Kynurenine pathway in Parkinson's disease-An update.

Parkinson's disease (PD) is a complex multi-factorial neurodegenerative disorder where various altered metabolic pathways contribute to the progression of the disease. Tryptophan (TRP) is a major precursor in kynurenine pathway (KP) and it has been discussed in various in vitro studies that the metabolites quinolinic acid (QUIN) causes neurotoxicity and kynurenic acid (KYNA) acts as neuroprotectant respectively. More studies are also focused on the effects of other KP metabolites and its enzymes as it has an association with ageing and PD pathogenesis. Until now, very few studies have targeted the role of genetic mutations in abnormal KP metabolism in adverse conditions of PD. Therefore, the present review gives an updated research studies on KP in connection with PD. Moreover, the review emphasizes on the urge for the development of biomarkers and also this would be an initiative in generating an alternative therapeutic approach for PD.

The role of Interleukin-4 in COVID-19 associated male infertility - A hypothesis.

COVID-19 is a present-day complex pandemic infection with unpredictable levels of morbidity and mortality in various global populations. COVID-19 is associated with the different comorbidities with its change in biological function such as causing heart dysfunction via deregulating ACE-2 receptor, gastrointestinal risk via causing vomiting, diarrhea, and abdominal pain, chronic kidney disease via proteinuria and hematuria, diabetes mellitus, liver injury via increasing ALT, AST and bilirubin level, lung injury, CNS risk, ocular risk, and cancer risk. In this, we are focused on the COVID-19 connected with male infertility. Some of the studies show that the patients of COVID-19 are associated with impaired spermatogenesis. Impaired spermatogenesis via COVID-19 decreases the level of testosterone by disturbing cytokines such as TNF-α, IL-4, IL-6, and IL-12 and further, attenuates the sperm count. COVID-19 is causing inflammation via TNF-α and interferons. IL-4 plays an eminent role in the activation of the JAK-STAT pathway and leads to the disturbing pro-inflammatory cytokine as well as further cause's male infertility. Th2 activates the IL-4 through IgG and IgE and mediates apoptosis with the triggering of STAT signaling. The activated STAT signaling augments Batf/Irf4, and the Bach2/Batf pathway. On the other hand, SARS-CoV-2 is activating the level of Th2 cells. So, we hypothesized that the augmented Th2 cells would disturb the level of IL-4, JAK-STAT signaling, Batf/Irf4, and Bach2/Batf pathway. The disturbed IL-4 decreases the level of the ACE-2 with the inflammation. This further leads to male infertility in COVID-19 patients. So, in this hypothesis, we focused on the role of IL-4 in COVID-19 patients associated with male infertility via Th2 cells and JAK-STAT signaling.