Chronic granulomatous disease: why an inflammatory disease?

Self-extinguishing relay waves enable homeostatic control of human neutrophil swarming

Neutrophils collectively migrate to sites of injury and infection. How these swarms are coordinated to ensure the proper level of recruitment is unknown. Using an ex vivo model of infection, we show that human neutrophil swarming is organized by multiple pulsatile chemoattractant waves. These waves propagate through active relay in which stimulated neutrophils trigger their neighbors to release additional swarming cues. Unlike canonical active relays, we find these waves to be self-terminating, limiting the spatial range of cell recruitment. We identify an NADPH-oxidase-based negative feedback loop that is needed for this self-terminating behavior. We observe near-constant levels of neutrophil recruitment over a wide range of starting conditions, revealing surprising robustness in the swarming process. This homeostatic control is achieved by larger and more numerous swarming waves at lower cell densities. We link defective wave termination to a broken recruitment homeostat in the context of human chronic granulomatous disease.

Inflammatory Complications in Chronic Granulomatous Disease

Chronic granulomatous disease (CGD) is a rare inborn error of immunity that typically manifests with infectious complications. As the name suggest though, inflammatory complications are also common, often affecting the gastrointestinal, respiratory, urinary tracts and other tissues. These can be seen in all various types of CGD, from X-linked and autosomal recessive to X-linked carriers. The pathogenetic mechanisms underlying these complications are not well understood, but are likely multi-factorial and reflect the body's attempt to control infections. The different levels of neutrophil residual oxidase activity are thought to contribute to the large phenotypic variations. Immunosuppressive agents have traditionally been used to treat these complications, but their use is hindered by the fact that CGD patients are predisposed to infection. Novel therapeutic agents, like anti-TNFa monoclonal antibodies, anakinra, ustekinumab, and vedolizumab offer promise for the future, while hematopoietic stem cell transplantation should also be considered in these patients.

The Multiple Faces of Nitric Oxide in Chronic Granulomatous Disease: A Comprehensive Update

Nitric oxide (NO), a signaling molecule, regulates multiple biological functions, including a variety of physiological and pathological processes. In this regard, NO participates in cutaneous inflammations, modulation of mitochondrial functions, vascular diseases, COVID-19, neurologic diseases, and obesity. It also mediates changes in the skeletal muscle function. Chronic granulomatous disease (CGD) is a primary immunodeficiency disorder characterized by the malfunction of phagocytes caused by mutations in some of the genes encoding subunits of the superoxide-generating phagocyte NADPH (NOX). The literature consulted shows that there is a relationship between the production of NO and the NADPH oxidase system, which regulates the persistence of NO in the medium. Nevertheless, the underlying mechanisms of the effects of NO on CGD remain unknown. In this paper, we briefly review the regulatory role of NO in CGD and its potential underlying mechanisms.

Identification of a novel mutation in CYBB gene in a Chinese neonate with X-linked chronic granulomatous disease: A case report

RATIONALE

X-linked chronic granulomatous disease (X-CGD) is an X-linked recessive disorder of the Nicotinamide adenine dinucleotide phosphate oxidase system that can cause primary immunodeficiency. Mutations in the CYBB gene located in Xp21.1 were accounting for X-CGD disease. More than 600 mutations have been identified as the cause of X-CGD in various populations worldwide.

PATIENT CONCERNS AND DIAGNOSIS

In this study, the proband suffered from elevated white blood cells (WBC, 23.65 × 109/L), mainly in neutral (16.4 × 109/L). The neutrophil oxidative index of the patient was 2.13, which was extremely low, whereas his mother was 69.0 (Ref >100). Next, next-generation sequencing of the primary immunodeficiency diseases -related gene panel was performed. One novel mutation was identified in the CYBB gene in the CGD case: c.55C>G in exon 2. The mutation was verified by Sanger sequencing. The mother of the patient was heterozygous for the c.55C>G mutation, and the father was normal. These mutations were not present in the 100 unrelated normal controls.

INTERVENTIONS AND OUTCOMES

The patient died from severe and uncontrollable pulmonary infection at 3 months of age.

