, 2010), whereas the CD103?CX3CR1+ mononuclear gut phagocytes originate from Ly6Chigh monocytes that are recruited to the inflamed nevertheless mucosal tissues and differentiate into CX3CRlow CD11b+ cells (Bar-On et al., 2011; Rivollier et al., 2012; Bain et al., 2013). Further phenotypic analysis revealed that a significant proportion of the HLA-DR+CD172a+ cells expressed E-Cadherin or CX3CR1 in lymphoid and nonlymphoid CD tissues (Fig. 1 C). When the HLA-DR+CD172a+ cells were further subdivided according to E-Cadherin and CX3CR1 expression, it appeared that the CX3CR1?E-Cadherin? cells predominated over the CX3CR1+E-Cadherin+ cells in both the mLNs and LP (Fig. 1 D). Importantly, these two cell populations, together with the CX3CR1?E-Cadherin+ cells, significantly accumulated in the mLNs and inflamed gut mucosa of CD patients.

The frequency of CX3CR1+E-Cadherin? cells was augmented in the LP but not in the mLNs of CD donors. In fact, the CX3CR1+ cells in the mLNs coexpressed CD1c but not CD123 and are thus considered to be conventional DCs. The percentage of HLA-DR+CD172a+ CD1c?CD123? cells significantly increased in the samples from CD patients, further indicating that the HLA-DR+CD172a+ cells that accumulated in the mLNs are distinct from resident DCs (unpublished data). Notably, similar proportions of CD1c and CD123 DC subsets were detected in the mLNs and gut tissues of control and CD patients (Fig. 1 E). Collectively, these findings provide the first evidence for the detection and accumulation of HLA-DR+CD172a+ cells in the lymphoid and mucosal tissues of CD patients, regardless of their expression of CX3CR1 and/or E-Cadherin.

TNF and IL-1�� are selectively produced by CD172a+ cells in the peripheral tissues of CD patients We next evaluated the proinflammatory profile of HLA-DR+CD172a+ cells in peripheral tissues. As depicted in Fig. 2, mLN cells and ex vivo�Cisolated LPMCs from CD patients spontaneously expressed IL-1�� and TNF without the addition of exogenous stimuli. Notably, the CD172a+ but not CD172a? cells represented the major source of spontaneous IL-1�� and TNF production (Fig. 2 A). The frequency of CD172a+ IL-1��+ or TNF+ cells in the mLNs and inflamed intestinal mucosa from CD patients was significantly higher compared with in noninflamed or control specimens (Fig. 2 B).

In fact, TNF and IL-1�� were coproduced by ~15�C50% of the HLA-DR+CD172a+ cells, which mainly comprised the CX3CR1?E-Cadherin? and CX3CR1+E-Cadherin? subsets in mLNs and LPMC, respectively (Fig. 2 C and not depicted). Carfilzomib Thus, these data indicate that proinflammatory cytokine production is restricted to CD172a+ cells in CD patients. Figure 2. Proinflammatory cytokine production is restricted to CD172a+ cells in the mLNs and LPMC from CD patients. Freshly isolated mLN cells and ex vivo isolated LPMC were stained for cell surface CD172a and HLA-DR followed by intracytoplasmic staining for IL-1�� …