Innate defects of the IL-12/IFN-γ axis in susceptibility to infections by mycobacteria and salmonella

Protein tyrosine phosphatase 1B in metabolic diseases and drug development

Protein tyrosine phosphatase 1B (PTP1B), a non-transmembrane phosphatase, has a major role in a variety of signalling pathways, including direct negative regulation of classic insulin and leptin signalling pathways, and is implicated in the pathogenesis of several cardiometabolic diseases and cancers. As such, PTP1B has been a therapeutic target for over two decades, with PTP1B inhibitors identified either from natural sources or developed throughout the years. Some of these inhibitors have reached phase I and/or II clinical trials in humans for the treatment of type 2 diabetes mellitus, obesity and/or metastatic breast cancer. In this Review, we summarize the cellular processes and regulation of PTP1B, discuss evidence from in vivo preclinical and human studies of the association between PTP1B and different disorders, and discuss outcomes of clinical trials. We outline challenges associated with the targeting of this phosphatase (which was, until the past few years, viewed as difficult to target), the current state of the field of PTP1B inhibitors (and dual phosphatase inhibitors) and future directions for manipulating the activity of this key metabolic enzyme.

Consanguineous marriages increase the incidence of recurrent tuberculosis: Evidence from whole exome sequencing

BACKGROUND

In this study, we have identified multiple mutations in the IL-12R1 gene among Pakistani patients who have inherited them through consanguineous marriages. These patients have experienced severe Bacille-Calmette-Guérin (BCG) infection as well as recurrent tuberculosis. We will demonstrate the pivotal role of interleukin (IL)-12/interferon (IFN)-γ axis in the regulation of mycobacterial diseases.

METHODOLOGY

First, we checked the patients' medical records, and then afterward, we assessed interferon-gamma (IFN-γ) production through ELISA. Following that, DNA was extracted to investigate IL-12/IFN- abnormalities. Whole exome sequencing was conducted through Sanger sequencing. Secretory cytokine levels were compared from healthy control of the same age groups and they were found to be considerably less in the disease cohort. To evaluate the probable functional impact of these alterations, an in silico study was performed.

RESULTS

The study found that the patients' PBMCs produced considerably less IFN-γ than expected. Analysis using flow cytometry showed that activated T cells lacked surface expression of IL-12Rβ1. Exon 7 of the IL-12Rβ1 gene, which encodes a portion of the cytokine binding region (CBR), and exon 10, which encodes the fibronectin-type III (FNIII) domain, were found to have the mutations c.641 A > G; p.Q214R and c.1094 T > C; p.M365T, respectively. In silico analysis showed that these mutations likely to have a deleterious effect on protein function.

CONCLUSION

Our findings indicate the significant contribution of the IL-12/IFN-γ is in combating infections due to mycobacterium. Among Pakistani patients born to consanguineous marriages, the identified mutations in the IL-12Rβ-1 gene provide insights into the genetic basis of severe BCG infections and recurrent tuberculosis. The study highlights the potential utility of newborn screening in regions with mandatory BCG vaccination, enabling early detection and intervention for primary immunodeficiencies associated with mycobacterial infections. Moreover, the study suggests at the potential role of other related genes such as IL-23Rβ1, TYK2, or JAK2 in IFN-γ production, warranting further investigation.

Whole Exome Sequence Analysis for Inborn Errors of IL-12/IFN-γ Axis in Patient with Recurrent Typhoid Fever

Background

The IL-12/IFN-γ axis pathways play a vital role in the control of intracellular pathogens such as Salmonella typhi.

Objective

The study is aimed at using whole exome sequencing (WES) to screen out genetic defects in IL-12/IFN-γ axis in patients with recurrent typhoid fever.

Methods

WES using next-generation sequencing was performed on a single patient diagnosed with recurrent typhoid fever. Following alignment and variant calling, exomes were screened for mutations in 25 genes that are involved in the IL-12/IFN-γ axis pathway. Each variant was assessed by using various bioinformatics mutational analysis tools such as SIFT, Polyphen2, LRT, MutationTaster, and MutationAssessor.

Results

Out of 25 possible variations in the IL-12/IFN-γ axis genes, only 2 probable disease-causing mutations were identified. These variations were rare and include mutations in IL23R and ZNFX I. Other pathogenic mutations were found, but they were not considered likely to cause disease based on various mutation predictors.

Conclusion

Applying WES to the patient with recurrent typhoid fever detects variants that are not much important as other genes in the IL-12/IFN-γ axis. Results of the current study suggest that a large population sizes would be needed to examine the functional relevance of IL-12/IFN-γ axis genes with recurrent typhoid fever.

Disseminated nontuberculous mycobacterial infection in a patient with idiopathic CD4 lymphocytopenia and IFN-γ neutralizing antibodies: a case report

BACKGROUND

Disseminated nontuberculous mycobacterial (NTM) infection usually occurs in immunodeficient patients, such as those with human immunodeficiency virus infection and idiopathic CD4 lymphopenia. However, disseminated NTM diseases have also been reported in immunocompetent patients. Autoantibodies to interferon-gamma (IFN-γ) are known to be involved in disseminated NTM disease, although anti-IFN-γ antibodies are mainly seen in immunocompetent patients rather than those with immunodeficiency. Here, we report a rare case of disseminated NTM patient with idiopathic CD4 lymphopenia and anti-IFN-γ antibodies.

CASE PRESENTATION

A 64-year-old Asian male presented with fever, back pain, anorexia and weight loss. Physical examination revealed subcutaneous masses in the forehead, sternoclavicular joint, and right inguinal region. Computed tomography showed multiple osteosclerotic changes with soft structures and osteolytic changes. Both blood and sputum cultures were positive for Mycobacterium intracellulare, confirming the presence of disseminated NTM infection. Histopathological evaluation of the subcutaneous mass in the right inguinal region showed numerous granulomas consisting of epithelioid cells with Langhans-type giant cells. He was diagnosed with idiopathic CD4 lymphocytopenia. Interestingly, he also had anti-IFN-γ autoantibodies with suppression of IFN-γ-dependent signal transducer and activator of transcription 1 (STAT1) phosphorylation. Two-drug combination therapy with clarithromycin and ethambutol was started for the NTM infection, which resulted in a favorable disease course.

CONCLUSIONS

In patients with disseminated NTM infection, idiopathic CD4 lymphocytopenia and anti-IFN-γ autoantibody-positive immunodeficiency can be coexisted. It is necessary to clarify the pathogenesis and clinical course of CD4 lymphocytopenic conditions and IFN-γ neutralizing antibody-positive in the disseminated NTM disease.

