Serum SUR1 and TRPM4 in patients with subarachnoid hemorrhage.

Neuroinflammation plays an important role in neuronal injury after aneurysmal subarachnoid hemorrhage (aSAH). Sulfonylurea receptor 1 (SUR1) and transient receptor potential cation channel subfamily M member 4 (TRPM4) receptors play an important role in the pathogenesis of several neural injuries, such as neural edema, spinal cord damage, stroke, and neuronal damage in aSAH. This study aimed to investigate the relationship of serum SUR1 and TRPM4 levels with the neurological status within the first 15 days after aSAH. In this prospective study, blood samples were collected from 44 consecutive patients on the 1st, 4th, and 14th days after aSAH. Serum SUR1 and TRPM4 levels were measured using an enzyme-linked immunosorbent assay kit. Glasgow coma scale and World Federation of Neurosurgical Societies (WFNS) scores upon presentation and Glasgow outcome scale (GOS) score on the 14th day were recorded. Serum SUR1 and TRPM4 levels on the 1st, 4th, and 14th days were significantly higher in patients with aSAH than in normal individuals. This increase in the levels varied among the 1st, 4th, and 14th days. On the first day, a correlation was observed between serum SUR1, but not TRPM4, levels and the WFNS score. Moreover, on the 14th day, an association of serum SUR1 and TRPM4 levels with the GOS score was noted. Serum SUR1 and TRPM4 levels were significantly upregulated in the peripheral blood samples. Further study is warranted to establish the utility of SUR1 and TRPM4 as biomarkers in patients with aSAH.

Transient receptor potential melastatin 2 channels are overexpressed in myalgic encephalomyelitis/chronic fatigue syndrome patients.

BACKGROUND: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is hallmarked by a significant reduction in natural killer (NK) cell cytotoxicity, a mechanism tightly regulated by calcium (Ca2+). Interestingly, interleukin-2 (IL-2) increases NK cell cytotoxicity. Transient receptor potential melastatin 2 (TRPM2) ion channels are fundamental for Ca2+ signalling in NK cells. This pilot investigation aimed to characterise TRPM2 and CD38 surface expression in vitro on NK cells in ME/CFS patients. This investigation furthermore examined the pharmaceutical effect of 8-bromoadenosine phosphoribose (8-Br-ADPR) and N6-Benzoyladenosine-3',5'-cyclic monophosphate (N6-Bnz-cAMP) on TRPM2 and CD38 surface expression and NK cell cytotoxicity between ME/CFS and healthy control (HC) participants. METHODS: Ten ME/CFS patients (43.45 ± 12.36) and 10 HCs (43 ± 12.27) were age and sex-matched. Isolated NK cells were labelled with fluorescent antibodies to determine baseline and drug-treated TRPM2 and CD38 surface expression on NK cell subsets. Following IL-2 stimulation, NK cell cytotoxicity was measured following 8-Br-ADPR and N6-Bnz-cAMP drug treatments by flow cytometry. RESULTS: Baseline TRPM2 and CD38 surface expression was significantly higher on NK cell subsets in ME/CFS patients compared with HCs. Post IL-2 stimulation, TRPM2 and CD38 surface expression solely decreased on the CD56DimCD16+ subset. 8-Br-ADPR treatment significantly reduced TRPM2 surface expression on the CD56BrightCD16Dim/- subset within the ME/CFS group. Baseline cell cytotoxicity was significantly reduced in ME/CFS patients, however no changes were observed post drug treatment in either group. CONCLUSION: Overexpression of TRPM2 on NK cells may function as a compensatory mechanism to alert a dysregulation in Ca2+ homeostasis to enhance NK cell function in ME/CFS, such as NK cell cytotoxicity. As no improvement in NK cell cytotoxicity was observed within the ME/CFS group, an impairment in the TRPM2 ion channel may be present in ME/CFS patients, resulting in alterations in [Ca2+]i mobilisation and influx, which is fundamental in driving NK cell cytotoxicity. Differential expression of TRPM2 between NK cell subtypes may provide evidence for their role in the pathomechanism involving NK cell cytotoxicity activity in ME/CFS.

TRP Channels Expression Profile in Human End-Stage Heart Failure.

