Airway allergy causes alveolar macrophage death, profound alveolar disorganization and surfactant dysfunction.

Respiratory disorders caused by allergy have been associated to bronchiolar inflammation leading to life-threatening airway narrowing. However, whether airway allergy causes alveolar dysfunction contributing to the pathology of allergic asthma remains unaddressed. To explore whether airway allergy causes alveolar dysfunction that might contribute to the pathology of allergic asthma, alveolar structural and functional alterations were analyzed during house dust mite (HDM)-induced airway allergy in mice, by flow cytometry, light and electron microscopy, monocyte transfer experiments, assessment of intra-alveolarly-located cells, analysis of alveolar macrophage regeneration in Cx3cr1 cre:R26-yfp chimeras, analysis of surfactant-associated proteins, and study of lung surfactant biophysical properties by captive bubble surfactometry. Our results demonstrate that HDM-induced airway allergic reactions caused severe alveolar dysfunction, leading to alveolar macrophage death, pneumocyte hypertrophy and surfactant dysfunction. SP-B/C proteins were reduced in allergic lung surfactant, that displayed a reduced efficiency to form surface-active films, increasing the risk of atelectasis. Original alveolar macrophages were replaced by monocyte-derived alveolar macrophages, that persisted at least two months after the resolution of allergy. Monocyte to alveolar macrophage transition occurred through an intermediate stage of pre-alveolar macrophage and was paralleled with translocation into the alveolar space, Siglec-F upregulation, and downregulation of CX3CR1. These data support that the severe respiratory disorders caused by asthmatic reactions not only result from bronchiolar inflammation, but additionally from alveolar dysfunction compromising an efficient gas exchange.

Resident macrophage-dependent immune cell scaffolds drive anti-bacterial defense in the peritoneal cavity.

Peritoneal immune cells reside unanchored within the peritoneal fluid in homeostasis. Here, we examined the mechanisms that control bacterial infection in the peritoneum using a mouse model of abdominal sepsis following intraperitoneal Escherichia coli infection. Whole-mount immunofluorescence and confocal microscopy of the peritoneal wall and omentum revealed that large peritoneal macrophages (LPMs) rapidly cleared bacteria and adhered to the mesothelium, forming multilayered cellular aggregates composed by sequentially recruited LPMs, B1 cells, neutrophils, and monocyte-derived cells (moCs). The formation of resident macrophage aggregates (resMφ-aggregates) required LPMs and thrombin-dependent fibrin polymerization. E. coli infection triggered LPM pyroptosis and release of inflammatory mediators. Resolution of these potentially inflammatory aggregates required LPM-mediated recruitment of moCs, which were essential for fibrinolysis-mediated resMφ-aggregate disaggregation and the prevention of peritoneal overt inflammation. Thus, resMφ-aggregates provide a physical scaffold that enables the efficient control of peritoneal infection, with implications for antimicrobial immunity in other body cavities, such as the pleural cavity or brain ventricles.

Self-medication with oral corticosteroids reported by patients with ulcerative colitis: characteristics, reasons and patients' behaviors.

BACKGROUND: Few studies have examined self-medication with corticosteroids among patients with ulcerative colitis (UC). AIMS: To assess the frequency of self-medication with oral corticosteroids in UC patients, and associated factors and reasons. METHODS: An anonymous, voluntary, web-based survey was administered to adults with UC recruited via a Spanish patient association (ACCU) and hospital gastroenterology departments. Information was provided by patients; no clinical data were collected. Descriptive statistics and comparisons of frequencies are displayed. RESULTS: Among 546 respondents (mean age 39.9 years, median duration of UC since diagnosis 7 years,) 36 (6.6%) reported self-medication with oral corticosteroids during the past year (once: 23 patients; 2-3 times: 10 patients; >3 times: 3 patients). Self-medication was more common among patients managed in general gastroenterology vs. inflammatory bowel disease clinics [23 (9.0%) vs. 11 (2.9%), P = 0.019], patients with no regular follow-up [4 (22.2%) vs. 32 (6.1%), P = 0.026] and patients with more flares (P < 0.001). Patients who stored steroids from previous flares (17.9% vs. 6.0%, P < 0.001) or who lived with a partner taking steroids (9.3% vs. 1.1%, P = 0.038) were more likely to self-medicate than other patients. Common reasons for self-medicating included the need for quick symptom relief (55.6%), fear of worsening (47.2%) and difficulty in getting an appointment (25.0%). Only seven patients (19.4%) informed their physician when they started self-medicating and only four (11.1%) declared they would not start corticosteroids again. CONCLUSION: Self-medication with oral corticosteroids is not a common practice among patients with UC in Spain, but several areas of improvement exist.

Inflammatory Ly6Chigh Monocytes Protect against Candidiasis through IL-15-Driven NK Cell/Neutrophil Activation.

Neutrophils play a crucial role in defense against systemic candidiasis, a disease associated with a high mortality rate in patients receiving immunosuppressive therapy, although the early immune mechanisms that boost the candidacidal activity of neutrophils remain to be defined in depth. Here, we used a murine model of systemic candidiasis to explore the role of inflammatory Ly6Chigh monocytes in NK cell-mediated neutrophil activation during the innate immune response against C. albicans. We found that efficient anti-Candida immunity required a collaborative response between the spleen and kidney, which relied on type I interferon-dependent IL-15 production by spleen inflammatory Ly6Chigh monocytes to drive efficient activation and GM-CSF release by spleen NK cells; this in turn was necessary to boost the Candida killing potential of kidney neutrophils. Our findings unveil a role for IL-15 as a critical mediator in defense against systemic candidiasis and hold promise for the design of IL-15-based antifungal immunotherapies.