Rhinovirus Replication in Human Macrophages Induces NF-κB-Dependent Tumor Necrosis Factor Alpha Production

Abstract

Rhinoviruses (RV) are the major cause of acute exacerbations of asthma and chronic obstructive pulmonary disease (COPD). Rhinoviruses have been shown to activate macrophages, but rhinovirus replication in macrophages has not been reported. Tumor necrosis factor alpha (TNF-␣) is implicated in the pathogenesis of acute exacerbations, but its cellular source and mechanisms of induction by virus infection are unclear. We hypothesized that rhinovirus replication in human macrophages causes activation and nuclear translocation of NF-B, leading to TNF-␣ production. Using macrophages derived from the human monocytic cell line THP-1 and from primary human monocytes, we demonstrated that rhinovirus replication was productive in THP-1 macrophages, leading to release of infectious virus into supernatants, but was limited in monocytederived macrophages, likely due to type I interferon production, which was robust in monocyte-derived but deficient in THP-1-derived macrophages. Similar to bronchial epithelial cells, only small numbers of cells supported complete virus replication. We demonstrated RV-induced activation of NF-B and colocalization of p65/NF-B nuclear translocation with virus replication in both macrophage types. The infection induced TNF-␣ release in a time-and dose-dependent, RV serotype-and receptor-independent manner and was largely (THP-1 derived) or completely (monocyte derived) dependent upon virus replication. Finally, we established the requirement for NF-B but not p38 mitogen-activated protein kinase in induction of TNF-␣. These data suggest RV infection of macrophages may be an important source of proinflammatory cytokines implicated in the pathogenesis of exacerbations of asthma and COPD. They also confirm inhibition of NF-B as a promising target for development of new therapeutic intervention strategies.

Rhinovirus-Induced Macrophage Cytokine Expression Does Not Require Endocytosis or Replication

“…A small amount of viral replication has been noted in RV-infected peripheral blood monocyte-derived macrophages but not in BAL-derived macrophages (3,4). Nevertheless, in these studies, ex vivo exposure to UV-irradiated, replicationdeficient RV induced similarly robust production of TNF-a (3) and IP-10 (6).…”

“…Although it has been demonstrated that macrophages allow RV entry (3,4,7,25), the ability of RV to replicate in macrophages remains controversial. BMMs were infected with RV or replication-deficient UV-RV.…”

“…However, it is conceivable that RV directly infects airway inflammatory cells. Recent studies indicate that inoculation of monocytes with RV induces cytokine expression in vitro (3)(4)(5)(6)(7)(8), although the level of viral replication in these cells is small or negligible. Recently, we demonstrated that, in ovalbumin (OVA)-sensitized and -challenged mice, RV colocalizes with eotaxin-and IL-4-positive lung macrophages (9), suggesting that lung macrophages may play a role in the airway inflammatory response to RV in vivo.…”

RSV infection modulates IL-15 production and MICA levels in respiratory epithelial cells

“…AS602868 inhibits the activation of the IKK kinase responsible for the degradation of NF-kB inhibitors, and consequently decreases intracellular levels of NF-kB [13]. We used the IKK2 inhibitor AS602868 at a concentration previously shown to be optimal for rhinovirus-induced tumour necrosis factor-a inhibition without cell toxicity [13].…”

“…The effect of NF-kB activation on RSV-induced IL-15 production was evaluated using an IkB kinase (IKK)2 inhibitor (AS602868) as previously described [13]. AS602868 inhibits the activation of the IKK kinase responsible for the degradation of NF-kB inhibitors, and consequently decreases intracellular levels of NF-kB [13].…”