A transcriptomic analysis of the effects of macrophage polarization and endotoxin tolerance on the response to Salmonella

Salmonella is an intracellular pathogen causing significant morbidity and mortality. Its ability to grow inside macrophages is important to virulence, and is dependent on the activation state of the macrophages. Classically activated M1 macrophages are non-permissive for Salmonella growth, while alternatively activated M2 macrophages are permissive for Salmonella growth. Here we showed that endotoxin-primed macrophages (MEP), such as those associated with sepsis, showed similar levels of Salmonella resistance to M1 macrophages after 2 hr of intracellular infection, but at the 4 hr and 24 hr time points were susceptible like M2 macrophages. To understand this mechanistically, transcriptomic sequencing, RNA-Seq, was performed. This showed that M1 and MEP macrophages that had not been exposed to Salmonella, demonstrated a process termed here as primed activation, in expressing relatively higher levels of particular anti-infective genes and pathways, including the JAK-STAT (Janus kinase-signal transducer and activator of transcription) pathway. In contrast, in M2 macrophages these genes and pathways were largely expressed only in response to infection. Conversely, in response to infection, M1 macrophages, but not MEP macrophages, modulated additional genes known to be associated with susceptibility to Salmonella infection, possibly contributing to the differences in resistance at later time points. Application of the JAK inhibitor Ruxolitinib before infection reduced resistance in M1 macrophages, supporting the importance of early JAK-STAT signalling in M1 resistance to Salmonella.

HLJ1 amplifies endotoxin-induced sepsis severity by promoting IL-12 heterodimerization in macrophages

Heat shock protein (HSP) 40 has emerged as a key factor in both innate and adaptive immunity, whereas the role of HLJ1, a molecular chaperone in HSP40 family, in modulating endotoxin-induced sepsis severity is still unclear. During lipopolysaccharide (LPS)-induced endotoxic shock, HLJ1 knockout mice shows reduced organ injury and IFN-γ (interferon-γ)-dependent mortality. Using single-cell RNA sequencing, we characterize mouse liver nonparenchymal cell populations under LPS stimulation, and show that HLJ1 deletion affected IFN-γ-related gene signatures in distinct immune cell clusters. In CLP models, HLJ1 deletion reduces IFN-γ expression and sepsis mortality rate when mice are treated with antibiotics. HLJ1 deficiency also leads to reduced serum levels of IL-12 in LPS-treated mice, contributing to dampened production of IFN-γ in natural killer cells but not CD4⁺ or CD8⁺ T cells, and subsequently to improved survival rate. Adoptive transfer of HLJ1-deleted macrophages into LPS-treated mice results in reduced IL-12 and IFN-γ levels and protects the mice from IFN-γ-dependent mortality. In the context of molecular mechanisms, HLJ1 is an LPS-inducible protein in macrophages and converts misfolded IL-12p35 homodimers to monomers, which maintains bioactive IL-12p70 heterodimerization and secretion. This study suggests HLJ1 causes IFN-γ-dependent septic lethality by promoting IL-12 heterodimerization, and targeting HLJ1 has therapeutic potential in inflammatory diseases involving activated IL-12/IFN-γ axis.

An Updated Review on MSMD Research Globally and A Literature Review on the Molecular Findings, Clinical Manifestations, and Treatment Approaches in China

Mendelian susceptibility to mycobacterial disease (MSMD) arises from a group of rare inherited errors of immunity that result in selective susceptibility of otherwise healthy people to clinical disease caused by low virulence strains of mycobacteria, such as Mycobacterium bovis Bacille Calmette-Guérin (BCG) and environmental mycobacteria. Patients have normal resistance to other pathogens and no overt abnormalities in routine immunological and hematological evaluations for primary immunodeficiencies. At least 19 genes and 34 clinical phenotypes have been identified in MSMD. However, there have been no systematic reports on the clinical characteristics and genetic backgrounds of MSMD in China. In this review, on the one hand, we summarize an update findings on molecular defects and immunological mechanisms in the field of MSMD research globally. On the other hand, we undertook a systematic review of PubMed (MEDLINE), the Cochrane Central Register of Controlled Trials (CENTRAL), Web of Science, EMBASE, CNKI, and Wanfang to identify articles published before Jan 23, 2022, to summarize the clinical characteristics, diagnosis, treatment, and prognosis of MSMD in China. All the English and Chinese publications were searched without any restriction on article types.

Improving Technology to Diagnose Tuberculous Meningitis: Are We There Yet?

Diagnosis of tuberculous meningitis (TBM) remains challenging due to a paucity of high-performance diagnostics. Even those that have reasonable sensitivity are not adequate to 'rule out' TBM. Therefore, a combination of clinical factors alongside microbiological, molecular, and radiological investigations are utilized, depending on availability. A low threshold for starting empiric therapy in the appropriate clinical scenario remains crucial for good outcomes in many cases. Herein, we review the current TBM diagnostics landscape with a focus on limitations frequently encountered, such as diagnostic test performance, cost, laboratory infrastructure, and clinical expertise. Though molecular technologies, particularly GeneXpert MTB/Rif Ultra, have been a step forward, diagnosis of TBM remains difficult. We also provide an overview of promising technologies, such as cerebrospinal fluid (CSF) lactate, a new lipoarabinomannan test (FujiLAM), metagenomic next-generation sequencing, and transcriptomics that may further improve our TBM diagnostic capacity and lead to better outcomes.

The Role of the Oral Immune System in Oropharyngeal Candidiasis-Facilitated Invasion and Dissemination of Staphylococcus aureus

Candida albicans and Staphylococcus aureus account for most invasive fungal and bacterial bloodstream infections (BSIs), respectively. However, the initial point of invasion responsible for S. aureus BSIs is often unclear. Recently, C. albicans has been proposed to mediate S. aureus invasion of immunocompromised hosts during co-colonization of oral mucosal surfaces. The status of the oral immune system crucially contributes to this process in two distinct ways: firstly, by allowing invasive C. albicans growth during dysfunction of extra-epithelial immunity, and secondly following invasion by some remaining function of intra-epithelial immunity. Immunocompromised individuals at risk of developing invasive oral C. albicans infections could, therefore, also be at risk of contracting concordant S. aureus BSIs. Considering the crucial contribution of both oral immune function and dysfunction, the aim of this review is to provide an overview of relevant aspects of intra and extra-epithelial oral immunity and discuss predominant immune deficiencies expected to facilitate C. albicans induced S. aureus BSIs.

Changes in NK Cell Subsets and Receptor Expressions in HIV-1 Infected Chronic Patients and HIV Controllers

Natural killer (NK) cells are major effectors of the innate immune response and purported to play an influential role in the spontaneous control of HIV infection. In the present study, we compared the phenotypes of NK cells in the peripheral blood of three groups of subjects with chronic HIV-1 infection, HIV controllers, and healthy donors. The results showed that CD56⁺/CD16^- NK cell subsets decreased in chronic patients and remained unchanged in controllers. Notably, we found that people living with chronic HIV-1 infection had suppressed NKp80, NKp46, and NKG2D expressions on NK cells compared to healthy donors, while HIV controllers remained unchanged. In contrast, NKG2D expression was substantially higher in controllers than in chronic patients (M=97.67, p<0.001). There were no significant differences in inhibitory receptors KIR3DL1 and KIR2DL1 expressions. In addition, plasma cytokine IFN-γ, TNF-α and IL-12showed higher levels in HIV controllers compared to chronic patients. Overall, our study revealed that, as compared to chronic patients, HIV controllers show an increased activating receptors expression and higher number ofCD56⁺/CD16^-NK cell subset, with increased expression levels of plasma cytokines, suggesting that higher immune activation in controllers may have a key role in killing and suppressing HIV.

