REGULATION OF SOCS EXPRESSION IN MACROPHAGES IN RESPONSE TO BORRELIA AND IL-10

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We recently demonstrated that in vitro stimulation of mouse J774 macrophages with IL-10 together with either live spirochetes or other stimulants, including spirochetal lipoproteins and sonicated spirochetes, additively augmented the expression of the suppressor of cytokine signaling (SOCS) 3 in these cells. The expression of SOCS3 correlated with IL-10-mediated inhibition of the expression of several concomitantly elicited pro-inflammatory cytokines. Also, the fact that live and sonicated spirochetes as well as lipoproteins alone induced SOCS3 expression indicates that the spirochete may also control inflammation via a mechanism independent from that involving IL-10. Our hypothesis is that the expression of SOCS3 induced by B. burgdorferi alone in macrophages is functionally important in the control of inflammation during the course of Lyme disease. To begin to address this hypothesis J774 macrophages were stimulated with sonicated B. burgdorferi spirochetes and RNA samples were collected at 24 hr post-stimulation for real time PCR array analyses. The PCR array data revealed the up and down-regulation of the expression of several cytokines and chemokines. To determine the role of SOCS3 as a mediator of the inflammatory response induced by B. burgdorferi, we silenced the SOCS3 gene in macrophages stimulated with sonicated spirochetes. RNA samples were collected at 24 hr and subjected to genome-wide transcriptomics using mouse oligonucleotide microarrays. Silencing of the SOCS3 gene in macrophages stimulated with sonicated spirochetes resulted in a reversal of the expression of several cytokines (IL-1beta, IL-16, IL15ra, TGFbeta1) chemokines (CCL4, CCL5, CCL6) and other inflammatory mediators (CD40lg, TOLLIP TNFrsf1b). Cytokine ELISA also verified that SOCS3 mediates the production of IL-1beta at the protein level. This study demonstrates that SOCS3 induced by B. burgdorferi alone is functionally important in the control of inflammation in Lyme disease.