Objectives: Many studies indicate the involvement of transient receptor potential (TRP) channels in the development of heart hypertrophy. However, the data is often conflicted and has originated in animal models. Here, we provide systematic analysis of TRP channels expression in human failing myocardium. Methods and results: Left-ventricular tissue samples were isolated from explanted hearts of NYHA III-IV patients undergoing heart transplants (n = 43). Quantitative real-time PCR was performed to assess the mRNA levels of TRPC, TRPM and TRPV channels. Analysis of functional, clinical and biochemical data was used to confirm an end-stage heart failure diagnosis. Compared to myocardium samples from healthy donor hearts (n = 5), we detected a distinct increase in the expression of TRPC1, TRPC5, TRPM4 and TRPM7, and decreased expression of TRPC4 and TRPV2. These changes were not dependent on gender, clinical or biochemical parameters, nor functional parameters of the heart. We detected, however, a significant correlation of TRPC1 and MEF2c expression. Conclusions: The end-stage heart failure displays distinct expressional changes of TRP channels. Our findings provide a systematic description of TRP channel expression in human heart failure. The results highlight the complex interplay between TRP channels and the need for deeper analysis of early stages of hypertrophy and heart failure development.

The expression of TRPM7 in serum of patients with sepsis, its influences on inflammatory factors and prognosis, and its diagnostic value.

OBJECTIVE: This study aimed to investigate the expression of TRPM7 in the serum of patients with sepsis and its influences on inflammatory factors and prognosis. PATIENTS AND METHODS: A prospective analysis was performed. 78 patients with sepsis were enrolled in the experimental group and treated from May 2015 to April 2017 in the Emergency Department of The Second Hospital of Dalian Medical University, and 75 healthy people were collected in the control group and received physical examinations during the same period. Real-time quantitative PCR was used to detect the relative expression of TRPM7, and sandwich enzyme-linked immunosorbent assay (ELISA) was applied to measure the serum expression levels of TNF-α, IL-6, and IL-10 in patients. Besides, the receiver operating characteristic (ROC) curve was drawn to analyze the diagnostic value of TRPM7. RESULTS: The serum level of TRPM7 mRNA in the experimental group was higher than that in the control group (p<0.05). The serum levels of TNF-α, IL-6, and IL-10 in the experimental group were significantly higher than those in the control group (p<0.05). The optimal cut-off point value for the diagnosis of sepsis was 0.841; the specificity was 86%, and the sensitivity was 99%. Based on the survival data of the experimental group and the average expression level of TRPM7 which was 1.38, patients with a TRPM7 expression level less than 1.38 were divided into the low expression group, while those with a TRPM7 expression level equal or more than 1.38 were divided into the high expression group. The survival rate of the high expression group was significantly lower than that of the low expression group (p<0.05). CONCLUSIONS: In summary, TRPM7, with high expression level in the serum of patients with sepsis is expected to be a potential prognostic indicator for sepsis.

Aberrant Deactivation-Induced Gain of Function in TRPM4 Mutant Is Associated with Human Cardiac Conduction Block.

A gain-of-function mutation in the Ca2+-activated transient receptor potential melastatin member 4 (TRPM4A432T) is linked to life-threatening cardiac conduction disturbance, but the underlying mechanism is unclear. For deeper insights, we used photolysis of caged Ca2+, quantitative Ca2+, and electrophysiological measurements. TRPM4A432T's 2-fold larger membrane current was associated with 50% decreased plasma membrane expression. Kinetic analysis unveiled 4-fold slower deactivation that was responsible for the augmented membrane current progressively rising during repetitive human cardiac action potentials. Rational mutagenesis of TRPM4 at position 432 revealed that the bulkiness of the amino acid was key to TRPM4A432T's aberrant gating. Charged amino acids rendered the channel non-functional. The slow deactivation caused by an amino acid substitution at position 432 from alanine to the bulkier threonine represents a key contributor to the gain of function in TRPM4A432T. Thus, our results add a mechanism in the etiology of TRP channel-linked human cardiac channelopathies.

TRPM7 Kinase Controls Calcium Responses in Arterial Thrombosis and Stroke in Mice.

