Autophagy as a Target for Drug Development Of Skin Infection Caused by Mycobacteria.

Pathogenic mycobacteria species may subvert the innate immune mechanisms and can modulate the activation of cells that cause disease in the skin. Cutaneous mycobacterial infection may present different clinical presentations and it is associated with stigma, deformity, and disability. The understanding of the immunopathogenic mechanisms related to mycobacterial infection in human skin is of pivotal importance to identify targets for new therapeutic strategies. The occurrence of reactional episodes and relapse in leprosy patients, the emergence of resistant mycobacteria strains, and the absence of effective drugs to treat mycobacterial cutaneous infection increased the interest in the development of therapies based on repurposed drugs against mycobacteria. The mechanism of action of many of these therapies evaluated is linked to the activation of autophagy. Autophagy is an evolutionary conserved lysosomal degradation pathway that has been associated with the control of the mycobacterial bacillary load. Here, we review the role of autophagy in the pathogenesis of cutaneous mycobacterial infection and discuss the perspectives of autophagy as a target for drug development and repurposing against cutaneous mycobacterial infection.

In Vitro Anti-proliferative Activity and Mechanism of Action of Anemone nemorosa.

Anemone nemorosa is part of the Ranunculaceae genus Anemone (order Ranunculales) which comprises more than 150 species. Various parts of the plant have been used for the treatment of numerous medical conditions such as headaches, tertian agues, rheumatic gout, leprosy, lethargy, eye inflammation as well as malignant and corroding ulcers. The Anemone plants have been found to contain various medicinal compounds with anti-cancer, immunomodulatory, anti-inflammatory, anti-oxidant and anti-microbial activities. To date there has been no reported evidence of its use in the treatment of cancer. However, due to the reported abundance of saponins which usually exert anti-cancer activity via cell cycle arrest and the induction of apoptosis, we investigated the mode of cell death induced by an aqueous A. nemorosa extract by using HeLa cervical cancer cells. Cisplatin was used as a positive control. With a 50% inhibitory concentration (IC50) of 20.33 ± 2.480 µg/mL, treatment with A. nemorosa yielded a delay in the early mitosis phase of the cell cycle. Apoptosis was confirmed through fluorescent staining with annexin V-FITC. Apoptosis was more evident with A. nemorosa treatment compared to the positive control after 24 and 48 h. Tetramethylrhodamine ethyl ester staining showed a decrease in mitochondrial membrane potential at 24 and 48 h. The results obtained imply that A. nemorosa may have potential anti-proliferative properties.

A new clerodane furano diterpene glycoside from Tinospora cordifolia triggers autophagy and apoptosis in HCT-116 colon cancer cells.

ETHNOPHARMACOLOGICAL RELEVANCE: Tinospora cordifolia is a miraculous ayurvedic herb used in the treatment of innumerable diseases such as diabetes, gonorrhea, secondary syphilis, anaemia, rheumatoid arthritis, dermatological diseases, cancer, gout, jaundice, asthma, leprosy, in the treatment of bone fractures, liver & intestinal disorders, purifies the blood, gives new life to the whole body; (rejuvenating herb) and many more. Recent studies have revealed the anticancer potential of this plant but not much work has been done on the anticancer chemical constituents actually responsible for its amazing anticancer effects. This prompted us to investigate this plant further for new potent anticancer molecules. AIM OF THE STUDY: The present study was designed to isolate and identify new promising anticancer candidates from the aqueous alcoholic extract of T. cordifolia using bioassay-guided fractionation. MATERIALS AND METHODS: The structures of the isolated compounds were determined on the basis of spectroscopic data interpretation and that of new potent anticancer molecule, TC-2 was confirmed by a single-crystal X-ray crystallographic analysis of its corresponding acetate. The in vitro anti-cancer activity of TC-2 was evaluated by SRB assay and the autophagic activity was investigated by immunofluorescence microscopy. Annexin-V FITC and PI dual staining was applied for the detection of apoptosis. The studies on Mitochondrial Membrane potential and ROS (Reactive oxygen species) production were also done. RESULTS: Bioassay guided fractionation and purification of the aqueous alcoholic stem extract of Tinospora cordifolia led to the isolation of a new clerodane furano diterpene glycoside (TC-2) along with five known compounds i.e. cordifolioside A (ß-D-Glucopyranoside,4-(3-hydroxy-1-propenyl)- 2,6-dimethoxyphenyl 3-O-D-apio-ß-D-furanosyl) (TC-1), ß-Sitosterol(TC-3), 2ß,3ß:15,16-Diepoxy- 4α, 6ß-dihydroxy-13(16),14-clerodadiene-17,12:18,1-diolide (TC-4), ecdysterone(TC-5) and tinosporoside(TC-6). TC-2 emerged as a potential candidate for the treatment of colon cancer. CONCLUSION: The overall study on the bioassay guided isolation of T.cordifolia identified and isolated a new clerodane furano diterpenoid that exhibited anticancer activity via induction of mitochondria mediated apoptosis and autophagy in HCT116 cells. We have reported a promising future candidate for treating colon cancer.

