Researchers at Karolinska Institutet have identified a link between common strep throat infections and the onset of guttate psoriasis, a specific form of the autoimmune skin condition, according to a study published in eBioMedicine. The findings suggest that alterations in the behavior of key immune cells, triggered by the bacterial infection, play a role in the development of the disease.
The study builds on decades of observations connecting streptococcal infections to psoriasis. Previous research, including a 2016 study published in Acta Derm Venereol, has demonstrated a significant association between throat infections and exacerbations of chronic plaque psoriasis. That research indicated that tonsillectomy may offer benefit to some patients, suggesting a direct causal link between the tonsils – a common site of streptococcal colonization – and the disease.
Specifically, the newly identified immune cell activity centers around T cells. Researchers found that in individuals predisposed to psoriasis, streptococcal infections involving beta hemolytic streptococci expressing M protein can trigger an immune response. This M protein, as noted in a 2018 article in the Journal of the American Academy of Dermatology, cross-reacts with human epidermal keratins, leading to T cell activation and subsequent skin inflammation.
The connection isn’t universal across all types of psoriasis. A study in the Journal of Medical Genetics found that streptococcal infection appears to be more strongly associated with a particular subtype of non-pustular psoriasis characterized by early onset – before age 40 – a positive family history, and the presence of specific HLA molecules (Cw6, B13, or B57). This suggests a genetic component influencing susceptibility to streptococcus-triggered psoriasis.
While the precise mechanisms are still under investigation, the findings offer potential avenues for targeted therapies. Understanding how streptococcal infections initiate or worsen psoriasis could lead to new preventative strategies or treatments focused on modulating the immune response. The Karolinska Institutet researchers are continuing to investigate the specific immune pathways involved, with a focus on identifying potential therapeutic targets.
