Gata6 regulates aspartoacylase expression in resident peritoneal macrophages and controls their survival

The transcription factor Gata6 regulates proliferation and differentiation of epithelial and endocrine cells and cancers. Among hematopoietic cells, Gata6 is expressed selectively in resident peritoneal macrophages. We thus examined whether the loss of Gata6 in the macrophage compartment affected peritoneal macrophages, using Lyz2-Cre x Gata6flox/flox mice to tackle this issue. In Lyz2-Cre x Gata6flox/flox mice, the resident peritoneal macrophage compartment, but not macrophages in other organs, was contracted, with only a third the normal number of macrophages remaining. Heightened rates of death explained the marked decrease in peritoneal macrophage observed. The metabolism of the remaining macrophages was skewed to favor oxidative phosphorylation and alternative activation markers were spontaneously and selectively induced in Gata6-deficient macrophages. Gene expression profiling revealed perturbed metabolic regulators, including aspartoacylase (Aspa), which facilitates generation of acetyl CoA. Mutant mice lacking functional Aspa phenocopied the higher propensity to death and led to a contraction of resident peritoneal macrophages. Thus, Gata6 regulates differentiation, metabolism, and survival of resident peritoneal macrophages

Migratory CD103+ dendritic cells suppress helminth-driven type 2 immunity through constitutive expression of IL-12

CD8alpha(+) and CD103(+) dendritic cells (DCs) play a central role in the development of type 1 immune responses. However, their role in type 2 immunity remains unclear. We examined this issue using Batf3(-/-) mice, in which both of these DC subsets are missing. We found that Th2 cell responses, and related events such as eosinophilia, alternative macrophage activation, and immunoglobulin class switching to IgG1, were enhanced in Batf3(-/-) mice responding to helminth parasites. This had beneficial or detrimental consequences depending on the context. For example, Batf3 deficiency converted a normally chronic intestinal infection with Heligmosomoides polygyrus into an infection that was rapidly controlled. However, liver fibrosis, an IL-13-mediated pathological consequence of wound healing in chronic schistosomiasis, was exacerbated in Batf3(-/-) mice infected with Schistosoma mansoni. Mechanistically, steady-state production of IL-12 by migratory CD103(+) DCs, independent of signals from commensals or TLR-initiated events, was necessary and sufficient to exert the suppressive effects on Th2 response development. These findings identify a previously unrecognized role for migratory CD103(+) DCs in antagonizing type 2 immune responses

IL-10R Blockade during Chronic Schistosomiasis Mansoni Results in the Loss of B Cells from the Liver and the Development of Severe Pulmonary Disease

In schistosomiasis patients, parasite eggs trapped in hepatic sinusoids become foci for CD4+ T cell-orchestrated granulomatous cellular infiltrates. Since the immune response is unable to clear the infection, the liver is subjected to ongoing cycles of focal inflammation and healing that lead to vascular obstruction and tissue fibrosis. This is mitigated by regulatory mechanisms that develop over time and which minimize the inflammatory response to newly deposited eggs. Exploring changes in the hepatic inflammatory infiltrate over time in infected mice, we found an accumulation of schistosome egg antigen-specific IgG1-secreting plasma cells during chronic infection. This population was significantly diminished by blockade of the receptor for IL-10, a cytokine implicated in plasma cell development. Strikingly, IL-10R blockade precipitated the development of portal hypertension and the accumulation of parasite eggs in the lungs and heart. This did not reflect more aggressive Th2 cell responsiveness, increased hepatic fibrosis, or the emergence of Th1 or Th17 responses. Rather, a role for antibody in the prevention of severe disease was suggested by the finding that pulmonary involvement was also apparent in mice unable to secrete class switched antibody. A major effect of anti-IL-10R treatment was the loss of a myeloid population that stained positively for surface IgG1, and which exhibited characteristics of regulatory/anti-inflammatory macrophages. This finding suggests that antibody may promote protective effects within the liver through local interactions with macrophages. In summary, our data describe a role for IL-10-dependent B cell responses in the regulation of tissue damage during a chronic helminth infection

Schistosoma mansoni Infection-Induced Transcriptional Changes in Hepatic Macrophage Metabolism Correlate With an Athero-Protective Phenotype

<p> Hepatic macrophages play an essential role in the granulomatous response to infection</p> <p>with the parasitic helminth Schistosoma mansoni , but the transcriptional changes</p> <p>that underlie this effect are poorly understood. To explore this, we sorted the two</p> <p>previously recognized hepatic macrophage populations (perivascular and Kupffer cells)</p> <p>from naïve and S. mansoni -infected male mice and performed microarray analysis as</p> <p>part of the Immunological Genome Project. The two hepatic macrophage populations</p> <p>exhibited remarkably different genomic profiles. However, this diversity was substantially</p> <p>reduced following infection with S. mansoni , and in fact, both populations demonstrated</p> <p>increases in transcripts of the monocyte lineage, suggesting that both populations</p> <p>may be replenished by monocytes following infection. Pathway analysis showed a</p> <p>profound alteration in global metabolic pathways, including changes to phospholipid</p> <p>and cholesterol metabolism, as well as amino acid biosynthesis and glucagon</p> <p>signaling. These changes suggest a possible mechanism for the previously reported</p> <p>athero-protective effects of S. mansoni infection. Indeed, we find that male ApoE null</p> <p>mice fed a high-fat diet in combination with S. mansoni infection have reduced plaque</p> <p>area and increased glucose tolerance as compared to control mice. Transcript analysis</p> <p>of infected and control high-fat diet fed ApoE−/− mice confirm that ApoC1 , Psat1 ,</p> <p>and Gys1 are all altered by infection, suggesting that altered hepatic macrophage</p> <p>metabolism is associated with S. mansoni - induced protection from hyperlipidemia,</p> <p>atherosclerosis, and glucose intolerance. These results suggest a previously unknown</p> <p>and unreported role of hepatic macrophages in the modulation of whole body lipid and</p> <p>glucose metabolism during infection and provide a template for examining the role of immunomodulation on the long-term metabolism of the host.</p

