EGFR-driven lung adenocarcinomas coopt alveolar macrophage metabolism and function to support EGFR signaling and growth.

The limited efficacy of currently approved immunotherapies in EGFR-driven lung adenocarcinoma (LUAD) underscores the need to better understand alternative mechanisms governing local immunosuppression to fuel novel therapies. Elevated surfactant and GM-CSF secretion from the transformed epithelium induces tumor-associated alveolar macrophage (TA-AM) proliferation which supports tumor growth by rewiring inflammatory functions and lipid metabolism. TA-AM properties are driven by increased GM-CSF-PPARγ signaling and inhibition of airway GM-CSF or PPARγ in TA-AMs suppresses cholesterol efflux to tumor cells, which impairs EGFR phosphorylation and restrains LUAD progression. In the absence of TA-AM metabolic support, LUAD cells compensate by increasing cholesterol synthesis, and blocking PPARγ in TA-AMs simultaneous with statin therapy further suppresses tumor progression and increases proinflammatory immune responses. These results reveal new therapeutic combinations for immunotherapy resistant EGFR-mutant LUADs and demonstrate how cancer cells can metabolically co-opt TA-AMs through GM-CSF-PPARγ signaling to provide nutrients that promote oncogenic signaling and growth.

Prostaglandin E2 controls the metabolic adaptation of T cells to the intestinal microenvironment.

Immune cells must adapt to different environments during the course of an immune response. Here we study the adaptation of CD8+ T cells to the intestinal microenvironment and how this process shapes the establishment of the CD8+ T cell pool. CD8+ T cells progressively remodel their transcriptome and surface phenotype as they enter the gut wall, and downregulate expression of mitochondrial genes. Human and mouse intestinal CD8+ T cells have reduced mitochondrial mass, but maintain a viable energy balance to sustain their function. We find that the intestinal microenvironment is rich in prostaglandin E2 (PGE2), which drives mitochondrial depolarization in CD8+ T cells. Consequently, these cells engage autophagy to clear depolarized mitochondria, and enhance glutathione synthesis to scavenge reactive oxygen species (ROS) that result from mitochondrial depolarization. Impairing PGE2 sensing promotes CD8+ T cell accumulation in the gut, while tampering with autophagy and glutathione negatively impacts the T cell pool. Thus, a PGE2-autophagy-glutathione axis defines the metabolic adaptation of CD8+ T cells to the intestinal microenvironment, to ultimately influence the T cell pool.

EGFR-Driven Lung Adenocarcinomas Co-opt Alveolar Macrophage Metabolism and Function to Support EGFR Signaling and Growth.

The limited efficacy of currently approved immunotherapies in EGFR-driven lung adenocarcinoma (LUAD) underscores the need to better understand alternative mechanisms governing local immunosuppression to fuel novel therapies. Elevated surfactant and GM-CSF secretion from the transformed epithelium induces tumor-associated alveolar macrophage (TA-AM) proliferation, which supports tumor growth by rewiring inflammatory functions and lipid metabolism. TA-AM properties are driven by increased GM-CSF-PPARγ signaling and inhibition of airway GM-CSF or PPARγ in TA-AMs suppresses cholesterol efflux to tumor cells, which impairs EGFR phosphorylation and restrains LUAD progression. In the absence of TA-AM metabolic support, LUAD cells compensate by increasing cholesterol synthesis, and blocking PPARγ in TA-AMs simultaneous with statin therapy further suppresses tumor progression and increases proinflammatory immune responses. These results reveal new therapeutic combinations for immunotherapy-resistant EGFR-mutant LUADs and demonstrate how cancer cells can metabolically co-opt TA-AMs through GM-CSF-PPARγ signaling to provide nutrients that promote oncogenic signaling and growth. SIGNIFICANCE: Alternate strategies harnessing anticancer innate immunity are required for lung cancers with poor response rates to T cell-based immunotherapies. This study identifies a targetable, mutually supportive, metabolic relationship between macrophages and transformed epithelium, which is exploited by tumors to obtain metabolic and immunologic support to sustain proliferation and oncogenic signaling.

CD8+ T cells in the cancer-immunity cycle.

CD8+ T cells are end effectors of cancer immunity. Most forms of effective cancer immunotherapy involve CD8+ T cell effector function. Here, we review the current understanding of T cell function in cancer, focusing on key CD8+ T cell subtypes and states. We discuss factors that influence CD8+ T cell differentiation and function in cancer through a framework that incorporates the classic three-signal model and a fourth signal-metabolism-and also consider the impact of the tumor microenvironment from a T cell perspective. We argue for the notion of immunotherapies as "pro-drugs" that act to augment or modulate T cells, which ultimately serve as the drug in vivo, and for the importance of overall immune health in cancer treatment and prevention. The progress in understanding T cell function in cancer has and will continue to improve harnessing of the immune system across broader tumor types to benefit more patients.

