niveau de D-dimères et les niveaux de cytokines et de chimiokines. Dans la troisième étude, nous avons observé que les participants vaccinés présentaient significativement moins de symptômes de PCC. Notre étude fournit une meilleure compréhension de la physiopathologie du PCC et de l'effet de la vaccination sur le profil clinique et inflammatoire du PCC, ce qui pourrait aider à la conception d'outils de gestion clinique et de recherche futurs.Since the emergence of the SARS-CoV-2 pandemic in December 2019, over 675 million confirmed cases have been reported globally, with 4.6 million cases in Canada alone. Although most individuals recover without residual disease, 10-20% of survivors report symptoms persisting beyond four weeks after SARS-CoV-2 infection, such as fatigue, cognitive impairments, cough, anxiety, depression, chest pain, and others known as long-COVID or post SARS-CoV-2 condition (PCC). Consequently, the pathophysiology, diagnosis, and management of PCC have become a significant focus of research. To contribute to the understanding of PCC, we conducted the IPCO (Institut de Recherches cliniques de Montréal (IRCM) Post-COVID-19 Research Clinic) project, hypothesizing that 1 SARS-CoV-2 infected individuals in Quebec would present frequent and varied signs and symptoms post-acute phase, affecting different organ systems, and that 2 high D-dimer level in PCC is irrelevant to thromboembolic events , and 3 in individuals with PCC, COVID-19 vaccination would decrease PCC symptoms by reducing inflammation. To evaluate these hypotheses, we enrolled participants aged >18 years, one to 18 months post-acute infection, with at least one persistent symptom, and scheduled baseline and follow-up visits at 3-6 months, 1 year, and 2 years post-acute infection. Each visit involved clinical evaluations, sampling, laboratory evaluations, diet and well-being questionnaires, and pulmonary and cardiac physiology evaluations. Based on a German study that categorized PCC symptoms and individuals into three severity groups, we classified our participants into three severity levels: non/mild (PCC score 26.25). This thesis reports the results of three IPCO studies. In the descriptive study, we observed that fatigue, memory problems, and headaches were the most common PCC symptoms, with the majority of our participants being female and managed as outpatients during the acute phase. In the cross-sectional study, we noted significant differences in health and well-being measurements at all time points, but no significant difference in physiological tests' results between different severity groups. In the longitudinal study, markers of inflammation improved over time, but the basal metabolic rate and body fat increased. In the second study, we observed a high prevalence of participants having D-dimer levels in blood, which were not associated with thromboembolic events, and no correlation between D-dimer levels and blood cytokine/ chemokine levels. In the third study, we observed that vaccinated participants had significantly fewer PCC symptoms, fewer organ systems affected, higher well-being scores, and lower blood cytokine/chemokine levels than the non-vaccinated group. We also observed correlations between certain cytokines/chemokines, as well as between clinical parameters and certain cytokines/chemokines. Our study provides a better understanding of the pathophysiology of PCC and effect of vaccination on the clinical and inflammatory profile of PCC, which could assist future research and clinical management tool design

Portal Hypertension

Portal hypertension is a clinical syndrome defined by a portal venous pressure gradient, exceeding 5 mm Hg. In this book the causes of its development and complications are described. Authors have presented personal experiences on conducting patients with various displays of portal hypertension. Moreover, the book presents modern data about molecular mechanisms of pathogenesis of portal hypertension in liver cirrhosis, the information about the original predictor of risk of bleeding from gastro-esophageal varices and new methods for their conservative treatment

Varicella zoster virus vasculopathy

Varicella zoster virus (VZV) associated vasculopathy has long been identified as a major risk factor for arterial ischaemic stroke (AIS) in both adults and children. The exact mechanisms of VZV-induced pathological vascular remodelling leading to AIS have however not been fully elucidated, thus hampering current therapeutic approaches for AIS prevention. Previous immunohistochemical analysis of the morphology and composition of the arterial wall, and the location of viral antigen in the adventitia of patients with early VZV cerebral vasculopathy suggested that human brain vascular adventitial fibroblasts (HBVAF) may be the point of VZV entry into the cerebral arterial wall. In this thesis, I explored the hypothesis that VZV exerts direct pathogenic effects affecting different cells of the vasculature that could result in occlusive cerebral vasculopathy. I showed that following infection in vitro, VZV promotes HBVAF transdifferentiation to myofibroblasts, with subsequent proliferation and migration as identified by induction of α-SMA and EdU expression, and scratch assay repair. RNAseq profile analysis of VZV-infected HBVAF revealed significant upregulation of a number of genes in the infected cells, highlighting pathways possibly underlying the morphological changes described. I also examined the interaction of VZV-infected HBVAF with endothelial cells, and showed activation and dysfunction in cultured endothelial cells induced by conditioned media from VZV-infected HBVAF. Further experiments revealed that VZV-infected HBVAF release proinflammatory cytokines and chemokines that could contribute to the pathogenesis of cerebral arteriopathy. Lastly, I explored whether some of these effects on endothelial cells could be mediated by microparticle (MP) release. MP are membrane vesicles that are released from cells upon activation or during apoptosis, and are key inflammatory and endothelial dysfunction mediators in several vascular diseases. I showed that MP derived from VZV infected HBVAF contain VZV particles as detected by flow cytometry, electron microscopy and mass spectrometry. These MP-VZV complexes could infect healthy HBVAF, and might suggest a completely novel mechanism of VZV infectivity with potential relevance to viral induced changes locally in the cerebral vasculature. In conclusion, these novel findings suggest that in the context of VZV related cerebral arteriopathy, HBVAF are important players for initiation and propagation of vascular inflammation and remodelling, and that MP act as key facilitators of cross talk an viral propagation between endothelial cells and neighbouring HBVAFs. These observations suggest an entirely novel mechanism of VZV vasculopathy that furthers our understanding of the pathogenesis of AIS

