Proteomic characterization of human proinflammatory M1 and anti-inflammatory M2 macrophages and their response to Candida albicans.

In response to different stimuli, macrophages can differentiate into either a pro-inflammatory subtype (M1, classically activated macrophages) or acquire an anti-inflammatory phenotype (M2, alternatively activated macrophages). Candida albicans is the most important opportunistic fungus in nosocomial infections, and it is contended by neutrophils and macrophages during the first steps of the invasive infection. Murine macrophages responses to C. albicans have been widely studied, whereas the responses of human-polarized macrophages remain less characterized. In this study, we have characterized the proteomic differences between human M1- and M2-polarized macrophages, both in basal conditions and in response to C. albicans, by quantitative proteomics (2DE). This proteomic approach allowed us to identify metabolic routes and cytoskeletal rearrangement components that are the most relevant differences between M1 and M2 macrophages. The analysis has revealed fructose-1,6-bisphosphatase 1, a critical enzyme in gluconeogenesis, up-regulated in M1, as a novel protein marker for macrophage polarization. Regarding the response to C. albicans, an M1-to-M2 switch in polarization was observed. This M1-to-M2 switch might contribute to Candida pathogenicity by decreasing the generation of specific immune responses, thus enhancing fungal survival and colonization, or instead, may be part of the host attempt to reduce the inflammation and limit the damage of the infection.

Naturally occurring 2-substituted (1,3)-beta-D-glucan producing Lactobacillus suebicus and Pediococcus parvulus strains with potential utility in the production of functional foods.

We have isolated three lactic acid bacteria (Lactobacillus suebicus CUPV221, Pediococcus parvulus CUPV1 and P. parvulus CUPV22) that produced high levels of 2-substituted (1,3)-beta-D-glucans which increased the viscosity of the growth media. The (1,3)-beta-D-glucan consisted of two main molecular species, with masses of approximately 10(7) and 10(4) Da, whose proportions varied among the strains. The three strains survived exposure to saliva and simulated gastric conditions at pH 5, with P. parvulus CUPV22 surviving at pH 3.1, and L. suebicus CUPV221 surviving at pH 1.8. All strains were resistant to pancreatin and bile salts. P. parvulus CUPV22 exhibited the highest adhesion (10.5%) to Caco-2 cells, which decreased to 1.2% after washing the cells. Finally, P. parvulus CUPV22 and L. suebicus CUPV221 induced the production of inflammation-related cytokines by polarized macrophages, and interestingly, L. suebicus stimulated the production of cytokine IL-10. These results indicate that the three strains have potential utility for the production of functional foods.

The human CD6 gene is transcriptionally regulated by RUNX and Ets transcription factors in T cells.

CD6 is a lymphocyte surface receptor involved in lymphocyte activation and differentiation processes that is constitutively expressed on developing and mature T cells and on the B1a cells. To define the molecular basis for the tissue-specific expression of CD6 we have identified the transcription factors that control the activity of the proximal regulatory region of the human CD6 gene. The TATA-less CD6 promoter contains multiple transcriptional start sites, and its preferential activity in human T lymphocytes is dependent on RUNX- and Ets-binding sites located within a highly conserved region. RUNX and Ets-1 factors transactivated the CD6 promoter through recognition of the -215 and -230 binding sites, respectively. Chromatin immunoprecipitation assays revealed that RUNX1 constitutively occupies the CD6 promoter in vivo, and knockdown experiments demonstrated that the steady-state level of CD6 mRNA is dependent on the expression of RUNX1, RUNX3 and Ets-1 transcription factors. Therefore, RUNX1/3 and Ets1 control the expression of CD6 in human T lymphocytes, thus expanding the range of T-cell specific and developmentally regulated lymphocyte gene targets involved in T-cell activation and differentiation.