Clinical characteristics of pulmonary Mycobacterium avium complex disease in patients with interstitial lung disease.

OBJECTIVE: Mycobacterium avium complex pulmonary disease (MAC-PD) is occasionally complicated by interstitial lung disease (ILD) in clinical practice, but clinical studies are limited. This study aims to elucidate the clinical and imaging characteristics of MAC-PD in patients with ILD. METHODS: We retrospectively analyzed imaging and clinical data from medical records of 54 consecutive ILD patients diagnosed with MAC-PD from 2011 to 2021 at our institution. We compared the imaging and clinical data of these patients with 2218 ILD patients diagnosed at our institution. RESULTS: The mean age of the patients was 74 years, with 25 males and 29 females, and a mean body mass index (BMI) of 20.0 kg/m2. Compared to all ILD patients, ILD-associated MAC-PD had older ages, lower BMI. The most common underlying ILD diagnosis was unclassifiable interstitial pneumonia. MAC-PD imaging classification was nodular-bronchiectatic (NB) type in 17 patients, fibro-cavitary (FC) type in 15 patients, and unclassifiable (UC) type in 22 patients. Many UC types were difficult to diagnose due to the absence of clear findings indicative of MAC infection. Chronic pulmonary aspergillosis complication was 24.1 %. The mean survival of ILD-associated MAC-PD was 55.6 months, shorter than that of regular MAC-PD. The UC type had a shorter survival than the NB type, similar to the FC type. CONCLUSION: MAC-PD associated with ILD frequently complicates chronic pulmonary aspergillosis and has a poor prognosis. The most common imaging type, UC type, particularly has a shorter survival. Careful management is essential for MAC-PD associated with ILD.

Mycobacterium abscessus lymphadenitis in bone marrow transplant patient.

Non-tuberculous mycobacteria (NTM) are acid-fast bacteria categorized into rapidly growing and slow growing mycobacteria. NTM are more common in transplant patients who are immunocompromised. Here we report the case of a post- bone marrow transplant adolescent male presenting with submandibular swelling and fever. The gland was excised and the histopathology showed chronic granulomatous inflammation. Culture grew Mycobacterium abscessus which was sensitive to amikacin, linezolid and clarithromycin. A good response was achieved on therapy.

Interleukin-1ß triggers the differentiation of macrophages with enhanced capacity to present mycobacterial antigen to T cells.

The rapid differentiation of monocytes into macrophages (MΦ) and dendritic cells is a pivotal aspect of the innate immune response. Differentiation is triggered following recognition of microbial ligands that activate pattern recognition receptors or directly by pro-inflammatory cytokines. We demonstrate that interleukin-1ß (IL-1ß) induces the rapid differentiation of monocytes into CD209(+) MΦ, similar to activation via Toll-like receptor 2/1, but with distinct phenotypic and functional characteristics. The IL-1ß induced MΦ express higher levels of key markers of phagocytosis, including the Fc-receptors CD16 and CD64, as well as CD36, CD163 and CD206. In addition, IL-1ß-induced MΦ exert potent phagocytic activity towards inert particles, oxidized low-density lipoprotein and mycobacteria. Furthermore, IL-1ß-induced MΦ express higher levels of HLA-DR and effectively present mycobacterial antigens to T cells. Therefore, the ability of IL-1ß to induce monocyte differentiation into MΦ with both phagocytosis and antigen-presenting function is a distinct part of the innate immune response in host defence against microbial infection.

Protective Effect of Intestinal Helminthiasis Against Tuberculosis Progression Is Abrogated by Intermittent Food Deprivation.

Background: Tuberculosis (TB) is still a major challenge for humankind. Because regions with the highest incidence also have a high prevalence of helminthiasis and nutritional scarcity, we wanted to understand the impact of these on TB progression. Methods: We have developed an experimental murine model for active TB in C3HeB/FeJ, coinfected with Trichuris muris and Heligmosomoides polygyrus nematodes, and exposed to an environmental mycobacterium (M. manresensis) and intermittent fasting. Cause-effect relationships among these factors were explored with Partial Least Squares Path modelling (PLSPM). Results: Previous parasitization had a major anti-inflammatory effect and reduced systemic levels of ADA, haptoglobin, local pulmonary levels of IL-1ß, IL-6, TNF-α, CXCL-1, CXCL-5 and IL-10. Oral administration of heat-killed M. manresensis resulted in a similar outcome. Both interventions diminished pulmonary pathology and bacillary load, but intermittent food deprivation reduced this protective effect increasing stress and inflammation. The PLSPM revealed nematodes might have protective effects against TB progression. Conclusions: Significantly higher cortisol levels in food-deprivation groups showed it is a stressful condition, which might explain its deleterious effect. This highlights the impact of food security on TB eradication policies and the need to prioritize food supply over deworming activities.