Reducing LPS content in cockroach allergens increases pulmonary cytokine production without increasing inflammation: A randomized laboratory study

<p>Abstract</p> <p>Background</p> <p>Endotoxins are ubiquitously present in the environment and constitute a significant component of ambient air. These substances have been shown to modulate the allergic response, however a consensus has yet to be reached whether they attenuate or exacerbate asthmatic responses. The current investigation examined whether reducing the concentration of lipopolysaccharide (LPS) in a house dust extract (HDE) containing high concentrations of both cockroach allergens <abbrgrp><abbr bid="B1">1</abbr></abbrgrp> and LPS would attenuate asthma-like pulmonary inflammation.</p> <p>Methods</p> <p>Mice were sensitized with CRA and challenged with the intact HDE, containing 182 ng of LPS, or an LPS-reduced HDE containing 3 ng LPS, but an equivalent amount of CRA. Multiple parameters of asthma-like pulmonary inflammation were measured.</p> <p>Results</p> <p>Compared to HDE challenged mice, the LPS-reduced HDE challenged mice had significantly reduced TNFα levels in the bronchoalveolar lavage fluid. Plasma levels of IgE and IgG1 were significantly reduced, however no change in CRA-specific IgE was detected. In HDE mice, plasma IgG2a levels were similar to naïve mice, while LPS-reduced HDE mice had significantly greater concentrations. Reduced levels of LPS in the HDE did not decrease eosinophil or neutrophil recruitment into the alveolar space. Equivalent inflammatory cell recruitment occurred despite having generally higher pulmonary concentrations of eotaxins and CXC chemokines in the LPS-reduced HDE group. LPS-reduced HDE challenge induced significantly higher concentrations of IFNγ, and IL-5 and IL-13 in the BAL fluid, but did not decrease airways hyperresponsiveness or airway resistance to methacholine challenge. <it>Conclusion: </it>These data show that reduction of LPS levels in the HDE does not significantly protect against the severity of asthma-like pulmonary inflammation.</p

Endpoints in pediatric pain studies

Assessing pain intensity in (preverbal) children is more difficult than in adults. Tools to measure pain are being used as primary endpoints [e.g., pain intensity, time to first (rescue) analgesia, total analgesic consumption, adverse effects, and long-term effects] in studies on the effects of analgesic drugs. Here, we review current and promising new endpoints used in pediatric pain assessment studies

Involvement of TLR2 and TLR4 in inflammatory immune responses induced by fine and coarse ambient air particulate matter

Induction of proinflammatory mediators by alveolar macrophages exposed to ambient air particulate matter has been suggested to be a key factor in the pathogenesis of inflammatory and allergic diseases in the lungs. However, receptors and mechanisms underlying these responses have not been fully elucidated. In this study, we examined whether TLR2, TLR4, and the key adaptor protein, MyD88, mediate the expression of proinflammatory cytokines and chemokines by mouse peritoneal macrophages exposed to fine and coarse PM. TLR2 deficiency blunted macrophage TNF-α and IL-6 expression in response to fine (PM2.5), while not affecting cytokine-inducing ability of coarse NIST Standard Reference Material (SRM 1648) particles. In contrast, TLR4−/− macrophages showed inhibited cytokine expression upon stimulation with NIST SRM 1648 but exhibited normal responses to PM2.5. Preincubation with polymyxin B markedly suppressed the capacity of NIST SRM 1648 to elicit TNF-α and IL-6, indicating endotoxin as a principal inducer of cytokine responses. Overexpression of TLR2 in TLR2/4-deficient human embryonic kidney 293 cells imparted PM2.5 sensitivity, as judged by IL-8 gene expression, whereas NIST SRM 1648, but not PM2.5 elicited IL-8 expression in 293/TLR4/MD-2 transfectants. Engagement of TLR4 by NIST SRM 1648 induced MyD88-independent expression of the chemokine RANTES, while TLR2-reactive NIST IRM PM2.5 failed to up-regulate this response. Consistent with the shared use of MyD88 by TLR2 and TLR4, cytokine responses of MyD88−/− macrophages to both types of air PM were significantly reduced. These data indicate differential utilization of TLR2 and TLR4 but shared use of MyD88 by fine and coarse air pollution particles