Cytokine Receptors-Regulators of Antimycobacterial Immune Response

Cytokine receptors are critical regulators of the antimycobacterial immune response, playing a key role in initiating and coordinating the recruitment and activation of immune cells during infection. They recognize and bind specific cytokines and are involved in inducing intracellular signal transduction pathways that regulate a diverse range of biological functions, including proliferation, differentiation, metabolism and cell growth. Due to mutations in cytokine receptor genes, defective signaling may contribute to increased susceptibility to mycobacteria, allowing the pathogens to avoid killing and immune surveillance. This paper provides an overview of cytokine receptors important for the innate and adaptive immune responses against mycobacteria and discusses the implications of receptor gene defects for the course of mycobacterial infection.

The Interleukins Orchestrate Mucosal Immune Responses to Salmonella Infection in the Intestine

Salmonella infection remains one of the major public health problems in the world, with increasing resistance to antibiotics. The resolution is to explore the pathogenesis of the infection and search for alternative therapy other than antibiotics. Immune responses to Salmonella infection include innate and adaptive immunity. Flagellin or muramyl dipeptide from Salmonella, recognized by extracellular Toll-like receptors and intracellular nucleotide-binding oligomerization domain2, respectively, induce innate immunity involving intestinal epithelial cells, neutrophils, macrophages, dendric cells and lymphocytes, including natural killer (NK) and natural killer T (NKT) cells. The cytokines, mostly interleukins, produced by the cells involved in innate immunity, stimulate adaptive immunity involving T and B cells. The mucosal epithelium responds to intestinal pathogens through its secretion of inflammatory cytokines, chemokines, and antimicrobial peptides. Chemokines, such as IL-8 and IL-17, recruit neutrophils into the cecal mucosa to defend against the invasion of Salmonella, but induce excessive inflammation contributing to colitis. Some of the interleukins have anti-inflammatory effects, such as IL-10, while others have pro-inflammatory effects, such as IL-1β, IL-12/IL-23, IL-15, IL-18, and IL-22. Furthermore, some interleukins, such as IL-6 and IL-27, exhibit both pro- and anti-inflammatory functions and anti-microbial defenses. The majority of interleukins secreted by macrophages and lymphocytes contributes antimicrobial defense or protective effects, but IL-8 and IL-10 may promote systemic Salmonella infection. In this article, we review the interleukins involved in Salmonella infection in the literature.

The Role of NRF2 in Mycobacterial Infection

The incidence of pulmonary nontuberculous mycobacterial (NTM) infection is increasing worldwide, and its clinical outcomes with current chemotherapies are unsatisfactory. The incidence of tuberculosis (TB) is still high in Africa, and the existence of drug-resistant tuberculosis is also an important issue for treatment. To discover and develop new efficacious anti-mycobacterial treatments, it is important to understand the host-defense mechanisms against mycobacterial infection. Nuclear erythroid 2 p45-related factor-2 (NRF2) is known to be a major regulator of various antioxidant response element (ARE)-driven cytoprotective gene expressions, and its protective role has been demonstrated in infections. However, there are not many papers or reviews regarding the role of NRF2 in mycobacterial infectious disease. Therefore, this review focuses on the role of NRF2 in the pathogenesis of Mycobacterium tuberculosis and Mycobacterium avium infection.

IL-23 orchestrating immune cell activation in arthritis

IL-23 is a cytokine member of the IL-12 superfamily. These heterodimeric cytokines offer broad immune regulatory activity with potential effector function in inflammatory arthritis. IL-23 is a pro-inflammatory cytokine secreted by dendritic cells and macrophages. It plays a key role in both innate and adaptive immunity. By promoting and maintaining T cell differentiation into Th17 T cells, IL-23 is a key player in the pathogenesis of rheumatic diseases. Data from pre-clinical IL-23 knockout models show the major importance of IL-23 in development of arthritis. The induction and maintenance of type 17 cells, which secrete IL-17A and other pro-inflammatory cytokines, contributes to local synovial inflammation and skin inflammation in PsA, and perhaps in RA. Commensurate with this, therapeutic strategies targeting IL-23 have proven efficient in PsA in several studies, albeit not yet in RA.

Novel IL-β12R1 deficiency-mediates recurrent cutaneous leishmaniasis

BACKGROUND

The IL-12/IFN-γ axis plays a vital role in the control of intramacrophagic pathogens including Leishmania infections.

OBJECTIVE

The aim of this study was to investigate genetic defects in the IL-12/IFN-γ axis in cutaneous leishmaniasis patients, using immunological and genetic evaluation.

METHODS

Enzyme-linked immunosorbent assay was used to quantify IFN-γ , while flow cytometry was performed to analyze surface IL-12Rβ1/IL-12Rβ2 expression and phosphorylation of signal transducers as well as the activator of transcription 4 (pSTAT4). Sequencing was carried out for genetic analysis.

RESULTS

The peripheral blood mononuclear cells from the two patients (P1 and P2) demonstrated impaired production of IFN-γ. Furthermore, abolishment of the surface expression of Il-12Rβ1 was observed in lymphocytes, with consequent impairment of STAT4 phosphorylation in the lymphocytes of P1 and P2. IL-12Rββ1 deficiency was identified, which was caused by a novel homozygous missense mutation (c.485>T/p.P162L) and a novel homozygous nonsense mutation (c.805G>T/P.E269*) in the IL-12Rβ2 gene of P1 and P2, respectively. In silico analyses predicted these novel mutations as being pathogenic, causing truncated proteins, with consequent inactivation.

CONCLUSION

Our data have expanded the phenotype and mutation spectra associated with IL-12Rβ1 deficiency, and suggest that patients with CL should be screened for mutations in genes of the IL-12/IFN-γ axis.

Hematopoietic Stem Cell Transplantation for Patients with Autosomal Recessive Complete INF-λ Receptor 2 Deficiency: Experience in Oman

Autosomal recessive complete INF-γ receptor-2 (IFN-γR2) deficiency is a rare, potentially fatal primary immune deficiency that predisposes to disseminated mycobacterial disease. Hematopoietic stem cell transplantation (HSCT) is currently the only curative treatment. Few patients have been reported so far. Here we report the outcomes of HSCT in 7 patients with IFNγ-R2 deficiency from 3 Omani families who underwent HSCT at Sultan Qaboos University Hospital in Oman. All patients were homozygous for the same mutation (c.-175_+102del) of INFGR2. Four patients underwent HLA-matched related donor (MRD) HSCT (3 siblings and 1 parent), and the other 3 underwent T cell-depleted (TCD) haploidentical HSCT from a family donor. The stem cell source was peripheral blood stem cells in 5 patients and bone marrow in 2 patients. Five patients received myeloablative conditioning, and 2 had reduced-intensity conditioning. The overall survival rate was 85.7%, and the event-free survival was 71.4%. One of the 7 patients died on day +31 with gram-negative sepsis, and the other 6 patients were cured from their original disease (median follow-up of 78.5 months). One patient had primary graft failure following a TCD-haploidentical transplantation and underwent successful retransplantation from another haploidentical relative. Three patients received a donor lymphocyte infusion for mixed chimerism. Our findings indicate that HSCT is curative for complete IFN-γR2 deficiency. In this cohort from Oman, 85.7% of the patients were cured with either an MRD or a TCD haploidentical transplantation. Genetic analysis at birth in children of high-risk couples permits early diagnosis, prevents the morbidity of BCG vaccination, and can enable safer and more successful transplantation outcomes.