The ß1-adrenergic receptor links sympathetic nerves to T cell exhaustion.

CD8+ T cells are essential components of the immune response against viral infections and tumours, and are capable of eliminating infected and cancerous cells. However, when the antigen cannot be cleared, T cells enter a state known as exhaustion1. Although it is clear that chronic antigen contributes to CD8+ T cell exhaustion, less is known about how stress responses in tissues regulate T cell function. Here we show a new link between the stress-associated catecholamines and the progression of T cell exhaustion through the ß1-adrenergic receptor ADRB1. We identify that exhausted CD8+ T cells increase ADRB1 expression and that exposure of ADRB1+ T cells to catecholamines suppresses their cytokine production and proliferation. Exhausted CD8+ T cells cluster around sympathetic nerves in an ADRB1-dependent manner. Ablation of ß1-adrenergic signalling limits the progression of T cells towards the exhausted state in chronic infection and improves effector functions when combined with immune checkpoint blockade (ICB) in melanoma. In a pancreatic cancer model resistant to ICB, ß-blockers and ICB synergize to boost CD8+ T cell responses and induce the development of tissue-resident memory-like T cells. Malignant disease is associated with increased catecholamine levels in patients2,3, and our results establish a connection between the sympathetic stress response, tissue innervation and T cell exhaustion. Here, we uncover a new mechanism by which blocking ß-adrenergic signalling in CD8+ T cells rejuvenates anti-tumour functions.

Friend or Foe - Tc17 cell generation and current evidence for their importance in human disease.

The term Tc17 cells refers to interleukin 17 (IL-17)-producing CD8+ T cells. While IL-17 is an important mediator of mucosal defense, it is also centrally involved in driving the inflammatory response in immune-mediated diseases, such as psoriasis, multiple sclerosis, and inflammatory bowel disease. In this review, we aim to gather the current knowledge on the phenotypic and transcriptional profile, the in vitro and in vivo generation of Tc17 cells, and the evidence pointing towards a relevant role of Tc17 cells in human diseases such as infectious diseases, cancer, and immune-mediated diseases.

Exhaustion of CD39-Expressing CD8+ T Cells in Crohn's Disease Is Linked to Clinical Outcome.

BACKGROUND & AIMS: Exhaustion of CD8 T cells has been suggested to inform different clinical outcomes in Crohn's disease, but detailed analyses are lacking. This study aimed to identify the role of exhaustion on a single-cell level and identify relevant CD8 T cell populations in Crohn's disease. METHODS: Blood and intestinal tissue from 58 patients with Crohn's disease (active disease or remission) were assessed for CD8 T cell expression of exhaustion markers and their cytokine profile by highly multiplexed flow and mass cytometry. Key disease-associated subsets were sorted and analyzed by RNA sequencing. CD39 inhibition assays were performed in vitro. RESULTS: Activated CD39+ and CD39+PD-1+ CD8 T cell subsets expressing multiple exhaustion markers were enriched at low frequency in active Crohn's disease. Their cytokine production capacity was inversely linked to the Harvey-Bradshaw Index. Subset-level protein and transcriptome profiling revealed co-existence of effector and exhaustion programs in CD39+ and CD39+ PD-1+CD8 T cells, with CD39+ cells likely originating from the intestine. CD39 enzymatic activity controlled T cell cytokine production. Importantly, transcriptional exhaustion signatures were enriched in remission in CD39-expressing subsets with up-regulation of TOX. Subset-level transcriptomics revealed a CD39-related gene module that is associated with the clinical course. CONCLUSIONS: These data showed a role for the exhaustion of peripheral CD39-expressing CD8 T cell subsets in Crohn's disease. Their low frequency illustrated the utility of single-cell cytometry methods for identification of relevant immune populations. Importantly, the link of their exhaustion status to the clinical activity and their specific gene signatures have implications for exhaustion-based personalized medicine approaches.

Ustekinumab Inhibits T Follicular Helper Cell Differentiation in Patients With Crohn's Disease.

