Dysregulated STAT3 signaling and T cell immunometabolic dysfunction define a targetable, high mortality subphenotype of critically ill children.

Sepsis is the leading cause of death of hospitalized children worldwide. Despite the established link between immune dysregulation and mortality in pediatric sepsis, it remains unclear which host immune factors contribute causally to adverse sepsis outcomes. Identifying modifiable pathobiology is an essential first step to successful translation of biologic insights into precision therapeutics. We designed a prospective, longitudinal cohort study of 88 critically ill pediatric patients with multiple organ dysfunction syndrome (MODS), including patients with and without sepsis, to define subphenotypes associated with targetable mechanisms of immune dysregulation. We first assessed plasma proteomic profiles and identified shared features of immune dysregulation in MODS patients with and without sepsis. We then employed consensus clustering to define three subphenotypes based on protein expression at disease onset and identified a strong association between subphenotype and clinical outcome. We next identified differences in immune cell frequency and activation state by MODS subphenotype and determined the association between hyperinflammatory pathway activation and cellular immunophenotype. Using single cell transcriptomics, we demonstrated STAT3 hyperactivation in lymphocytes from the sickest MODS subgroup and then identified an association between STAT3 hyperactivation and T cell immunometabolic dysregulation. Finally, we compared proteomics findings between patients with MODS and patients with inborn errors of immunity that amplify cytokine signaling pathways to further assess the impact of STAT3 hyperactivation in the most severe patients with MODS. Overall, these results identify a potentially pathologic and targetable role for STAT3 hyperactivation in a subset of pediatric patients with MODS who have high severity of illness and poor prognosis.

Leveraging Systems Immunology to Optimize Diagnosis and Treatment of Inborn Errors of Immunity.

Inborn errors of immunity (IEI) are monogenic disorders that can cause diverse symptoms, including recurrent infections, autoimmunity and malignancy. While many factors have contributed, the increased availability of next-generation sequencing has been central in the remarkable increase in identification of novel monogenic IEI over the past years. Throughout this phase of disease discovery, it has also become evident that a given gene variant does not always yield a consistent phenotype, while variants in seemingly disparate genes can lead to similar clinical presentations. Thus, it is increasingly clear that the clinical phenotype of an IEI patient is not defined by genetics alone, but is also impacted by a myriad of factors. Accordingly, we need methods to amplify our current diagnostic algorithms to better understand mechanisms underlying the variability in our patients and to optimize treatment. In this review, we will explore how systems immunology can contribute to optimizing both diagnosis and treatment of IEI patients by focusing on identifying and quantifying key dysregulated pathways. To improve mechanistic understanding in IEI we must deeply evaluate our rare IEI patients using multimodal strategies, allowing both the quantification of altered immune cell subsets and their functional evaluation. By studying representative controls and patients, we can identify causative pathways underlying immune cell dysfunction and move towards functional diagnosis. Attaining this deeper understanding of IEI will require a stepwise strategy. First, we need to broadly apply these methods to IEI patients to identify patterns of dysfunction. Next, using multimodal data analysis, we can identify key dysregulated pathways. Then, we must develop a core group of simple, effective functional tests that target those pathways to increase efficiency of initial diagnostic investigations, provide evidence for therapeutic selection and contribute to the mechanistic evaluation of genetic results. This core group of simple, effective functional tests, targeting key pathways, can then be equitably provided to our rare patients. Systems biology is thus poised to reframe IEI diagnosis and therapy, fostering research today that will provide streamlined diagnosis and treatment choices for our rare and complex patients in the future, as well as providing a better understanding of basic immunology.

Long-Term Outcomes and Health-Related Quality of Life in a Swiss Patient Group with Esophageal Atresia.

INTRODUCTION: Surgical treatment of esophageal atresia (EA) has markedly improved, allowing the focus to shift from short-term complications and mortality to long-term complications and quality of life. Health-related quality of life (HRQoL) is variable and reported to range from reduced to unimpaired in patients with repaired EA. We assessed the HRQoL, determined the prevalence of long-term complications and their possible impact on the HRQoL in patients who had correction of EA in Switzerland. Further, we also investigated in the general well-being of their parents. MATERIALS AND METHODS: Patients with EA repair in Switzerland between 1985 and 2011 were enrolled. Long-term complications were assessed by enquiring disease-related symptoms, standardized clinical examinations, and analysis of radiographs. HRQoL was inquired using different validated questionnaires (KIDSCREEN-27, World Health Organization [WHO]-5, and Gastrointestinal Quality of Life Index [GIQLI]). Patients were grouped according to their age. In underage patients, general well-being of the parents was assessed using the WHO-5 questionnaire. RESULTS: Thirty patients were included with a mean age of 11.3 ± 5.7 years. Long-term complications were present in 63% of all patients. HRQoL in underage patients was comparable to the provided reference values and rated as good, while adult patients reported a reduced HRQoL. The presence of gastroesophageal reflux disease symptoms was associated with reduced HRQoL in underage patients. Parents of underage patients stated a good general well-being. CONCLUSION: Long-term complications among patients with repair of EA in Switzerland are common. HRQoL in underage patients is good and general well-being of their parents is unimpaired. Adult patients reported a reduced HRQoL, consistent with other reports. As long-term complications may manifest only later in life, a structured follow-up of patients with an EA repair during childhood and adolescence is needed.