Understanding the Reciprocal Interplay Between Antibiotics and Host Immune System: How Can We Improve the Anti-Mycobacterial Activity of Current Drugs to Better Control Tuberculosis?

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb) infection, remains a global health threat despite recent advances and insights into host-pathogen interactions and the identification of diverse pathways that may be novel therapeutic targets for TB treatment. In addition, the emergence and spread of multidrug-resistant Mtb strains led to a low success rate of TB treatments. Thus, novel strategies involving the host immune system that boost the effectiveness of existing antibiotics have been recently suggested to better control TB. However, the lack of comprehensive understanding of the immunomodulatory effects of anti-TB drugs, including first-line drugs and newly introduced antibiotics, on bystander and effector immune cells curtailed the development of effective therapeutic strategies to combat Mtb infection. In this review, we focus on the influence of host immune-mediated stresses, such as lysosomal activation, metabolic changes, oxidative stress, mitochondrial damage, and immune mediators, on the activities of anti-TB drugs. In addition, we discuss how anti-TB drugs facilitate the generation of Mtb populations that are resistant to host immune response or disrupt host immunity. Thus, further understanding the interplay between anti-TB drugs and host immune responses may enhance effective host antimicrobial activities and prevent Mtb tolerance to antibiotic and immune attacks. Finally, this review highlights novel adjunctive therapeutic approaches against Mtb infection for better disease outcomes, shorter treatment duration, and improved treatment efficacy based on reciprocal interactions between current TB antibiotics and host immune cells.

Type I IFNs facilitate innate immune control of the opportunistic bacteria Burkholderia cenocepacia in the macrophage cytosol

The mammalian immune system is constantly challenged by signals from both pathogenic and non-pathogenic microbes. Many of these non-pathogenic microbes have pathogenic potential if the immune system is compromised. The importance of type I interferons (IFNs) in orchestrating innate immune responses to pathogenic microbes has become clear in recent years. However, the control of opportunistic pathogens-and especially intracellular bacteria-by type I IFNs remains less appreciated. In this study, we use the opportunistic, Gram-negative bacterial pathogen Burkholderia cenocepacia (Bc) to show that type I IFNs are capable of limiting bacterial replication in macrophages, preventing illness in immunocompetent mice. Sustained type I IFN signaling through cytosolic receptors allows for increased expression of autophagy and linear ubiquitination mediators, which slows bacterial replication. Transcriptomic analyses and in vivo studies also show that LPS stimulation does not replicate the conditions of intracellular Gram-negative bacterial infection as it pertains to type I IFN stimulation or signaling. This study highlights the importance of type I IFNs in protection against opportunistic pathogens through innate immunity, without the need for damaging inflammatory responses.

Inborn Errors of Immunity: how to diagnose them?

OBJECTIVES

Inborn Errors of Immunity are characterized by infectious conditions and manifestations of immune dysregulation. The diversity of clinical phenotypes can make it difficult to direct the laboratory investigation. This article aims to update the investigation of immunological competence in the context of primary defects of the immune system.

SOURCE OF DATA

Searches were carried out on Pubmed to review articles published in the last five years, in English, French or Spanish, using the terms "diagnosis" OR "investigation" AND "immunodeficiency" or "primary immunodeficiency" or "inborn errors of immunity" NOT "HIV". Recent textbook editions have also been consulted.

SUMMARY OF FINDINGS

The immune system competence investigation should be started based on clinical phenotypes. Relevant data are: characterization of infectious conditions (location, recurrence, types of infectious agents, response to treatment), age during symptom onset and associated manifestations (growth impairment, allergy, autoimmunity, malignancies, fever and signs of inflammation without the identification of infection or autoimmunity) and family history. These data contribute to the selection of tests to be performed.

CONCLUSIONS

The diagnostic investigation of Inborn Errors of Immunity should be guided by the clinical characterization of patients, aiming to optimize the use of complementary tests. Many diagnoses are attained only through genetic tests, which are not always available. However, the absence of a diagnosis of certainty should never delay the implementation of therapeutic measures that preserve patient life and health.

Changes in the Immune Phenotype and Gene Expression Profile Driven by a Novel Tuberculosis Nanovaccine: Short and Long-Term Post-immunization

Deciphering protection mechanisms against Mycobacterium tuberculosis (Mtb) remains a critical challenge for the development of new vaccines and therapies. We analyze the phenotypic and transcriptomic profile in lung of a novel tuberculosis (TB) nanoparticle-based boosting mucosal vaccine Nano-FP1, which combined to BCG priming conferred enhanced protection in mice challenged with low-dose Mtb. We analyzed the vaccine profile and efficacy at short (2 weeks), medium (7 weeks) and long term (11 weeks) post-vaccination, and compared it to ineffective Nano-FP2 vaccine. We observed several changes in the mouse lung environment by both nanovaccines, which are lost shortly after boosting. Additional boosting at long-term (14 weeks) recovered partially cell populations and transcriptomic profile, but not enough to enhance protection to infection. An increase in both total and resident memory CD4 and CD8 T cells, but no pro-inflammatory cytokine levels, were correlated with better protection. A unique gene expression pattern with differentially expressed genes revealed potential pathways associated to the immune defense against Mtb. Our findings provide an insight into the critical immune responses that need to be considered when assessing the effectiveness of a novel TB vaccine.

Modeling the immune response to Salmonella during typhoid

Several facets of the host immune response to Salmonella infection have been studied independently at great depths to understand the progress and pathogenesis of Salmonella infection. The circumstances under which a Salmonella-infected individual succumbs to an active disease, evolves as a persister or clears the infection are not understood in detail. We have adopted a system-level approach to develop a continuous-time mechanistic model. We considered key interactions of the immune system state variables with Salmonella in the mesenteric lymph node to determine the final disease outcome deterministically and exclusively temporally. The model accurately predicts the disease outcomes and immune response trajectories operational during typhoid. The results of the simulation confirm the role of anti-inflammatory (M2) macrophages as a site for persistence and relapsing infection. Global sensitivity analysis highlights the importance of both bacterial and host attributes in influencing the disease outcome. It also illustrates the importance of robust phagocytic and anti-microbial potential of M1 macrophages and dendritic cells (DCs) in controlling the disease. Finally, we propose therapeutic strategies for both antibiotic-sensitive and antibiotic-resistant strains (such as IFN-γ therapy, DC transfer and phagocytic potential stimulation). We also suggest prevention strategies such as improving the humoral response and macrophage carrying capacity, which could complement current vaccination schemes for enhanced efficiency.

A hemodialysis patient with Mycobacterium avium complex pericarditis in which remarkable presepsin elevation was not accompanied by procalcitonin elevation

Background

The application of presepsin for diagnosing infections in hemodialysis (HD) patients has not been confirmed yet. In addition, whether presepsin can detect atypical mycobacterial infection or not remains unknown.

Case presentation

We describe the case of a 66-year-old male HD patient with pericardial tamponade. Mycobacterium avium complex (MAC) was identified from a culture of pericardial effusion. The patient showed a clinical improvement after approximately 1 year without the administration of antibiotics. Remarkably, high plasma presepsin values were observed without an increase in serum procalcitonin values. The patient’s presepsin values decreased after the treatment of MAC induced pericarditis.

Conclusions

We found a HD patient with mycobacterium avium complex pericarditis with remarkable presepsin elevation unaccompanied by PCT elevation.

