BTK drives neutrophil activation for sterilizing antifungal immunity.

We describe a previously-unappreciated role for Bruton's tyrosine kinase (BTK) in fungal immune surveillance against aspergillosis, an unforeseen complication of BTK inhibitors (BTKi) used for treating B-cell lymphoid malignancies. We studied BTK-dependent fungal responses in neutrophils from diverse populations, including healthy donors, BTKi-treated patients, and X-linked agammaglobulinemia patients. Upon fungal exposure, BTK was activated in human neutrophils in a TLR2-, Dectin-1-, and FcγR-dependent manner, triggering the oxidative burst. BTK inhibition selectively impeded neutrophil-mediated damage to Aspergillus hyphae, primary granule release, and the fungus-induced oxidative burst by abrogating NADPH oxidase subunit p40phox and GTPase RAC2 activation. Moreover, neutrophil-specific Btk deletion in mice enhanced aspergillosis susceptibility by impairing neutrophil function, not recruitment or lifespan. Conversely, GM-CSF partially mitigated these deficits by enhancing p47phox activation. Our findings underline the crucial role of BTK signaling in neutrophils for antifungal immunity and provide a rationale for GM-CSF use to offset these deficits in susceptible patients.

Prospective evaluation of patients with non-cirrhotic portal hypertension: A single centre study.

BACKGROUND: Non-cirrhotic portal hypertension (NCPH) is a spectrum of liver diseases, including porto-sinusoidal vascular disorder, with portal hypertension (PH) in the absence of cirrhosis. The natural history and diagnostic approach to NCPH are not well understood. AIM: We aimed to evaluate disease progression and outcomes in NCPH. METHODS: Patients with or at risk for NCPH were enrolled in a single centre prospective study; two groups were formed based on the presence of specific features of PH, such as varices, collaterals, portal hypertensive gastropathy or portal hypertensive bleeding. All participants underwent a baseline liver biopsy. Liver stiffness measurement (LSM), and imaging were repeated every 6-12 months. RESULTS: Fifteen patients without specific features of PH (Group I), and 35 patients with specific features (Group II) were enrolled. The median follow-up time was 50 months. Group II had higher hepatic venous pressure gradients, non-invasive measures of PH and a lower platelet count (PLT) when compared to Group I. Rates of survival and decompensation were similar in both groups. Patients with PLT ≤100 K/mcL had lower survival compared to those with PLT >100 K/mcL. Patients with LSM ≥10 kPa had lower survival and survival without decompensation when compared to patients with LSM <10 kPa. CONCLUSIONS: Patients irrespective of specific features of PH had similar survival or survival without decompensation. Patients without specific features are at risk for disease progression and should be monitored closely. Thrombocytopenia and increased LSM are associated with severe forms of liver disease, which are strongly associated with outcomes.

Evaluating the efficacy and safety of pozelimab in patients with CD55 deficiency with hyperactivation of complement, angiopathic thrombosis, and protein-losing enteropathy disease: an open-label phase 2 and 3 study.

