Canine distemper virus induces human osteoclastogenesis through NF-kappaB and sequestosome 1/P62 activation.
Previous studies have implicated CDV in the pathogenesis of Paget's disease; however, there has been no direct evidence that CDV can infect human cells. We studied the effects of CDV on osteoclastogenesis in vitro and showed that CDV had a dose-dependent effect on osteoclastogenesis, through a possible mechanism involving activation of NF-kappaB and sequestosome 1/p62.


BACKGROUND
Paget's disease is characterized by a dramatic increase in size and number of osteoclasts. The etiology of the disorder is still unclear; however, evidence points to either a viral infection or a genetic susceptibility or a combination of both. Previously, we have shown that canine distemper virus (CDV) RNA is present in Pagetic bone. However, the effects of CDV on human osteoclast formation in vitro have not been studied previously.


METHODS
Replicate cultures (n = 5) of purified human osteoclast precursors were infected with increasing doses of CDV and cultured on dentine slices for 14 days. Osteoclasts were stained for TRACP, and the dentine slices were examined for evidence of resorption. Control cells were incubated in the absence of virus. In each case, 10 high-power microscopy fields were analyzed. Immunocytochemical analyses were performed for p65, Gab2, sequestosome 1/p62, and ubiquitin.


RESULTS
CDV dose-dependently increased osteoclast number and size (p < 0.0001, ANOVA), and there was a concomitant increase in resorption (p < 0.0001, ANOVA). CDV infection induced nuclear translocation of p65 and led to a dramatic increase in sequestosome 1/p62 and ubiquitin expression.


CONCLUSIONS
These results provide the first conclusive proof that CDV can infect and replicate in human osteoclast precursors, raising possible zoonotic implications for CDV. The increased osteoclastogenesis is accompanied by NF-kappaB and sequestosome 1/p62 activation. This study provides further evidence for the possible role of paramyxoviruses in the pathogenesis of Paget's disease.
Selby
Peter L
PL
Vitamin D Research Group, University School of Medicine, Manchester Royal Infirmary, Oxford Road, Manchester, United Kingdom.
Davies
Michael
M
Mee
Andrew P
AP
D048868:Adaptor Proteins, Signal Transducing; D004217:Distemper Virus, Canine / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D016328:NF-kappa B / Q000378:metabolism*; D010001:Osteitis Deformans / Q000473:pathology* / Q000821:virology; D010010:Osteoclasts / Q000378:metabolism* / Q000821:virology*; D010252:Paramyxoviridae / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D000071456:Sequestosome-1 Protein
D048868:Adaptor Proteins, Signal Transducing; D016328:NF-kappa B; D011506:Proteins; C099718:SQSTM1 protein, human; D000071456:Sequestosome-1 Protein