Cell and Tissue Interactions ofTreponema pallidumin Primary and Secondary Syphilitic Skin Lesions: An Ultrastructural Study of Serial Sections

Abstract

There are limited reports on the ultrastructure of syphilis skin lesions. The aim of this study has been to perform an electron microscopic investigation of the morphology and the tissue distribution of treponemes in primary and secondary cutaneous lesions. Three cases of primary syphilitic chancre and one case of secondary syphilis were included. Prominent epidermal abnormalities in the primary chancre and a perivascular inflammatory infiltrate in the secondary lesion were found by light microscopy. Ultrastructurally, spirochetes were located mainly in the blood vessel walls and dermal tissue of the chancre lesions. In the secondary syphilis case, spirochetes were more abundant between epidermal keratinocytes. Most of them adjusted to the intercellular spaces. Occasionally, the electron microscopy images were highly suggestive of an intracellular location. Both the ultrastructural and immunohistochemical examination of the primary and secondary syphilis lesions showed a paradoxical distribution of the causative microorganisms compared to the light microscopic changes. In addition, the ultrastructural findings strongly suggest that Treponema pallidum subspecies pallidum invades tissues, not only through an intercellular, but also through a transcellular pathway.

Syphilis: using modern approaches to understand an old disease

“…T. pallidum traverses the tight junctions between endothelial cells (25,26) to enter the perivascular spaces, where large numbers of treponemes and immune cells accumulate. Based on electron microscopy images of secondary syphilis skin lesions, T. pallidum may also use transcytosis to spread through the endothelium (27). T. pallidum can induce the production of MMP-1 (28), which degrades collagen and may facilitate access to and egress from the bloodstream, resulting in systemic spread.…”

Clinicopathological, dermoscopic, and ultrastructural observation of annular secondary syphilis on the penis

“…10 Immunohistochemistry and electron microscopy show that the spirochetes in secondary syphilis are abundant in the lower epidermis and scant in the papillary dermis. 10,11 On electron microscopy, the spirochetes contain central axial filaments and peripheral electronlucid halo, and are located in intercellular spaces and membranal invaginations. 10,11 In conclusion, the dermoscopic findings are nonspecific in genital annular syphilis and larger studies could facilitate their clinical relevance in syphilis.…”

<p>Classification and Staging of Morgellons Disease: Lessons from Syphilis</p>

“…[41][42][43] In vitro studies demonstrate that intracellular sequestration enables Borrelia resistance to antibiotic treatment, and may provide a mechanism for persistent infection. 41,42 Likewise, T. pallidum can localize intracellularly within keratinocytes, fibroblasts, spermatocytes, interstitial cells and Leydig cells, [44][45][46][47] and T. denticola can invade human gingival epithelial cells. 48 Macrophages and keratinocytes are the cells in which intracellular Borrelia is most frequently observed.…”