OBJECTIVE: TRPM7 (transient receptor potential cation channel, subfamily M, member 7) is a ubiquitously expressed bifunctional protein comprising a transient receptor potential channel segment linked to a cytosolic α-type serine/threonine protein kinase domain. TRPM7 forms a constitutively active Mg2+ and Ca2+ permeable channel, which regulates diverse cellular processes in both healthy and diseased conditions, but the physiological role of TRPM7 kinase remains largely unknown. APPROACH AND RESULTS: Here we show that point mutation in TRPM7 kinase domain deleting the kinase activity in mice (Trpm7R/R ) causes a marked signaling defect in platelets. Trpm7R/R platelets showed an impaired PIP2 (phosphatidylinositol-4,5-bisphosphate) metabolism and consequently reduced Ca2+ mobilization in response to stimulation of the major platelet receptors GPVI (glycoprotein VI), CLEC-2 (C-type lectin-like receptor), and PAR (protease-activated receptor). Altered phosphorylation of Syk (spleen tyrosine kinase) and phospholipase C γ2 and ß3 accounted for these global platelet activation defects. In addition, direct activation of STIM1 (stromal interaction molecule 1) with thapsigargin revealed a defective store-operated Ca2+ entry mechanism in the mutant platelets. These defects translated into an impaired platelet aggregate formation under flow and protection of the mice from arterial thrombosis and ischemic stroke in vivo. CONCLUSIONS: Our results identify TRPM7 kinase as a key modulator of phospholipase C signaling and store-operated Ca2+ entry in platelets. The protection of Trpm7R/R mice from acute ischemic disease without developing intracranial hemorrhage indicates that TRPM7 kinase might be a promising antithrombotic target.

TRPM4 mRNA expression levels in peripheral blood mononuclear cells from multiple sclerosis patients.

Recent studies have suggested a role of the cation channel TRPM4 in mediating neurodegeneration in experimental autoimmune encephalomyelitis and multiple sclerosis (MS). We aimed to extrapolate central nervous system findings to the blood compartment by determining TRPM4 expression in peripheral blood mononuclear cells from 12 healthy controls (HC) and 64 untreated MS patients. TRPM4 mRNA expression levels were comparable between HC and MS patients with primary progressive MS (n=17), secondary progressive MS (n=19), and relapsing-remitting MS during clinical remission (n=21) and relapses (n=7). These findings do not support a role of TRPM4 in the peripheral blood compartment of MS patients.

Identification of autoantibodies against TRPM1 in patients with paraneoplastic retinopathy associated with ON bipolar cell dysfunction.

BACKGROUND: Paraneoplastic retinopathy (PR), including cancer-associated retinopathy (CAR) and melanoma-associated retinopathy (MAR), is a progressive retinal disease caused by antibodies generated against neoplasms not associated with the eye. While several autoantibodies against retinal antigens have been identified, there has been no known autoantibody reacting specifically against bipolar cell antigens in the sera of patients with PR. We previously reported that the transient receptor potential cation channel, subfamily M, member 1 (TRPM1) is specifically expressed in retinal ON bipolar cells and functions as a component of ON bipolar cell transduction channels. In addition, this and other groups have reported that human TRPM1 mutations are associated with the complete form of congenital stationary night blindness. The purpose of the current study is to investigate whether there are autoantibodies against TRPM1 in the sera of PR patients exhibiting ON bipolar cell dysfunction. METHODOLOGY/PRINCIPAL FINDINGS: We performed Western blot analysis to identify an autoantibody against TRPM1 in the serum of a patient with lung CAR. The electroretinograms of this patient showed a severely reduced ON response with normal OFF response, indicating that the defect is in the signal transmission between photoreceptors and ON bipolar cells. We also investigated the sera of 26 patients with MAR for autoantibodies against TRPM1 because MAR patients are known to exhibit retinal ON bipolar cell dysfunction. Two of the patients were found to have autoantibodies against TRPM1 in their sera. CONCLUSION/SIGNIFICANCE: Our study reveals TRPM1 to be one of the autoantigens targeted by autoantibodies in at least some patients with CAR or MAR associated with retinal ON bipolar cell dysfunction.