Programming effects of maternal and gestational obesity on offspring metabolism and metabolic inflammation.

With the increasing prevalence of obesity in women of reproductive age there is a need to understand the ramifications of this on offspring. The purpose of this study is to investigate the programming effects of maternal obesity during preconception and the preconception/gestational period on adiposity and adipose tissue inflammation in offspring using an animal model. Adult female C57Bl/6J mice were assigned either normal diet, high fat diet (HFD) prior to pregnancy, or HFD prior to and through pregnancy. Some offspring were maintained on normal diet while others started HFD later in life. Offspring were assessed for body composition and metabolic responses. Lipid storing tissues were evaluated for expansion and inflammation. Male offspring from the preconception group had the greatest weight gain, most subcutaneous adipose tissue, and largest liver mass when introduced to postnatal HFD. Male offspring of the preconception/gestation group had worsened glucose tolerance and an increase in resident (CD11c-) adipose tissue macrophages (ATMs) when exposed to postnatal HFD. Female offspring had no significant difference in any parameter between the diet treatment groups. In conclusion, this study demonstrates that prenatal and pregnancy windows have independent programming effects on offspring. Preconception exposure affects body composition and adiposity while gestation exposure affects metabolism and tissue immune cell phenotypes.

LKB1 expressed in dendritic cells governs the development and expansion of thymus-derived regulatory T cells.

Liver Kinase B1 (LKB1) plays a key role in cellular metabolism by controlling AMPK activation. However, its function in dendritic cell (DC) biology has not been addressed. Here, we find that LKB1 functions as a critical brake on DC immunogenicity, and when lost, leads to reduced mitochondrial fitness and increased maturation, migration, and T cell priming of peripheral DCs. Concurrently, loss of LKB1 in DCs enhances their capacity to promote output of regulatory T cells (Tregs) from the thymus, which dominates the outcome of peripheral immune responses, as suggested by increased resistance to asthma and higher susceptibility to cancer in CD11cΔLKB1 mice. Mechanistically, we find that loss of LKB1 specifically primes thymic CD11b+ DCs to facilitate thymic Treg development and expansion, which is independent from AMPK signalling, but dependent on mTOR and enhanced phospholipase C ß1-driven CD86 expression. Together, our results identify LKB1 as a critical regulator of DC-driven effector T cell and Treg responses both in the periphery and the thymus.

Distinctly regulated functions and mobilization of CD11c-positive cells elicited by TLR3- and IPS-1 signaling in the cornea.

The human ocular surface epithelium expresses TLR3, which recognizes double-stranded (ds) RNA mimicking polyinosine-polycytidylic acid (polyI:C). Its stimulation induces the secretion of the inflammatory cytokines such as interleukin (IL)-6, IL-8, and type I interferon. The cytoplasmic helicase proteins RIG-I and MDA5 are also expressed on the ocular surface. We investigated the function of TLR3 in the cornea of CD11c- YFP+ and TLR3 KO CD11c- YFP+ mice. We also examined the function of IPS-1, an adaptor molecule common to RIG-I and/or MDA5, in IPS-1 KO CD11c- YFP+ mice. In the central corneal epithelium of CD11c- YFP+ mice, the infiltration of CD11c- YFP+ cells was significantly upregulated 48 h after polyI:C stimulation; it was significantly downregulated in the stromal layer of their central and peripheral cornea. On the other hand, in the corneal epithelium of TLR3 KO CD11c- YFP+- and wild-type mice, the movement of CD11c- YFP+ cells was different from CD11c- YFP+ mice. This suggests that TLR3 knock-out (KO) interferes with their movement from the peripheral- to the central cornea or lymph nodes and that it may be similar in IPS-1 KO CD11c-YFP+ - and wild-type mice. Under normal conditions, the number of CD11c- YFP+ cells in the central and peripheral corneal epithelium, but not in the stromal layer, is significantly greater in TLR3 KO CD11c- YFP+- than CD11c- YFP+ mice. In IPS-1 KO CD11c- YFP+ mice, their number in the stromal layer, but not in the epithelium of the central and peripheral cornea, was significantly greater than in CD11c- YFP+ mice. Our findings suggest that CD11c+ dendritic cell (DC) migration in the corneal epithelium is regulated by TLR3, whereas CD11c+ DC migration in the stromal layer of the cornea is regulated by IPS-1. These observations, together with our earlier findings, imply that TLR3 and IPS-1 contribute distinctly to the regulation of innate immune responses and tissue inflammation elicited by CD11c+ DCs to maintain homeostasis in corneal tissues.

Depletion of CD11c+ Cells Does Not Influence Outcomes in Mice Subjected to Transient Middle Cerebral Artery Occlusion.

OBJECTIVE: While it has been shown that different T-cell subsets have a detrimental role in the acute phase of ischemic stroke, data on the impact of dendritic cells (DC) are missing. Classic DC can be characterized by the cluster of differentiation (CD)11c surface antigen. METHODS: In this study, we depleted CD11c+ cells by using a CD11c-diphtheria toxin (DTX) receptor mouse strain that allows selective depletion of CD11c+ cells by DTX injection. For stroke induction, we used the model of transient middle cerebral artery occlusion (tMCAO) and analyzed stroke volume and functional outcome on days 1 and 3 as well as expression of prototypical pro- and anti-inflammatory cytokines on day 1 after tMCAO. Three different protocols for CD11c+ cell depletion, tMCAO duration, and readout time point were applied. RESULTS: Injection of DTX (5 or 100 ng/g) reliably depleted CD11c+ cells without influencing the fractions of other immune cell subsets. CD11c+ cell depletion had no impact on stroke volume, but mice with a longer DTX pretreatment performed worse than those with vehicle treatment. CD11c+ cell depletion led to a decrease in cortical interleukin (IL)-1ß and IL-6 messenger ribonucleic acid levels. CONCLUSIONS: We show, for the first time, that CD11c+ cell depletion does not influence stroke volume in a mouse model of focal cerebral ischemia. Nevertheless, given the unspecificity of the CD11c surface antigen for DC, mouse models that allow a more selective depletion of DC are needed to investigate the role of DC in stroke pathophysiology.

IL-10 control of CD11c+ myeloid cells is essential to maintain immune homeostasis in the small and large intestine.

Although IL-10 promotes a regulatory phenotype of CD11c+ dendritic cells and macrophages in vitro, the role of IL-10 signaling in CD11c+ cells to maintain intestinal tolerance in vivo remains elusive. To this aim, we generated mice with a CD11c-specific deletion of the IL-10 receptor alpha (Cd11ccreIl10rafl/fl). In contrast to the colon, the small intestine of Cd11ccreIl10rafl/fl mice exhibited spontaneous crypt hyperplasia, increased numbers of intraepithelial lymphocytes and lamina propria T cells, associated with elevated levels of T cell-derived IFNγ and IL-17A. Whereas naive mucosal T-cell priming was not affected and oral tolerance to ovalbumin was intact, augmented T-cell function in the lamina propria was associated with elevated numbers of locally dividing T cells, expression of T-cell attracting chemokines and reduced T-cell apoptosis. Upon stimulation, intestinal IL-10Rα deficient CD11c+ cells exhibited increased activation associated with enhanced IL-6 and TNFα production. Following colonization with Helicobacter hepaticus Cd11ccreIl10rafl/fl mice developed severe large intestinal inflammation characterized by infiltrating T cells and increased levels of Il17a, Ifng, and Il12p40. Altogether these findings demonstrate a critical role of IL-10 signaling in CD11c+ cells to control small intestinal immune homeostasis by limiting reactivation of local memory T cells and to protect against Helicobacter hepaticus-induced colitis.