Because the early events occur within skin, this disease potentially offered a new human model whereby skin biopsies could allow direct study of the kinetics of the CD1 induction process in vivo or ex vivo 25, 26.

Here, we report that natural learn more and experimental B. burgdorferi infection upregulates cell surface expression of CD1a, CD1b and CD1c in the dermis of human skin. Although CD1d and NKT cells are thought to act at the earliest stages of the innate response, we found that the process of group 1 CD1 induction requires antecedent signaling through TLR-2 and a days long series of events whereby the cell-to-cell spread of cytokines leads to CD1 appearance on maturing DCs. Cilomilast These studies support a role for CD1 in host response in human Lyme disease and demonstrate a previously unknown pathway whereby IL-1β cleavage leads to selective induction of group 1 CD1 proteins after infection. Mechanistic studies of group 1 CD1 induction have been carried out using dispersed blood monocytes 12, 13, 19, highlighting the need for studies of infected human tissues. To determine whether group 1 CD1 proteins are induced within skin during natural B. burgdorferi infection, we first studied frozen sections of EM skin lesions from ten patients

with Lyme disease. The diagnosis of Lyme disease was confirmed by culture or serology, or in most instances, by both methods (Table 1). In addition to culture-positivity, three patients had evidence of spirochetes in the blood and >6 symptoms, including fever, headache, stiff neck, arthralgias, myalgias and fatigue; and two had multiple EM skin lesions. Eight patients were infected with B. burgdorferi OspC type A or K strains, the two most common B. burgdorferi genotypes 27, 28. Hoechst from dye staining viewed at low power showed nuclei clustering in rete patterns that corresponded to the dermal–epidermal junction (Fig. 1A), as confirmed in serial sections stained with hematoxylin and eosin (not shown). In two color immunohistochemistry

samples stained with anti-CD1a, many large cells were seen in the epidermis, likely representing Langerhans cells (LC), a DC subtype that constitutively expresses CD1a (Fig. 1A). In contrast, CD1b and CD1c in normal skin were consistently seen at low levels on about 1% of dermal cells (Fig. 1B and data not shown). For two patients (Table 1 – A and J), CD1b and CD1c could be detected with bright staining on many (∼5%) large cells in the dermis (Table 1, Fig. 1A). One of these two patients (A) had severe infection, with a positive PCR test for B. burgdorferi DNA in blood, >6 symptoms, and multiple EM lesions. Both patients (A and J) were infected with the OspC type A genotype, a particularly virulent B. burgdorferi subtype that grows to high numbers in EM lesions 27, 28.