Susceptibility to mycobacterial infections in children with X-linked chronic granulomatous disease: a review of 17 patients living in a region endemic for tuberculosis

Disseminated Bacillus Calmette-Guérin lymphadenitis in a patient with gp91phox- chronic granulomatous disease 25 years after vaccination

A boy developed ipsilateral axillary lymphadenitis after Bacillus Calmette-Guérin (BCG) inoculation at the age of 5 months. Subsequently, he was diagnosed with X-linked chronic granulomatous disease (CGD) by the nitroblue tetrazolium assay when he was 4 years old. Body computerized tomography (CT) performed at the age of 25 years showed enlarged lymph nodes in the left periclavicular and axillary regions, and was confirmed by gallium scintigraphy. Mycobacterial culture, smear, and polymerase chain reaction (PCR) of the sputum and gastric fluid were negative. Whole-blood IFN-gamma assay was negative as well. Mycobacterium bovis BCG was isolated from the lymph node biopsy by PCR amplification and culture. No mutation of the IFN-gamma receptor 1 could be identified. In conclusion, CGD can be the underlying condition for BCG-itis; whole-blood IFN-gamma assay might be useful in differentiating BCG infection and tuberculosis in CGD patients; BCG vaccination is contraindicated in X-linked CGD.

NADPH oxidase 2 interaction with TLR2 is required for efficient innate immune responses to mycobacteria via cathelicidin expression

Gp91(phox)/NADPH oxidase (NOX) 2 is the main catalytic component of NOX, which mediates the phagocytic killing of ingested pathogens via the production of reactive oxygen species (ROS). However, Mycobacterium tuberculosis (Mtb) is relatively resistant to the microbicidal effects of ROS. Thus, the exact roles of NOX2 in the innate immune control against Mtb infection are not fully resolved. In this study, we show that NOX2 is essential for TLR2-dependent inflammatory responses and 1,25-dihydroxyvitamin D(3) (1,25D(3))-mediated antimicrobial activity against Mtb via cathelicidin expression. NOX2-null macrophages prominently abrogated Mtb-induced ROS production and inflammatory signaling activation in a TLR2-dependent manner. Mtb triggered a physical association between NOX2 and TLR2. In addition, the knockdown of NOX2 inhibited 1,25D(3)-triggered antimicrobial activity against viable Mtb through the modulation of cathelicidin expression in human macrophages. Treatment of NOX2 knocked down cells with cathelicidin restored the 1,25D(3)-induced antimicrobial effect, suggesting that the NOX2-dependent induction of cathelicidin in macrophages is part of a defensive strategy against Mtb. Furthermore, cathelicidin expression was required for the Mtb-induced release of ROS and the production of proinflammatory cytokines/chemokines, indicating a positive circuit of inflammation in response to Mtb. Our data collectively demonstrate a novel regulatory mechanism for TLR2-dependent innate responses to Mtb involving crosstalk between NOX2 and TLR2 and the expression of cathelicidin.

Chronic granulomatous disease: the European experience

CGD is an immunodeficiency caused by deletions or mutations in genes that encode subunits of the leukocyte NADPH oxidase complex. Normally, assembly of the NADPH oxidase complex in phagosomes of certain phagocytic cells leads to a “respiratory burst”, essential for the clearance of phagocytosed micro-organisms. CGD patients lack this mechanism, which leads to life-threatening infections and granuloma formation. However, a clear picture of the clinical course of CGD is hampered by its low prevalence (∼1∶250,000). Therefore, extensive clinical data from 429 European patients were collected and analyzed. Of these patients 351 were males and 78 were females. X-linked (XL) CGD (gp91^phox deficient) accounted for 67% of the cases, autosomal recessive (AR) inheritance for 33%. AR-CGD was diagnosed later in life, and the mean survival time was significantly better in AR patients (49.6 years) than in XL CGD (37.8 years), suggesting a milder disease course in AR patients. The disease manifested itself most frequently in the lungs (66% of patients), skin (53%), lymph nodes (50%), gastrointestinal tract (48%) and liver (32%). The most frequently cultured micro-organisms per episode were Staphylococcus aureus (30%), Aspergillus spp. (26%), and Salmonella spp. (16%). Surprisingly, Pseudomonas spp. (2%) and Burkholderia cepacia (<1%) were found only sporadically. Lesions induced by inoculation with BCG occurred in 8% of the patients. Only 71% of the patients received antibiotic maintenance therapy, and 53% antifungal prophylaxis. 33% were treated with γ-interferon. 24 patients (6%) had received a stem cell transplantation. The most prominent reason of death was pneumonia and pulmonary abscess (18/84 cases), septicemia (16/84) and brain abscess (4/84). These data provide further insight in the clinical course of CGD in Europe and hopefully can help to increase awareness and optimize the treatment of these patients.