BACKGROUND & AIMS: The pathogenesis of chronic inflammatory bowel diseases (Crohn's disease [CD] and ulcerative colitis) involves dysregulated TH1 and TH17 cell responses, which can be targeted therapeutically by the monoclonal antibody Ustekinumab directed against the joint p40 subunit of IL-12 and IL-23. These cytokines may also regulate the differentiation of T follicular helper (TFH) cells, which promote B cell function in germinal centers. However, the role of TFH cells in CD pathogenesis and impact of Ustekinumab therapy on TFH cell fate in patients are poorly defined. METHODS: Lymphocytes were isolated from peripheral blood (n=45) and intestinal biopsies (n=15) of CD patients or healthy controls (n=21) and analyzed by flow cytometry to assess TFH cell phenotypes and functions ex vivo. In addition, TFH cell differentiation was analyzed in the presence of Ustekinumab in vitro. RESULTS: TFH cell frequencies in the intestine as well as peripheral blood were associated with endoscopic as well as biochemical evidence of CD activity. CD patients with clinical response to Ustekinumab, but not those with response to anti-TNF antibodies, displayed reduced frequencies of circulating TFH cells in a concentration-dependent manner while the TFH phenotype was not affected by Ustekinumab therapy. In keeping with this notion, TFH cell differentiation was inhibited by Ustekinumab in vitro while TFH cell maintenance was not affected. Moreover, Ustekinumab therapy resulted in reduced germinal center activity in CD patients in vivo. CONCLUSIONS: These data implicate TFH cells in the pathogenesis of CD and indicate that Ustekinumab therapy affects TFH cell differentiation, which may influence TFH-mediated immune functions in UST-treated CD patients.

IL-2 contributes to cirrhosis-associated immune dysfunction by impairing follicular T helper cells in advanced cirrhosis.

BACKGROUND & AIMS: Patients with decompensated cirrhosis suffer from recurrent infections and inadequate responses to prophylactic vaccinations. However, many patients present with hypergammaglobulinemia (HGG), indicating a sustained ability to generate antibody responses. As follicular T helper (Tfh) cells are central facilitators of humoral immunity, we hypothesized that Tfh cell responses may be altered in advanced liver disease and we aimed to identify the mechanisms underlying any such alterations. METHODS: Tfh, regulatory T (Treg) cells, B cells, circulating cytokines and immunoglobulins were analyzed in cohorts of patients with compensated (n = 37) and decompensated cirrhosis (n = 82) and in non-cirrhotic controls (n = 45). Intrahepatic T cells were analyzed in 8 decompensated patients. The influence of IL-2 on Tfh cell function was evaluated in vitro, including Tfh cell cloning and T cell-B cell co-cultures with clones and primary tonsil-derived Tfh cells. RESULTS: Tfh cell frequencies were reduced in patients with decompensated cirrhosis, with phenotypic signatures indicative of increased IL-2 signaling. Soluble IL-2 receptor (sCD25) was elevated in these patients and CD4 T cells were more responsive to IL-2 signaling, as characterized by STAT5 phosphorylation. IL-2 exposure in vitro diminished the Tfh phenotype and resulted in impaired Tfh helper function in co-culture experiments with naïve B cells. Tfh cells were barely detectable in cirrhotic livers. IL-2 signatures on Tfh cells in decompensated patients correlated with immunoglobulin levels, which were found to be associated with improved survival. CONCLUSIONS: Tfh cell impairment represents a previously underestimated feature of cirrhosis-associated immune dysfunction that is driven by IL-2. The presence of HGG in decompensated patients predicts an intact Tfh cell compartment and is associated with a favorable outcome. LAY SUMMARY: Patients with advanced cirrhosis often fail to generate protective immunity after prophylactic vaccinations and suffer from recurring infections that are associated with high mortality. Follicular T helper (Tfh) cells are specialized CD4 T cells that enable the emergence of antibody responses against microbial pathogens. This report demonstrates that Tfh cells are impaired in patients with advanced cirrhosis due to interleukin-2 signaling, a cytokine that is known to impair the generation of Tfh cells.

Ustekinumab serum concentrations are associated with clinical outcomes in Crohn's disease - a regional multi-center pilot study.

BACKGROUND AND AIM: The role of therapeutic drug monitoring (TDM) in ustekinumab (UST) therapy for Crohn's disease (CD) has not been established, as only few studies have analyzed the relationship between UST serum concentrations and clinical outcome. In this pilot study, we retrospectively examined the potential of UST-concentrations (cUST) 8 weeks after induction (cUSTw8) to predict clinical response at week 16. METHODS: Serum samples and clinical data from patients (n = 72) with moderate to severely active CD who received intravenous induction with UST were retrospectively analyzed. cUST were quantitated using liquid chromatography-tandem mass spectrometry (LC-MSMS). A receiver-operating characteristic (ROC) curve and area under ROC curve (AUROC) was computed to analyze the predictive potential of cUSTw8 for clinical response at week 16 and to determine the minimal therapeutic UST trough concentration. RESULTS: Forty-four patients (61 %) achieved clinical response to UST therapy at week 16. cUSTw8 was moderately effective to predict clinical response with a minimal therapeutic cUSTw8 of 2.0 mg/l (AUC 0.72, p = 0.001). CONCLUSION: Trough concentrations of UST 8 weeks after induction predict clinical response to therapy in week 16 with moderate sensitivity and specificity. TDM using LC-MSMS could prove beneficial in personalized UST therapy of patients with CD by identifying individuals with subtherapeutic concentrations who might benefit from dose escalation.

