ABSTRACT
ObjectivesTo study the mechanism of brain damage caused byStaphylococcus epidermidis (SE) in mice. Methods A total of 80 neonatal mice of postnatal day 1 (PND1) were divided into SE group (48 mice), normal saline (NS) group (16 mice) and control group (16 mice). Mice in SE group were intravenously injected with 50 μl SE (108/ml). Mice in NS group were given 50 μl NS. Mice in control group were not intervened. At different time points after SE injection (6 h, 24 h, 72 h, 5 d, 7 d), the CFU of brain, blood, and spleen were calculated. Serial sections of parafifn-embedded brain tissue were used for detection of ionized calcium-binding adaptor moleculor1 (Iba-1) by immunohistochemical staining. The positive cells were calculated. ELISA was used to measure the levels of tumor necrosis factor alpha (TNF-α), interleukin-1β (IL-1β), interleukin-5 (IL-5), interleukin-6 (IL-6) of brain at 6 h and 24 h after SE injection.Results There was no SE in brain in different time points. The CFU was at the highest level at 6 h and then decreased after 24 h in blood and spleen. The Iba-1 positive cells in SE group were signiifcantly increased compared to NS group and control group at 24 h and 72 h (P0.05). The levels of TNF-α, IL-1β, IL-5, and IL-6 were signiifcantly higher in SE group than those in NS and control at 6 h and 24 h (P<0.05). The levels of TNF-α, IL-1β, IL-5, and IL-6 were signiifcantly lower in SE group at 24 h than those in SE group at 6 h (P<0.01).Conclusions It is suggested that cytokines produced by microglias may be the mediators of SE-caused brain damage.
ABSTRACT
Objectives To study the influence of Staphylococcus epidermidis (SE) on the neonatal mice of different ages. Methods A total of 60 neonatal mice including postnatal day 1(PND1) and postnatal day 3(PND3) were divided into SE group, normal saline (NS) group and control group, with 20 mice each. Mice in SE group were intravenously injected with 50μl SE (108/ml). Mice in NS group were given 50μl NS and mice in control group was not intervened. On postnatal day 14, the brain, liver and spleen obtained from mice were weighted. Serial sections of paraffin-embedded brain tissue were used for the detec-tion of microtubule associated protein-2 (MAP-2) and myelin basic protein (MBP) by immumohistochemical staining, and then the areas and volumes of grey and white matter were calculated. Result The mortality of PND1 mice in SE and NS group was 60.0%and 40.0%, respectively, and there was no difference between two groups (P>0.05). The mortality of PND3 mice in SE and NS group was 10.0%and 0.0%, respectively, and there was no difference between two groups (P>0.05). There were no dif-ferences in body weight, body weight gain, spleen and liver weights and organ coefficient between PND1 and PND3 mice (P>0.05). In PND1 mice, the areas and volumes of grey and white matter were significantly smaller in SE group than those in NS group (P0.05). Conclusions SE infection can result in brain injury in PND1 mice, but has no effect on brain tissues of PND3 mice.
ABSTRACT
Las células dendríticas (CDs) son esenciales en el desarrollo y regulación la respuesta inmunitaria (RI). Existen controversias en cuanto al potencial de inducción de la RI por las CDs en el período neonatal. Se ha propuesto que la RI específica de un neonato depende de la relación cuantitativa CD/linfocito T, y del momento, etapa neonatal o adulta, del encuentro con el antígeno, lo que parece influir sobre las propiedades fenotípicas y biológicas de las CDs, modificando su comportamiento. Por tal motivo, nos planteamos evaluar el efecto de un antígeno, Leishmania mexicana (L. mexicana) y de las citoquinas TNFa y RANTES sobre las características fenotípicas y propiedades migratorias, in vitro, de las CDs esplénicas provenientes de ratones BALB/c neonatos y adultos, usando citometría de flujo y la cámara de Boyden. Las CDs de ratones neonatos y adultos, en condiciones basales, expresan de manera similar, las moléculas CD40, CD86, CMHII y CD54. Este mismo fenómeno se observó al incubar dichas células con el Ag (L. mexicana) a excepción de la molécula CD40 cuya intensidad de expresión se elevó significativamente (P<0,05) en ambos grupos de estudio. El índice de migración de las CDs en presencia de medio de cultivo condicionado de L. mexicana, RANTES y TNFa fue mayor en adultos que en neonatos. Estos resultados muestran que las CDs neonatales son fenotípicamente similares a las adultas. Ante los mismos estímulos se comportan de manera diferente, sugiriendo la existencia de otros factores, que pudieran explicar la mayor susceptibilidad a infecciones en la etapa neonatal.
Dendritic cells (DCs) are essential in the development and regulation of the immune response (IR). The inherent potential of DCs to induce a specific immune response in the neonatal period is controversial. It has been suggested that the specific IR in neonates depends on the quantitative relation of DC/T lymphocytes, as well as on the neonatal or adult age at which the interaction antigen/DC/T lymphocytes occurs. This suggests that this contact has an influence on the phenotypic and/or biological properties of DCs, which modifies its behavior. Therefore, the effects of Leishmania mexicana (L. mexicana) and of TNFa and RANTES cytokines on immunophenotypical characteristics were evaluated on spleen DCs, from neonate and adult BALB/c mice, by using flow cytometry and in vitro migratory properties with a Boyden Chamber. In basal conditions, neonate and adult DCs express the same molecules (CD40, CD86, MHCII and CD54). When the DCs interact with the antigen L. mexicana, the expression of these molecules are similar in adults and in neonates, with the exception of CD40 whose intensity of expression was raised (P<0,05) in both groups. The rate of migration of the DCs in a culture medium conditioned of L. mexicana, RANTES and TNFa was higher in adults than in newborn mice. These observations suggest that neonatal and adult mice DCs have similar phenotypic characteristics. Under the effect of the same stimulus they respond differently; suggesting that other factors are involved in the higher susceptibility that newborns have to infections.