CD14 Influences Host Immune Responses and Alternative Activation of Macrophages during Schistosoma mansoni Infection

Antigen-presenting cell (APC) plasticity is critical for controlling inflammation in metabolic diseases and infections. The roles that pattern recognition receptors (PRRs) play in regulating APC phenotypes are just now being defined. We evaluated the expression of PRRs on APCs in mice infected with the helminth parasite Schistosoma mansoni and observed an upregulation of CD14 expression on macrophages. Schistosome-infected Cd14^−/− mice showed significantly increased alternative activation of (M2) macrophages in the livers compared to infected wild-type (wt) mice. In addition, splenocytes from infected Cd14^−/− mice exhibited increased production of CD4⁺-specific interleukin-4 (IL-4), IL-5, and IL-13 and CD4⁺Foxp3⁺IL-10⁺ regulatory T cells compared to cells from infected wt mice. S. mansoni-infected Cd14^−/− mice also presented with smaller liver egg granulomas associated with increased collagen deposition compared to granulomas in infected wt mice. The highest expression of CD14 was found on liver macrophages in infected mice. To determine if the Cd14^−/− phenotype was in part due to increased M2 macrophages, we adoptively transferred wt macrophages into Cd14^−/− mice and normalized the M2 and CD4⁺ Th cell balance close to that observed in infected wt mice. Finally, we demonstrated that CD14 regulates STAT6 activation, as Cd14^−/− mice had increased STAT6 activation in vivo, suggesting that lack of CD14 impacts the IL-4Rα-STAT6 pathway, altering macrophage polarization during parasite infection. Collectively, these data identify a previously unrecognized role for CD14 in regulating macrophage plasticity and CD4⁺ T cell biasing during helminth infection.     

Immunomodulatory Glycan Lacto-N-Fucopentaose III Requires Clathrin-Mediated Endocytosis To Induce Alternative Activation of Antigen-Presenting Cells

The mechanism of alternative activation of antigen-presenting cells (APCs) is largely unknown. Lacto-N-fucopentaose III (LNFPIII) is a biologically conserved pentasaccharide that contains the Lewis^x trisaccharide. LNFPIII conjugates and schistosome egg antigens, which contain the Lewis^x trisaccharide, drive alternative activation of APCs and induce anti-inflammatory responses in vivo, preventing inflammation-based diseases, including psoriasis, transplant organ rejection, and metabolic disease. In this study, we show that LNFPIII conjugates and schistosome egg antigens interact with APCs via a receptor-mediated process, requiring internalization of these molecules through a clathrin/dynamin-dependent but caveolus-independent endocytic pathway. Using inhibitors/small interfering RNA (siRNA) against dynamin and clathrin, we show for the first time that endocytosis of Lewis^x-containing glycans is required to drive alternative maturation of antigen-presenting cells and Th2 immune responses. We identified mouse SIGNR-1 as a cell surface receptor for LNFPIII conjugates. Elimination of SIGNR-1 showed no effect on uptake of LNFPIII conjugates, suggesting that other receptors bind to and facilitate uptake of LNFPIII conjugates. We demonstrate that disruption of actin filaments partially prevented the entry of LNFPIII conjugates into APCs and that LNFPIII colocalizes with both early and late endosomal markers and follows the classical endosomal pathway leading to lysosome maturation. The results of this study show that the ability of LNFPIII to induce alternative activation utilizes a receptor-mediated process that requires a dynamin-dependent endocytosis. Thus, key steps have been defined in the previously unknown mechanism of alternative activation that ultimately leads to induction of anti-inflammatory responses.     

Novel biochemical properties of a CRP/FNR family transcription factor from Mycobacterium tuberculosis

Cyclic AMP (cAMP) receptor protein (CRP)/fumarate nitrate reductase regulator (FNR) family proteins are actively associated with defense against low oxygen stress, starvation and extreme temperature conditions. They are DNA-binding proteins and regulate target genes carrying the regulatory CRP/FNR cognate nucleotide sequence elements. Recombinant protein encoded by the Mycobacterium tuberculosis ORF Rv3676, a putative CRP/FNR regulator, was purified from Escherichia coli and was found to exist as dimer, devoid of any metal cation cofactor. Purified rRv3676 exhibited cAMP binding in a concentration-dependent manner. At lower concentrations of cAMP (6-10 microM) rRv3676 shows positive cooperativity; at 10 microM cAMP the protein exists in the most open conformation. rRv3676 could bind specifically to the putative CRP/FNR nucleotide sequence elements as evident from electrophoretic mobility shift assay.     

Fetal sex-determination in Delhi: a population-based investigation

A population-based cross-sectional inquiry was carried out in Delhi to assess the practice of fetal sex determination, sex-selective abortions and awareness about the related law. A total of 1514 respondents, selected through multistage cluster sampling from all across Delhi, were interviewed using a pretested, semistructured questionnaire. Legal awareness (73.6%) was significantly better among the male and urban respondents. Only 39 (2.6%) of the respondents had ever gone for fetal sex determination. In 17 (43.6%) of them, it was done in spite of being aware of its unlawfulness, and in 33 (84.6%), the couple had one or more living male children. Frequency of fetal sex determination was comparable for slum and urban areas. Fifty-six additional cases of fetal sex determination, occurring in the neighbourhood of the respondents, were also reported. A total of 28 cases of female feticide were reported. Awareness about the illegality of fetal sex determination has improved, compared with the 1997-1998 data collected from East Delhi (55.3-73.6%). However, this comparison also shows a marginal increase in the practice of fetal sex determination (2.1-2.6%). In all cases of feticide, a qualified doctor was involved. A number of couples abandoned the abortion plan midway, even after detecting that the fetus was female, and there were occasional cases where the doctor refused to abort the female fetus.