Subsets Of CD103 Research Articles

Regulatory Immune Mechanisms in Tolerance to Food Allergy.

Oral tolerance can develop after frequent exposure to food allergens. Upon ingestion, food is digested into small protein fragments in the gastrointestinal tract. Small food particles are later absorbed into the human body. Interestingly, some of these ingested food proteins can cause allergic immune responses, which can lead to food allergy. So far it has not been completely elucidated how these proteins become immunogenic and cause food allergies. In contrast, oral tolerance helps to prevent the pathologic reactions against different types of food antigens from animal or plant origin. Tolerance to food is mainly acquired by dendritic cells, epithelial cells in the gut, and the gut microbiome. A subset of CD103+ DCs is capable of inducing T regulatory cells (Treg cells) that express anti-inflammatory cytokines. Anergic T cells also contribute to oral tolerance, by reducing the number of effector cells. Similar to Treg cells, B regulatory cells (Breg cells) suppress effector T cells and contribute to the immune tolerance to food allergens. Furthermore, the human microbiome is an essential mediator in the induction of oral tolerance or food allergy. In this review, we outline the current understanding of regulatory immune mechanisms in oral tolerance. The biological changes reflecting early consequences of immune stimulation with food allergens should provide useful information for the development of novel therapeutic treatments.

Batf3-Dependent Intestinal Dendritic Cells Play a Critical Role in the Control of Cryptosporidium parvum Infection.

Understanding the protective immune response to Cryptosporidium parvum infection is of critical importance to reduce the widespread impact caused by this disease in young individuals. Here, we analyzed the various subsets of CD103+ and CD103- intestinal dendritic cells (DCs) of wild-type and Batf3-/- neonatal mice at homoeostasis and investigated their role during infection. Neonatal Batf3-/- mice had a low CD103+/CD103- DC ratio, resulting in higher susceptibility to the acute phase of the infection and they could not cure the infection. Early during infection, CD103- DCs of Batf3-/- neonates had a lower ability to produce interleukin-12 than their wild-type littermates and lower levels of interferon-gamma mRNA were detected in the infected mucosa. Amplification of CD103+ DCs in Batf3-/- neonates prior to infectious challenge reduced their susceptibility to infection. CD103+ DCs thus outperform CD103- DCs in controlling C. parvum infections and represent a primary target of host-directed immunotherapies dedicated to neonates.

RelB+ Steady-State Migratory Dendritic Cells Control the Peripheral Pool of the Natural Foxp3+ Regulatory T Cells.

Thymus-derived natural Foxp3+ CD4+ regulatory T cells (nTregs) play a key role in maintaining immune tolerance and preventing autoimmune disease. Several studies indicate that dendritic cells (DCs) are critically involved in the maintenance and proliferation of nTregs. However, the mechanisms how DCs manage to keep the peripheral pool at constant levels remain poorly understood. Here, we describe that the NF-κB/Rel family transcription factor RelB controls the frequencies of steady-state migratory DCs (ssmDCs) in peripheral lymph nodes and their numbers control peripheral nTreg homeostasis. DC-specific RelB depletion was investigated in CD11c-Cre × RelBfl/fl mice (RelBDCko), which showed normal frequencies of resident DCs in lymph nodes and spleen while the subsets of CD103− Langerin− dermal DCs (dDCs) and Langerhans cells but not CD103+ Langerin+ dDC of the ssmDCs in skin-draining lymph nodes were increased. Enhanced frequencies and proliferation rates were also observed for nTregs and a small population of CD4+ CD44high CD25low memory-like T cells (Tml). Interestingly, only the Tml but not DCs showed an increase in IL-2-producing capacity in lymph nodes of RelBDCko mice. Blocking of IL-2 in vivo reduced the frequency of nTregs but increased the Tml frequencies, followed by a recovery of nTregs. Taken together, by employing RelBDCko mice with increased frequencies of ssmDCs our data indicate a critical role for specific ssmDC subsets for the peripheral nTreg and IL-2+ Tml frequencies during homeostasis.

