Staphylococcus epidermidis is an opportunistic pathogen and, due to its ability to establish biofilms, is a leading causative agent of indwelling medical device-associated infection. The presence of high amounts of dormant bacteria is a hallmark of biofilms, making them more tolerant to antimicrobials and to the host immune response. We observed that S. epidermidis biofilms grown in excess glucose accumulated high amounts of viable but non-culturable (VBNC) bacteria, as assessed by their low ratio of culturable bacteria over the number of viable bacteria. This effect, which was a consequence of the accumulation of acidic compounds due to glucose metabolism, was counteracted by high extracellular levels of calcium and magnesium added to the culture medium allowing modulation of the proportions of VBNC bacteria within S. epidermidis biofilms. Using bacterial inocula obtained from biofilms with high and low proportions of VBNC bacteria, their stimulatory effect on murine macrophages was evaluated in vitro and in vivo. The inoculum enriched in VBNC bacteria induced in vitro a lower production of tumour necrosis factor alpha, interleukin-1 and interleukin-6 by bone-marrow-derived murine macrophages and, in vivo, a lower stimulatory effect on peritoneal macrophages, assessed by increased surface expression of Gr1 and major histocompatibility complex class II molecules. Overall, these results show that environmental conditions, such as pH and extracellular levels of calcium and magnesium, can induce dormancy in S. epidermidis biofilms. Moreover, they show that bacterial suspensions enriched in dormant cells are less inflammatory, suggesting that dormancy can contribute to the immune evasion of biofilms.

RESUMO -A psoríase é uma doença inflamatória crónica que atinge 2 a 3% da população. Vários estudos têm demonstrado que a psoríase se associa a um aumento de risco de doença cardiovascular devido ao aumento da prevalência de fatores de risco cardiovasculares tradicionais, e à inflamação sistémica crónica que promove o desenvolvimento de disfunção endotelial e aterosclerose prematura. Esta revisão da literatura tem como objetivo avaliar o impacto dos inibidores do fator de necrose tumoral alfa na função endotelial e no risco de doença cardiovascular nos doentes com psoríase moderada a grave. Os estudos realizados até ao momento sugerem que o tratamento da psoríase com estes fármacos se associa a melhoria dos marcadores de disfunção endotelial e aterosclerose subclínica e a diminuição do risco de doença cardiovascular. PALAVRAS-CHAVE -