Protective effect of dapsone on cognitive impairment induced by propofol involves hippocampal autophagy.

Post-operative cognitive dysfunction (POCD) is a commonly seen postoperative complication in elderly patients and its underlying mechanisms are still unclear. Autophagy, a degradation mechanism of cellular components, is required for cell survival and many physiological processes. Although propofol is one of the most commonly used intravenous anesthetics, investigations into its mechanisms and effects on cognition in aged rodents are relatively scarce. In this study, we evaluate the influence of propofol on learning and memory, and identify the potential role of hippocampal autophagy in propofol-induced cognitive alterations in aged rats. The results demonstrate that 4h propofol exposure significantly impaired cognitive performance through the inhibition of hippocampal autophagy. Diaminodiphenyl sulfone (dapsone, DDS), which was used as an anti-leprosy drug, has been found to have neuroprotective effects. We have previously demonstrated that DDS can improve surgical stress induced depression- and anxiety-like behavior. We therefore aimed to investigate the effects of DDS on propofol-induced cognitive dysfunction and associated hippocampal autophagy responses. Pretreatment with 5mg/kg or 10mg/kg body weight DDS significantly improved the behavioral disorder and upregulated the inhibited autophagic response in aged rats. Our exploration is the first to establish an in vivo link between central autophagy and cognitive dysfunction in aged hippocampus after propofol anesthesia and demonstrate that the prophylactic effect of DDS on the cognitive impairment induced by propofol involves autophagy. These findings may imply a potential novel target for the treatment in patients with propofol anesthesia-induced cognitive impairment.

Autophagy: A brief overview in perspective of dermatology.

Autophagy, literally meaning "self-eating," is an intracellular catabolic process of delivering cytosol and/or its specific content to the lysosomes for degradation.The resulting macromolecular constituents are recycled and utilized again by the cells. Basal level autophagy plays an important role in cellular homeostasis through the elimination of the old or damaged organelles, as well as aggregated intracellular proteins. Autophagy refers to sequestration of intact organelles along with a portion of cytosol, into a double-or multi-membrane structure known as phagophore, which elongates, and after closure, forms a vesicular structure known as the autophagosome. Subsequently, the mature autophagosome fuses with a lysosome, thereby forming a single membrane structure, an autolysosome. Autophagy plays a critical role in inflammation, autoimmunity and cellular differentiation. Skin serves as the first line of defense against a variety of environmental insults and autophagy is thought to be a form of an endogenous defense mechanism against such environmental derangements. Autophagy has been linked with keratinocyte differentiation and melanocyte survival, as well as with the pathogenesis of diverse skin disorders including systemic lupus erythematosus, systemic sclerosis, psoriasis, vitiligo, infectious skin diseases and cancer. Autophagy has been one of the most studied phenomena in cell biology and pathophysiology, and given its broad clinical implications, has become a major target for drug discovery. The last decade has seen a substantial upsurge in autophagy-related research and publications; still, the dermatology literature appears to be less initiated. Autophagy will probably change our understanding of dermatological disorders/medicines. Hence, a basic knowledge of autophagy is a prerequisite to understand the developments in the field of autophagy-related research.

mTOR independent regulation of macroautophagy by Leucine Rich Repeat Kinase 2 via Beclin-1.

Leucine rich repeat kinase 2 is a complex enzyme with both kinase and GTPase activities, closely linked to the pathogenesis of several human disorders including Parkinson's disease, Crohn's disease, leprosy and cancer. LRRK2 has been implicated in numerous cellular processes; however its physiological function remains unclear. Recent reports suggest that LRRK2 can act to regulate the cellular catabolic process of macroautophagy, although the precise mechanism whereby this occurs has not been identified. To investigate the signalling events through which LRRK2 acts to influence macroautophagy, the mammalian target of rapamycin (mTOR)/Unc-51-like kinase 1 (ULK1) and Beclin-1/phosphatidylinositol 3-kinase (PI3K) pathways were evaluated in astrocytic cell models in the presence and absence of LRRK2 kinase inhibitors. Chemical inhibition of LRRK2 kinase activity resulted in the stimulation of macroautophagy in a non-canonical fashion, independent of mTOR and ULK1, but dependent upon the activation of Beclin 1-containing class III PI3-kinase.