Genomics and metabonomics in severe alcoholic hepatitis

Severe alcoholic hepatitis is a florid presentation of alcohol-related liver disease and is associated with very high short-term mortality, in excess of 20% within 28 days. Severe alcoholic hepatitis occurs in a minority of patients who develop alcohol-related liver disease. A combination of genetic and environmental factors is likely to predispose to severe alcoholic hepatitis. To date the clinical phenotype has not been extensively examined in candidate gene studies and has been the subject of a single, small genome-wide association study. A genome-wide association study of severe alcoholic hepatitis identified two loci potentially associated with the risk of developing severe alcoholic hepatitis: i) A strong association with PNPLA3, a well-recognised risk locus for alcohol-related liver disease, and ii) a novel but weaker association with SLC38A4, an amino acid transporter. The primary genetic variant at each locus was evaluated to determine whether there was an influence on disease phenotype or outcome. The primary variant in PNPLA3, rs738409, is a missense variant. Analyses indicated a deleterious effect of homozygosity on medium-term survival in addition to more severe disease on baseline histology and a slower recovery in liver function over the short-term period; consistent with established literature in alcohol-related cirrhosis. In contrast the primary variant in SLC38A4, rs11183620, is intronic with no clear evidence for an effect on gene expression or function. Analyses did not indicate an influence on histology, clinical phenotypes or outcomes. In light of the locus’ novelty further work was undertaken to determine any potential contribution to disease pathogenesis. SLC38A4 was down-regulated in whole liver tissue in severe alcoholic hepatitis. Experiments with cell lines in culture suggested the pro-inflammatory cytokine IL-1 as a potential driver. SLC38A4 knockdown resulted in upregulation of some cellular responses associated with nutrient deprivation. There was no influence of the variant on serum amino acid profiles. The functional significance of SLC38A4 down-regulation remains the subject of ongoing work.Open Acces

The Genetics of Anti-Neutrophil Cytoplasmic Antibody Associated Vasculitis (AAV)

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a multi-systemic autoimmune disorder with evidence of circulating pathogenic ANCA. There are two main antigenic targets: proteinase 3 (PR3) and myeloperoxidase (MPO). Previous genome-wide association studies (GWAS) have provided evidence that PR3-AAV and MPO-AAV are genetically distinct autoimmune syndromes, though only three loci specific to PR3-AAV and one to MPO-AAV have been identified to date. With the European Vasculitis Genetics Consortium, we conducted a larger GWAS, powered to discover additional risk loci in both PR3-AAV and MPO-AAV independently. A meta-analysis of two European cohorts was conducted, comprising 1,610 PR3-AAV cases, 870 MPO-AAV cases and 11,947 controls. For PTPN22 (rs6679677), a further replication cohort, previously genotyped using the Sequenom MassARRAY platform, and comprising 1,122 PR3-AAV and 347 MPO-AAV cases and 1,531 controls was included in the combined analysis. This is the largest genome-wide association study of AAV to date and we have identified a total of 12 AAV susceptibility loci. Previously genome-wide significant loci were confirmed, including HLA class II, SERPINA1, PRTN3 and PTPN22. Seven new genome-wide significant loci were identified: three associated with PR3-AAV (BCL2L11-MIR4435-2HG, EBF3-MGMT, IGHV1-69), two with MPO-AAV (BACH2, ANKRD11-SPG7) and two shared by both (CTLA-4 and DGUOK-TET3). Further analyses based on common variants suggested that a substantial component of the genetic architecture was shared between PR3-AAV and MPO-AAV, similar to that observed between ulcerative colitis and Crohn’s disease. In addition, Mendelian randomisation analysis confirmed that a higher eosinophil count increased the risk of PR3-AAV but not MPO-AAV, and this effect might, in part, be modulated by MIR4435-2HG through prolongation of eosinophil survival. MIR4435-2HG encodes a long non-coding RNA that plays a critical role in the regulation of BCL2L11 transcription (a Bcl2 family member essential for controlling apoptosis) in myeloid cells and hence their lifespan. We have also identified a missense variant in IGHV1-69 (rs11845244) that leads to a loss in neutralising function of antibodies generated against the NEAT2 domain of Staphylococcus aureus. This therefore provides a plausible host genetic factor in determining the susceptibility to infectious disease and as a potential driver of PR3-AAV. Overall, this study provides key novel insights into disease biology for AAV and potential therapeutic targets.Wellcome Trust Clinical PhD Fellowshi