Neutralization of Streptolysin S-Dependent and Independent Inflammatory Cytokine IL-1β Activity Reduces Pathology During Early Group A Streptococcal Skin Infection

Abstract

The bacterial pathogen Group A Streptococcus (GAS) has been shown to induce a variety of human diseases ranging in severity from pharyngitis to toxic shock syndrome and necrotizing fasciitis. GAS produces a powerful peptide toxin known as Streptolysin S (SLS). Though long recognized as a potent cytolysin, recent evidence from our lab has shown that SLS-dependent cytotoxicity is mediated through activation of the pro-inflammatory mediators p38 MAPK and NFκB. These findings led us to hypothesize that activation of p38 MAPK and NFκB signaling drive the production of pro-inflammatory cytokines which, in turn, serve as positive feedback signals to initiate cytotoxicity in infected host cells. To address this hypothesis, we utilized a cytokine array to characterize the SLS-dependent pro-inflammatory cytokine response to GAS infection in human keratinocytes. From these studies, IL-1β was found to be markedly upregulated in the presence of SLS, and further investigation revealed that this cytokine contributes to cytotoxicity in human keratinocytes during infection. Subcutaneous infection studies were performed in mice to address the physiological impact of increased IL-1β production. These studies demonstrated that IL-1β is produced during GAS skin infection in an SLS-dependent manner. Furthermore, inhibition of this cytokine and the upstream kinases and other signaling mediators that drive its production reduced SLS-mediated lesion formation early in the infection process. Together, our findings indicate that pharmacological inhibition of this inflammatory axis holds promise as a therapeutic strategy to reduce tissue destruction during severe invasive Group A Streptococcal infections.

Synergistic Effect of Berberine Hydrochloride and Fluconazole Against Candida albicans Resistant Isolates

“…According to our results, BBH + FLC, BBH alone and FLC alone reduce Rh6G excretion by decreasing CDR1 and CDR2 mRNA expression. Previous studies reported that Eucalyptal D ( Xu et al, 2019 ) geraniol ( Singh and Sharma, 2018 ) and magnolol ( Sun L. M. et al, 2015 ) which are substrates for Cdr1p efflux pumps, exert synergistic effects by simultaneously upregulating CDR1 and CDR2 expression, while competitively inhibiting FLC efflux. Numerous studies suggest that synergy results from increased intracellular drug accumulation caused by downregulated efflux pump genes in FLC-resistant strains ( Garcia-Gomes et al, 2012 ; Zhu et al, 2014 ; Shao et al, 2016 ).…”

“…To evaluate the combined BBH and FLC effect on resistant C. albicans drug efflux, Rh6G assays were performed as previously described, with some modifications ( Xu et al, 2019 ). The cells were first incubated with constant shaking (200 rpm) in fresh RPMI 1640 at 35°C for 2 h to exhaust cellular energy stores.…”

Immunization With a Secreted Esterase Protects Mice Against Multiple Serotypes (M1, M3, and M28) of Group A Streptococcus

“…Classically activated macrophages participate in key proinflammatory responses and enhance antigen presentation and pathogen clearance (Imai et al, 2018;Valderrama and Nizet, 2018;Hafner et al, 2019). IL-1β is a neutrophil recruitment factor produced by macrophages and DCs upon exposure to GAS (Valderrama et al, 2017;Flaherty et al, 2018;Liu et al, 2019). Recent research has discovered that an optimal level of IL-1β must be produced to eliminate pathogens and avoid excessive tissue lesion formation and mortality (Castiglia et al, 2016;Flaherty et al, 2018).…”

“…IL-1β is a neutrophil recruitment factor produced by macrophages and DCs upon exposure to GAS (Valderrama et al, 2017;Flaherty et al, 2018;Liu et al, 2019). Recent research has discovered that an optimal level of IL-1β must be produced to eliminate pathogens and avoid excessive tissue lesion formation and mortality (Castiglia et al, 2016;Flaherty et al, 2018). Thus, the survival of control mice producing inadequate amounts of these cytokines reduced because of impaired bacterial clearance.…”

Protein kinase D mediates inflammatory responses of human placental macrophages to Group B Streptococcus

“…Extracellular bacteria and media were aspirated and the cells were washed with PBS and RPMI 1640 supplemented with 2% FBS, 100μg/ml gentamicin (Gibco), and 5μg/ml penicillin G (Sigma). The cells were incubated in 100nM PMA at 37°C with 5% CO 2 for 6 hrs prior to collecting the culture media for cytokine profiling as previously described 26 . The Abcam Human Cytokine Antibody Array Kit (ab133998), was performed according to the manufacturer's instructions with an Amersham Imager 600 (GE Life Sciences).…”