Monocytes/macrophages are innate immune cells that play a crucial role in the resolution of inflammation. In presence of Th2 cytokines interleukin-4 (IL-4) and interleukin-13 (IL-13), they display an anti-inflammatory profile and this activation pathway is known as alternative activation. In this study we compare and differentiate pathways mediated by IL-4 and IL-13 activation of human monocytes/macrophage. Here we report differential regulation of IL-4 and IL-13 signaling in monocytes/macrophages starting from IL-4/IL-13 cytokine receptors to Jak-Stat-mediated signaling pathways that ultimately control expression of several infl1ammatory genes. Our data demonstrate that while the receptor-associated tyrosine kinases Jak2 and Tyk2 are activated after the recruitment of IL-13 to its receptor (containing IL-4Rα and IL-13Rα1), IL-4 stimulates Jak1 activation. We further show that Jak2 is upstream of Stat3 activation and Tyk2 controls Stat1 and Stat6 activation in response to IL-13 stimulation. In contrast, Jak1 regulates Stat3 and Stat6 activation in IL-4-induced monocytes. Our results further reveal that while IL-13 utilizes both IL-4Rα-Jak2-Stat3 and IL-13Rα1-Tyk2-Stat1/Stat6 signaling pathways, IL-4 can only use the IL-4Rα-Jak1-Stat3/Stat6 cascade to regulate the expression of some critical inflammatory genes including 15-lipoxygenase (15-LO), monoamine oxidase A (MAO-A) and scavenger receptor CD36. Moreover, we demonstrate here that IL-13 and IL-4 can uniquely affect the expression of particular genes like dual specificity phosphatase 1 (DUSP1) and tissue inhibitor of metalloprotease-3 (TIMP3) and do so through different Jak kinaes. As evidence of differential regulation of gene function by IL-4 and IL-13, we further report that MAO-A-mediated reactive oxygen species (ROS) generation is influenced by different Jak kinases. Collectively, these results have major implications for understanding the mechanism and function of alternatively activated monocytes/macrophages by IL-4 and IL-13 and add novel insights into the pathogenesis and potential treatment of different inflammatory diseases.

Objective-Although consumption of dietary supplements containing pomegranate extract by arthritis patients is on the rise, efficacy of such preparations in suppressing joint inflammation and damage is not known. The present study was designed to evaluate a standardized preparation of pomegranate extract (POMx) using collagen-induced arthritis in mice (CIA)-a widely used animal model of rheumatoid arthritis (RA).Methods-CIA susceptible DBA/1 mice were fed POMx by gavage before and after immunization with chicken type-II collagen (CII). Severity of clinical arthritis was scored using a visual scoring system. Arthritic joints were analyzed by histopathology and graded. Lysates were generated from mouse joints and the levels of anti-type-II collagen IgG and inflammatory cytokines IL-1β, IL-6 and TNF-α were quantified by ELISA. Effect of POMx on LPS-induced NO production was determined by Griess reaction and MAP kinase activation was studied by Western immunoblotting in mouse macrophages.Results-Consumption of POMx potently delayed the onset and reduced the incidence of CIA in mice. Severity of arthritis was also significantly lower in POMx -fed animals. Histopathology of the arthritic joints from POMx-fed mice demonstrated reduced joint infiltration by the inflammatory cells and the destruction of bone and cartilage were alleviated. Levels of IL-6 were significantly decreased in the joints of POMx-fed mice with CIA. In mouse macrophages, POMx abrogated multiple signal transduction pathways and downstream mediators implicated in RA pathogenesis.Conclusions-Our studies suggest that inhibition of a spectrum of signal transduction pathways and the downstream pathogenic cellular response by POMx or compounds derived from it may be a useful approach for the prevention of onset and severity of inflammatory arthritis.

Background: Mast cells and basophils are multifunctional effector cells and contain plentiful secretary granules in their cytoplasm. These cell types are involved in several inflammatory and immune events and are known to produce an array of mediators including a broad spectrum of cytokines. Pomegranate fruit is rich in anthocyanins and hydrolysable tannins; a group of polyphenolic compounds shown to be potent antioxidant with anti-inflammatory activity. However, no studies have been undertaken to investigate whether a polyphenol-rich pomegranate fruit extract (POMx) inhibits the inflammatory activity of activated human mast cells and basophils. The aim of this study was to examine whether POMx modulates inflammatory reactions using human basophilic cell line KU812.