Targeting streptococcal infections in the management of patients with psoriasis

The pathogenesis of psoriasis, actually, is not fully understood, long-time clinical observation substantiated microbial infections intimate relationship with onset, in particular, an association between streptococcal throat infection Interestingly, worsening is exclusively associated with throat infection by beta haemolytic streptococci expressing M protein, that cross-reacts with human epidermal keratins and is targeted by T cells from psoriasis patients. We performed evaluation of Streptococcal infection: throat swabs were positive in 61 patients (pt) (21,63%) and 22 HC (10,23 %). Antistreptolysin O titer (ASO) was positive (>200Ul/mL) in 132 pt (47,03%) and 64 HC (29,76%). T cell clones obtained from skin of pt with psoriasis were typed and tested in response to streptococcal antigens. In 41 of 282 pt we obtained clones specific for S. pyogenes group A; from the lesional skin of these 41 pt we obtained 2422 clones in total, of which 52 clones CD8+ (2%) and 2370 CD4+ (98%) clones. The 52 CD8+ clones showed a cytokine profile of Tc1 type. Of the 2370 CD4+ clones obtained, 1226 were Th1 (51,72%), 632 Th17 (26,66%), 387 Th1 / Th17 (16,32%) and 125 Th0 (5,27%). The prevalence of Streptoccoccal infection in pt with psoriasis is higher than HC. The results from the immunological studies demonstrated that in all pt with positive swab S. pyogenes specific T lymphocytes were present in lesional skin and that the majority of these clones has a Th1 and/or Th17 profile. In conclusion, on the basis of our results, the presence of streptococcal infection could be relevant to the disease activity in psoriasis.