Maternal schistosomiasis impairs offspring Interleukin-4 production and B cell expansion.

Epidemiological studies have identified a correlation between maternal helminth infections and reduced immunity to some early childhood vaccinations, but the cellular basis for this is poorly understood. Here, we investigated the effects of maternal Schistosoma mansoni infection on steady-state offspring immunity, as well as immunity induced by a commercial tetanus/diphtheria vaccine using a dual IL-4 reporter mouse model of maternal schistosomiasis. We demonstrate that offspring born to S. mansoni infected mothers have reduced circulating plasma cells and peripheral lymph node follicular dendritic cells at steady state. These reductions correlate with reduced production of IL-4 by iNKT cells, the cellular source of IL-4 in the peripheral lymph node during early life. These defects in follicular dendritic cells and IL-4 production were maintained long-term with reduced secretion of IL-4 in the germinal center and reduced generation of TFH, memory B, and memory T cells in response to immunization with tetanus/diphtheria. Using single-cell RNASeq following tetanus/diphtheria immunization of offspring, we identified a defect in cell-cycle and cell-proliferation pathways in addition to a reduction in Ebf-1, a key B-cell transcription factor, in the majority of follicular B cells. These reductions are dependent on the presence of egg antigens in the mother, as offspring born to single-sex infected mothers do not have these transcriptional defects. These data indicate that maternal schistosomiasis leads to long-term defects in antigen-induced cellular immunity, and for the first time provide key mechanistic insight into the factors regulating reduced immunity in offspring born to S. mansoni infected mothers

Metabolic reprogramming of the myeloid lineage by Schistosoma mansoni infection persists independently of antigen exposure.

Macrophages have a defined role in the pathogenesis of metabolic disease and cholesterol metabolism where alternative activation of macrophages is thought to be beneficial to both glucose and cholesterol metabolism during high fat diet induced disease. It is well established that helminth infection protects from metabolic disease, but the mechanisms underlying protection are not well understood. Here, we investigated the effects of Schistosoma mansoni infection and cytokine activation in the metabolic signatures of bone marrow derived macrophages using an approach that integrated transcriptomics, metabolomics, and lipidomics in a metabolic disease prone mouse model. We demonstrate that bone marrow derived macrophages (BMDM) from S. mansoni infected male ApoE-/- mice have dramatically increased mitochondrial respiration compared to those from uninfected mice. This change is associated with increased glucose and palmitate shuttling into TCA cycle intermediates, increased accumulation of free fatty acids, and decreased accumulation of cellular cholesterol esters, tri and diglycerides, and is dependent on mgll activity. Systemic injection of IL-4 complexes is unable to recapitulate either reductions in systemic glucose AUC or the re-programing of BMDM mitochondrial respiration seen in infected males. Importantly, the metabolic reprogramming of male myeloid cells is transferrable via bone marrow transplantation to an uninfected host, indicating maintenance of reprogramming in the absence of sustained antigen exposure. Finally, schistosome induced metabolic and bone marrow modulation is sex-dependent, with infection protecting male, but not female mice from glucose intolerance and obesity. Our findings identify a transferable, long-lasting sex-dependent reprograming of the metabolic signature of macrophages by helminth infection, providing key mechanistic insight into the factors regulating the beneficial roles of helminth infection in metabolic disease

The splenic and hepatic IL-4 response is similar between anti-IL-10R and isotype control treated mice.

<p>Balb/c 4get or Balb/c 4get/KN2 mice were infected for 10 – 12 weeks and then treated bi-weekly for 4 weeks with rat anti-IL10R antibody or rat isotype control antibody, and administered BrdU for 7 days before sacrifice. Naïve Balb/c 4get or Balb/c 4get/KN2 mice were similarly treated with antibodies and BrdU. Isolated spleen cells and cells isolated from livers were analyzed by flow cytometry for expression of the markers indicated. Data shown in <b>A</b> and <b>F</b> are from gated lymphocytes. Data shown in <b>B</b> – <b>E,</b> and <b>G</b> are from gated CD4 T cells. Data shown are concatenated from 3 – 5 mice per group. Numbers show the percentages of cells that fall within indicated gates. <b>H</b>, Numbers of CD4⁺, GFP⁺ CD4+ and GFP⁺ HuCD2⁺ CD4+ T cells within liver tissues of infected or naïve mice after treatment with anti-IL-10R or control antibody. Data represent mean plus/minus SD of results from 3 – 5 mice per group. All data shown are representative of three separate experiments with 3 – 5 mice/group.</p