Host Immune Response and Novel Diagnostic Approach to NTM Infections

The incidence and prevalence of non-tuberculous mycobacteria (NTM) infections are steadily increasing worldwide, partially due to the increased incidence of immunocompromised conditions, such as the post-transplantation state. The importance of proper diagnosis and management of NTM infection has been recently recognized. Host immunological responses play integral roles in vulnerability to NTM infections, and may contribute to the onset of specific types of NTM infection. Furthermore, distinct NTM species are known to affect and attenuate these host immune responses in unique manners. Therefore, host immune responses must be understood with respect to each causative NTM species. Here, we review innate, cellular-mediated, and humoral immunity to NTM and provide perspectives on novel diagnostic approaches regarding each NTM species.

Mendelian susceptibility to mycobacterial disease: recent discoveries

Mendelian susceptibility to mycobacterial disease (MSMD) is caused by inborn errors of IFN-γ immunity. Affected patients are highly and selectively susceptible to weakly virulent mycobacteria, such as environmental mycobacteria and Bacillus Calmette-Guérin vaccines. Since 1996, disease-causing mutations have been reported in 15 genes, with allelic heterogeneity leading to 30 genetic disorders. Here, we briefly review the progress made in molecular, cellular, immunological, and clinical studies of MSMD since the last review published in 2018. Highlights include the discoveries of new genetic etiologies of MSMD: autosomal recessive (AR) complete deficiencies of (1) SPPL2a, (2) IL-12Rβ2, and (3) IL-23R, and (4) homozygosity for TYK2 P1104A, resulting in selective impairment of responses to IL-23. The penetrance of SPPL2a deficiency for MSMD is high, probably complete, whereas that of IL-12Rβ2 and IL-23R deficiencies, and TYK2 P1104A homozygosity, is incomplete, and probably low. SPPL2a deficiency has added weight to the notion that human cDC2 and Th1* cells are important for antimycobacterial immunity. Studies of IL-12Rβ2 and IL-23R deficiencies, and of homozygosity for P1104A TYK2, have shown that both IL-12 and IL-23 are required for optimal levels of IFN-γ. These recent findings illustrate how forward genetic studies of MSMD are continuing to shed light on the mechanisms of protective immunity to mycobacteria in humans.

The parkin-coregulated gene product PACRG promotes TNF signaling by stabilizing LUBAC

The Parkin-coregulated gene (PACRG), which encodes a protein of unknown function, shares a bidirectional promoter with Parkin (PRKN), which encodes an E3 ubiquitin ligase. Because PRKN is important in mitochondrial quality control and protection against stress, we tested whether PACRG also affected these pathways in various cultured human cell lines and in mouse embryonic fibroblasts. PACRG did not play a role in mitophagy but did play a role in tumor necrosis factor (TNF) signaling. Similarly to Parkin, PACRG promoted nuclear factor κB (NF-κB) activation in response to TNF. TNF-induced nuclear translocation of the NF-κB subunit p65 and NF-κB-dependent transcription were decreased in PACRG-deficient cells. Defective canonical NF-κB activation in the absence of PACRG was accompanied by a decrease in linear ubiquitylation mediated by the linear ubiquitin chain assembly complex (LUBAC), which is composed of the two E3 ubiquitin ligases HOIP and HOIL-1L and the adaptor protein SHARPIN. Upon TNF stimulation, PACRG was recruited to the activated TNF receptor complex and interacted with LUBAC components. PACRG functionally replaced SHARPIN in this context. In SHARPIN-deficient cells, PACRG prevented LUBAC destabilization, restored HOIP-dependent linear ubiquitylation, and protected cells from TNF-induced apoptosis. This function of PACRG in positively regulating TNF signaling may help to explain the association of PACRG and PRKN polymorphisms with an increased susceptibility to intracellular pathogens.

A Loss-of-Function Mutation in the Integrin Alpha L (Itgal) Gene Contributes to Susceptibility to Salmonella enterica Serovar Typhimurium Infection in Collaborative Cross Strain CC042

Salmonella is an intracellular bacterium found in the gastrointestinal tract of mammalian, avian, and reptilian hosts. Mouse models have been extensively used to model in vivo distinct aspects of human Salmonella infections and have led to the identification of several host susceptibility genes. We have investigated the susceptibility of Collaborative Cross strains to intravenous infection with Salmonella enterica serovar Typhimurium as a model of human systemic invasive infection. In this model, strain CC042/GeniUnc (CC042) mice displayed extreme susceptibility with very high bacterial loads and mortality. CC042 mice showed lower spleen weights and decreased splenocyte numbers before and after infection, affecting mostly CD8⁺ T cells, B cells, and all myeloid cell populations, compared with control C57BL/6J mice. CC042 mice also had lower thymus weights with a reduced total number of thymocytes and double-negative and double-positive (CD4⁺, CD8⁺) thymocytes compared to C57BL/6J mice. Analysis of bone marrow-resident hematopoietic progenitors showed a strong bias against lymphoid-primed multipotent progenitors. An F2 cross between CC042 and C57BL/6N mice identified two loci on chromosome 7 (Stsl6 and Stsl7) associated with differences in bacterial loads. In the Stsl7 region, CC042 carried a loss-of-function variant, unique to this strain, in the integrin alpha L (Itgal) gene, the causative role of which was confirmed by a quantitative complementation test. Notably, Itgal loss of function increased the susceptibility to S. Typhimurium in a (C57BL/6J × CC042)F1 mouse background but not in a C57BL/6J mouse inbred background. These results further emphasize the utility of the Collaborative Cross to identify new host genetic variants controlling susceptibility to infections and improve our understanding of the function of the Itgal gene.

MAL adaptor (TIRAP) S180L polymorphism and severity of disease among tuberculosis patients

OBJECTIVE

Though several genetic variants have been recognized to be associated with susceptibility to Tuberculosis (TB) infection and disease, a recent observation on the association of TIRAP C975T (S180L) variants with TB disease severity in mice model prompted us to assess their relevance in humans. In addition, TIRAP variants have also been reported to be associated with varied circulating Interferon-gamma induced protein (IP-10) levels. We investigated the association of TIRAP variants with severity of TB disease and IP-10 production in humans, which may be useful in predicting poor clinical outcome.

METHODS

Culture positive symptomatic adult pulmonary TB (PTB) patients enrolled between August 2014 and October 2017 were included in this investigation. Allelic discrimination PCR and conventional IP-10 quantification methods were employed for genotyping and IP-10 measurement followed by statistical investigations to analyse patients' variables.

RESULTS

Among 211 participants, C/C allele was identified in 70% (n = 147); 26% (n = 55) and 4% (n = 9) had C/T and T/T alleles respectively. There was no significant association between TIRAP variants and smear grade, chest-X-ray score, symptom severity score and circulating IP-10 levels. However, significant association was observed between i) circulating IP-10 levels and time to Mycobacterium Growth Indicator Tube (MGIT) culture conversion (p =0.032); ii) smear grade among active TB patients and circulating IP-10 levels (p =0 .032).

CONCLUSIONS

Although mice experiments showed promising results with more severe disease in C/C and T/T individuals, we did not observe any such association in humans.

