title: HCMV-encoded UL128 enhances TNF-α and IL-6 expression and promotes PBMC proliferation through the MAPK/ERK pathway in vitro.
abstract: Cytomegalovirus (CMV) infection enhances expression of several cytokines, such as tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), granulocyte macrophage colony-stimulating factor (GM-CSF), and IL-8, to the benefit of virus replication and dissemination. However, the stimulus for certain cytokine production remains unclear. CMV encodes a series of proteins that alter and/or mimic functions of leukocyte migration, activation, and cytokine responses. Our study revealed that human CMV (HCMV)-encoded UL128 protein, which contains signal peptides and has similar amino acid sequences to the CC chemokine, recruits monocytes as human β chemokine (microphage inflammatory protein 1α). Using RNA interference technology, we constructed an HCMV (UL128⁺/UL128⁻)-infected tissue cell (MRC-5) and peripheral blood mononuclear cell (PBMC) co-culture system. We measured 6 cytokine levels (IL-2, IL-4, IL-6, IL-10, TNF-α, and interferon-γ [IFN-γ]) in the supernatant, and found significantly elevated IL-6 and elevated TNF-α levels in the HCMV UL128⁺-infected group. Conversely, we observed decreased levels in the UL128-knockout supernatant. PBMCs presented with UL128 (50 ng/mL) demonstrated better cell viability than the UL128-absent group. Finally, the MAPK/ERK pathway was found to be involved in UL128 induction of cell proliferation. Selective induction of cytokine expression indicates that HCMV-encoded UL128 is a potent inducer of several inflammatory mediators.
authors.affiliation: Department of Pediatrics, Children's Hospital Affiliated with the Medical College, Zhejiang University, Zhejiang Key Laboratory for Diagnosis and Therapy of Neonatal Diseases, Hangzhou, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Zheng
authors.forename: Ran
authors.initials: R
authors.lastname: Tao
authors.forename: Huihui
authors.initials: H
authors.lastname: Gao
authors.forename: Jun
authors.initials: J
authors.lastname: Xu
authors.forename: Shiqiang
authors.initials: S
authors.lastname: Shang
authors.forename: Ning
authors.initials: N
authors.lastname: Zhao
mesh_terms: D049109:Cell Proliferation; D002470:Cell Survival; D002478:Cells, Cultured; D018920:Coculture Techniques; D003470:Culture Media / Q000737:chemistry; D003587:Cytomegalovirus / Q000276:immunology*; D006801:Humans; D015850:Interleukin-6 / Q000096:biosynthesis*; D007963:Leukocytes, Mononuclear / Q000276:immunology; D020935:MAP Kinase Signaling System; D008562:Membrane Glycoproteins / Q000276:immunology*; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis*; D014759:Viral Envelope Proteins / Q000276:immunology*
chemical_list: D003470:Culture Media; C508600:IL6 protein, human; D015850:Interleukin-6; D008562:Membrane Glycoproteins; D014409:Tumor Necrosis Factor-alpha; C532797:UL128 protein, human cytomegalovirus; D014759:Viral Envelope Proteins