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. 2007 Dec;130(1-2):228-40.
doi: 10.1016/j.virusres.2007.06.016. Epub 2007 Jul 31.

Activation of human monocytes after infection by human coronavirus 229E

Marc Desforges  1 , Tina C Miletti, Mylène Gagnon, Pierre J Talbot
Affiliations

Activation of human monocytes after infection by human coronavirus 229E

Marc Desforges et al. Virus Res. 2007 Dec.

Abstract

Human coronaviruses (HCoV) are recognized respiratory pathogens that may be involved in other pathologies such as central nervous system (CNS) diseases. To investigate whether leukocytes could participate in respiratory pathologies and serve as vector for viral spread towards other tissues, the susceptibility of human leukocytic cell lines and peripheral blood mononuclear cells (PBMC) to HCoV-229E and HCoV-OC43 infection was investigated. Human primary monocytes/macrophages were susceptible to HCoV-229E infection, but strongly restricted HCoV-OC43 replication. Moreover, productive HCoV-229E infection of primary monocytes and of the THP-1 monocytic cell line led to their activation, as indicated by the production of pro-inflammatory mediators, including TNF-alpha, CCL5, CXCL10 and CXCL11 and MMP-9. Moreover, an in vitro chemotaxis assay showed that motility towards chemokines of THP-1 cells and primary monocytes was increased following an acute or persistent HCoV-229E infection. Taken together, these results suggest that infected monocytes could serve as a reservoir for HCoV-229E, become activated, participate in the exacerbation of pulmonary pathologies, as well as serve as potential vectors for viral dissemination to host tissues, where it could be associated with other pathologies.

