Transient Receptor Potential Ion Channels in the Etiology and Pathomechanism of Chronic Fatigue Syndrome/Myalgic Encephalomyelitis

Chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) is a disabling condition of unknown cause having multi-system manifestations. Our group has investigated the potential role of transient receptor potential (TRP) ion channels in the etiology and pathomechanism of this illness. Store-operated calcium entry (SOCE) signaling is the primary intracellular calcium signaling mechanism in non-excitable cells and is associated with TRP ion channels. While the sub-family (Canonical) TRPC has been traditionally associated with this important cellular mechanism, a member of the TRPM sub-family group (Melastatin), TRPM3, has also been recently identified as participating in SOCE in white matter of the central nervous system. We have identified single nucleotide polymorphisms (SNPs) in TRP genes in natural killer (NK) cells and peripheral blood mononuclear cells (PBMCs) in CFS/ME patients. We also describe biochemical pathway changes and calcium signaling perturbations in blood cells from patients. The ubiquitous distribution of TRP ion channels and specific locations of sub-family group members such as TRPM3 suggest a contribution to systemic pathology in CFS/ME.

Decreased Expression of TRPM3 and mAChRM3 in the Small Intestine in Chronic Fatigue Syndrome/Myalgic Encephalomyelitis

Introduction: Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (CFS/ME) is often associated with gastrointestinal disturbance and inflammatory markers;however, there have been no histological studies performed in the small intestine from CFS/ME patients. The aim of this investigation was to assess the expression of certain inflammatory markers and inflammatory receptors, namely transient receptor potential melastin 3 (TRPM3) ion channels and muscarinic acetylcholine M3 (mAChRM3) receptors, in small intestinal tissues in a case controlled study comprising a CFS/ME patient and a healthy non-fatigued control. Method: Immunohistochemistry was performed on a small intestinal biopsy from a CFS/ME patient (age = 50;female) with self-reported symptoms of gastrointestinal disturbance and a non-fatigued control (NFC), (age = 28;female). Semi-quantitative analysis of expression was undertaken for interferon-gamma (IFNy), interleukin-1 alpha (IL-1α), tumour necrosis factor-alpha (TNFα), TRPM3 ion channels and mAChRM3 acetylcholine receptors. Results: There was significantly decreased expression of TRPM3 in the CFS/ME patient (35% ±9%) and a significant decrease in mAChRM3 in the CFS/ME patient (54% ±9%). There was no difference in IL-1α between CFS/ME patient and NFC, however;there was an increase in IFNy (13% ±6%) in the CFS/ME patient compared to NFC. There was a difference observed in TNFα in CFS/ME compared to NFC. Conclusion: Differences were noted in the expression of specific TRP ion channels and cholinergic receptors in CFS/ME compared with NFC, with CFS/ME demonstrating decreased TRPM3 and mAChRM3. Further, IFNy was increased, and TNFα decreased, in the small intestine of the CFS/ME patient with reported gastrointestinal disturbance.

Transient Receptor Potential Melastatin 3 and Intracellular Calcium in Natural Killer Cells in Multiple Sclerosis

Background: Natural killer (NK) cell phenotypes have reported to be implicated in the pathomechanism of Multiple Sclerosis (MS). Several investigators have observed reduced peripheral numbers, reduced cytotoxic activity, and altered CD56Dim and CD56Bright NK cell phenotypes. This current project, for the first time, investigates the NK cell cytotoxicity, calcium mobilisation and transient receptor potential melastatin 3 (TRPM3) surface expression. Methods: NK cell cytotoxic activity and calcium signaling were examined in CD56Dim and CD56Bright NK cells before and after stimulation using Ionomycin, Pregnenolone sulphate, 2-Aminoethoxydiphenyl borate and Thapsigargin. Purified NK cells were labelled with antibodies to determine TRPM3, CD69 and CD107a surface expression using flow cytometry. Results: Twenty-two MS patients and 22 healthy controls were recruited for this project. Twelve of the 22 previously received Alemtuzumab (Lemtrada®) and the remaining ten reported nil medication. We report TRPM3 was significantly increased in untreated MS patients compared with healthy controls and treated MS patients (p-value 0.034). There was a significant decrease in CD69 surface expression on CD56Dim NK cell phenotype for untreated MS patients (p-value 0.031) and treated MS patients (p-value 0.036). We report altered calcium mobilisation in CD56Bright NK cells and to a lesser extent CD56Dim NK cells between healthy controls, treated and untreated MS patients. Conclusion: This investigation suggests variations in TRPM3 expression and calcium mobilisation of NK cells may be implicated in the pathogenesis of MS. Further investigation is required to determine the mechanism by which alemtuzumab alters calcium signaling in NK cells.