Identifying Toll-like Receptor Expression in Cutaneous Sarcoidosis

Abstract

Toll-like receptors (TLRs) are known to be expressed in the skin. Antigenic stimulation of TLRs in the skin has been implicated in several inflammatory dermatologic diseases including psoriasis, syphilis, atopic dermatitis, and cutaneous T-cell lymphoma. However, the expression of TLRs in cutaneous sarcoidosis has not yet been defined. Expression of TLRs 1-9 was examined in cutaneous sarcoid by immunohistochemical staining. It was found that TLRs 5 and 6 stained most intensely in both the granulomas and epidermis of the sarcoid cases. TLRs 2, 3, 4, 7, and 8 stained more intensely compared with normal skin. All sarcoidosis cases showed an increased level of staining compared with the control. The nuclear factor-kappa B activation pathway was confirmed by staining for p65. All cases strongly stained for p65 in the granulomas and varied in staining intensity in the epidermis. The identified TLR expression in cutaneous sarcoidosis indicates that a bacterial antigen could be an etiologic agent of the disease. Future studies that clearly define the etiology of sarcoid will lead to better therapies and a better prognosis for affected patients.

The role of pattern recognition receptors in lung sarcoidosis

“…TLR6 forms a heterodimer with TLR2 and binds bacterial lipoproteins (Huizenga et al 2015). A similar inflammatory response using TLRs 2, 5 and Page9 6 could be involved in the pathogenesis of sarcoidosis.…”

“…They found that TLRs 5 and 6 stained most intensely in both the granulomas and epidermis of the sarcoid cases. The expression of TLRs 2, 3, 4, 5, 6, 7, and 8 was increased in the dermis and epidermis of cutaneous sarcoid compared with normal skin (Huizenga et al 2015). TLR5 recognizes…”

“…Huizenga et al examined the expression of the TLRs 1-9 in cutaneous sarcoid by immunohistochemical staining (Huizenga et al 2015). They found that TLRs 5 and 6 stained most intensely in both the granulomas and epidermis of the sarcoid cases.…”

“…These results suggest that a bacterium could be the cause of the granulomas formed in cutaneous sarcoid. Future studies that clearly define the etiology of sarcoid will lead to better therapies and a better prognosis for affected patients (Huizenga et al 2015).…”

Therapeutic targeting of Toll-like receptors in cutaneous disorders

“…Farnesol up-regulated TLR6 only in C. albicans-treated cells. This study showed Psoriasis 1, 2, 4, 5, 9 [51] Lichen planus 1, 2, 4, 9 [56,58] Pemphigus 2, 3, 4 [60] SLE 7, 9 [62,65] Sarcoidosis 2 --8 [64] Systemic sclerosis 3, 4 [65,66] Non-melanoma skin cancers 4, 1 --3, 5 --8 [ …”