BACKGROUND: CD55 deficiency with hyperactivation of complement, angiopathic thrombosis, and protein-losing enteropathy (CHAPLE) is an ultra-rare genetic disorder characterised by intestinal lymphatic damage, lymphangiectasia, and protein-losing enteropathy caused by overactivation of the complement system. We assessed the efficacy and safety of pozelimab, an antibody blocking complement component 5. METHODS: This open-label, single-arm, historically controlled, multicentre phase 2 and 3 study evaluated ten patients with CHAPLE disease. This study was conducted at three hospitals in Thailand, Türkiye, and the USA. Patients aged 1 year or older with a clinical diagnosis of CHAPLE disease and a CD55 loss-of-function variant identified by genetic analysis and confirmed by flow cytometry or western blot of CD55 from peripheral blood cells were eligible for this study. Patients received a single intravenous loading dose of pozelimab 30 mg per kg of bodyweight, followed by a once-per-week subcutaneous dose over the treatment period based on bodyweight at a concentration of 200 mg/mL as either a single injection (<40 kg bodyweight) or two injections (≥40 kg bodyweight). The primary endpoint was proportion of patients with serum albumin normalisation with an improvement in active clinical outcomes and no worsening in inactive clinical outcomes (frequency of problematic abdominal pain, bowel movement frequency, facial oedema severity, and peripheral oedema severity) at week 24 compared with baseline, assessed in the full analysis set. This study is registered with ClinicalTrials.gov (NCT04209634) and is active but not recruiting. FINDINGS: 11 patients were recruited between Jan 27, 2020, and May 12, 2021, ten of which were enrolled in the study and included in the analysis populations. The efficacy data corresponded to all patients completing the week 48 assessment and having at least 52 weeks of treatment exposure, and the safety data included an additional 90 days of follow-up and corresponded to all patients having at least 72 weeks of treatment. Patients were predominantly paediatric (with a median age of 8·5 years), and originated from Türkiye, Syria, Thailand, and Bolivia. Patients had markedly low weight-for-age and stature-for-age at baseline, and mean albumin at baseline was 2·2 g/dL, which was considerably less than the local laboratory reference range. After pozelimab treatment, all ten patients had serum albumin normalisation and improvement with no worsening in clinical outcomes. There was a complete inhibition of the total complement activity. Nine patients had adverse events; two were severe events, and one patient had an adverse event considered related to pozelimab. INTERPRETATION: Pozelimab inhibits complement overactivation and resolves the clinical and laboratory manifestations of CHAPLE disease. Pozelimab is the only currently approved therapeutic drug for patients with this life-threatening, ultra-rare condition. In patients with protein-losing enteropathy where known causes have been excluded, testing for a CD55 deficiency should be contemplated. A diagnosis of CHAPLE disease should lead to early consideration of treatment with pozelimab. FUNDING: Regeneron Pharmaceuticals and the Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health.

Blau syndrome NOD2 mutations result in loss of NOD2 cross-regulatory function.

The studies described here provide an analysis of the pathogenesis of Blau syndrome and thereby the function of NOD2 as seen through the lens of its dysfunction resulting from Blau-associated NOD2 mutations in its nucleotide-binding domain (NBD). As such, this analysis also sheds light on the role of NOD2 risk polymorphisms in the LRR domain occurring in Crohn's disease. The main finding was that Blau NOD2 mutations precipitate a loss of canonical NOD2 signaling via RIPK2 and that this loss has two consequences: first, it results in defective NOD2 ligand (MDP)-mediated NF-κB activation and second, it disrupts NOD2-mediated cross-regulation whereby NOD2 downregulates concomitant innate (TLR) responses. Strong evidence is also presented favoring the view that NOD2-mediated cross-regulation is under mechanistic control by IRF4 and that failure to up-regulate this factor because of faulty NOD2 signaling is the proximal cause of defective cross-regulation and the latter's effect on Blau syndrome inflammation. Overall, these studies highlight the role of NOD2 as a regulatory factor and thus provide additional insight into its function in inflammatory disease. Mutations in the nucleotide binding domain of the CARD15 (NOD2) gene underlie the granulomatous inflammation characterizing Blau syndrome (BS). In studies probing the mechanism of this inflammation we show here that NOD2 plasmids expressing various Blau mutations in HEK293 cells result in reduced NOD2 activation of RIPK2 and correspondingly reduced NOD2 activation of NF-κB. These in vitro studies of NOD2 signaling were accompanied by in vivo studies showing that BS-NOD2 also exhibit defects in cross-regulation of innate responses underlying inflammation. Thus, whereas over-expressed intact NOD2 suppresses TNBS-colitis, over-expressed BS-NOD2 does not; in addition, whereas administration of NOD2 ligand (muramyl dipeptide, MDP) suppresses DSS-colitis in Wild Type (WT) mice it fails to do so in homozygous or heterozygous mice bearing a NOD2 Blau mutation. Similarly, mice bearing a Blau mutation exhibit enhanced anti-collagen antibody-induced arthritis. The basis of such cross-regulatory failure was revealed in studies showing that MDP-stimulated cells bearing BS-NOD2 exhibit a reduced capacity to signal via RIPK2 as well as a reduced capacity to up-regulate IRF4, a factor shown previously to mediate NOD2 suppression of NF-κB activation. Indeed, TLR-stimulated cells bearing a Blau mutation exhibited enhanced in vitro cytokine responses that are quieted by lentivirus transduction of IRF4. In addition, enhanced anti-collagen-induced joint inflammation in mice bearing a Blau mutation was accompanied by reduced IRF4 expression in inflamed joint tissue and IRF4 expression was reduced in MDP-stimulated cells from BS patients. Thus, inflammation characterizing Blau syndrome are caused, at least in part, by faulty canonical signaling and reduce IRF4-mediated cross-regulation.

