Differential accumulation and function of proinflammatory 6-sulfo LacNAc dendritic cells in lymph node and colon of Crohn's versus ulcerative colitis patients

Human Slan DCs have been studied in patients with psoriasis, rheumatoid arthritis, cancer, and autoimmune diseases. In this study, we investigated the frequency, phenotype, and function of Slan DCs in blood, colon, as well as mLNs of patients with IBD. We first show that the frequency of circulating CD14(dull)Slan DCs was reduced in CD patients refractory to immunosuppressive drugs or TNF-alpha blockers relative to untreated CD, UC, and healthy subjects. In blood of CD patients, Slan DCs expressed CD172a, as detected by CD47 fusion protein binding, when compared with its lack of expression in control subjects. Next, we demonstrate that CD172a(+)Slan DCs that produced IL-1 beta and TNF-alpha accumulated in mLNs and colons of CD patients. The CD172a(+)Slan DCs upregulated their expression of CD14 in CD tissues and the proinflammatory cytokines were produced in CD14(bright)CD172a(+)Slan DCs. By contrast, no difference was noted in the frequency of Slan DCs between inflamed, noninflamed colonic mucosa of UC patients and control, non-IBD donors. Finally, the percentage of cytokine-producing Slan DCs also augmented in response to TLR2 and NOD2 in in vitro stimulation in PBMCs of CD, but not UC, patients. In conclusion, we propose that proinflammatory CD14(bright)CD172a(+)Slan DCs are a distinguishing feature between CD and UC, as these cells accumulate uniquely in mLNs and colonic mucosa of CD patients. Thus, Slan DCs may contribute to CD immunopathogenesis.