Expression and function of osteopontin variants in HCV-related liver disease and hepatocellular carcinoma.

Osteopontin (OPN) is a highly secreted multi-functional sialoprotein that is widely expressed in tissues, blood and urine. It is involved in a number of normal physiological functions, but is also significantly elevated in a number of cancers. While OPN is significantly expressed in hepatocellular carcinoma (HCC) little is known as to its role and if it is expressed in the pre-cancerous hepatitis C virus (HCV) infected liver. In this thesis we show that OPN is expressed in the liver and in HCC as three variants, the full-length protein OPN-A and two splice variants OPN-B and OPN-C. Through production of stable Huh-7 cells expressing the OPN variants, we show for the first time that all variants increase proliferation of a range of cultured hepatoma cell lines in a paracrine manner through interactions with the cell surface OPN receptor CD44. Similarly, OPN-A (and to a lesser extent OPN-B and –C) accelerated Huh-7 derived tumor growth in a nude mouse model. We also show for the first time expression of all three OPN variants in the non-diseased liver as it was previously thought that splicing was a feature specific for tumor cells. Clinically, OPN is known to be highly expressed in HCC, however, its expression in chronic hepatitis C is not well documented. In this thesis we show that OPN mRNA expression is elevated in the HCV-infected liver with a trend towards increased expression as liver disease progresses. Consistent with an increase in mRNA, serum OPN levels were also increased in the HCV-infected liver although we could find no correlation with degree of liver disease. However, our sample size was small and this section of the thesis needs repeating with a larger HCV-infected patient cohort. Furthermore, we show that elevated OPN expression is not specific to the HCV-infected liver as OPN is also elevated in the HBV-infected and alcoholic liver suggesting that HCV does not drive OPN expression but is more likely as a result of the inflammatory process in the viral infected liver. Interestingly we also show that there is a shift of OPN expression from bile duct epithelial cells in the non-diseased liver to the hepatocyte in the HCV-infected liver which raises the question as to the role of OPN in hepatocyte transformation to facilitate the development of HCC. Our evaluation of serum OPN expression also suggests that OPN has potential as both a diagnostic and potentially prognostic biomarker for not only HCC (arising from HBV and HCV infections and alcohol abuse) but also the earlier stages of HCV-related liver disease. This work for the first time characterises the expression of all OPN variants in the liver including HCC and may be useful for identifying targeted OPN-based therapeutic approaches for HCC and other cancers. Furthermore it also suggests that monitoring OPN in chronic hepatitis C may be useful in monitoring liver disease progression and early detection of HCC.Thesis (Ph.D.) -- University of Adelaide, School of Molecular and Biomedical Science, 201

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Effect of Antiplatelet Therapy on Survival and Organ Support–Free Days in Critically Ill Patients With COVID-19

International audienc