Melatonin modulates metabolic adaptation of pancreatic stellate cells subjected to hypoxia

Melatonin Interplay in Physiology and Disease-The Fountain of Eternal Youth Revisited

Melatonin (N-acetyl-5-methoxytryptamine) is a hormone associated with the regulation of biological rhythms. The indoleamine is secreted by the pineal gland during the night, following a circadian rhythm. The highest plasmatic levels are reached during the night, whereas the lowest levels are achieved during the day. In addition to the pineal gland, other organs and tissues also produce melatonin, like, for example, the retina, Harderian glands, gut, ovaries, testes, skin, leukocytes, or bone marrow. The list of organs is extensive, including the cerebellum, airway epithelium, liver, kidney, adrenals, thymus, thyroid, pancreas, carotid body, placenta, and endometrium. At all these locations, the availability of melatonin is intended for local use. Interestingly, a decline of the circadian amplitude of the melatonin secretion occurs in old subjects in comparison to that found in younger subjects. Moreover, genetic and environmental factors are the primary causes of diseases, and oxidative stress is a key contributor to most pathologies. Numerous studies exist that show interesting effects of melatonin in different models of disease. Impairment in its secretion might have deleterious consequences for cellular physiology. In this regard, melatonin is a natural compound that is a carrier of a not yet completely known potential that deserves consideration. Thus, melatonin has emerged as a helpful ally that could be considered as a guard with powerful tools to orchestrate homeostasis in the body, majorly based on its antioxidant effects. In this review, we provide an overview of the widespread actions of melatonin against diseases preferentially affecting the elderly.

Melatonin in Chemo/Radiation Therapy; Implications for Normal Tissues Sparing and Tumor Suppression: An Updated Review

Resistance to therapy and the toxicity of normal tissue are the major problems for efficacy associated with chemotherapy and radiotherapy. Drug resistance is responsible for most cases of mortality associated with cancer. Furthermore, their side effects can decrease the quality of life for surviving patients. An enhancement in the tumor response to therapy and alleviation of toxic effects remain unsolved challenges. One of the interesting topics is the administration of agents with low toxicity to protect normal tissues and/or sensitize cancers to chemo/radiotherapy. Melatonin is a natural body hormone that is known as a multitasking molecule. Although it has antioxidant properties, a large number of experiments have uncovered interesting effects of melatonin that can increase the therapeutic efficacy of chemo/radiation therapy. Melatonin can enhance anticancer therapy efficacy through various mechanisms, cells such as the immune system, and modulation of cell cycle and death pathways, tumor suppressor genes, and also through suppression of some drug resistance mediators. However, melatonin may protect normal tissues through the suppression of inflammation, fibrosis, and massive oxidative stress in normal cells and tissues. In this review, we will discuss the distinct effects of melatonin on both tumors and normal tissues. We review how melatonin may enhance radio/chemosensitivity of tumors while protecting normal tissues such as the lung, heart, gastrointestinal system, reproductive system, brain, liver, and kidney.

Autophagy and the pancreas: Healthy and disease states

Macroautophagy/autophagy is an intracellular degradation pathway that has an important effect on both healthy and diseased pancreases. It protects the structure and function of the pancreas by maintaining organelle homeostasis and removing damaged organelles. A variety of pancreas-related diseases, such as diabetes, pancreatitis, and pancreatic cancer, are closely associated with autophagy. Genetic studies that address autophagy confirm this view. Loss of autophagy homeostasis (lack or overactivation) can lead to a series of adverse reactions, such as oxidative accumulation, increased inflammation, and cell death. There is growing evidence that stimulating or inhibiting autophagy is a potential therapeutic strategy for various pancreatic diseases. In this review, we discuss the multiple roles of autophagy in physiological and pathological conditions of the pancreas, including its role as a protective or pathogenic factor.

The mechanism of IL-13 targeting IL-13Rα2 in regulating oral mucosal FBs through PI3K/AKT/mTOR

OBJECTIVE

The objective of this investigation was to examine the presence of interleukin (IL)-13 and its receptor IL-13Rα2 in the tissues of oral submucous fibrosis (OSF), investigate their biological functions, and explore the underlying mechanisms involved in the development of OSF.

MATERIALS AND METHODS

The expression of IL-13 and IL-13Rα2 in the oral mucosa of patients with OSF and normal individuals was determined through immunohistochemistry and reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Primary fibroblasts (FBs) were extracted through enzymatic digestion and then cultured. Immunofluorescence was employed to identify the FB cultures and the location of IL-13Rα2. The effects of IL-13/IL-13Rα2/PI3K/AKT/mTOR on the migration, proliferation, and secretion of fiber-related proteins of FBs were explored via the wound healing assay, CCK-8 assay, EDU assay, and RT-qPCR. The impact of IL-13Rα2 silencing and PI3K/AKT inhibition on the effect of IL-13 on FBs was analyzed by RT-qPCR and Western blotting.

RESULTS

IL-13 and IL-13Rα2 were highly expressed in OSF. Primary FBs were successfully extracted and cultured. IL-13Rα2 was found to be localized in myofibroblasts. IL-13 promoted the proliferation, migration, and secretion of fibril-associated proteins in FBs. The proliferation, migration, and secretion of fibril-associated proteins of FBs were decreased following IL-13Rα2 silencing and inhibition of the PI3K/AKT/mTOR pathway.

CONCLUSION

IL-13 may promote the proliferation, migration, and secretion of fiber-related proteins of FBs through the PI3K/AKT/mTOR pathway by targeting IL-13Rα2.

Melatonin protects oogenesis from hypobaric hypoxia-induced fertility damage in mice

Environmental hypoxia adversely affects reproductive health in humans and animals at high altitudes. Therefore, how to alleviate the follicle development disorder caused by hypoxia exposure and to improve the competence of fertility in plateau non-habituated female animals are important problems to be solved urgently. In this study, a hypobaric hypoxic chamber was used for 4 weeks to simulate hypoxic conditions in female mice, and the effects of hypoxia on follicle development, proliferation and apoptosis of granulosa cells, reactive oxygen species (ROS) levels in MII oocyte and 2-cell rate were evaluated. At the same time, the alleviating effect of melatonin on hypoxic exposure-induced oogenesis damage was evaluated by feeding appropriate amounts of melatonin daily under hypoxia for 4 weeks. The results showed that hypoxia exposure significantly increased the proportion of antral follicles in the ovary, the number of proliferation and apoptosis granulosa cells in the follicle, and the level of ROS in MII oocytes, eventually led to the decline of oocyte quality. However, these defects were alleviated when melatonin was fed under hypoxia conditions. Together, these findings suggest that hypoxia exposure impaired follicular development and reduced oocyte quality, and that melatonin supplementation alleviated the fertility reduction induced by hypoxia exposure.