Patterns of Immune Dysregulation in Primary Immunodeficiencies: A Systematic Review.

BACKGROUND: Immune dysregulation is as important as susceptibility to infection in defining primary immunodeficiencies (PIDs). Because of the variability and nonspecificity of the symptoms of PIDs, diagnosis can be delayed-especially if a patient presents with immune dysregulation. Diagnosis is then based on certain combinations of symptoms and relies on the clinician's ability to recognize a pattern. So far there is no large report linking patterns of immune dysregulations to the underlying genetic defects. OBJECTIVE: To identify immune dysregulatory patterns associated with PIDs and to help clinicians to detect an underlying PID in certain patients with noninfectious inflammatory diseases. METHOD: A systematic literature review was performed. RESULTS: We included 186 articles that reported on n = 745 patients. The most common immune dysregulation category was "autoimmunity" (62%, n = 463), followed by "intestinal disease" (38%, n = 283) and "lymphoproliferation" (36%, n = 268). Most patients (67%) had 1 or more symptoms of immune dysregulation. Autoimmune hemolytic anemia, the most common autoimmune phenotype, was most frequently reported in patients with LPS responsive beige-like anchor protein deficiency (when combined with hypogammaglobulinemia or gastrointestinal symptoms), activation-induced cytidine deaminase deficiency (when combined with autoimmune hepatitis), or RAG1 deficiency (when it was the only symptom of immune dysregulation). Eczema, allergies, and asthma were reported in 34%, 4%, and 4% of the patients, respectively. CONCLUSION: Patterns of immune dysregulation may help the physician to recognize specific PIDs. This systematic review provides clinicians with an overview to better assess patients with immune dysregulation.

Obesity-Induced Increase in Cystatin C Alleviates Tissue Inflammation.

We recently demonstrated that removal of one kidney (uninephrectomy [UniNx]) in mice reduced high-fat diet (HFD)-induced adipose tissue inflammation, thereby improving adipose tissue and hepatic insulin sensitivity. Of note, circulating cystatin C (CysC) levels were increased in UniNx compared with sham-operated mice. Importantly, CysC may have anti-inflammatory properties, and circulating CysC levels were reported to positively correlate with obesity in humans and as shown here in HFD-fed mice. However, the causal relationship of such observation remains unclear. HFD feeding of CysC-deficient (CysC knockout [KO]) mice worsened obesity-associated adipose tissue inflammation and dysfunction, as assessed by proinflammatory macrophage accumulation. In addition, mRNA expression of proinflammatory mediators was increased, whereas markers of adipocyte differentiation were decreased. Similar to findings in adipose tissue, expression of proinflammatory cytokines was increased in liver and skeletal muscle of CysC KO mice. In line, HFD-induced hepatic insulin resistance and impairment of glucose tolerance were further aggravated in KO mice. Consistently, chow-fed CysC KO mice were more susceptible to lipopolysaccharide-induced adipose tissue inflammation. In people with obesity, circulating CysC levels correlated negatively with adipose tissue Hif1α as well as IL6 mRNA expression. Moreover, healthy (i.e., insulin-sensitive) subjects with obesity had significantly higher mRNA expression of CysC in white adipose tissue. In conclusion, CysC is upregulated under obesity conditions and thereby counteracts inflammation of peripheral insulin-sensitive tissues and, thus, obesity-associated deterioration of glucose metabolism.

Abdominal compartment syndrome and decompressive laparotomy in children: a 9-year single-center experience.