Disseminated Mycobacterium avium complex infection mimicking malignancy in a patient with anti-IFN-γ autoantibodies: a case report

Background

Disseminated nontuberculous mycobacteria (NTM) infections occur mostly in immunocompromised patients. Therefore, it is difficult to diagnose disseminated NTM infections in patients without history of immunocompromised diseases or using immunosuppressant. Patients with anti-interferon-γ (IFN-γ) autoantibodies are vulnerable to intracellular infections, such as disseminated NTM. Currently, there is no widely used and efficient technique for the detection of anti-IFN-γ autoantibodies. Herein, we report a case of an apparently healthy patient with disseminated Mycobacterium avium complex (MAC) infection who tested positive for anti-IFN-γ autoantibodies.

Case presentation

A 64-year-old non-immunocompromised and apparently healthy Asian male presented to the emergency department with complaints of progressive chest pain for about 6 months and weight loss. A bulging tumour was found in the anterior chest wall. Chest computed tomography showed a lung mass over the right lower lobe and an osteolytic lesion with a soft tissue component at the sternum. Sonography-guided biopsies for the osteolytic lesion and sputum culture confirmed the presence of disseminated MAC infection. In addition, positive test result of anti-IFN-γ autoantibodies was noted. The patient was prescribed antibiotics. The lesions over the right lower lobe and sternum attenuated following the antibiotic treatment.

Conclusion

Detection of anti-IFN-γ autoantibodies is important among previously healthy people with disseminated NTM infection. Presence of anti-IFN-γ autoantibodies may suggest a high risk of severe intracellular infection, such as disseminated NTM infection.

IL-12Rβ1 deficiency corresponding to concurrency of two diseases, mendelian susceptibility to mycobacterial disease and Crohn's disease

Background

The interleukin-12 receptor β1 (IL-12Rβ1) deficiency is a primary immunodeficiency (PID), affecting the immunological pathway of interleukin 12/interferon- γ (IL12/IFN-γ) axis and interleukin 23 receptor (IL23R). Defect in this pathway is mainly affecting the cellular immunity-related disorders. IL-12Rβ1 is a receptor chain of both the IL-12 and the IL-23 receptors and thus, deficiency of IL-12Rβ1 abolishes both IL-12 and IL-23 signaling.

Material and methods

In this study, we performed whole exon sequencing and confirmatory Sanger sequencing in IL-12Rβ1. Evaluation of the IL12/IFN-γ axis was performed by assessment of patients’ whole blood cell to IL12/IFN-γ responding. Total and surface IL-12Rβ1expression was evaluated, in peripheral blood mononuclear cells (PBMCs) and T cell- derived PBMCs, and Th17 count was assessed.

Results

In the present study, we described a c.1791 + 2T > G mutation at a splicing site position in IL-12Rβ1, using whole exome sequencing, and confirmed with targeted Sanger sequencing in a 26- year-old patient with Mendelian susceptibility to mycobacterial disease (MSMD) and Crohn's disease (CD). Complete lack of IL-12Rβ1 protein expression was detected in patient's PBMCs, compared to the healthy control. Furthermore, no IL-12Rβ1 protein was expressed on the cell surface. Interestingly, IL-12Rβ1-mutant cells showed an impaired response to IL12, and Bacillus Calmette–Guérin stimulation, confirming that the mutation is causative in this patient.

Conclusion

A 3′splicing site mutation in IL12Rβ1, can be corresponding to the abolished expression of IL12Rβ1 in patients' cells, and associated with an impaired IL12-mediated signaling, which may lead not only to MSMD, but also to inflammatory bowel disease (IBD).

Life-Threatening Infections Due to Live-Attenuated Vaccines: Early Manifestations of Inborn Errors of Immunity

Live-attenuated vaccines (LAVs) can protect humans against 12 viral and three bacterial diseases. By definition, any clinical infection caused by a LAV that is sufficiently severe to require medical intervention attests to an inherited or acquired immunodeficiency that must be diagnosed or identified. Self-healing infections can also result from milder forms of immunodeficiency. We review here the inherited forms of immunodeficiency underlying severe infections of LAVs. Inborn errors of immunity (IEIs) underlying bacille Calmette-Guérin (BCG), oral poliovirus (OPV), vaccine measles virus (vMeV), and oral rotavirus vaccine (ORV) disease have been described from 1951, 1963, 1966, and 2009 onward, respectively. For each of these four LAVs, the underlying IEIs show immunological homogeneity despite genetic heterogeneity. Specifically, BCG disease is due to inborn errors of IFN-γ immunity, OPV disease to inborn errors of B cell immunity, vMeV disease to inborn errors of IFN-α/β and IFN-λ immunity, and ORV disease to adaptive immunity. Severe reactions to the other 11 LAVs have been described yet remain "idiopathic," in the absence of known underlying inherited or acquired immunodeficiencies, and are warranted to be the focus of research efforts. The study of IEIs underlying life-threatening LAV infections is clinically important for the affected patients and their families, as well as immunologically, for the study of the molecular and cellular basis of host defense against both attenuated and parental pathogens.

Neonatal Cytomegalovirus Palatal Ulceration and Bocavirus Pneumonitis Associated With a Defect of Lymphocyte Cytotoxicity Caused by Mutations in UNC13D

Single gene defects that impair lymphocyte cytotoxicity can predispose to severe viral infection that normally remains subclinical. The classic severe presentation is hemophagocytic lymphohistiocytosis. Here, we report the case of a neonate who presented with cytomegalovirus palatal ulceration and bocavirus pneumonitis secondary to impaired cytotoxicity caused by biallelic mutations in the UNC13D gene.

Paracoccidioidomycosis Associated With a Heterozygous STAT4 Mutation and Impaired IFN-γ Immunity

Background

Mutations in genes affecting interferon-γ (IFN-γ) immunity have contributed to understand the role of IFN-γ in protection against intracellular pathogens. However, inborn errors in STAT4, which controls interleukin-12 (IL-12) responses, have not yet been reported. Our objective was to determine the genetic defect in a family with a history of paracoccidioidomycosis.

Methods

Genetic analysis was performed by whole-exome sequencing and Sanger sequencing. STAT4 phosphorylation (pSTAT4) and translocation to the nucleus, IFN-γ release by patient lymphocytes, and microbicidal activity of patient monocytes/macrophages were assessed. The effect on STAT4 function was evaluated by site-directed mutagenesis using a lymphoblastoid B cell line (B-LCL) and U3A cells.

Results

A heterozygous missense mutation, c.1952 A>T (p.E651V) in STAT4 was identified in the index patient and her father. Patient's and father's lymphocytes showed reduced pSTAT4, nuclear translocation, and impaired IFN-γ production. Mutant B-LCL and U3A cells also displayed reduced pSTAT4. Patient's and father's peripheral blood mononuclear cells and macrophages demonstrated impaired fungicidal activity compared with those from healthy controls that improved in the presence of recombinant human IFN-γ, but not rhIL-12.

Conclusion

Our data suggest autosomal dominant STAT4 deficiency as a novel inborn error of IL-12-dependent IFN-γ immunity associated with susceptibility to paracoccidioidomycosis.

