The association of sore throat and psoriasis might be explained by histologically distinctive tonsils and increased expression of skin-homing molecules by tonsil T cells

Abstract

SummaryRecent studies have highlighted the involvement of the palatine tonsils in the pathogenesis of psoriasis, particularly among patients with recurrent throat infections. However, the underlying immunological mechanism is not well understood. In this study we confirm that psoriasis tonsils are infected more frequently by β-haemolytic Streptococci, in particular Group C Streptococcus, compared with recurrently infected tonsils from patients without skin disease. Moreover, we show that tonsils from psoriasis patients contained smaller lymphoid follicles that occupied a smaller tissue area, had a lower germinal centre to marginal zone area ratio and contained fewer tingible body macrophages per unit area compared with recurrently infected tonsils from individuals without skin disease. Psoriasis patients' tonsils had a higher frequency of skin-homing [cutaneous lymphocyte-associated antigen

HLA-Cw6 homozygosity in plaque psoriasis is associated with streptococcal throat infections and pronounced improvement after tonsillectomy: A prospective case series

“…Combined carrier frequency of Lancefield groups A, C or G Streptococcus or Streptococcus anginosus was almost 70% in homozygous and heterozygous HLA-Cw*0602 patients compared with 43% of non-carriers. S. anginosus can cause pharyngitis, is sometimes β-haemolytic and carries a typeable Lancefield group antigen, A, C, G or F. 35 The genetic background of psoriasis is thus associated with both asymptomatic and symptomatic streptococcal throat infections compared to age and sex matched controls, 7,36 and streptococcal tonsillitis has long been associated with flares of guttate psoriasis, 5,37,38 as well as exacerbation of plaque psoriasis. 6,7,39 It should be noted that the participants included in the current study all had a history of psoriasis exacerbation in association with sore throat, which applies to approximately 40 percent of patients with plaque psoriasis in Iceland.…”

Throat Infections are Associated with Exacerbation in a Substantial Proportion of Patients with Chronic Plaque Psoriasis

“…Chronic stimulation by streptococci in the tonsils gives rise to a set of pathogenic skin-homing (CLA+) T cells (25). The link between streptococcal throat infections and psoriasis is supported by several lines of research, including increased T cell responses to streptococcal-derived peptides (26–28), shared T cell receptor rearrangements in psoriasis tonsil and skin-homing and skin-resident T cells (29), increased streptococcal-reactive IgG titers in the blood of patients with plaque psoriasis (30) and increased throat carriage rate of streptococci amongst patients with psoriasis (13, 14). Once generated in the tonsils, skin-homing T cells can migrate to the dermis and epidermis where they are thought to cross-react with skin-derived epitopes such as keratins (28, 29, 30, Shen Z, J Dermatol Sci.…”

“…The high level of streptococcal throat carriage and infections in patients with plaque psoriasis is noteworthy, with the carrier rate for groups A, C and G streptococci as high as 44 percent (14). Long-term treatment with antibiotics has not been effective for psoriasis (36).…”

“…Moreover, such infections are about 10 times more frequent in patients with plaque psoriasis compared to age- and sex-matched household controls (13). Recently it was reported that tonsils from patients with psoriasis are more frequently infected with β-haemolytic streptococci, especially group C streptococci, than recurrently infected tonsils from patients without psoriasis (14). Nevertheless, the immunological basis for the association of psoriasis and streptococcal throat infections is still under investigation.…”

A New Player on the Psoriasis Block: IL-17A- and IL-22-Producing Innate Lymphoid Cells

“…Considering recent evidence that psoriasis patients’ tonsils have a higher frequency of skin-homing lymphocytes (Sigurdardottir et al , 2013) and that psoriasis patients often report onset or worsening of their skin disease after Streptococcal infection (Gudjonsson et al , 2003), it will be interesting to determine whether tonsil-resident ILC3s in psoriasis patients upregulate CLA following Steptococcal infection. Such a relationship would support a role for ILC3s in psoriasis initiation and pathogenesis.…”