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Figures

Fig. 1
Fig. 1
Human primary monocytes and macrophages, as well as THP-1 cells, are susceptible to a productive HCoV-229E infection and to virus-induced cell death at high MOI. (A) Kinetics of infectious HCoV production in culture medium of human primary monocytes and macrophages. (B) Kinetics of infectious HCoV production in undifferentiated and PMA-differentiated THP-1 cells. In panels A and B, the limit of detection is 0.5 TCID50/mL. (C) Evaluation of cell morphology and of the relative metabolic mitochondrial activity, indicative of cell viability, at 3 dpi in primary monocytes and macrophages, as well as in the undifferentiated and PMA-differentiated THP-1 cell line. All infections were performed at an MOI of 1, which induced cell death in a significant portion of the cell culture. Syncytia-like structures are easily observed in primary macrophages and PMA-differentiated THP-1 cells.
Fig. 2
Fig. 2
Infectious HCoV-229E production and cell viability depends on the starting MOI in the human THP-1 monocytic cell line and in primary human monocytes. (A) Kinetics of infectious HCoV-229E production in culture medium after infection at different MOI (0.01, 0.1, and 1) over a 72-h period. (B) Evaluation of the relative cellular metabolic mitochondrial activity, indicative of cell viability, after infection by HCoV-229E (229E 1: infection at MOI of 1; 229E 0.1: infection at MOI of 0.1; 229E 0.01: infection at MOI of 0.01). Cell survival was in direct correlation with the starting MOI. Dotted lines represent the limit of detection of 0.5 TCID50/mL. Results are representative of two independent experiments.
Fig. 3
Fig. 3
Primary human monocytes and THP-1 cells are susceptible to HCoV-229E infection and THP-1 cells sustain a long-term productive infection by HCoV-229E. Infections were performed at an MOI of 0.1. Detection of HCoV-229E S protein (green), using HCoV-229E Mab 5-11H.6 in: (A) HCoV-229E-infected THP-1 cells and primary monocytes at 24 and 48 hpi; (B) THP-1 cells after 10 passages representing 2 months in culture (persistently infected cells). Cell nuclei were stained with DAPI (blue). White arrows indicate antigen-positive cells. Infectious virus titers in medium (extracellular) and within cells (intracellular) are indicated as log TCID50/mL, showing that the long-term infection of THP-1 cells was weakly productive. Magnification 200×.
Fig. 4
Fig. 4
Primary human monocytes and THP-1 cells showed a similar cytokine/chemokine profile after HCoV-229E infection. Evaluation of the profile of cytokines and chemokines secreted in mock-infected and HCoV-229E-infected THP-1 cells and primary monocytes using the Cytokine Array Proteome Profiler at 48 hpi. Cytokines/chemokines that were detected in the supernatant of HCoV-229E-infected THP-1 cells are circled and those that were in the supernatant of HCoV-229E-infected primary monocytes are boxed. Results are representative of two independent experiments.
Fig. 5
Fig. 5
Production and secretion of TNF-α and MMP-9 was significantly increased in THP-1 cells and primary monocytes after HCoV-229E infection. (A) TNF-α secretion in mock-infected THP-1 cells and primary monocytes, and in HCoV-229E-infected cells (MOI of 0.1 and 1) for 24, 48, and 72 h. (B) MMP-9 secretion in mock-infected or HCoV-229E-infected cells (MOI of 0.1) at 72 hpi. Cell supernatants were collected and assayed for MMP-9 content by gelatin-based zymography on polyacrylamide gels. (C) Active MMP-9 secretion in mock-infected and HCoV-229E-infected THP-1 cells and primary monocytes (MOI of 0.1) over a period of 72 h. Results are representative of two independent experiments. The levels of statistical significance between mock- and HCoV-infected cells were evaluated for each condition. The p values were calculated by a t-test and are represented by * where the difference between mock and infected cells was significant. *p < 0.05; **p < 0.01.
Fig. 6
Fig. 6
THP-1 cell and primary monocyte motility and chemokine-driven migration are increased after HCoV-229E infection. Infections were performed at a MOI of 0.1. (A) Chemotaxis assay showed that HCoV-229E infection of THP-1 cells by itself induced a significant increase in cell motility and migration across Transwell inserts. CCL5 and CXCL12-driven migration was also significantly increased following infection but CCL2-driven migration was only significantly modified at 24 hpi and in persistently infected cells. (B) A comparative chemotaxis assay showed that both THP-1 cell and primary human monocyte motility and chemokine-driven migration across Transwell inserts was significantly increased. CCL5-driven migration was already significantly increased at 24 hpi and remained at that level until 48 hpi and CXCL12-driven migration was significantly increased at 48 hpi. CCL2-driven migration was only significantly increased at 24 hpi for the THP-1 cells but not significantly modified for primary monocytes. (C) A representative field of THP-1 cells and primary monocytes that have migrated across Transwell inserts and were allowed to adhere to poly-d-lysine-coated glass slides. Detection of HCoV-229E S protein (green cells with white arrows) was performed using the Mab 5-11H.6. Cell nuclei were stained with DAPI (blue). Results are representative of three independent experiments. Mock-infected THP-1 cells (THP-mock) at 24, 48 hpi and at 60 dpi (persist: persistently infected kept in culture for 2 months, representing 10 passages) were compared to HCoV-229E-infected THP-1 cells (THP-229E-0.1) at 24, 48 hpi and 60 dpi and mock-infected primary monocytes (PrimaryMono-mock) at 24 and 48 hpi were compared to HCoV-229E-infected primary monocytes (PrimaryMono-229E-0.1) at 24 and 48 hpi. The levels of statistical significance between mock- and HCoV-infected cells were evaluated for each condition. The p values were calculated by a t-test and are represented by * where the difference between mock and infected cells was significant. *p < 0.05; **p < 0.01; ***p < 0.001.
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References

    1. Altmeyer R. Virus attachment and entry offer numerous targets for antiviral therapy. Curr. Pharm. Des. 2004;10:3701–3712. - PubMed
    1. Arbour N., Day R., Newcombe J., Talbot P.J. Neuroinvasion by human respiratory coronaviruses. J. Virol. 2000;74:8913–8921. - PMC - PubMed
    1. Ashmun R.A., Look A.T. Metalloprotease activity of CD13/aminopeptidase N on the surface of myeloid cells. Blood. 1990;75:462–469. - PubMed
    1. Bar-Or A., Nuttall R.K., Duddy M., Alter A., Kim H.J., Ifergan I., Pennington C.J., Bourgoin P., Edwards D.R., Yong V.W. Analyses of all matrix metalloproteinase members in leukocytes emphasize monocytes as major inflammatory mediators in multiple sclerosis. Brain. 2003;126:2738–2749. - PubMed
    1. Calderon T.M., Eugenin E.A., Lopez L., Kumar S.S., Hesselgesser J., Raine C.S., Berman J.W. A role for CXCL12 (SDF-1α) in the pathogenesis of multiple sclerosis: regulation of CXCL12 expression in astrocytes by soluble myelin basic protein. J. Neuroimmunol. 2006;177:27–39. - PubMed

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