PURPOSE: Abdominal compartment syndrome (ACS) in children results in 100% mortality if left untreated. Decompressive laparotomy (DL) is the only effective treatment if conservative medical therapies have failed. This study aims to determine the incidence of ACS among pediatric patients who underwent an emergency laparotomy (EL), to describe the effect of DL on clinical and laboratory parameters and, to make a better prediction on fatal outcome, to analyze variables and their association with mortality. METHODS: This retrospective study includes 418 children up to the age of 16 years who underwent EL between January 2010 and December 2018 at our tertiary pediatric referral center. ACS was defined according to the latest guidelines of the World Society of the Abdominal Compartment Syndrome. RESULTS: Fourteen patients had emergency DL for ACS. 6 h preoperatively; median intra-abdominal pressure (IAP) and abdominal perfusion pressure (APP) were 22.5 mmHg and 29 mmHg, respectively. After DL, IAP decreased and APP increased, both by an average of 60%. Six patients survived, eight patients had a fatal outcome, resulting in a mortality of 57%. An age under 1 year, weight under the 3rd percentile, an open abdomen treatment, an intestinal resection and an elevated serum lactate > 1.8 mmol/L were associated with an increased relative risk of death. CONCLUSIONS: Improving the outcome in pediatric patients with ACS by removing or attenuating risk factors is difficult. This emphasizes the need for early diagnosis and prompt DL once the diagnosis of ACS is made.

Distinct molecular response patterns of activating STAT3 mutations associate with penetrance of lymphoproliferation and autoimmunity.

Germline STAT3 gain-of-function (GOF) mutations have been linked to poly-autoimmunity and lymphoproliferation with variable expressivity and incomplete penetrance. Here we studied the impact of 17 different STAT3 GOF mutations on the canonical STAT3 signaling pathway and correlated the molecular results with clinical manifestations. The mutations clustered in three groups. Group 1 mutants showed altered STAT3 phosphorylation kinetics and strong basal transcriptional activity. They were associated with the highest penetrance of lymphoproliferation and autoimmunity. Group 2 mutants showed a strongly inducible transcriptional reporter activity and were clinically less penetrant. Group 3 mutants were mostly located in the DNA binding domain and showed the strongest DNA binding affinity despite a poor transcriptional reporter response. Thus, the GOF effect of STAT3 mutations is determined by a heterogeneous response pattern at the molecular level. The correlation of response pattern and clinical penetrance indicates a significant contribution of mutation-determined effects on disease manifestations.

Epithelial proliferation in inflammatory skin disease is regulated by tetratricopeptide repeat domain 7 (Ttc7) in fibroblasts and lymphocytes.

BACKGROUND: Mutations in tetratricopeptide repeat domain 7A (TTC7A) and its mouse orthologue, Ttc7, result in a multisystemic disease, mostly affecting the epithelial barriers and immune system. Despite successful hematopoietic stem cell transplantation, ongoing progression of gastrointestinal manifestations can be life-threatening in TTC7A-deficient patients. OBJECTIVE: We sought to identify whether TTC7A mutations dysregulate epithelial cells only or whether a cell-intrinsic defect in lymphocytes or other cells contributes to disease manifestations. METHODS: Ttc7-mutated (Ttc7fsn/fsn) mice were crossed to generate double-mutant (Rag2-/-Ttc7fsn/fsn) and triple-mutant (Rag2-/-IL2rg-/-Ttc7fsn/fsn) mice. These models, together with bone marrow chimeras, were used to explore the role of adaptive and innate lymphocytes in the flaky skin phenotype. The effect of the Ttc7fsn/fsn mutation on stromal cells was tested in a xenograft model in conjunction with transcriptomic analysis of Ttc7fsn/fsn fibroblasts. RESULTS: We observed that the severity of epithelial hyperproliferation was accentuated by lymphocytes, whereas the phenotype was not induced by transfer of Ttc7-mutated hematopoietic cells. Furthermore, mice completely lacking the lymphocytic compartment were not protected from epithelial hyperproliferation. Ttc7-mutated mouse fibroblasts expressed increased transcript levels of insulin-like growth factor 1 (Igf1) and the antimicrobial protein regenerating islet-derived protein 3γ (Reg3γ). In a xenograft model Ttc7-mutated fibroblasts markedly increased epithelial proliferation of keratinocytes. Thus Ttc7-mutated fibroblasts were identified as potent instigators of epithelial hyperproliferation. CONCLUSION: Our results reveal a previously unsuspected fundamental cell-extrinsic role of Ttc7. We have identified potential candidates for molecularly targeted treatment strategies that will need to be evaluated in future preclinical studies.

MHC-II Deficiency Among Egyptians: Novel Mutations and Unique Phenotypes.