Chinese patients with defective IL-12/23-interferon-gamma circuit in Taiwan: partial dominant interferon-gamma receptor 1 mutation presenting as cutaneous granuloma and IL-12 receptor beta1 mutation as pneumatocele

BACKGROUND

IL-12/23-interferon-gamma circuit enhances reactive oxygen species (ROS) synthesis in macrophage to attack intracellular pathogens such as mycobacteria and salmonella. Defective ROS in patients with chronic granulomatous disease (CGD) have increased susceptibility to these pathogens. However, patients with defective IL-12/23-interferon-gamma circuit rather than CGD are not recognized in Taiwan, endemic for tuberculosis and salmonella.

AIM

The purpose of this study was to identify Taiwanese patients with defective IL-12/23-IFN-gamma circuit.

PATIENTS AND METHODS

In a long-term molecular study of primary immunodeficiency diseases (PIDD), the tentative CGD patients presenting with Bacille Calmette-Guerin (BCG)-induced infection, refractory atypical mycobacterial cutaneous granuloma and osteomyelitis, recurrent salmonella sepsis, and pneumatocele were studied for the IL-12/23-IFN-gamma circuit. ROS was first measured to exclude CGD. Candidate genes of IL12RB1, IFNRG1, IL12p40, IFNRG2, signal transducer and activator of transcription-1, and NF-kappaB essential modulator and their encoding protein expressions were analyzed.

RESULTS

Of the 175 Taiwanese PIDD patients during a 28-year period, three patients from two unrelated families were identified with the hotspot INFRG1 deletion mutation (818del4) and had CGD features, presenting as cutaneous granuloma, and multiple osteomyelitis infected by non-tuberculosis mycobacteria, Mycobacteria avium complex and Mycobacterium scrofulaceum. Another with mis-sense IL12RB1 mutation (Arg211Pro) was noted as recurrent Salmonella enteritidis D sepsis and pneumatocele.

CONCLUSION

Patients with defective IL-12/23-IFN-gamma circuit may resemble or overlap CGD manifestations of refractory cutaneous atypical mycobacterial granuloma and salmonella pneumatocele.

The multifunctional histone-like protein Lsr2 protects mycobacteria against reactive oxygen intermediates

Mycobacterium tuberculosis has evolved a number of strategies to survive within the hostile environment of host phagocytes. Reactive nitrogen and oxygen intermediates (RNI and ROI) are among the most effective antimycobacterial molecules generated by the host during infection. Lsr2 is a M. tuberculosis protein with histone-like features, including the ability to regulate a variety of transcriptional responses in mycobacteria. Here we demonstrate that Lsr2 protects mycobacteria against ROI in vitro and during macrophage infection. Furthermore, using macrophages derived from NOS(-/-) and Phox(-/-) mice, we demonstrate that Lsr2 is important in protecting against ROI but not RNI. The protection provided by Lsr2 protein is not the result of its ability to either bind iron or scavenge hydroxyl radicals. Instead, electron microscopy and DNA-binding studies suggest that Lsr2 shields DNA from reactive intermediates by binding bacterial DNA and physically protecting it. Thus, Lsr2 appears to be a unique protein with both histone-like properties and protective features that may be central to M. tuberculosis pathogenesis. In addition, evidence indicates that lsr2 is an essential gene in M. tuberculosis. Because of its essentiality, Lsr2 may represent an excellent candidate as a drug target.