A New Subset of CD103+CD8α+ Dendritic Cells in the Small Intestine Expresses TLR3, TLR7, and TLR9 and Induces Th1 Response and CTL Activity

CD103(+) dendritic cells (DCs) are the major conventional DC population in the intestinal lamina propria (LP). Our previous report showed that a small number of cells in the LP could be classified into four subsets based on the difference in CD11c/CD11b expression patterns: CD11c(hi)CD11b(lo) DCs, CD11c(hi)CD11b(hi) DCs, CD11c(int)CD11b(int) macrophages, and CD11c(int)CD11b(hi) eosinophils. The CD11c(hi)CD11b(hi) DCs, which are CD103(+), specifically express TLR5 and induce the differentiation of naive B cells into IgA(+) plasma cells. These DCs also mediate the differentiation of Ag-specific Th17 and Th1 cells in response to flagellin. We found that small intestine CD103(+) DCs of the LP (LPDCs) could be divided into a small subset of CD8α(+) cells and a larger subset of CD8α(-) cells. Flow cytometry analysis revealed that CD103(+)CD8α(+) and CD103(+)CD8α(-) LPDCs were equivalent to CD11c(hi)CD11b(lo) and CD11c(hi)CD11b(hi) subsets, respectively. We analyzed a novel subset of CD8α(+) LPDCs to elucidate their immunological function. CD103(+)CD8α(+) LPDCs expressed TLR3, TLR7, and TLR9 and produced IL-6 and IL-12p40, but not TNF-α, IL-10, or IL-23, following TLR ligand stimulation. CD103(+)CD8α(+) LPDCs did not express the gene encoding retinoic acid-converting enzyme Raldh2 and were not involved in T cell-independent IgA synthesis or Foxp3(+) regulatory T cell induction. Furthermore, CD103(+)CD8α(+) LPDCs induced Ag-specific IgG in serum, a Th1 response, and CTL activity in vivo. Accordingly, CD103(+)CD8α(+) LPDCs exhibit a different function from CD103(+)CD8α(-) LPDCs in active immunity. This is the first analysis, to our knowledge, of CD8α(+) DCs in the LP of the small intestine.

Decreased frequencies of CD4+CD25+Foxp3+ cells and the potent CD103+ subset in peripheral lymph nodes correlate with autoimmune disease predisposition in some strains of mice

The CD4+CD25+Foxp3+ cells are essential for regulation of the immune response, and the integrin, CD103 (αEβ7), identifies a potent subset of these cells. Defects in CD4+CD25+Foxp3+ cells are thought to contribute to susceptibility to autoimmune disease in predisposed individuals. Studies evaluating the quality and quantity of CD4+CD25+Foxp3+ regulatory cell populations in the context of autoimmune disease susceptibility have been inconclusive, and few if any, have analyzed the CD103 subset. In this study, we analyzed regulatory T cells (Tregs) from different strains of mice with varying degrees of susceptibility to autoimmune disease. We found no differences in the ability of CD4+CD25+ or the CD103+ subset of Tregs from young female (NZB × NZW)F1 (BWF1), SJL, C57BL/6, or BALB/c mice to suppress CD4+CD25− responders in vitro. Analysis of CD4+Foxp3+ and CD4+CD25+CD103+ cell frequencies in lymphoid organs revealed that BWF1 mice had dramatically lower percentages of both populations in the lymph node (LN) than the other strains, and lower percentages in the spleen in all but the C57BL/6 strain. We next determined whether these findings extended to another autoimmune-prone strain. Similar to BWF1 mice, percentages of CD4+Foxp3+ and CD4+CD25+CD103+ cells were significantly lower in predisease NOD mice. The low frequencies of CD4+Foxp3+ and CD4+CD25+CD103+ cells in BWF1 and NOD mice were not due to deficiencies in either thymic production or homeostatic proliferation. These data indicate that decreased percentages of CD4+Foxp3+ cells and particularly, CD4+CD25+CD103+ cells in LN correlate with the predisposition to spontaneous development of autoimmune disease.