TRPA1 deficiency is protective in cuprizone-induced demyelination-A new target against oligodendrocyte apoptosis.

Multiple sclerosis is a chronic inflammatory, demyelinating degenerative disease of the central nervous system. Current treatments target pathological immune responses to counteract the inflammatory processes. However, these drugs do not restrain the long-term progression of clinical disability. For this reason, new therapeutic approaches and identification of novel target molecules are needed to prevent demyelination or promote repair mechanisms. Transient Receptor Potential Ankyrin 1 (TRPA1) is a nonselective cation channel with relatively high Ca2+ permeability. Its pathophysiological role in central nervous system disorders has not been elucidated yet. In the present study, we aimed to assess the distribution of TRPA1 in the mouse brain and reveal its regulatory role in the cuprizone-induced demyelination. This toxin-induced model, characterized by oligodendrocyte apoptosis and subsequent primary demyelination, allows us to investigate the nonimmune aspects of multiple sclerosis. We found that TRPA1 is expressed on astrocytes in the mouse central nervous system. Interestingly, TRPA1 deficiency significantly attenuated cuprizone-induced demyelination by reducing the apoptosis of mature oligodendrocytes. Our data suggest that TRPA1 regulates mitogen-activated protein kinase pathways, as well as transcription factor c-Jun and a proapoptotic Bcl-2 family member (Bak) expression resulting in enhanced oligodendrocyte apoptosis. In conclusion, we propose that TRPA1 receptors enhancing the intracellular Ca2+ concentration modulate astrocyte functions, and influence the pro or anti-apoptotic pathways in oligodendrocytes. Inhibition of TRPA1 receptors might successfully diminish the degenerative pathology in multiple sclerosis and could be a promising therapeutic target to limit central nervous system damage in demyelinating diseases. GLIA 2016;64:2166-2180.

Sághy É ，Sipos É ，Ács P ，Bölcskei K ，Pohóczky K ，Kemény Á ，Sándor Z ，Szőke É ，Sétáló G Jr ，Komoly S ，Pintér E ... -  《-》

Behavioural alterations and morphological changes are attenuated by the lack of TRPA1 receptors in the cuprizone-induced demyelination model in mice.

We have recently reported that the Transient Receptor Potential Ankyrin 1 (TRPA1) receptor deficiency significantly attenuated cuprizone-induced demyelination by reducing the apoptosis of mature oligodendrocytes. The aim of the present study was to gather additional data on the role of TRPA1 by investigating the time course of behavioural alterations and morphological changes in cuprizone-treated TRPA1 receptor gene-deficient mice. Demyelination was induced by feeding male wild-type (WT) and TRPA1 gene-deleted (TRPA1 KO) mice with 0.2% cuprizone for 6 weeks. Behavioural tests were performed once per week to follow cuprizone-induced functional changes. Mechanonociceptive thresholds were investigated by a dynamic plantar aesthesiometer and von Frey filaments. Motor performance was assessed by accelerating RotaRod and horizontal grid tests. For the study of spontaneous activity, the open field test was used. The time course of corpus callosum demyelination was also followed weekly by magnetic resonance imaging (MRI). Histological analysis of myelin loss was performed with Luxol Fast Blue (LFB) staining at week 3 and electron microscopy (EM) at week 6. Astrocyte and microglia accumulation at week 3 was assessed by immunohistochemistry (IHC). Cuprizone treatment induced no changes in mechanonociception or motor performance. In the open arena, cuprizone-treated mice spent more time with locomotion, their mean velocity was significantly higher and the distance they travelled was longer than untreated mice. No statistical difference was detected between WT and TRPA1 KO mice in these parameters. On the other hand, significantly increased rearing behaviour was induced in WT mice compared to TRPA1 KO animals. Morphological changes detected with MRI, LFB, IHC and EM analysis revealed reduced damage of the myelin and attenuated accumulation of astrocytes and microglia in cuprizone-treated TRPA1 KO animals, at each examined time point. Our recent data further suggest that inhibition of TRPA1 receptors could be a promising therapeutic approach to limit central nervous system damage in demyelinating diseases.

Bölcskei K ，Kriszta G ，Sághy É ，Payrits M ，Sipos É ，Vranesics A ，Berente Z ，Ábrahám H ，Ács P ，Komoly S ，Pintér E ... -  《-》

Cuprizone-induced graded oligodendrocyte vulnerability is regulated by the transcription factor DNA damage-inducible transcript 3.

Oligodendrocytes are integral to efficient neuronal signaling. Loss of myelinating oligodendrocytes is a central feature of many neurological diseases, including multiple sclerosis (MS). The results of neuropathological studies suggest that oligodendrocytes react with differing sensitivity to toxic insults, with some cells dying early during lesion development and some cells being resistant for weeks. This proposed graded vulnerability has never been demonstrated but provides an attractive window for therapeutic interventions. Furthermore, the biochemical pathways associated with graded oligodendrocyte vulnerability have not been well explored. We used immunohistochemistry and serial block-face scanning electron microscopy (3D-SEM) to show that cuprizone-induced metabolic stress results in an "out of phase" degeneration of oligodendrocytes. Although expression induction of stress response transcription factors in oligodendrocytes occurs within days, subsequent oligodendrocyte apoptosis continues for weeks. In line with the idea of an out of phase degeneration of oligodendrocytes, detailed ultrastructural reconstructions of the axon-myelin unit demonstrate demyelination of single internodes. In parallel, genome wide array analyses revealed an active unfolded protein response early after initiation of the cuprizone intoxication. In addition to the cytoprotective pathways, the pro-apoptotic transcription factor DNA damage-inducible transcript 3 (DDIT3) was induced early in oligodendrocytes. In advanced lesions, DDIT3 was as well expressed by activated astrocytes. Toxin-induced oligodendrocyte apoptosis, demyelination, microgliosis, astrocytosis, and acute axonal damage were less intense in the Ddit3-null mutants. This study identifies DDIT3 as an important regulator of graded oligodendrocyte vulnerability in a MS animal model. Interference with this stress cascade might offer a promising therapeutic approach for demyelinating disorders.

Fischbach F ，Nedelcu J ，Leopold P ，Zhan J ，Clarner T ，Nellessen L ，Beißel C ，van Heuvel Y ，Goswami A ，Weis J ，Denecke B ，Schmitz C ，Hochstrasser T ，Nyamoya S ，Victor M ，Beyer C ，Kipp M ... -  《-》

Investigation of Cuprizone-Induced Demyelination in mGFAP-Driven Conditional Transient Receptor Potential Ankyrin 1 (TRPA1) Receptor Knockout Mice.

Kriszta G ，Nemes B ，Sándor Z ，Ács P ，Komoly S ，Berente Z ，Bölcskei K ，Pintér E ... -  《Cells》

Protective and therapeutic role of 2-carba-cyclic phosphatidic acid in demyelinating disease.

Yamamoto S ，Yamashina K ，Ishikawa M ，Gotoh M ，Yagishita S ，Iwasa K ，Maruyama K ，Murakami-Murofushi K ，Yoshikawa K ... -  《Journal of Neuroinflammation》