BACKGROUND: MHC class II deficiency leads to defective CD4+ T-cell function that results from impaired antigen presentation. A genetic disorder in 1 of 4 genes results in this syndrome that is associated with the clinical phenotype of combined immunodeficiency. OBJECTIVE: To describe the clinical, immunological, and molecular characteristics of 10 Egyptian patients from 9 different families having presented with MHC class II deficiency between 2012 and 2017. METHODS: An initial diagnosis based on the combination of clinical features and low HLA-DR expression by flow cytometry was confirmed by genetic analyses. RESULTS: Symptoms included failure to thrive (n = 9), persistent diarrhea (n = 5), and pneumonia (n = 8). Septicemia due to coagulase-negative staphylococci (n = 1) and Candida krusei (n = 1) was diagnosed. Nine patients orally received the live attenuated polio vaccine, of whom 3 developed acute flaccid paralysis thereafter. Nine patients received the BCG vaccine and none developed obvious signs of BCGitis. Four patients carried RFXANK gene mutations, 3 carried RFX5 gene mutations, 1 carried a CIITA gene mutation, and none carried RFXAP gene mutations. Six of the 7 detected mutations were previously unreported mutations: c.431T>C, c.247_250delTCAG, and c.600delG in the RFXANK gene; c.116+1G>A and c.715C>T in the RFX5 gene; and c.929delA in the CIITA gene. CONCLUSIONS: Given that Egypt is a North African country with a high rate of consanguinity, MHC class II deficiency is not rare. However, the molecular defects differ from those reported in nearby countries. Early diagnosis must be based on suspicious clinical signs and laboratory diagnosis because the defect can be missed by T-cell receptor excision circles based on neonatal screening.

Lymphadenopathy driven by TCR-Vγ8Vδ1 T-cell expansion in FAS-related autoimmune lymphoproliferative syndrome.

FAS-dependent apoptosis in Vδ1 T cells makes the latter possible culprits for the lymphadenopathy observed in patients with FAS mutations.Rapamycin and methylprednisolone resistance should prompt clinicians to look for Vδ1 T cell proliferation in ALPS-FAS patients.

Differential expression of epithelial­mesenchymal transition and stem cell markers in intrinsic subtypes of breast cancer.

The transcription factors SLUG and SOX9 have been shown to define mammary stem cell state. Similarly, epithelial­mesenchymal transition (EMT) markers (E-Cadherin, mTOR) have been shown to play a role in tumor-progression and metastatic potential in breast cancer. Finally, SOX10 is known to be expressed in breast cancer as well. The overexpressions of EMT and stem cell markers have been shown to correlate with poor overall survival. In this study, we examined whether the expression of these markers correlates with intrinsic subtypes of breast cancer and whether there is a prognostic difference in their expression-profile. We analyzed 617 breast cancer samples from two tissue micro arrays. Breast cancer samples were categorized into three groups according to hormone receptor expression and HER2-status as Luminal A/B, HER2-positive, and triple negative subgroup. Immunohistochemical expressions of SLUG, SOX9, SOX10, E-Cadherin, and mTOR were semi-quantitatively analyzed using a two-tiered and three-tiered scoring system in which cytoplasmic and nuclear stains were considered. Strong nuclear expression of SLUG was observed preferentially in triple negative but not in Luminal A/B or HER2-positive cases (24 vs. 3 and 0 %, p < 0.001). Loss of SOX9 in the nuclear stain was less frequent in triple negative than in Luminal A/B or HER2-positive cases (4 vs. 9 vs. 13 %, p < 0.001). Expression of nuclear SOX10 was lower in triple negative than in Luminal A/B and HER2-positive cases (67 vs.78 and 79 %, p = 0.012). E-Cadherin loss was observed only in Luminal A/B tumors (p = 0.016), no difference in the mTOR expression was seen between any of the three groups. No correlation to conventional histopathological-parameters or stage could be established in our cohort. Our study shows an inversed preferential nuclear expression of SLUG, SOX10, and SOX9 in triple negative and non-triple negative cases. This information is important in understanding the biology of triple negative breast cancer, also in terms of future studies dealing with targeted therapies based on the alterations of EMT and stem cell markers.

Photochemical targeting of antigens to the cytosol for stimulation of MHC class-I-restricted T-cell responses.

Tumour chemotherapy with drugs is typically associated with severe systemic and local side effects for which reason immunotherapy represents a safer alternative. However, vaccination often fails to generate the required cytotoxic CD8 T-cell responses due to insufficient access of antigens to the cytosol and the MHC class I pathway of antigen presentation. One important issue of tumour research is therefore to develop strategies that allow cytosolic targeting or endosomal escape of tumour antigens. The objective of the current study was to test whether endocytosed antigen could be delivered to MHC class I by means of photochemical internalisation (PCI). Briefly, the antigen and the photosensitiser Amphinex were loaded in vitro onto bone-marrow-derived murine dendritic cells (DCs). After light activation, which is supposed to cause disruption of OVA- and Amphinex-containing endosomes, the DCs were cultured with OVA-specific CD8 T cells or used for immunisation of mice. PCI facilitated CD8 T-cell responses as measured by IFN-γ secretion in vitro and CD8 T-cell proliferation in vivo. In conclusion, the current proof-of-concept study is the first to describe PCI-mediated immunisation and the results revealed the feasibility of this novel technology in autologous vaccination for stimulation of CD8 T-cell responses.