Gene expression in chronic granulomatous disease and interferon-γ receptor-deficient cells treated in vitro with interferon-γ

Interferon-γ (IFN-γ) plays an important role in innate and adaptive immunity against intracellular infections and is used clinically for the prevention and control of infections in chronic granulomatous disease (CGD) and inborn defects in the IFN-γ/interleukin (IL)-12 axis. Using transcriptome profiling (RNA-seq), we sought to identify differentially expressed genes, transcripts and exons in Epstein-Barr virus-transformed B lymphocytes (B-EBV) cells from CGD patients, IFN-γ receptor deficiency patients, and normal controls, treated in vitro with IFN-γ for 48 hours. Our results show that IFN-γ increased the expression of a diverse array of genes related to different cellular programs. In cells from normal controls and CGD patients, IFN-γ-induced expression of genes relevant to oxidative killing, nitric oxide synthase pathway, proteasome-mediated degradation, antigen presentation, chemoattraction, and cell adhesion. IFN-γ also upregulated genes involved in diverse stages of messenger RNA (mRNA) processing including pre-mRNA splicing, as well as others implicated in the folding, transport, and assembly of proteins. In particular, differential exon expression of WARS (encoding tryptophanyl-transfer RNA synthetase, which has an essential function in protein synthesis) induced by IFN-γ in normal and CGD cells suggests that this gene may have an important contribution to the benefits of IFN-γ treatment for CGD. Upregulation of mRNA and protein processing related genes in CGD and IFNRD cells could mediate some of the effects of IFN-γ treatment. These data support the concept that IFN-γ treatment may contribute to increased immune responses against pathogens through regulation of genes important for mRNA and protein processing.

Molecular, Immunological, and Clinical Features of 16 Iranian Patients with Mendelian Susceptibility to Mycobacterial Disease

PURPOSE

Mendelian susceptibility to mycobacterial disease (MSMD) is a rare primary immunodeficiency, triggered by non-tuberculous mycobacteria or Bacillus Calmette-Guérin (BCG) vaccines and characterized by severe diseases. All known genetic etiologies are inborn errors of IFN-γ-mediated immunity. Here, we report the molecular, cellular, and clinical features of patients from 15 Iranian families with disseminated disease without vaccination (2 patients) or following live BCG vaccination (14 patients).

METHODS

We used whole blood samples from 16 patients and 12 age-matched healthy controls. To measure IL-12 and IFN-γ, samples were activated by BCG plus recombinant human IFN-γ or recombinant human IL-12. Immunological assessments and genetic analysis were also done for the patients.

RESULTS

Eight patients affected as a result of parental first-cousin marriages. Seven patients originated from multiplex kindred with positive history of death because of tuberculosis or finding the MSMD-related gene mutations. Two patients died due to mycobacterial disease at the ages of 8 months and 3.7 years. The remaining patients were alive at the last follow-up and were aged between 2 and 13 years. Patients suffered from infections including chronic mucocutaneous candidiasis (n = 10), salmonellosis (n = 2), and Leishmania (responsible for visceral form) (n = 2). Thirteen patients presented with autosomal recessive (AR) IL-12Rβ1 deficiency, meaning their cells produced low levels of IFN-γ. Bi-allelic IL12RB1 mutations were detected in nine of patients. Three patients with AR IL-12p40 deficiency (bi-allelic IL12B mutations) produced low levels of both IL-12 and IFN-γ. Overall, we found five mutations in the IL12RB1 gene and three mutations in the IL12B gene. Except one mutation in exon 5 (c.510C>A) of IL12B, all others were previously reported to be loss-of-function mutations.

CONCLUSIONS

We found low levels of IFN-γ production and failure to respond to IL12 in 13 Iranian MSMD patients. Due to complicated clinical manifestations in affected children, early cellular and molecular diagnostics is crucial in susceptible patients.

Evaluation of interleukin-12 receptor β1 and interferon gamma receptor 1 deficiency in patients with disseminated BCG infection

INTRODUCTION

Disseminated BCG infections among other complications of Bacillus Calmette-Guérin (BCG) vaccine are rare and have occurred in children with immunodeficiency disorders such as mendelian susceptibility to mycobacterial disease (MSMD) which could be due to defects in some elements of IL-12/IFN-γ axis. MSMD-causing mutations have been identified in 10 genes during the last two decades. Among them, mutations in the IL12Rβ1 and IFNγR1 genes constitute about 80% of recorded cases of MSMD syndrome. The aim of this study was to investigate IL-12Rβ1 and IFN-γR1 deficiencies in patients with disseminated BCG infection.

METHODS

This study was performed on 31 children with disseminated BCG infections who referred to children's medical center. Whole blood cell culture was performed in presence of BCG, IL-12 and IFN-γ stimulators. The supernatants were assayed for IFN-γ and IL-12p70 by ELISA method. In order to evaluate IL12Rβ1 and IFN-γR1 receptors expression, flow cytometry staining was performed on the patients' T-cells stimulated with PHA.

RESULTS

Flow cytometry staining of 31 Iranian patients with disseminated BCG infections with the average age of 43 months showed lack of the expression of IL-12Rβ1 and IFN-γR1 genes in PHA-T-cells of the nine and one patients, respectively in whom the incomplete production of IFN-γ and IL-12 was reported by ELISA. Among these 10 patients, eight cases had related parents (80%).

CONCLUSION

It is recommended that to avoid BCG complications, screening be performed for MSMD before BCG inoculation in individuals with positive family history of primary immunodeficiency diseases and inhabitants of areas with high frequency of consanguinity.

Laboratory evaluation of the IFN-γ circuit for the molecular diagnosis of Mendelian susceptibility to mycobacterial disease

The integrity of the interferon (IFN)-γ circuit is necessary to mount an effective immune response to intra-macrophagic pathogens, especially Mycobacteria. Inherited monogenic defects in this circuit that disrupt the production of, or response to, IFN-γ underlie a primary immunodeficiency known as Mendelian susceptibility to mycobacterial disease (MSMD). Otherwise healthy patients display a selective susceptibility to clinical disease caused by poorly virulent mycobacteria such as BCG (bacille Calmette-Guérin) vaccines and environmental mycobacteria, and more rarely by other intra-macrophagic pathogens, particularly Salmonella and M. tuberculosis. There is high genetic and allelic heterogeneity, with 19 genetic etiologies due to mutations in 10 genes that account for only about half of the patients reported. An efficient laboratory diagnostic approach to suspected MSMD patients is important, because it enables the establishment of specific therapeutic measures that will improve the patient's prognosis and quality of life. Moreover, it is essential to offer genetic counseling to affected families. Herein, we review the various genetic and immunological diagnostic approaches that can be used in concert to reach a molecular and cellular diagnosis in patients with MSMD.

Case report of myeloperoxidase deficiency associated with disseminated paracoccidioidomycosis and peritoneal tuberculosis

Myeloperoxidase (MOP) is present in monocyte and neutrophil lysosomes, catalyzing hydrogen peroxide and chloride ion conversion to hypochlorous acid. MOP seems to destroy pathogens during phagocytosis by neutrophils and is considered an important defense against innumerous bacteria. We present a patient who had MOP deficiency, who presented with a subacute form of paracoccidioidomycosis and later with peritoneal tuberculosis. MOP deficiency leads to the diminished destruction of phagocytized pathogens. This case gives important evidence of an association between MOP deficiency and increased susceptibility to infection by Paracoccidioides brasiliensis and Mycobacterium tuberculosis.

