IADR Abstract Archives
Activation of Toll-like Receptors by Putative FCGS Pathogens
Objectives: Feline chronic gingivostomatitis (FCGS) is a common and extremely painful disease in cats, with a complex multifactorial aetiology. Several pathogens are putatively involved in the disease, such as T. forsythia, P. circumdentaria and Feline Calicivirus (FCV). Using comparative human and feline models we aimed to investigate the role of these pathogens in the development of this disease by determining whether they stimulate macrophage toll like receptors (TLRs).
Methods: Mononuclear phagocytes were challenged with varying multiplicities of infection (MOIs) of putative bacterial pathogens from the literature. Additionally, they were challenged with two bacteria found to be prevalent in FCGS using high throughput sequencing; Pasteurella multocida subsp. multocida and P. multocida subsp. septica. For control purposes cells were also stimulated with a known oral commensal of cats, Bergeyella zoohelcum. The production of the proinflammatory chemokine interleukin-8 (IL-8) by mononuclear phagocytes was analysed using ELISA and RT-PCR. TLR activation was confirmed using the THP1-XBlue cell line, which produces secreted embryonic alkaline phosphatase (SEAP), in response to TLR activation and induction of the NF-ΚB transcription factor.
Results: All the putative pathogenic bacteria were found to stimulate TLRs. Of the bacteria investigated, T. forsythia had the greatest stimulatory effect followed by P. circumdentaria, P. multocida subsp multocida and P. multocida subsp. septica respectively. There was a strong correlation between TLR activation and IL-8 production. The commensal, B. zoohelcum had the smallest stimulatory effect.
Conclusions: The commensal B. zoohelcum had a low level stimulatory effect; this low immunological response is congruent with other studies on gut commensals. The putative pathogenic bacteria, particularly T. forsythia, had a strong stimulatory effect on mononuclear phagocytes and induced an innate immune response. In cats, failure to clear this pathogenic threat could result in the chronic activation of the innate immune response and be important in the pathogenesis of FCGS.
Methods: Mononuclear phagocytes were challenged with varying multiplicities of infection (MOIs) of putative bacterial pathogens from the literature. Additionally, they were challenged with two bacteria found to be prevalent in FCGS using high throughput sequencing; Pasteurella multocida subsp. multocida and P. multocida subsp. septica. For control purposes cells were also stimulated with a known oral commensal of cats, Bergeyella zoohelcum. The production of the proinflammatory chemokine interleukin-8 (IL-8) by mononuclear phagocytes was analysed using ELISA and RT-PCR. TLR activation was confirmed using the THP1-XBlue cell line, which produces secreted embryonic alkaline phosphatase (SEAP), in response to TLR activation and induction of the NF-ΚB transcription factor.
Results: All the putative pathogenic bacteria were found to stimulate TLRs. Of the bacteria investigated, T. forsythia had the greatest stimulatory effect followed by P. circumdentaria, P. multocida subsp multocida and P. multocida subsp. septica respectively. There was a strong correlation between TLR activation and IL-8 production. The commensal, B. zoohelcum had the smallest stimulatory effect.
Conclusions: The commensal B. zoohelcum had a low level stimulatory effect; this low immunological response is congruent with other studies on gut commensals. The putative pathogenic bacteria, particularly T. forsythia, had a strong stimulatory effect on mononuclear phagocytes and induced an innate immune response. In cats, failure to clear this pathogenic threat could result in the chronic activation of the innate immune response and be important in the pathogenesis of FCGS.