Nodular regenerative hyperplasia in X-linked agammaglobulinemia: An underestimated and severe complication.

BACKGROUND: Late-onset complications in X-linked agammaglobulinemia (XLA) are increasingly recognized. Nodular regenerative hyperplasia (NRH) has been reported in primary immunodeficiency but data in XLA are limited. OBJECTIVES: This study sought to describe NRH prevalence, associated features, and impact in patients with XLA. METHODS: Medical records of all patients with XLA referred to the National Institutes of Health between October 1994 and June 2019 were reviewed. Liver biopsies were performed when clinically indicated. Patients were stratified into NRH+ or NRH- groups, according to their NRH biopsy status. Fisher exact test and Mann-Whitney test were used for statistical comparisons. RESULTS: Records of 21 patients with XLA were reviewed, with a cumulative follow-up of 129 patient-years. Eight patients underwent ≥1 liver biopsy of whom 6 (29% of the National Institutes of Health XLA cohort) were NRH+. The median age at NRH diagnosis was 20 years (range, 17-31). Among patients who had liver biopsies, alkaline phosphatase levels were only increased in patients who were NRH+ (P = .04). Persistently low platelet count (<100,000 per µL for >6 months), mildly to highly elevated hepatic venous pressure gradient and either hepatomegaly and/or splenomegaly were present in all patients who were NRH+. In opposition, persistently low platelet counts were not seen in patients who were NRH-, and hepatosplenomegaly was observed in only 1 patient who was NRH-. Hepatic venous pressure gradient was normal in the only patient tested who was NRH-. All-cause mortality was higher among patients who were NRH+ (5 of 6, 83%) than in the rest of the cohort (1 of 15, 7% among patients who were NRH- and who were classified as unknown; P = .002). CONCLUSIONS: NRH is an underreported, frequent, and severe complication in XLA, which is associated with increased morbidity and mortality.

Robust Antibody and T Cell Responses to SARS-CoV-2 in Patients with Antibody Deficiency.

Immunocompromised patients, including those with inborn errors of immunity (IEI), may be at increased risk for severe or prolonged infections with SARS-CoV-2 (Zhu et al. N Engl J Med. 382:727-33, 2020; Guan et al. 2020; Minotti et al. J Infect. 81:e61-6, 2020). While antibody and T cell responses to SARS-CoV-2 structural proteins are well described in healthy convalescent donors, adaptive humoral and cellular immunity has not yet been characterized in patients with antibody deficiency (Grifoni et al. Cell. 181:1489-1501 e1415, 2020; Burbelo et al. 2020; Long et al. Nat Med. 26:845-8, 2020; Braun et al. 2020). Herein, we describe the clinical course, antibody, and T cell responses to SARS-CoV-2 structural proteins in a cohort of adult and pediatric patients with antibody deficiencies (n = 5) and controls (related and unrelated) infected with SARS-CoV-2. Five patients within the same family (3 with antibody deficiency, 2 immunocompetent controls) showed antibody responses to nucleocapsid and spike proteins, as well as SARS-CoV-2 specific T cell immunity at days 65-84 from onset of symptoms. No significant difference was identified between immunocompromised patients and controls. Two additional unrelated, adult patients with common variable immune deficiency were assessed. One did not show antibody response, but both demonstrated SARS-CoV-2-specific T cell immunity when evaluated 33 and 76 days, respectively, following SARS-CoV-2 diagnosis. This report is the first to show robust T cell activity and humoral immunity against SARS-CoV-2 structural proteins in some patients with antibody deficiency. Given the reliance on spike protein in most candidate vaccines (Folegatti et al. Lancet. 396:467-78, 2020; Jackson et al. N Engl J Med. 383:1920-31, 2020), the responses are encouraging. Additional studies will be needed to further define the timing of onset of immunity, longevity of the immune response, and variability of response in immunocompromised patients.