LESSONS

The identification of these mutations in this study further expands the spectrum of known CYBB gene mutations and contributes to the genetic counseling and prenatal molecular diagnosis of X-CGD.

Neutrophil swarming delays the growth of clusters of pathogenic fungi

Neutrophils employ several mechanisms to restrict fungi, including the action of enzymes such as myeloperoxidase (MPO) or NADPH oxidase, and the release of neutrophil extracellular traps (NETs). Moreover, they cooperate, forming “swarms” to attack fungi that are larger than individual neutrophils. Here, we designed an assay for studying how these mechanisms work together and contribute to neutrophil's ability to contain clusters of live Candida. We find that neutrophil swarming over Candida clusters delays germination through the action of MPO and NADPH oxidase, and restricts fungal growth through NET release within the swarm. In comparison with neutrophils from healthy subjects, those from patients with chronic granulomatous disease produce larger swarms against Candida, but their release of NETs is delayed, resulting in impaired control of fungal growth. We also show that granulocyte colony-stimulating factors (GCSF and GM-CSF) enhance swarming and neutrophil ability to restrict fungal growth, even during treatment with chemical inhibitors that disrupt neutrophil function.

Neutrophils employ several mechanisms to control the growth of fungi, including enzymes, reactive oxygen species, extracellular traps, and formation of “swarms”. Here, Hopke et al. study how the different mechanisms work together, using an in vitro assay with human neutrophils and clusters of live Candida cells.

Neutrophils: Innate Effectors of TB Resistance?

Certain individuals are able to resist Mycobacterium tuberculosis infection despite persistent and intense exposure. These persons do not exhibit adaptive immune priming as measured by tuberculin skin test (TST) and interferon-γ (IFN-γ) release assay (IGRA) responses, nor do they develop active tuberculosis (TB). Genetic investigation of individuals who are able to resist M. tuberculosis infection shows there are likely a combination of genetic variants that contribute to the phenotype. The contribution of the innate immune system and the exact cells involved in this phenotype remain incompletely elucidated. Neutrophils are prominent candidates for possible involvement as primers for microbial clearance. Significant variability is observed in neutrophil gene expression and DNA methylation. Furthermore, inter-individual variability is seen between the mycobactericidal capacities of donor neutrophils. Clearance of M. tuberculosis infection is favored by the mycobactericidal activity of neutrophils, apoptosis, effective clearance of cells by macrophages, and resolution of inflammation. In this review we will discuss the different mechanisms neutrophils utilize to clear M. tuberculosis infection. We discuss the duality between neutrophils' ability to clear infection and how increasing numbers of neutrophils contribute to active TB severity and mortality. Further investigation into the potential role of neutrophils in innate immune-mediated M. tuberculosis infection resistance is warranted since it may reveal clinically important activities for prevention as well as vaccine and treatment development.

Tread carefully: A functional variant in the human NADPH oxidase 4 (NOX4) is not disease causing

In this study, we report a paediatric patient with a lethal phenotype of respiratory distress, failure to thrive, pancreatic insufficiency, liver dysfunction, hypertrophic cardiomyopathy, bone marrow suppression, humoral and cellular immune deficiency. To identify the genetic basis of this unusual clinical phenotype and potentially make available the option of future prenatal testing, whole exome sequencing (WES) was used followed by functional studies in a bid to confirm pathogenicity. The WES we identified a homozygous novel variant, AK298328; c.9_10insGAG; p.[Glu3dup], in NOX4 in the proband, and parental heterozygosity for the variant (confirmed by Sanger sequencing). NADPH Oxidase 4 NOX4 (OMIM 605261) encodes an enzyme that functions as the catalytic subunit of the NADPH oxidase complex. NOX4 acts as an oxygen sensor, catalysing the reduction of molecular oxygen, mainly to hydrogen peroxide (H₂O₂). However, although, our functional data including 60% reduction in NOX4 protein levels and a 75% reduction in the production of H₂O₂ in patient fibroblast extracts compared to controls was initially considered to be the likely cause of the phenotype in our patient, the potential contribution of the NOX4 variant as the primary cause of the disease was clearly excluded based on following pieces of evidence. First, Sanger sequencing of other family members revealed that two of the grandparents were also homozygous for the NOX4 variant, one of who has fibromuscular dysplasia. Second, re-evaluation of more recent variant databases revealed a high allele frequency for this variant. Our case highlights the need to re-interrogate bioinformatics resources as they are constantly evolving, and is reminiscent of the short-chain acyl-CoA dehydrogenase deficiency (SCADD) story, where a functional defect in fatty acid oxidation has doubtful clinical ramifications.

