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Schistosomiasis is a neglected tropical disease caused by worms of the genus Schistosoma spp. The progression of disease results in intense tissue fibrosis and high mortality rate. After egg deposition by adult worms, the inflammatory response is characterized by the robust activation of type 2 immunity. Monocytes and macrophages play critical roles during schistosomiasis. Inflammatory Ly6Chigh monocytes are recruited from the blood to the inflammatory foci and differentiate into alternatively activated macrophages (AAMs), which promote tissue repair. The common chain of b2-integrins (CD18) regulates monocytopoiesis and mediates resistance to experimental schistosomiasis. There is still limited knowledge about mechanisms controlled by CD18 that impact monocyte development and effector cells such as macrophages during schistosomiasis. Here, we show that CD18low mice chronically infected with S. mansoni display monocyte progenitors with reduced proliferative capacity, resulting in the accumulation of the progenitor cell denominated proliferating-monocyte (pMo). Consequently, inflammatory Ly6Chigh and patrolling Ly6Clow monocytes are reduced in the bone marrow and blood. Mechanistically, low CD18 expression decreases Irf8 gene expression in pMo progenitor cells, whose encoded transcription factor regulates CSFR1 (CD115) expression on the cell surface. Furthermore, low CD18 expression affects the accumulation of inflammatory Ly6Chigh CD11b+ monocytes in the liver while the adoptive transference of these cells to infected-CD18low mice reduced the inflammatory infiltrate and fibrosis in the liver. Importantly, expression of Il4, Chil3l3 and Arg1 was downregulated, CD206+PD-L2+ AAMs were reduced and there were lower levels of IL-10 in the liver of CD18low mice chronically infected with S. mansoni. Overall, these findings suggest that CD18 controls the IRF8-CD115 axis on pMo progenitor cells, affecting their proliferation and maturation of monocytes. At the same time, CD18 is crucial for the appropriate polarization and function of AAMs and tissue repair during chronic schistosomiasis. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the prevalence and seasonality of human respiratory syncytial virus (HRSV) in children aged 0 to 6 years, hospitalized with acute lower respiratory infection (ALRI) in São José do Rio Preto, SP, Brazil, and the association between age, diagnosis, and HRSV. Methods: Between May 2004 and September 2005, we studied 290 consecutive episodes of community-acquired ALRI in children aged 0 to 6 years admitted to the Hospital de Base of São José do Rio Preto. In order to detect HRSV, nasopharyngeal secretion samples were collected and RT-PCR molecular analysis was performed. Results: The HRSV prevalence was 29.3% for the cases of hospitalized patients with ALRI. ALRI was common in infants (median age = 13.5 months). HRSV was more frequent in cases of bronchiolitis (64%) and during the first year of life (35%). Episodes of HRSV infection occurred between fall and spring, showing higher frequency in 2004 than in 2005. Clinical and radiological criteria were not sufficient to establish the diagnosis of infection with HRSV. Antibiotic therapy was used in 78.8% of episodes of HRSV. Conclusions: There was a high prevalence of HRSV in children aged 0 to 6 years who were hospitalized for ALRI, predominantly in younger patients or those with bronchiolitis. The circulation of the virus varied in the two years studied. Our results suggest the need for laboratory diagnosis of HRSV in the clinical practice. [ABSTRACT FROM AUTHOR]

Scorpion envenomation is a leading cause of morbidity and mortality among accidents caused by venomous animals. Major clinical manifestations that precede death after scorpion envenomation include heart failure and pulmonary edema. Here, we demonstrate that cardiac dysfunction and fatal outcomes caused by lethal scorpion envenomation in mice are mediated by a neuro-immune interaction linking IL-1 receptor signaling, prostaglandin E2, and acetylcholine release. IL-1R deficiency, the treatment with a high dose of dexamethasone or blockage of parasympathetic signaling using atropine or vagotomy, abolished heart failure and mortality of envenomed mice. Therefore, we propose the use of dexamethasone administration very early after envenomation, even before antiserum, to inhibit the production of inflammatory mediators and acetylcholine release, and to reduce the risk of death. Cardiac dysfunction is a major complication that precedes death after scorpion envenomation. Here, authors show that heart failure and mortality are caused by excessive acetylcholine release, which requires IL-1R-dependent PGE2 production. Dexamethasone treatment effectively inhibits cardiac dysfunction and mortality. [ABSTRACT FROM AUTHOR]

Leukotriene B 4 (LTB 4 ) is essential for host immune defence. It increases neutrophil recruitment, phagocytosis and pathogen clearance, and decreases oedema and inflammasome activation. The host response and the role of LTB 4 during Achromobacter xylosoxidans infection remain unexplored. Wild-type (129sv) and LTB 4 deficient (Alox5 -/- ) mice were intratracheally infected with A. xylosoxidans. Wild-type 129sv infected mice survived beyond the 8 th day post-infection, exhibited increased levels of LTB 4 in the lung on the 1 st day, while levels of PGE 2 increased on the 7 th day post-infection. Infected Alox5 -/- mice showed impaired bacterial clearance, increased lung inflammation, and succumbed to the infection by the 7 th day. We found that exogenous LTB 4 does not affect the phagocytosis of A. xylosoxidans by alveolar macrophages in vitro. However, treatment of infected animals with LTB 4 protected from mortality, by reducing the bacterial load and inflammation via BLT 1 signalling, the high affinity receptor for LTB 4 . Of importance, we uncovered that LTB 4 induces gene and protein expression of α-defensin-1 during the infection. This molecule is essential for bacterial clearance and exhibits potent antimicrobial activity by disrupting A. xylosoxidans cell wall. Taken together, our data demonstrate a major role for LTB 4 on the control of A. xylosoxidans infection.