Purification of T Cell Populations.

This article describes a procedure for isolating T cell subpopulations using various methods including indirect panning and immunopanning by microarray. In these methods, cells are selected by their capacity to bind to antibody-coated plates (or slides) on the basis of particular cell-surface markers. Such methods can be superior to the antibody/complement lysis method (Alternate Protocol), as they can select additional cell population for analysis. © 2020 by John Wiley & Sons, Inc. Basic Protocol 1: Isolation of T cell populations by indirect panning Basic Protocol 2: Immunopanning with microarray Alternate Protocol: Isolation of T cell populations by antibody/complement-mediated cytotoxicity.

Bruton tyrosine kinase deficiency augments NLRP3 inflammasome activation and causes IL-1ß-mediated colitis.

Bruton tyrosine kinase (BTK) is present in a wide variety of cells and may thus have important non-B cell functions. Here, we explored the function of this kinase in macrophages with studies of its regulation of the NLR family, pyrin domain-containing 3 (NLRP3) inflammasome. We found that bone marrow-derived macrophages (BMDMs) from BTK-deficient mice or monocytes from patients with X-linked agammaglobulinemia (XLA) exhibited increased NLRP3 inflammasome activity; this was also the case for BMDMs exposed to low doses of BTK inhibitors such as ibrutinib and for monocytes from patients with chronic lymphocytic leukemia being treated with ibrutinib. In mechanistic studies, we found that BTK bound to NLRP3 during the priming phase of inflammasome activation and, in doing so, inhibited LPS- and nigericin-induced assembly of the NLRP3 inflammasome during the activation phase of inflammasome activation. This inhibitory effect was caused by BTK inhibition of protein phosphatase 2A-mediated (PP2A-mediated) dephosphorylation of Ser5 in the pyrin domain of NLRP3. Finally, we show that BTK-deficient mice were subject to severe experimental colitis and that such colitis was normalized by administration of anti-IL-ß or anakinra, an inhibitor of IL-1ß signaling. Together, these studies strongly suggest that BTK functions as a physiologic inhibitor of NLRP3 inflammasome activation and explain why patients with XLA are prone to develop Crohn's disease.

RICK/RIP2 is a NOD2-independent nodal point of gut inflammation.

Previous studies have shown that inhibition of receptor-interacting serine/threonine kinase (RICK) (also known as RIP2) results in amelioration of experimental colitis. This role has largely been attributed to nucleotide-binding oligomerization domain 2 (NOD2) signaling since the latter is considered a major inducer of RICK activation. In this study, we explored the molecular mechanisms accounting for RICK-mediated inhibition of inflammatory bowel disease (IBD). In an initial series of studies focused on trinitrobenzene sulfonic acid (TNBS)-colitis and dextran sodium sulfate (DSS)-colitis we showed that down-regulation of intestinal RICK expression in NOD2-intact mice by intra-rectal administration of a plasmid expressing RICK-specific siRNA was accompanied by down-regulation of pro-inflammatory cytokine responses in the colon and protection of the mice from experimental colitis. Somewhat surprisingly, intra-rectal administration of RICK-siRNA also inhibited TNBS-colitis and DSS-colitis in NOD2-deficient and in NOD1/NOD2-double deficient mice. In complementary studies of humans with IBD we found that expression of RICK, cellular inhibitor of apoptosis protein 2 (cIAP2) and downstream signaling partners were markedly increased in inflamed tissue of IBD compared to controls without marked elevations of NOD1 or NOD2 expression. In addition, the increase in RICK expression correlated with disease activity and pro-inflammatory cytokine responses. These studies thus suggest that NOD1- or NOD2-independenent activation of RICK plays a major role in both murine experimental colitis and human IBD.