Seasonal variability of vitamin D status in patients with inflammatory bowel disease - A retrospective cohort study.

OBJECTIVES: Vitamin D deficiency predicts unfavorable disease outcomes in inflammatory bowel disease. Endogenous vitamin D synthesis is affected by seasonal factors including sunlight exposure, raising the question whether seasonality determines the risk of vitamin D deficiency and may mask other clinical risk factors. METHODS: Univariable and multiple regression analyses were performed in a retrospective cohort of 384 patients to determine risk factors for vitamin D deficiency. Since the observed 25-hydroxyvitamin D [25(OH)D] concentrations followed a sinusoidal pattern over the year, all 25(OH)D concentrations were normalized for the predicted variability of the respective day of analysis based on a sinusoidal regression analysis of 25(OH)D test results obtained in more than 86,000 control serum samples. RESULTS: Vitamin D deficiency was highly prevalent in patients with Crohn's disease or ulcerative colitis (63% and 55%, respectively) and associated with winter/spring seasons. After normalization of 25(OH)D concentrations for the day of analysis, vitamin D deficiency was associated with histories of complications related to inflammatory bowel disease, surgery, smoking and ongoing diarrhea while initial disease manifestation during adulthood, ongoing vitamin D supplementation and diagnosis of ulcerative colitis vs. Crohn's disease appeared to be protective. Multiple regression analyses revealed that vitamin D deficiency was associated with disease activity in Crohn's disease and anemia in ulcerative colitis patients. Only few deficient patients achieved sufficient 25(OH)D concentrations over time. However, increasing 25(OH)D concentrations correlated with improved Crohn's disease activity. CONCLUSIONS: Vitamin D deficiency was highly prevalent in patients with Crohn's disease and ulcerative colitis and dependent on the season of the year. Following normalization for seasonality by sinusoidal regression analysis, vitamin D deficiency was found to be associated with parameters of complicated disease course while increasing 25(OH)D concentrations over time correlated with reduced activity of Crohn's disease.

Vitamin D Inhibits Pro-Inflammatory T Cell Function in Patients With Inflammatory Bowel Disease.

BACKGROUND AND AIMS: Dysregulated T cell responses contribute to the pathogenesis of inflammatory bowel disease [IBD]. Because vitamin D [vitD] deficiency is a risk factor for adverse disease outcomes, we aimed to characterize the impact of vitD on intestinal and peripheral T cell profiles. METHODS: T cells were isolated from peripheral blood and intestinal biopsies of IBD patients, incubated with vitD and characterized by flow cytometry. To translate these in vitro findings to the clinic, serum vitD concentrations and clinical outcomes were correlated with T cell phenotype and function in a prospective patient cohort. RESULTS: Incubation of peripheral and intestinal T cells with 1,25(OH)2-vitD resulted in strongly reduced frequencies of pro-inflammatory CD4+ and CD8+ T cells producing interferon γ [IFNγ], interleukin-17 [IL-17], IL-22, IL-9 and tumour necrosis factor [TNF]. Univariable analysis of 200 IBD patients revealed associations of vitD deficiency with non-compliant vitD intake, season of the year and anaemia in Crohn's disease [CD] as well as disease activity in ulcerative colitis [UC]. Ex vivo immunophenotyping revealed that CD4+ and CD8+ T cell subsets were not substantially altered in vitD-deficient vs vitD-sufficient patients while regulatory T cell frequencies were reduced in UC and non-smoking CD patients with vitD deficiency. However, normalization of serum vitD concentrations in previously deficient CD patients resulted in significantly reduced frequencies of CD4+ T cells producing IFNγ, IL-17 and IL-22. CONCLUSION: vitD exerts profound anti-inflammatory effects on peripheral and intestinal CD4+ and CD8+ T cells of IBD patients in vitro and inhibits TH1 and TH17 cytokine production in CD patients in vivo.

Protein-losing pseudomembranous colitis with cap polyposis-like features.

Protein-losing enteropathy (PLE) is characterized by loss of serum proteins into the gastrointestinal tract. It may lead to hypoproteinemia and clinically present as protein deficiency edema, ascites, pleural or pericardial effusion and/or malnutrition. In most cases the site of protein loss is the small intestine. Here we present an unusual case of severe PLE in a 55-year old female with a one-year history of recurrent diarrhea, crampy abdominal pain, and peripheral edema. Endoscopy and MRI showed a diffuse inflammatory thickening of the sigmoid colon and the rectum. Surgical resection of the involved colon was performed and the symptoms were significantly resolved. The final histologic evaluation confirmed a diagnosis of a pseudomembranous colitis with cap polyposis-like features. Such a cause of PLE has never been described before.