Peroxisome Injury in Multiple Sclerosis: Protective Effects of 4-Phenylbutyrate in CNS-Associated Macrophages

Abstract

Multiple sclerosis (MS) is a progressive and inflammatory demyelinating disease of the CNS. Peroxisomes perform critical functions that contribute to CNS homeostasis. We investigated peroxisome injury and mitigating effects of peroxisome-restorative therapy on inflammatory demyelination in models of MS. Human autopsied CNS tissues (male and female), human cell cultures, and cuprizonemediated demyelination mice (female) were examined by RT-PCR, Western blotting, and immunolabeling. The therapeutic peroxisome proliferator, 4-phenylbutyrate (4-PBA) was investigated in vitro and in vivo. White matter from MS patients showed reduced peroxisomal transcript and protein levels, including PMP70, compared with non-MS controls. Cultured human neural cells revealed that human microglia contained abundant peroxisomal proteins. TNF-a-exposed microglia displayed reduced immunolabeling of peroxisomal proteins, PMP70 and PEX11b, which was prevented with 4-PBA. In human myeloid cells exposed to TNF-a or nigericin, suppression of PEX11b and catalase protein levels were observed to be dependent on NLRP3 expression. Hindbrains from cuprizoneexposed mice showed reduced Abcd1, Cat, and Pex5l transcript levels, with concurrent increased Nlrp3 and Il1b transcript levels, which was abrogated by 4-PBA. In the central corpus callosum, Iba-1 in CNS-associated macrophages and peroxisomal thiolase immunostaining after cuprizone exposure was increased by 4-PBA. 4-PBA prevented decreased myelin basic protein and neurofilament heavy chain immunoreactivity caused by cuprizone exposure. Cuprizone-induced neurobehavioral deficits were improved by 4-PBA treatment. Peroxisome injury in CNS-associated macrophages contributed to neuroinflammation and demyelination that was prevented by 4-PBA treatment. A peroxisome-targeted therapy might be valuable for treating inflammatory demyelination and neurodegeneration in MS.

COVID‐19 Induces Neuroinflammation and Suppresses Peroxisomes in the Brain

“…[38][39][40] Purity was assessed by immunofluorescence as previously described. 31,36,41,42 Vero-E6 cells (ATCC, USA) were cultured as previously described. 43 In vivo and in vitro studies were performed using a SARS-CoV-2 clinical isolate (B.1.279 [EPI_-ISL_3526025; CV56]), derived from a patient with COVID-19-associate pneumonia, which has been previously reported.…”

“…DNase treatment and cDNA synthesis was performed using random hexamer primers (Roche) and Superscript II reverse transcriptase (Invitrogen, Carlsbad, CA, USA) according to manufacturer's instructions. 31 Specific human and hamster immune genes were quantified by real-time RT-qPCR using the CFX 96 real-time system (Bio-Rad) and verified primers (Table S3) as previously described. 45 Detection of Viral RNA by Droplet Digital PCR SARS-CoV-2 RNA was quantified using 5 μL template cDNA and two established primer pairs with associated probes (Center for Disease Control, Atlanta) (Table S3).…”

“…33 Immunofluorescence labeling was performed, and images were acquired, as previously described (primary antibodies listed in Table S2). 31,46 Immunohistochemical staining was performed as previously described (primary antibodies listed in Table S2); immunostaining was performed with omission of the primary antibody but inclusion of the secondary antibodies to ensure specificity of epitope binding. 31,46 Immunoblot Analyses Total protein was determined by DC protein Assay Kit (Bio-Rad 5000112).…”

“…24,25 Peroxisomes also act as immunomodulatory hubs and regulate anti-viral and anti-inflammatory host immune responses through activation of mitochondrial antiviral signaling adaptor (MAVS) and nuclear factor kappa-light chain-enhancer of activated B-cells (NF-κB). [26][27][28] Peroxisome dysfunction has been implicated in several neuroinflammatory diseases, including multiple sclerosis, HIV-associated neurocognitive disorders, and Alzheimer's disease, [29][30][31] and contributes directly to the pathogenesis of neurotropic viruses such as Zika virus, human pegivirus, and HIV-1. 28,32,33 Furthermore, peroxisome biogenesis disorders, which are caused by mutations in PEX genes (which encode peroxisome biogenesis factors), are associated with neurological disorders.…”

Towards early detection of neurodegenerative diseases: A gut feeling

“…NDs are also characterized by abnormalities in peroxisomes and mitochondria ( Nunomura et al, 2001 ; Reddy and Beal, 2008 ; Reddy 2009 ; Kou et al, 2011 ; Cipolla and Lodhi, 2017 ; Aparicio et al, 2022 ; Fedele et al, 2022 ; Roczkowsky et al, 2022 ). These organelles are central to cellular metabolism, redox stress, and immune signaling ( Johannsen and Ravussin, 2009 ; Kou et al, 2011 ; Di Cara, 2020 ).…”