The Role of NLRP3 and IL-1ß in the Pathogenesis of Inflammatory Bowel Disease.

It is logical to assume that a major pro-inflammatory mechanism, i.e., the NLRP3 inflammasome would play a prominent role in the pathogenesis of the Inflammatory Bowel Disease (IBD) in humans. However, while both studies of murine models of gut disease and patients provide data that the main cytokine product generated by this inflammasome, IL-1ß, does in fact contribute to inflammation in IBD, there is no evidence that IL-1ß plays a decisive or prominent role in "ordinary" patients with IBD (Crohn's disease). On the other hand, there are several definable point mutations that result in over-active NLRP3 inflammasome activity and in these cases, the gut inflammation is driven by IL-1ß and is treatable by biologic agents that block the effects of this cytokine.

Suppression effect on IFN-γ of adipose tissue-derived mesenchymal stem cells isolated from ß2-microglobulin-deficient mice.

Administration of bone marrow-derived mesenchymal stem cells (MSCs) is a possible treatment for graft-versus-host disease (GVHD) following allogeneic hematopoietic stem cell transplantation and other inflammatory conditions. To address the mechanism of immunosuppression by MSCs, in particular those derived from adipose tissue (AMSCs), AMSCs were isolated from three different mouse strains, and the suppressive capacity of the AMSCs thus obtained to suppress interferon (IFN)-γ generation in mixed lymphocyte reaction cultures serving as an in vitro model of GVHD were assessed. It was revealed that the AMSCs had a potent capacity to suppress IFN-γ production regardless of their strain of origin and that such suppression was not associated with production of interleukin-10. In addition, the results demonstrated that ß2-microglobulin (ß2m)-deficient AMSCs from ß2m-/- mice were also potent suppressor cells, verifying the fact that the mechanism underlying the suppression by AMSCs is independent of major histocompatibility complex (MHC) class I expression or MHC compatibility. As AMSCs appear to have immunosuppressive properties, AMSCs may be a useful source of biological suppressor cells for the control of GVHD in humans.

CVID enteropathy is characterized by exceeding low mucosal IgA levels and interferon-driven inflammation possibly related to the presence of a pathobiont.

Common variable immunodeficiency (CVID), the most common symptomatic primary antibody deficiency, is accompanied in some patients by a duodenal inflammation and malabsorption syndrome known as CVID enteropathy (E-CVID).The goal of this study was to investigate the immunological abnormalities in CVID patients that lead to enteropathy as well as the contribution of intestinal microbiota to this process.We found that, in contrast to noE-CVID patients (without enteropathy), E-CVID patients have exceedingly low levels of IgA in duodenal tissues. In addition, using transkingdom network analysis of the duodenal microbiome, we identified Acinetobacter baumannii as a candidate pathobiont in E-CVID. Finally, we found that E-CVID patients exhibit a pronounced activation of immune genes and down-regulation of epithelial lipid metabolism genes. We conclude that in the virtual absence of mucosal IgA, pathobionts such as A. baumannii, may induce inflammation that re-directs intestinal molecular pathways from lipid metabolism to immune processes responsible for enteropathy.

Spleen and Liver Volumetrics as Surrogate Markers of Hepatic Venous Pressure Gradient in Patients With Noncirrhotic Portal Hypertension.

