Loss of CD103^+ intestinal dendritic cells during colonic inflammation

AIM:To investigate possible differences in dendritic cells(DC)within intestinal tissue of mice before and after induction of colitis. METHODS:Mucosal DC derived from intestinal tissue,as well as from mesenteric lymph nodes and spleen,were analyzed by fluorescence activated cell sorting(FACS) analysis.Supernatants of these cells were analyzed for secretion of different pro-and anti-inflammatory cytokines. Immunohistochemistry and immunofluorescence were performed on cryosections of mucosal tissue derived from animals with colitis as well as from healthy mice. RESULTS:It was shown that DC derived from healthy intestinal lamina propria(LP)represented an immature phenotype as characterized by low-level expression of costimulatory cytokines.In contrast to DC from spleen and mesenteric lymph nodes(MLN)that secreted proinflammatory cytokines,LP-DC produced high levels of the anti-inflammatory cytokine IL-10.After induction of mu-rine colitis in a CD4 + CD62L + transfer model or in chronic Dextran sulfate sodium-colitis,a marked increase of activated CD80 + DC could be observed within the inflamed colonic tissue.Interestingly,in contrast to splenic DC,a significant population of DC within MLN and colonic LP expressed the mucosal integrin CD103 which was lost during colitis. CONCLUSION:The constitutive secretion of antiinflammatory cytokines by immature DC within the intestinal LP might regulate the homeostatic balance between mucosal immunity and tolerance.CD103 + DC could mediate this important function.

Increased density of tolerogenic dendritic cells in the small bowel mucosa of celiac patients

AIM: To investigate the densities of dendritic cells(DCs) and FOXP3+ regulatory T cells(Tregs) and their interrelations in the small bowel mucosa in untreated celiac disease(CD) patients with and without type 1 diabetes(T1D).METHODS: Seventy-four patients(45 female, 29 male, mean age 11.1 ± 6.8 years) who underwent small bowel biopsy were studied. CD without T1 D was diagnosed in 18 patients, and CD with T1 D was diagnosed in 15 patients. Normal small bowel mucosa was found in two T1 D patients. Thirty-nine patients(mean age 12.8 ± 4.9 years) with other diagnoses(functional dyspepsia, duodenal ulcer, erosive gastritis, etc.) formed the control group. All CD patients had partial or subtotal villous atrophy according to the Marsh classification: Marsh grade Ⅲa in 9, grade Ⅲb in 21 and grade Ⅲc in 3 cases. Thirty-nine patients without CD and 2 with T1 D had normal small bowel mucosa(Marsh grade 0). The densities of CD11c+, IDO+, CD103+, Langerin(CD207+) DCs and FOXP3+ Tregs were investigated by immunohistochemistry(on paraffin-embedded specimens) and immunofluorescence(on cryostat sections) methods using a combination of mono- and double-staining. Sixtysixserum samples were tested for Ig A-tissue transglutaminase(t TG) using a fully automated Eli ATM Celikey Ig A assay(Pharmacia Diagnostics, Freiburg, Germany). RESULTS: The density of CD11c+ DCs was significantly increased in CD patients compared with patients with normal mucosa(21.67 ± 2.49 vs 13.58 ± 1.51, P = 0.007). The numbers of FOXP3+ cells were significantly higher in CD patients(10.66 ± 1.50 vs 1.92 ± 0.37, P = 0.0002) and in patients with CD and coexisting T1D(8.11 ± 1.64 vs 1.92 ± 0.37, P = 0.002) compared with patients with normal mucosa. The density of FOXP3+ cells significantly correlated with the histologicalgrade of atrophic changes in the small bowel mucosa according to the March classification(r = 0.62; P < 0.0001) and with levels of Ig A antibody(r = 0.55; P < 0.0001). The densities of IDO+ DCs were significantly higher in CD patients(21.6 ± 2.67 vs 6.26 ± 0.84, P = 0.00003) and in patients with CD and coexisting T1D(19.08 ± 3.61 vs 6.26 ± 0.84, P = 0.004) compared with patients with normal mucosa. A significant correlation was identified between the densities of IDO+ DCs and FOXP3+ T cells(r = 0.76; P = 0.0001). The mean values of CD103+ DCs were significantly higher in CD patients(10.66 ± 1.53 vs 6.34 ± 0.61, P = 0.01) and in patients with CD and associated T1D(11.13 ± 0.72 vs 6.34 ± 0.61, P = 0.00002) compared with subjects with normal small bowel mucosa. The mean value of Langerin+ DCs was higher in CD patients compared with persons with normal mucosa(7.4 ± 0.92 vs 5.64 ± 0.46, P = 0.04).CONCLUSION: The participation of diverse DC subsets in the pathological processes of CD and the possible involvement of tolerogenic DCs in Tregs development to maintain intestinal immunological tolerance in CD patients are revealed.

Human BDCA2^＋CD123^＋CD56^＋ dendritic cells （DCs） related to blastic plasmacytoid dendritic cell neoplasm represent a unique myeloid DC subset

Dendritic cells （DCs） comprise two functionally distinct subsets： plasmacytoid DCs （pDCs） and myeloid DCs （mDCs）. pDCs are specialized in rapid and massive se- cretion of type I interferon （IFN-I） in response to nucleic acids through Toll like receptor （TLR）-7 or TLR-9. In this report, we characterized a CD56^＋ DC population that express typical pDC markers including CD123 and BDCA2 but produce much less IFN-I comparing with pDCs. In addition, CD56^＋ DCs cluster together with mDCs but not pDCs by genome-wide transcriptional profiling. Accordingly, CD56^＋ DCs functionally resemble mDCs by producing IL-12 upon TLR4 stimulation and priming naive T cells without prior activation. These data suggest that the CD56^＋ DCs represent a novel mDC subset mixed with some pDC features. A CD4^＋CD56^＋ hematological malignancy was classified as blastic plasmacytoid dendritic cell neoplasm （BPDCN） due to its expression of characteristic molecules of pDCs.However, we demonstrated that BPDCN is closer to CD56^＋ DCs than pDCs by global gene-expression pro- filing. Thus, we propose that the CD4^＋CD56^＋ neoplasm may be a tumor counterpart of CD56^＋ mDCs but not pDCs.