Maternal distress in early life plays a role in the development of childhood asthma, especially if it continues beyond the postpartum period.

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Phosphoinositide 3-kinases (PI3K) regulate immune activation via their roles in signal transduction of multiple classes of receptors. Here, we examined the effect of genetic inactivation of the hemopoietic cell-restricted PI3K isoform p110d on systemic cytokine and chemokine responses and allergic airway inflammation. We found that type 2 cytokine responses (IL-4, IL-5 and IL-13) are significantly decreased in p110d mutants, whereas type 1 cytokine responses (IFN-c and CXCL10) were robust. Elevated IFN-c production during the primary response to ovalbumin (OVA) was associated with reduced production of the regulatory cytokine IL-10. IFN-c and IL-10 production normalized after secondary OVA immunization; however, type 2 cytokine production was persistently reduced. Type 2 cytokine-dependent airway inflammation elicited by intranasal challenge with OVA was dramatically reduced, with reduced levels of eosinophil recruitment and mucus production observed in the lungs. Induction of respiratory hyper-responsiveness to inhaled methacholine, a hallmark of asthma, was markedly attenuated in p110d-inactivated mice. Adoptive transfer of OVA-primed splenocytes from normal but not p110d-inactivated mice could induce airway eosinophilia in naive, airway-challenged recipient mice. These data demonstrate a novel functional role for p110d signaling in induction of type 2 responses in vivo and may offer a new therapeutic target for Th2-mediated airway disease. IntroductionPhosphoinositide 3-kinases (PI3K) are key signaling enzymes regulating immune function [1,2]. PI3K are activated by stimulation through a variety of receptor types, including antigen receptors, costimulatory receptors and certain cytokine receptors. PI3K function by phosphorylating specific plasma membrane phospholipids to generate short-lived, membrane-integral lipid [3,4]. Effects of regulatory subunit deficiencies on T cells are less clear: deficiency of the p85a regulatory subunit for class 1A PI3K was reported to have no effect on T cell activation in vitro, while deficiency in the p85b regulatory subunit increased T cell proliferation in vitro [5]. One group found that p85-deficient mice have enhanced responses to Leishmania infection [6], but reduced immunity to nematode infection [7], suggesting that impaired class IA PI3K signaling leads to an immune dysregulation rather than a general immunodeficiency. However, the interpretation of these studies is complicated because regulatory subunits each affect the stability and activity of multiple catalytic subunits and may have adaptor functions in signaling independent of PI3K catalytic subunits.Recent work has begun to explore the specific roles of different PI3K catalytic subunit isoforms in immune function. Analysis of p110a and p110b deficiency has been hindered by the lethality of these mutations [8,9]. Mice deficient in the class IB subunit p110c are viable and have defects in T cell development and activation, as well as severe defects in neutrophil function, while B cell activation appears normal [1...