Targeted Proteomics Reveals Inflammatory Pathways that Classify Immune Dysregulation in Common Variable Immunodeficiency

Patients with common variable immunodeficiency (CVID) can develop immune dysregulation complications such as autoimmunity, lymphoproliferation, enteritis, and malignancy, which cause significant morbidity and mortality. We aimed to (i) assess the potential of serum proteomics in stratifying patients with immune dysregulation using two independent cohorts and (ii) identify cytokine and chemokine signaling pathways that underlie immune dysregulation in CVID. A panel of 180 markers was measured in two multicenter CVID cohorts using Olink Protein Extension Assay technology. A classification algorithm was trained to distinguish CVID with immune dysregulation (CVIDid, n = 14) from CVID with infections only (CVIDio, n = 16) in the training cohort, and validated on a second testing cohort (CVIDid n = 23, CVIDio n = 24). Differential expression in both cohorts was used to determine relevant signaling pathways. An elastic net classifier using MILR1, LILRB4, IL10, IL12RB1, and CD83 could discriminate between CVIDid and CVIDio patients with a sensitivity of 0.83, specificity of 0.75, and area under the curve of 0.73 in an independent testing cohort. Activated pathways (fold change > 1.5, FDR-adjusted p < 0.05) in CVIDid included Th1 and Th17-associated signaling, as well as IL10 and other immune regulatory markers (LAG3, TNFRSF9, CD83). Targeted serum proteomics provided an accurate and reproducible tool to discriminate between patients with CVIDid and CVIDio. Cytokine profiles provided insight into activation of Th1 and Th17 pathways and indicate a possible role for chronic inflammation and exhaustion in immune dysregulation. These findings serve as a first step towards the development of biomarkers for immune dysregulation in CVID

Microbiome and Inflammation in Antibody Deficiency

Common variable immunodeficiency (CVID) is an immune deficiency that not only causes increased susceptibility to infection, but also to inflammatory complications such as autoimmunity, lymphoid proliferation, cancer and granulomatous disease. Recent findings implicate the microbiome as a driver of this systemic immune dysregulation. We investigated the role of gut and respiratory microbiota in inflammation and immune dysregulation in CVID. In this thesis we show that immune dysregulation in patients with CVID is a complex and heterogeneous disease that comprises profound chronic activation of the immune system. While previous research has already demonstrated that Immunoglobulin A (IgA), which is deficient in many CVID patients, plays a key role in homeostasis of the microbiome, we showed in a cross-sectional study in patients with stable CVID that chronic lung disease was associated with IgA deficiency and an abundance of specific oropharyngeal bacterial taxa (as compared to healthy controls). We additionally found further support for the hypothesis that a dysregulated gut microbiota contributes to systemic inflammation in CVID. In addition, we identified Enterococcus gallinarum as a pathogen of interest in CVID with immune dysregulation We conclude that in CVID, immune deficiency can result in microbial dysbiosis, including presence of specific pathogens that are associated with autoimmune disease, which exacerbates the deregulation and chronic activation of the immune system resulting in clinical disease

Immunoglobulin A and microbiota in primary immunodeficiency diseases

PURPOSE OF REVIEW: With the emergence of the microbiota as a potential driver of host inflammation, the role of iIgA is becoming increasingly important. This review discusses the current evidence regarding the effects of clinical IgA deficiency on the microbiota, and the possible role of microbial dysbiosis in driving inflammation in PID patients. RECENT FINDINGS: The gut microbiota has been investigated in selective IgA deficiency and common variable immunodeficiency, revealing an important role for IgA in maintaining gut microbiota homeostasis, with disparate effects of IgA on symbionts and pathobionts. Although IgA deficiency is associated with microbial translocation and systemic inflammation, this may be partially compensated by adequate IgG and IgM induction in IgA deficiency but not in common variable immunodeficiency. Therapeutic strategies aimed at correction of the microbiota mostly focus on fecal microbiota transplantation. Whether this may reduce systemic inflammation in PID is currently unknown. SUMMARY: Clinical IgA deficiency is associated with microbial dysbiosis and systemic inflammation. The evidence for microbiota-targeted therapies in PID is scarce, but indicates that IgA-based therapies may be beneficial, and that fecal microbiota transplantation is well tolerated in patients with antibody deficiency

Microbial Dysbiosis in Common Variable Immune Deficiencies : Evidence, Causes, and Consequences

Common variable immunodeficiency (CVID) is an immune disorder that not only causes increased susceptibility to infection, but also to inflammatory complications such as autoimmunity, lymphoid proliferation, malignancy, and granulomatous disease. Recent findings implicate the microbiome as a driver of this systemic immune dysregulation. Here, we critically review the current evidence for a role of the microbiome in the pathogenesis of CVID immune dysregulation, and describe the possible immunologic mechanisms behind causes and consequences of microbial dysbiosis in CVID. We integrate this evidence into a model describing a role for the gut microbiota in the maintenance of inflammation and immune dysregulation in CVID, and suggest research strategies to contribute to the development of new diagnostic tools and therapeutic targets

