Induction of Cytopathogenicity in Human Glioblastoma Cells by Chikungunya Virus

Abstract

Chikungunya virus (CHIKV), an arthritogenic old-world alphavirus, has been implicated in the central nervous system (CNS) infection in infants and elderly patients. Astrocytes are the major immune cells of the brain parenchyma that mediate inflammation. In the present study we found that a local isolate of CHIKV infect and activate U-87 MG cells, a glioblastoma cell line of human astrocyte origin. The infection kinetics were similar in infected U-87 MG cells and the human embryo kidney (HEK293) cells as indicated by immunofluorescence and plaque assays, 24h post-infection (p.i.). In infected U-87 MG cells, apoptosis was detectable from 48h p.i. evidenced by DNA fragmentation, PARP cleavage, loss of mitochondrial membrane potential, nuclear condensation and visible cytopathic effects in a dose and time-dependent manner. XBP1 mRNA splicing and eIF2α phosphorylation studies indicated the occurrence of endoplasmic reticulum stress in infected cells. In U-87 MG cells stably expressing a green fluorescent protein-tagged light chain-3 (GFP-LC3) protein, CHIKV infection showed increased autophagy response. The infection led to an enhanced expression of the mRNA transcripts of the pro-inflammatory cytokines IL-1β, TNF-α, IL-6 and CXCL9 within 24h p.i. Significant up-regulation of the proteins of RIG-I like receptor (RLR) pathway, such as RIG-I and TRAF-6, was observed indicating the activation of the cytoplasmic-cellular innate immune response. The overall results show that the U-87 MG cell line is a potential in vitro model for in depth study of these molecular pathways in response to CHIKV infection. The responses in these cells of CNS origin, which are inherently defective in Type I interferon response, could be analogous to that occurring in infants and very old patients who also have a compromised interferon-response. The results also point to the intriguing possibility of using this virus for studies to develop oncolytic virus therapy approaches against glioblastoma, a highly aggressive malignancy.

Neuropathogenesis of Chikungunya infection: astrogliosis and innate immune activation

“…As we anticipated infection of the CNS with Chikungunya [24,11,2,4], we attempted to determine cell types activated. As shown in Figure 1, there were diffuse punta of TLR2 (green) staining throughout gray matter, in 2/3 controls (A) and all macaques infected with Chikungunya (B).…”

“…Cultured gliomas are capable of being infected with Chikungunya virus [2], and recent studies have demonstrated that cultured astrocytes and oligodendrocytes are highly susceptible to Chikungunya infection [7,8]. Astrocytes are commonly the first cells activated in brain following viral infection [37].…”

“…This infection induces increased expression of numerous genes associated with viral infection including IL-6 and TLR3 [24]. Both of these genes can be expressed by astrocytes during viral neuroinflammation, and astrocyte-derived cells have recently been shown to be capable of infection by Chikungunya virus [2]. …”

The neurological complications of chikungunya virus: A systematic review

“…For the former, both RNA and virus have been isolated from CSF in severe CNS disease, consistent with direct neuroinvasion. Neurons, astrocytes, and oligodendrocytes (but not microglia) are susceptible to chikungunya infection in vitro; the former 2 cell types were shown to undergo apoptosis postinfection . In vivo, subcutaneous inoculation in macaques resulted in morphological changes in astrocytes, including cell body hypertrophy and alteration in the pattern of branching of their primary processes .…”

Chikungunya virus modulates the miRNA expression patterns in human synovial fibroblasts

“…Chikungunya infection is caused by Chikungunya virus (CHIKV), which is an RNA virus of the family Togaviridae . The CHIKV was first reported in Tanzania in 1952 and transmitted by the Aedes aegypti mosquito . It is considered a neglected tropical disease due to its prevalence in tropical and subtropical countries .…”