Leflunomide (LF) represents the prototype member of dihydroorotate dehydrogenase (DHODH) enzyme inhibitors. DHODH is a mitochondrial inner membrane enzyme responsible for catalytic conversion of dihydroorotate into orotate, a rate-limiting step in the de novo synthesis of the pyrimidine nucleotides. LF produces cellular depletion of pyrimidine nucleotides required for cell growth and proliferation. Based on the affected cells the outcome can be attainable as immunosuppression, antiproliferative, and/or the recently gained attention of the antiviral potentials of LF and its new congeners. Also, protein tyrosine kinase inhibition is an additional mechanistic benefit of LF, which inhibits immunological events such as cellular expansion and immunoglobulin production with an enhanced release of immunosuppressant cytokines. LF is approved for the treatment of autoimmune arthritis of rheumatoid and psoriatic pathogenesis. Also, LF has been used off-label for the treatment of relapsing-remitting multiple sclerosis. However, LF antiviral activity is repurposed and under investigation with related compounds under a phase-I trial as a SARS CoV-2 antiviral in cases with COVID-19. Despite success in improving patients' mobility and reducing joint destruction, reported events of LF-induced liver injury necessitated regulatory precautions. LF should not be used in patients with hepatic impairment or in combination with drugs elaborating a burden on the liver without regular monitoring of liver enzymes and serum bilirubin as safety biomarkers. This study aims to review the pharmacological and safety profile of LF with a focus on the LF-induced hepatic injury from the perspective of pathophysiology and possible protective agents.
Matched MeSH terms: Immunologic Factors/therapeutic use
The new coronavirus disease (COVID-19), caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), has recently put the world under stress, resulting in a global pandemic. Currently, there are no approved treatments or vaccines, and this severe respiratory illness has cost many lives. Despite the established antimicrobial and immune-boosting potency described for honey, to date there is still a lack of evidence about its potential role amid COVID-19 outbreak. Based on the previously explored antiviral effects and phytochemical components of honey, we review here evidence for its role as a potentially effective natural product against COVID-19. Although some bioactive compounds in honey have shown potential antiviral effects (i.e., methylglyoxal, chrysin, caffeic acid, galangin and hesperidinin) or enhancing antiviral immune responses (i.e., levan and ascorbic acid), the mechanisms of action for these compounds are still ambiguous. To the best of our knowledge, this is the first work exclusively summarizing all these bioactive compounds with their probable mechanisms of action as antiviral agents, specifically against SARS-CoV-2.
Matched MeSH terms: Immunologic Factors/therapeutic use
Flavokawain A is a chalcone that can be found in the kava-kava plant (Piper methsyticum) extract. The kava-kava plant has been reported to possess anti-cancer, anti-inflammatory and antinociceptive activities. The state of the immune system, and the inflammatory process play vital roles in the progression of cancer. The immunomodulatary effects and the anti-inflammatory effects of flavokawain A in a breast cancer murine model have not been studied yet. Thus, this study aimed to elucidate the basic mechanism as to how flavokawain A regulates and enhance the immune system as well as impeding the inflammatory process in breast cancer-challenged mice. Based on our study, it is interesting to note that flavokawain A increased the T cell population; both Th1 cells and CTLs, aside from the natural killer cells. The levels of IFN-γ and IL-2 were also elevated in the serum of flavokawain A-treated mice. Apart from that, flavokawain A also decreased the weight and volume of the tumor, and managed to induce apoptosis in them. In terms of inflammation, flavokawain A-treated mice had reduced level of major pro-inflammatory mediators; NO, iNOS, NF-KB, ICAM and COX-2. Overall, flavokawain A has the potential to not only enhance antitumor immunity, but also prevents the inflammatory process in a cancer-prone microenvironment.
A 28-year-old Malay man presented with progressive paraparesis over a period of 6 months. Magnetic resonance imaging of the spine revealed a thoracic intramedullary spinal cord tumor at the T-7 level with homogeneous enhancement following intravenous gadolinium administration. Laminectomy and partial decompression of the tumor was performed. Histological examination of the tumor revealed features of spindle cell hemangioendothelioma. The patient was managed with limited field radiotherapy followed by systemic interferon therapy. Good neurological improvement was seen subsequently. The patient has survived 48 months with growth restraint at the primary site, although residual neurological deficit persists. Immunotherapy should be considered as a treatment modality for intramedullary hemangioendothelioma of the spinal cord after surgery and radiotherapy.
Matched MeSH terms: Immunologic Factors/therapeutic use