Toll-like receptors in pathogenesis of neurodegenerative diseases and their therapeutic potential.

Toll-like receptors (TLRs) are a family of pattern-recognition receptors triggered by pathogen-derived and tissue-damage-related ligands. TLRs were previously believed to only be expressed in immune cells. However, it is now confirmed that they are ubiquitously expressed in cells within the body including neurons, astrocytes, and microglia of the central nervous system (CNS). Activation of TLRs is capable of inducing immunologic and inflammatory responses to injury or infection of CNS. This response is self-limiting that usually resolves once the infection has been eradicated or the tissue damage has been repaired. However, the persistence of inflammation-inducing insults or a failure in normal resolution mechanisms may result in overwhelming inflammation which may induce neurodegeneration. This implies that TLRs may play a role in mediating the link between inflammation and neurodegenerative diseases namely Alzheimer's disease, Parkinson's disease, Huntington's disease, stroke, and amyotrophic lateral sclerosis. So, new therapeutic approaches that specifically target TLRs may be developed by better understanding TLR expression mechanisms in the CNS and their connections to particular neurodegenerative disorders. Therefore, this review paper discussed the role of TLRs in neurodegenerative diseases.

Changes in plasma levels of endocrine hormones in lepromatous leprosy patients.

Background: Leprosy affects various endocrine glands and causes disorders in internal organs in addition to the skin and peripheral nerves. These disorders are often silent and remain undiagnosed or underreported. In particular, patterns of hormone changes during leprosy, especially in lepromatous leprosy (LL) patients, are often associated with dysregulation of different endocrine and sex hormones. The aim of this study was to assess changes in four endocrine hormones - namely cortisol, dehydroepiandrosterone (DHEA), growth hormone (GH), and leptin - among LL patients compared with apparently healthy controls. Method: In total, 80 plasma samples were systematically retrieved from a biorepository at the Armauer Hansen Research Institute (AHRI), based on quality, adequacy of sample volume, and appropriateness of linked clinical and sociodemographic data. Forty of the samples were obtained from LL patients (cases) and the remaining 40 from apparently healthy controls. Enzyme-linked immunosorbant assay (ELISA) was used to quantify levels of DHEA, cortisol, GH, and leptin hormones in the plasma samples. Data were analyzed using non-parametric statistics and the Mann-Whitney U-test (GraphPad Prism version 7.01). A p-value < 0.05 was considered statistically significant. Results: Plasma levels of cortisol concentration were significantly higher in LL cases (median = 111.4 ng/ml, range = 20.54-525.7) compared with healthy controls (median = 51.98 ng/ml, range = 3.805-328.4) (p = 0.003). Levels of GH and leptin were significantly lower in LL cases compared with healthy controls (median values for GH = 1.01 µIU/ml, range = 0.4625-86.82 and 2 µIU/ml, range = 0.5838-63.36, respectively (p = 0.022); median values for leptin = 891 pg/ml, range = 728.4-21816 and 5147 pg/ml, range = 730.4-52747, respectively (p < 0.0001)). There was an apparent reduction in the plasma levels of DHEA among LL cases compared with healthy controls (p = 0.297), although this difference was not statistically significant. Conclusion: Alterations in levels of endocrine hormones seen in LL patients reflect clinical and immunological conditions during lepromatous leprosy. However, large-scale studies are warranted to determine how leprosy causes such alterations in hormones and the interplay between endocrine hormones and the immune system during leprosy disease.

Leptin Deficiency May Influence the Divergence of Cell-Mediated Immunity Between Lepromatous and Tuberculoid Leprosy Patients.

Leprosy is a disease caused by an intracellular bacillus bacterium called Mycobacterium leprae which lives and multiplies in the hosts' macrophages and Schwann cells. Depending on the degree of the host's cell-mediated immunity (CMI) response to the bacilli, the disease manifests itself in five clinical spectra ranging from polar tuberculoid (TT) to polar lepromatous leprosy (LL). A very high level of T helper 1 (Th1) driven bacilli-specific CMI is seen in the TT form, whereas this response is essentially nonexistent in the LL form. As a result, there is very low or absent bacillary load and localized nodular lesions in TT patients. On the contrary, LL patients presented with high bacillary load and generalized lesions due to low CMI response. The mechanism underlying this divergence of CMI response is not clearly elucidated yet. However, mounting evidence links it to an elevated number of Th1 and Th17 suppressing CD4+ CD25+ FOXP3+ T regulatory cells (Treg cells) which are abundantly found in LL than in TT patients. The predominance of these cells in LL patients is partly attributed to a deficiency of leptin, the cytokine-like peptide hormone, in these patients. Becausea normal level of leptin promotes the proliferation and preferential differentiation of effector T cells (Th1 and Th17) while inhibiting the growth and functional responsiveness of the Treg cells. In contrast, leptin deficiency or neutralization was reported to exert the opposite effect on Treg cells and effector T cells. Other smaller subsets of lymphocytes such as gamma delta (γδ) T cells and B regulatory cells are also modulated by leptin level in the pathogenesis of leprosy. Leptin may therefore regulate the divergence of CMI between TT and LL patients by regulating the homeostasis of effector T cells and Treg cells, and this review will examine the underlying mechanism for this.

Genome Editing and Human Pluripotent Stem Cell Technologies for in vitro Monogenic Diabetes Modeling.

Diabetes is a metabolic disease characterized by chronic hyperglycemia. Polygenic diabetes, which encompasses type-1 and type-2 diabetes, is the most prevalent kind of diabetes and is caused by a combination of different genetic and environmental factors, whereas rare phenotype monogenic diabetes is caused by a single gene mutation. Monogenic diabetes includes Neonatal diabetes mellitus and Maturity-onset diabetes of the young. The majority of our current knowledge about the pathogenesis of diabetes stems from studies done on animal models. However, the genetic difference between these creatures and humans makes it difficult to mimic human clinical pathophysiology, limiting their value in modeling key aspects of human disease. Human pluripotent stem cell technologies combined with genome editing techniques have been shown to be better alternatives for creating in vitro models that can provide crucial knowledge about disease etiology. This review paper addresses genome editing and human pluripotent stem cell technologies for in vitro monogenic diabetes modeling.

Targeting Metabolic Reprogramming of T-Cells for Enhanced Anti-Tumor Response.

Cancer immunotherapy is an effective treatment option against cancer. One of the approaches of cancer immunotherapy is the modification of T cell-based anti-tumor immune responses. T-cells, a type of adaptive immune response cells responsible for cell-mediated immunity, have long been recognized as key regulators of immune-mediated anti-tumor immunity. T-cell activities have been reported to be suppressed or enhanced by changes in cell metabolism. Moreover, metabolic reprogramming during activation of T cells is required for the development of distinct differentiation profiles of these cells, which may allow the development of long-term cell-mediated anti-tumor immunity. However, T cells have been shown to undergo metabolic exhaustion in tumor microenvironment (TME) as it poses several obstacles to their function. Applications of several mechanistic solutions to improve the efficacy of T cell-based therapies including chimeric antigen receptor (CAR) T cell therapy are yet to be determined. Modifying the metabolic properties of these cells and employing them in cancer immunotherapy is a potential strategy for improving their anti-tumor activity and therapeutic efficacy. To give an insight, in this review paper, we endeavoured to cover metabolic reprogramming in cancer and T cells, signalling mechanisms involved in immuno-metabolic regulation, the effects of the TME on T cell metabolic fitness, and targeting metabolic reprogramming of T cells for an enhanced anti-tumor response.