MicroRNA-155 Modulates Macrophages' Response to Non-Tuberculous Mycobacteria through COX-2/PGE2 Signaling.

Non-tuberculous mycobacteria (NTM) have been recognized as a causative agent of various human diseases, including severe infections in immunocompromised patients, such as people living with HIV. The most common species identified is the Mycobacterium avium-intracellulare complex (MAI/MAC), accounting for a majority of infections. Despite abundant information detailing the clinical significance of NTM, little is known about host-pathogen interactions in NTM infection. MicroRNAs (miRs) serve as important post-transcriptional regulators of gene expression. Using a microarray profile, we found that the expression of miR-155 and cyclo-oxygenase 2 (COX-2) is significantly increased in bone-marrow-derived macrophages from mice and human monocyte-derived macrophages from healthy volunteers that are infected with NTM. Antagomir against miR-155 effectively suppressed expression of COX-2 and reduced Prostaglandin E2(PGE2) secretion, suggesting that COX-2/PGE2 expression is dependent on miR-155. Mechanistically, we found that inhibition of NF-κB activity significantly reduced miR-155/COX-2 expression in infected macrophages. Most importantly, blockade of COX-2, E-prostanoid receptors (EP2 and EP4) enhanced killing of MAI in macrophages. These findings provide novel mechanistic insights into the role of miR-155/COX-2/PGE2 signalling and suggest that induction of these pathways enhances survival of mycobacteria in macrophages. Defining host-pathogen interactions can lead to novel immunomodulatory therapies for NTM infections which are difficult to treat.

Macrophage Signaling Pathways in Pulmonary Nontuberculous Mycobacteria Infections.

The incidence and prevalence of nontuberculous mycobacteria (NTM) lung disease is rising worldwide and accounts for most clinical cases of NTM disease. NTM infections occur in both immunocompetent and immunocompromised hosts. Macrophages are the primary host cells that initiate an immune response to NTM. Defining the molecular events that govern the control of infection within macrophages is fundamental to understanding the pathogenesis of NTM disease. Here, we review key macrophage host signaling pathways that contribute to the host immune response to pulmonary NTM infections. In this review, we focus primarily on NTM that are known to cause lung disease, including Mycobacterium avium intracellulare, M. abscessus, and M. kansasii.

Pediatric glaucoma suspects.

PURPOSE: To report demographic and ocular features of pediatric glaucoma suspects in an ethnically diverse population of North Central Texas. DESIGN: Retrospective cross-sectional chart review. PARTICIPANTS: Subjects included 75 (136 eyes) pediatric glaucoma suspects. Patients with one or more of the following risk factors were included: cup-to disc (C/D) ratio of ≥0.6; intraocular pressure (IOP) ≥21 mmHg; family history of glaucoma; congenital glaucoma in the opposite eye; history of blunt trauma to either eye; and presence of either Sturge-Weber or Axenfeld-Rieger syndrome, or oculodermal melanocytosis. METHODS: Data were extracted from electronic patient medical records. Patient records with incomplete data were excluded. The main outcome measures were race, sex, age, IOP, C/D, family history of glaucoma; and glaucoma treatment. RESULTS: Subjects included 28 (37.3%) Hispanics, 20 (26.6%) African Americans, 20 (26.6%) Caucasians, and seven (9.3%) Asians. Forty (53.3%) of the patients were male. Suspicious optic disc was seen in 57 (76%); elevated IOP in 25 (33.3%); presence of family history in 13 (17.3%), and Sturge-Weber syndrome in nine (12%) patients. The average C/D ratio was 0.58±0.2. The C/D ratios of African American (0.65±0.2), Hispanic (0.63±0.2), and Asian (0.62±0.15) patients were significantly greater than those of Caucasians (0.43±0.18; P=0.0004, 0.0003, and 0.0139, respectively). Caucasian patients were the youngest (7.9±4.8 years). Eleven cases (14.7%) required medication. CONCLUSION: Thirty-three point seven percent of patients seen in the glaucoma clinic were glaucoma suspects. The most common risk factors for suspected glaucoma were suspicious optic discs, elevated IOP, and family history of glaucoma. Most patients required only close observation. Long-term follow-up of these patients is warranted to determine the mechanisms of conversion to glaucoma.