Possible mechanistic insights into iron homeostasis role of the action of 4-aminoquinolines (chloroquine/hydroxychloroquine) on COVID-19 (SARS-CoV-2) infection.

OBJECTIVE: With the recent direction in drug repurposing, many approved drugs have been evaluated to assess their effect on the coronavirus or SARS-CoV-2 infection (COVID-19). Driving this path, chloroquine (CQ) has been used in the treatment of malaria and hydroxychloroquine (HCQ) in immunomodulatory and anti-thrombotic action, playing a leading role in initial management of the viral infection. MATERIALS AND METHODS: Literature search was done using Google Scholar, PubMed and Scopus database using keywords "chloroquine" "SARS-CoV-2" "COVID-19" "mechanism of action" and articles of interest were selected providing evidence of the possible role of CQ in viral infection. RESULTS: In a bid to understand how and if CQ and HCQ would exert their anti-viral property, mechanistic exegesis was done to review various proposed mechanisms of action. This revealed the inhibition of viral attachment and entry, inhibition of enveloped glycoprotein, inhibition of the development and proliferation of new viral particles as the way they perform their action. There is an interplay between iron metabolism and homeostasis with COVID-19 infection and viral reproduction. CONCLUSIONS: This study aims to show the functional role of CQ and HCQ, as well as to provide possible mechanistic insight on the role of iron on viral infection, iron starvation and its downstream cellular pathways involving hepcidin and proinflammatory cytokines. The overall aim of providing possible mode of action of CQ and HCQ in the management of COVID-19 infection is exhibited via its anti-viral, anti-inflammatory and anti-thrombotic activities.

Multiple myeloma: the bone marrow microenvironment and its relation to treatment.

Multiple myeloma is the most common haematological malignancy yet currently it remains incurable. For decades the mainstay in therapy has been non-targeted approaches including genotoxic agents and immunosuppressants. With myeloma predominantly affecting an elderly population, who are vulnerable to aggressive therapy, these non-specific approaches have resulted in poor survival. However, in recent years an explosion of collaborative research into myeloma has identified molecular interactions between myeloma cells and the bone marrow microenvironment as promoting myeloma development and associated complications such as bone lesions due to osteolysis. At the same time, a better understanding of the adhesion molecules, cytokines and signalling pathways involved in myeloma has led to the development of new targeted therapies, which are improving the quality of life for patients and significantly extending median patient survival. This review explores the current understanding of molecular pathways that promote myeloma progression and lead to bone destruction, with particular reference to the influence of interactions with the bone marrow microenvironment. It describes molecular targets for therapy with reference to the new therapeutics and their improved efficacy. While the outlook for myeloma patients has improved in recent years as a result of these new approaches, drug resistance remains a problem and future therapies will also need to address the molecular mechanisms of resistance in order to improve further the outcome for patients with this disease.