ClpX-dependent regulatory pathway exacerbates <i>Streptococcus pyogenes</i> pathogenesis in diabetic skin infection

ABSTRACT Diabetes is associated with impaired immune function and increased susceptibility to severe bacterial infections, yet the pathogen-encoded mechanisms that exacerbate disease in this context remain poorly defined. Streptococcus pyogenes (group A Streptococcus [GAS]) causes invasive skin and soft tissue infections that are disproportionately severe in individuals with diabetes, often accompanied by delayed healing, excessive inflammation, and polymicrobial overgrowth. Here, we investigated how the GAS ClpX-dependent regulatory pathway (CDRP), a global virulence regulator, interacts with diabetic immune dysfunction to shape infection outcomes. Using two murine models of type I diabetes, we show that diabetic mice develop more severe and persistent GAS skin infections characterized by increased bacterial burden, exaggerated inflammatory responses, impaired neutrophil recruitment, excessive neutrophil extracellular trap (NET) accumulation, and frequent polymicrobial infections. Deletion of clpX significantly attenuated GAS virulence in both diabetic and non-diabetic hosts; however, the pathogenic consequences of CDRP were markedly amplified in the diabetic environment. In diabetic mice, CDRP promoted sustained inflammation, altered neutrophil behavior, impaired NET clearance, and enhanced tissue damage, leading to delayed resolution of infection. Mechanistically, ClpX-dependent virulence was associated with dysregulated protease-nuclease activity, excessive NET persistence, and defective neutrophil chemotaxis within diabetic lesions. Together, these findings indicate that while ClpX is a core regulator of GAS virulence, its downstream effects are disproportionately deleterious when host immune clearance is compromised. IMPORTANCE Diabetic patients experience disproportionately severe bacterial infections, yet the microbial mechanisms that exacerbate disease in this immunocompromised context remain incompletely understood. This study demonstrates that the Streptococcus pyogenes ClpX-dependent regulatory pathway, a central regulator of virulence, amplifies tissue damage and inflammatory dysfunction during diabetic skin infection. ClpX-dependent regulation exacerbates disease by intensifying neutrophil dysregulation, excessive NET accumulation, and impaired resolution of infection in an already compromised host environment. These findings underscore the importance of host-pathogen interactions in shaping infection severity and suggest that targeting pathogen regulatory pathways may be particularly effective in settings of immune dysfunction such as diabetes.