Managing Inflammatory Manifestations in Patients with Chronic Granulomatous Disease

Chronic granulomatous disease (CGD) is a primary immunodeficiency caused by lack of phagocyte nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, which results in inflammatory dysregulation and increased susceptibility to infections. Patients with CGD may develop severe obstructive disorders of the digestive tract as a result of their dysregulated inflammatory response. Despite a growing focus on inflammatory manifestations in CGD, the literature data on obstructive complications are far less extensive than those on infectious complications. Diagnosis and management of patients with concomitant predispositions to infections and hyperinflammation are particularly challenging. Although the inflammatory and granulomatous manifestations of CGD usually respond rapidly to steroid treatment, second-line therapies (immunosuppressants and biologics) may be required in refractory cases. Indeed, immunosuppressants (such as anti-tumor necrosis factor agents, thalidomide, and anakinra) have shown some efficacy, but the value of this approach is controversial, given the questionable risk-to-benefit ratio and the small numbers of patients treated to date. Significant progress in allogeneic hematopoietic stem cell transplantation (the only curative treatment for CGD) has been made through better supportive care and implementation of improved, reduced-intensity conditioning regimens. Gene therapy may eventually be an option for patients lacking a suitable donor; clinical trials with new, safer vectors are ongoing at a few centers.

Chronic Recurrent Multifocal Osteomyelitis and Thalidomide in Chronic Granulomatous Disease

Chronic granulomatous disease (CGD) is a primary immunodeficiency that leads to severe recurrent infection and inflammatory complications that are usually difficult to diagnose and treat. Several hyperinflammation mechanisms, such as decreased neutrophil apoptosis, toll-like receptor activation imbalance, Th17 cell induction, Nrf2 activity deficiency, and inflammasome activation, have been described in CGD patients However, there have been no reports of chronic recurrent multifocal osteomyelitis as an inflammatory complication in CGD, and the differential diagnosis of this condition with infectious osteomyelitis is challenging. Thalidomide has been used to treat several inflammatory manifestations in CGD patients with good clinical results. Here, we report the case of a previously asymptomatic 11-year-old boy who consulted for difficulty walking and pain at the back of the right thigh, with increased inflammatory markers. Multifocal bone involvement was seen on bone scintigraphy, and acute-phase reactants were elevated. On the basis of a suspected diagnosis of infectious osteomyelitis, broad-spectrum antibiotic therapy was started, with no clinical response. Bone biopsy and microbiological tests yielded negative results; at that point, chronic recurrent multifocal osteomyelitis was suspected. The patient was unresponsive to nonsteroidal antiinflammatory drugs and corticosteroids. Thalidomide was started, and within 6 months, clinical and radiologic resolution of the condition was achieved with no adverse effects. More than 1 year after stopping thalidomide, the patient remained free of symptoms and inflammatory parameters are within normal levels. Thalidomide has a favorable safety profile compared with other alternatives and could be considered a feasible therapeutic option for this type of condition in selected patients.

Ulcerative colitis associated with chronic granulomatous disease: case report

Chronic Granulomatous Disease (CGD) is an inherited primary immunodeficiency disease which increases the body's susceptibility to infections caused by certain bacteria and fungi. CGD is a rare disease, caused by four genes, one type is 1X linked and the other three are "autosomal recessive". Although clinical presentation is variable, but characteristic features are recurrent pneumonia, lymphadenitis, hepatic or other abscesses. Gastrointestinal tract symptoms are common in x-linked recessive form of CGD. These include gastric and esophageal obstruction and inflammatory bowel disease. GI involvement including small and large intestines, the findings of luminal narrowing and the presence of granuloma can make it difficult to distinguish from Crohn's disease. On the other hands according to the literature ulcerative colitis is rarely reported in patients with CGD. Our case presented with ulcerative colitis with CGD.