Chronically Activated T-cells Retain Their Inflammatory Properties in Common Variable Immunodeficiency

Purpose: Immune dysregulation complications cause significant morbidity and mortality in common variable immunodeficiency (CVID), but

Roux-Y Gastric Bypass and Sleeve Gastrectomy directly change gut microbiota composition independent of surgery type

Bariatric surgery in morbid obesity, either through sleeve gastrectomy (SG) or Roux-Y gastric bypass (RYGB), leads to sustainable weight loss, improvement of metabolic disorders and changes in intestinal microbiota. Yet, the relationship between changes in gut microbiota, weight loss and surgical procedure remains incompletely understood. We determined temporal changes in microbiota composition in 45 obese patients undergoing crash diet followed by SG (n = 22) or RYGB (n = 23). Intestinal microbiota composition was determined before intervention (baseline, S1), 2 weeks after crash diet (S2), and 1 week (S3), 3 months (S4) and 6 months (S5) after surgery. Relative to S1, the microbial diversity index declined at S2 and S3 (p < 0.05), and gradually returned to baseline levels at S5. Rikenellaceae relative abundance increased and Ruminococcaceae and Streptococcaceae abundance decreased at S2 (p < 0.05). At S3, Bifidobacteriaceae abundance decreased, whereas those of Streptococcaceae and Enterobacteriaceae increased (p < 0.05). Increased weight loss between S3-S5 was not associated with major changes in microbiota composition. No significant differences appeared between both surgical procedures. In conclusion, undergoing a crash diet and bariatric surgery were associated with an immediate but temporary decline in microbial diversity, with immediate and permanent changes in microbiota composition, independent of surgery type

Low IgA Associated With Oropharyngeal Microbiota Changes and Lung Disease in Primary Antibody Deficiency

Common Variable Immunodeficiency (CVID) and X-linked agammaglobulinemia (XLA) are primary antibody deficiencies characterized by hypogammaglobulinemia and recurrent infections, which can lead to structural airway disease (AD) and interstitial lung disease (ILD). We investigated associations between serum IgA, oropharyngeal microbiota composition and severity of lung disease in these patients. In this cross-sectional multicentre study we analyzed oropharyngeal microbiota composition of 86 CVID patients, 12 XLA patients and 49 healthy controls (HC) using next-generation sequencing of the 16S rRNA gene. qPCR was used to estimate bacterial load. IgA was measured in serum. High resolution CT scans were scored for severity of AD and ILD. Oropharyngeal bacterial load was increased in CVID patients with low IgA (p = 0.013) and XLA (p = 0.029) compared to HC. IgA status was associated with distinct beta (between-sample) diversity (p = 0.039), enrichment of (Allo)prevotella, and more severe radiographic lung disease (p = 0.003), independently of recent antibiotic use. AD scores were positively associated with Prevotella, Alloprevotella, and Selenomonas, and ILD scores with Streptococcus and negatively with Rothia. In clinically stable patients with CVID and XLA, radiographic lung disease was associated with IgA deficiency and expansion of distinct oropharyngeal bacterial taxa. Our findings highlight IgA as a potential driver of upper respiratory tract microbiota homeostasis

Immune dysregulation in patients with PTEN hamartoma tumor syndrome: Analysis of FOXP3 regulatory T cells

Background: Patients with heterozygous germline mutations in PTEN (phosphatase and tensin homologue deleted on chromosome 10) develop autoimmunity and lymphoid hyperplasia. Objectives: Since regulation of the phosphoinositol-3-kinase (PI3K) pathway is critical for maintaining regulatory T cell (Treg) functions we investigate Tregs in patients with heterozygous germline PTEN mutations (PTEN harmatoma tumour syndrome, PHTS). Methods: PHTS patients were assessed for immunological conditions, lymphocyte subsets, FOXP3+ Treg levels and phenotype. To determine the functional importance of phosphatases that control the PI3K pathway we assessed Treg induction in vitro, mitochondrial depolarization, and recruitment of PTEN to the immunological synapse. Results: Autoimmunity and peripheral lymphoid hyperplasia was found in 43% of 79 PHTS patients. Immune dysregulation in PHTS patients included lymphopenia, CD4+ T cell reduction and changes in T and B cell subsets. Although total CD4+FOXP3+ Treg numbers are reduced, frequencies are maintained in blood and intestine. Despite pathogenic PTEN mutations, the FOXP3+ T cells are phenotypically normal. We show that the phosphatase PHLPP downstream of PTEN is highly expressed in normal human Tregs and provides complementary phosphatase activity. PHLPP is indispensable for the differentiation of induced Tregs in vitro and Treg mitochondrial fitness. PTEN and PHLPP form a phosphatase network that is polarized at the immunological synapse. Conclusion: Heterozygous loss of function of PTEN in humans has an significant impact on T and B cell immunity. Assembly of the PTEN-PHLPP phosphatase network allows coordinated phosphatase activities at the site of T cell receptor activation, which is important for limiting PI3K hyperactivation in Tregs despite PTEN haploinsufficiency. </p