Frequency of Mycobacterium bovis and mycobacteria in primary immunodeficiencies

AIM

Susceptibility to mycobacterial diseases is observed in some primary immunodeficiency diseases. In this study, we aimed to evaluate mycobacterial infections in primary immunodeficiency diseases.

MATERIAL AND METHODS

Patients under follow-up by Ege University Pediatric Immunology Department for severe combined and combined immunodeficiencies, interleukin 12/ interferon gamma receptor deficiency, nuclear factor kappa-beta essential modulator deficiency and chronic granulomatosis disease were evaluated retrospectively in terms of the frequency and characteristics of mycobacterial infections using a questionnaire form for demographic properties, clinical features and laboratory tests.

RESULTS

A diagnosis of mycobacterial infection was made clinically in a total of 25 patients including five (11.3%) of 45 patients who had severe combined immune deficiency, 12 (52.3%) of 21 patients who had chronic granulomatous disease, four patients (100%) who had interferon gamma receptor 2 partical deficiency, two patients (100%) who had interleukin 12 receptor beta 1 deficiency and one patient (100%) who had nuclear factor kapa-beta essential modulator deficiency. Mycobacterium strain could be typed in 14 (33%) of these 25 patients including Mycobacterium bovis, Mycobacterium chelonea, Mycobacterium elephantis, Mycobacterium fortuitum, and Mycobacterium tuberculosis. All patients were treated with anti-tuberculosis therapy. Thirty-six percent of these 25 patients underwent hematopoietic stem cell transplantation. Eight patients (five before, three after transplantation) died.

CONCLUSIONS

Non-tuberculosis mycobacteria including mainly Mycobacterium bovis were observed with a higher rate compared to Mycobacterium tuberculosis in primary immunodeficiencies, especially in those affecting the interleukin 12/interferon gamma pathway. Early diagnosis of primary immunodeficiencies with neonatal screening program and preventing administration of the Bacille Calmette-Guerin vaccine in these patients is important.

Dendritic cell analysis in primary immunodeficiency

Purpose of review

Dendritic cells are specialized antigen-presenting cells which link innate and adaptive immunity, through recognition and presentation of antigen to T cells. Although the importance of dendritic cells has been demonstrated in many animal models, their contribution to human immunity remains relatively unexplored in vivo.

Given their central role in infection, autoimmunity, and malignancy, dendritic cell deficiency or dysfunction would be expected to have clinical consequences.

Recent findings

Human dendritic cell deficiency disorders, related to GATA binding protein 2 (GATA2) and interferon regulatory factor 8 (IRF8) mutations, have highlighted the importance of dendritic cells and monocytes in primary immunodeficiency diseases and begun to shed light on their nonredundant roles in host defense and immune regulation in vivo. The contribution of dendritic cell and monocyte dysfunction to the pathogenesis of primary immunodeficiency disease phenotypes is becoming increasingly apparent. However, dendritic cell analysis is not yet a routine part of primary immunodeficiency disease workup.

Summary

Widespread uptake of dendritic cell/monocyte screening in clinical practice will facilitate the discovery of novel dendritic cell and monocyte disorders as well as advancing our understanding of human dendritic cell biology in health and disease.

Novel RAG1 mutation and the occurrence of mycobacterial and Chromobacterium violaceum infections in a case of leaky SCID

Severe combined immunodeficiency (SCID) is a potentially fatal primary immunodeficiency (PID) that is caused by mutations in genes such as IL2RG, JAK3, IL7RA, RAG1, RAG2, and ADA. The products of these genes are involved in the development of several immune cells such as T, B and natural killer (NK) cells. Most of the SCID forms are autosomal recessive with the exception of IL2RG defects that cause an X-linked SCID. Among the different SCID types, there is a rare SCID form called leaky SCID, which is less severe when compared to the other classical SCID phenotypes. Leaky SCID can be caused by hypomorphic mutations in RAG1 and RAG2 that result in only partial loss of enzymatic function of the proteins respectively encoded by these genes. Here we report a novel missense mutation (c. 307C > T/p.H103Y) in the RAG1 gene in a patient with leaky SCID. In addition, we characterize the clinical and immunological features of this patient that developed along with other severe and recurrent infections such as mycobacterial diseases (BCGitis and pulmonary tuberculosis), the first occurrence of Chromobacterium violaceum in a patient with SCID. Understanding the increased susceptibility to mycobacteria presented by the patient, in which a functional investigation of IL-12/IFN-γ axis was performed, which demonstrated reduced production of IFN-γ in the supernatans of peripheral blood mononuclear cell cultures from the patient compared with those from healthy subjects. In conclusion, our data expands the molecular and clinical spectrum associated with the leaky SCID phenotype.

MPEG1/perforin-2 mutations in human pulmonary nontuberculous mycobacterial infections

Perforin-2 is a highly conserved pore-forming protein encoded by macrophage expressed gene 1 (MPEG1). A number of studies have shown that Perforin-2-deficient mice are unable to survive following a bacterial challenge that is nonlethal in WT mice. There is also recent evidence that Mpeg1+/- heterozygous mice display an intermediate killing ability compared with Mpeg1 WT and Mpeg1-/- mice. Despite these in vivo findings, to date, no perforin-2 deficiencies have been associated with human disease. Here, we report four patients with persistent nontuberculous mycobacterial infection who had heterozygous MPEG1 mutations. In vitro, neutrophils, macrophages, and B cells from these patients were unable to kill Mycobacterium avium as efficiently as normal controls. CRISPR mutagenesis validated the deleterious antibacterial activity of these mutations. These data suggest that perforin-2 haploinsufficiency may contribute to human susceptibility to infections with intracellular bacteria.

Interferon-gamma-dependent Immunity in Bacillus Calmette-Guérin Vaccine Osteitis Survivors

BACKGROUND

Inborn errors of interferon-gamma (IFN-γ)-mediated immunity underlie disseminated disease caused by Mycobacterium bovis Bacillus Calmette-Guérin (BCG) live vaccines. We hypothesized that some patients with osteitis after BCG vaccination may have an impaired IFN-γ immunity. Our aim was to investigate interleukin (IL)-12 and IFN-γ ex vivo production stimulated with BCG and BCG + IFN-γ or BCG + IL-12, respectively, in BCG osteitis survivors.

METHODS

Fresh blood samples were collected from 132 former BCG osteitis Finnish patients now aged 21-49 years, and IL-12 and IFN-γ were measured in cell cultures with and without stimulation with BCG and with BCG + IFN-γ or BCG + IL-12, respectively. As a pilot study, known disease-causing genes controlling IFN-γ immunity (IFNGR1, IFNGR2, STAT1, IL12B, IL12RB1, ISG15, IRF8, NEMO and CYBB) were investigated in 20 selected patients by whole exome sequencing.

RESULTS

By the limit of <5th percentile, ex vivo IL-12 concentration and increase in concentration was low in 5 and ex vivo IFN-γ concentration and increase in concentration was low in 6 patients (including 2 samples with both IL-12 and IFN-γ findings). By the limit of <10th percentile, an additional 6 and 4 patients were, respectively, detected (including 2 samples with both findings). With 2 exceptions, low concentrations and low increases in concentrations picked-up the same cases. Mutations in known disease-causing IFN-γ-related genes were not found in any of these patients.

CONCLUSION

These findings call for searching of mutations in new genes governing IFN-γ-dependent immunity to live BCG vaccine.