Introduction: Neurodegenerative diseases, such as multiple sclerosis (MS), often lead to the development of neurogenic lower urinary tract symptoms (LUTS). We previously characterized neurogenic bladder dysfunction in a mouse model of MS induced by a coronavirus, mouse hepatitis virus (MHV). The objective of this study was to identify genes and pathways linking neuroinflammation in the central nervous system with urinary bladder dysfunction to enhance our understanding of the mechanisms underlying LUTS in demyelinating diseases.
Methods: Adult C57BL/6 male mice (N=12) received either an intracranial injection of MHV (6,000 PFU) or sterile saline (control). The lumbosacral (L6-S2) spinal cord (SC) segments and urinary bladders were collected during acute infection stage (week 1) and at the first peak of demyelination (week 4) after inoculation with the virus. Total RNA was isolated and analyzed using Nanostring nCounter Neuroinflammation panel. The expression levels of 770 genes associated with neuroinflammation were assessed and compared between the specimens.
Results: Transcriptome analysis of SC specimens confirmed a significantly increased expression of 132 genes in MHV mice (tens to hundreds fold change) involved in the regulation of astrocyte, microglia and oligodendrocyte functions, neuroinflammation and immune responses. Out of 132 genes up-regulated in the SC, only 2 genes (siglec1, 46-fold in the SC, 2.6-fold at 1 week and 1.8-fold at 4 weeks in the bladder; and zbp1, 568-fold in the SC, 2.8-fold at 1 week and 2.2-fold at 4 weeks in the bladder) were up-regulated in the urinary bladders of MHV-infected mice. Additionally, two genes were significantly up-regulated (ttr, 2.2-fold at 1week and 1.7-fold at 4 weeks; and ms4a4a, 2.3-fold at 1week and 1.6-fold at 4 weeks), and two were down-regulated (asb2, -1.8-fold at 1 week and -1.6-fold at 4 weeks, and myct1, -1.7-fold at 1week and -1.6-fold at 4 weeks) exclusively in the urinary bladders of MHV mice.
Conclusions: Two genes, siglec1 (encodes type 1 transmembrane protein, expressed in microglia and macrophages, promotes neuroinflammation) and zbp1 (encodes a Z-DNA binding protein, plays role in the innate immune response) link the development of neuroinflammation in the central nervous system with neurogenic changes in the urinary bladders of MHV-infected mice. Further research is needed to establish a functional relationship between expression of these genes and neurogenic LUTS.
Source of Funding: NIH/NIDDK R01 DK116648 (to A.M.)