Noncirrhotic portal hypertension (NCPH) is a rare disease that may lead to serious clinical consequences. Currently, noninvasive tools for the assessment of NCPH are absent. We investigated the utility of spleen and liver volumetrics as a marker of the presence and severity of portal hypertension in this population. A cohort of NCPH patients evaluated between 2003 and 2015 was retrospectively studied. The association of spleen and liver volumes with the hepatic venous pressure gradient (HVPG) level was evaluated using locally weighted scatterplot smoothing curves. A cohort of patients with viral hepatitis-related liver disease was used as controls. Of the 86 patients with NCPH evaluated during the study period, 75 (mean age, 35 ± 17; 73% males) were included in the final analysis. Patients with portal hypertension had significantly higher spleen and liver to body mass index (BMI) ratios compared to patients with HVPG <5 mm Hg (39.5 ± 27.9 versus 22.8 ± 10.6 cm3/kg/m2, P = 0.003; 91.1 ± 40.1 versus 71.4 ± 16.7 cm3/kg/m2, P = 0.014, for spleen/BMI and liver/BMI, respectively). In contrast to the patients with viral hepatitis, a positive linear correlation was observed in the NCPH cohort between spleen/BMI and liver/BMI (above a cutoff of 25 and 80 cm3/kg/m2, respectively) and HVPG level. Additionally, only in the NCPH cohort was an increase in spleen/BMI range quartile predictive of a higher prevalence of portal hypertension and clinically significant portal hypertension (trend, P = 0.014 and 0.031, respectively). Conclusion: Spleen and liver volumetrics may have utility in the assessment of NCPH as a noninvasive biomarker that can be performed using routine radiologic examinations. Further studies are needed to validate these findings. (Hepatology Communications 2018; 00:000-000).

An increase in LRRK2 suppresses autophagy and enhances Dectin-1-induced immunity in a mouse model of colitis.

The LRRK2/MUC19 gene region constitutes a high-risk genetic locus for the occurrence of both inflammatory bowel diseases (IBDs) and Parkinson's disease. We show that dendritic cells (DCs) from patients with Crohn's disease (CD) and lymphoblastoid cell lines derived from patients without CD but bearing a high-risk allele (rs11564258) at this locus as heterozygotes exhibited increased LRRK2 expression in vitro. To investigate the immunological consequences of this increased LRRK2 expression, we conducted studies in transgenic mice overexpressing Lrrk2 and showed that these mice exhibited more severe colitis induced by dextran sodium sulfate (DSS) than did littermate control animals. This increase in colitis severity was associated with lamina propria DCs that showed increased Dectin-1-induced NF-κB activation and proinflammatory cytokine secretion. Colitis severity was driven by LRRK2 activation of NF-κB pathway components including the TAK1 complex and TRAF6. Next, we found that membrane-associated LRRK2 (in association with TAB2) caused inactivation of Beclin-1 and inhibition of autophagy. HCT116 colon epithelial cells lacking Beclin-1 exhibited increased LRRK2 expression compared to wild-type cells, suggesting that inhibition of autophagy potentially could augment LRRK2 proinflammatory signaling. We then showed that LRRK2 inhibitors decreased Dectin-1-induced TNF-α production by mouse DCs and ameliorated DSS-induced colitis, both in control and Lrrk2 transgenic animals. Finally, we demonstrated that LRRK2 inhibitors blocked TNF-α production by cultured DCs from patients with CD. Our findings suggest that normalization of LRRK2 activation could be a therapeutic approach for treating IBD, regardless of whether a LRRK2 risk allele is involved.

Loss-of-function CARD8 mutation causes NLRP3 inflammasome activation and Crohn's disease.

In these studies, we evaluated the contribution of the NLRP3 inflammasome to Crohn's disease (CD) in a kindred containing individuals having a missense mutation in CARD8, a protein known to inhibit this inflammasome. Whole exome sequencing and PCR studies identified the affected individuals as having a V44I mutation in a single allele of the T60 isoform of CARD8. The serum levels of IL-1ß in the affected individuals were increased compared with those in healthy controls, and their peripheral monocytes produced increased amounts of IL-1ß when stimulated by NLRP3 activators. Immunoblot studies probing the basis of these findings showed that mutated T60 CARD8 failed to downregulate the NLRP3 inflammasome because it did not bind to NLRP3 and inhibit its oligomerization. In addition, these studies showed that mutated T60 CARD8 exerted a dominant-negative effect by its capacity to bind to and form oligomers with unmutated T60 or T48 CARD8 that impeded their binding to NLRP3. Finally, inflammasome activation studies revealed that intact but not mutated CARD8 prevented NLRP3 deubiquitination and serine dephosphorylation. CD due to a CARD8 mutation was not effectively treated by anti-TNF-α, but did respond to IL-1ß inhibitors. Thus, patients with anti-TNF-α-resistant CD may respond to this treatment option.

BACH2 immunodeficiency illustrates an association between super-enhancers and haploinsufficiency.

The transcriptional programs that guide lymphocyte differentiation depend on the precise expression and timing of transcription factors (TFs). The TF BACH2 is essential for T and B lymphocytes and is associated with an archetypal super-enhancer (SE). Single-nucleotide variants in the BACH2 locus are associated with several autoimmune diseases, but BACH2 mutations that cause Mendelian monogenic primary immunodeficiency have not previously been identified. Here we describe a syndrome of BACH2-related immunodeficiency and autoimmunity (BRIDA) that results from BACH2 haploinsufficiency. Affected subjects had lymphocyte-maturation defects that caused immunoglobulin deficiency and intestinal inflammation. The mutations disrupted protein stability by interfering with homodimerization or by causing aggregation. We observed analogous lymphocyte defects in Bach2-heterozygous mice. More generally, we observed that genes that cause monogenic haploinsufficient diseases were substantially enriched for TFs and SE architecture. These findings reveal a previously unrecognized feature of SE architecture in Mendelian diseases of immunity: heterozygous mutations in SE-regulated genes identified by whole-exome/genome sequencing may have greater significance than previously recognized.

Tumor growth limited to subcutaneous site vs tumor growth in pulmonary site exhibit differential effects on systemic immunities.

To evaluate systemic immunity associated with tumor growth limited to a subcutaneous site versus growth proceeding at multiple tumor sites, we established syngeneic mouse subcutaneous and pulmonary tumor models by local subcutaneous and intravenous injection of colon carcinoma CT26 cells. We found that splenic myeloid-derived suppressor cell (MDSC) levels were significantly increased in the subcutaneous tumor model but not in the pulmonary tumor model. Furthermore, both CD4+ and CD8+ T cells as well as CD4+ Foxp3+ T cells were significantly decreased in the subcutaneous tumor model and were largely unchanged in the pulmonary tumor model. In addition, the subcutaneous model, but not the pulmonary model, displayed a Th1 polarization bias. This bias was characterized by decreased IL-4, IL-9, and IL-10 production, whereas the pulmonary model displayed increased production of IL-10. These results suggest that the mode of tumor development has differential effects on systemic immunity that may, in turn, influence approaches to treatment of cancer patients.

Akkermansia muciniphila mediates negative effects of IFNγ on glucose metabolism.

Cross-talk between the gut microbiota and the host immune system regulates host metabolism, and its dysregulation can cause metabolic disease. Here, we show that the gut microbe Akkermansia muciniphila can mediate negative effects of IFNγ on glucose tolerance. In IFNγ-deficient mice, A. muciniphila is significantly increased and restoration of IFNγ levels reduces A. muciniphila abundance. We further show that IFNγ-knockout mice whose microbiota does not contain A. muciniphila do not show improvement in glucose tolerance and adding back A. muciniphila promoted enhanced glucose tolerance. We go on to identify Irgm1 as an IFNγ-regulated gene in the mouse ileum that controls gut A. muciniphila levels. A. muciniphila is also linked to IFNγ-regulated gene expression in the intestine and glucose parameters in humans, suggesting that this trialogue between IFNγ, A. muciniphila and glucose tolerance might be an evolutionally conserved mechanism regulating metabolic health in mice and humans.