Modulación de la expresión de moléculas co-estimulatorias y de adhesión de las células de Langerhans por el lipofosfoglicano (LPG) de leishmania major / Modulation of the molecular expression co-stimulatory and the langerhans cell adherence by lipophosfoglicane (LPG) of leishmania major

Aunque el rol inmunológico central jugado por las LC durante la infección con Leishmania se conoce ampliamente, no se sabe si el LPG afecta su maduración y migración a los nódulos linfáticos. En el trabajo aquí referido presentamos evidencias de que la exposición de LG de ratones BALB/c al LPG tiene consecuencias en su maduración y fenotipo. Luego de una incubación de 24 h en presencia de LPG 3 ug ml-1 ocurre un aumento en la expresión de móleculas de superficie como la cadena alfa del receptor de interlukina-2 (CD25), la cual ha sido implicada en procesos de activación celular y las moléculas de adhesión CD31 (PECAM-1) y VE-cadherin (VE-CAD) implicadas en cambios de la migración celular. Estos cambios ocurren sin alteraciones en la expresión del MHC-clase II. Los efectos observados pueden ser mediados por factores solubles liberados por L. major al cultivo, como es el caso del dominio de carbohidratos de LPG ya que los mismos ocurren de forma similar cuando las LC se incuban en LCM

[Few ethnic differences in acute pediatric problems: 10 years of acute care in the Sophia Children's Hospital in Rotterdam]]. / Geringe etnische verschillen in spoedeisende problemen bij kinderen: 10 jaar acute hulp in het Sophia Kinderziekenhuis te Rotterdam.

OBJECTIVE: To evaluate whether there are differences in acute general paediatric problems and their severity between children with different ethnic backgrounds. DESIGN: Descriptive. METHOD: The following information was registered for patients who visited the paediatric emergency department at the Sophia Children's Hospital in Rotterdam, the Netherlands (1988 through to 1997): demographics, reason for encounter, diagnoses, diagnostics performed and follow-up. Ethnicity was determined by patient's surname. Analyses were performed using the chi 2 test, non-parametric Kruskal-Wallis test and multiple logistic regression. RESULTS: Fifty-one percent of all patients belonged to one of the ethnic minority groups. Infection-related problems were seen more often in Turkish (45%) and Moroccan (46%) children than in Dutch children (41%). Of those children with infection-related problems, the Turkish children were less likely to need X-rays (odds ratio: 0.73), laboratory diagnostics (0.72), an outpatient follow-up (0.79) or hospital admission (0.74). On the other hand, Moroccan paediatric patients were admitted slightly more frequently (to the intensive care department) and were more likely to have a lower respiratory tract infection (1.65). CONCLUSIONS: There were some differences between Dutch children and ethnic minorities in terms of the reasons for encounter and the severity of the problem. Compared with Dutch children, Turkish children presented with less severe infection-related problems, while Moroccan children had more severe infection problems.

Attenuated Toxoplasma gondii ts-4 mutants engineered to express the Leishmania antigen KMP-11 elicit a specific immune response in BALB/c mice.

In order to test recombinant Toxoplasma as adjuvant and live vaccine carrier in the infectious disease model of murine experimental leishmaniasis, we engineered the attenuated, temperature-sensitive Toxoplasma gondii strain ts-4 to express the heterologous Leishmania antigen kinetoplastid membrane protein-11 (KMP-11). Transgenic ts-4 clones were obtained which express KMP-11 as cytoplasmatic protein or target it to the secretory pathway of the tachyzoites. Immunization of BALB/c mice with these stably transformed parasites elicited proliferative responses to both T. gondii antigen and recombinant KMP-11. When challenged with Leishmania major, we observed significant protection in animals that had been vaccinated with the KMP-11-expressing ts-4 mutants. The adjuvant attenuated only the onset of the Leishmania infection, but animals were ultimately not able to control the disease. Thus, our findings demonstrate that recombinant Toxoplasma has the potential to serve as an efficient vaccine carrier for cutaneous leishmaniasis. Furthermore, they establish a protective role for the antigen KMP-11 when given in such a vaccine formulation.

Leishmania major lipophosphoglycan modulates the phenotype and inhibits migration of murine Langerhans cells.

Langerhans cells (LC), members of the dendritic cell family, play a central role in the initiation and regulation of the immune response against the protozoan parasite Leishmania major. LC take up antigens in the skin and transport them to the regional lymph nodes for presentation to T cells. However, it is not known whether LC functions are modulated by parasite antigens. In the present study, we examined the effect of a major parasite surface molecule, L. major lipophosphoglycan (LPG), on the maturation of LC and their migratory properties. The results show that exposure to LPG did not affect the expression of major histocompatibility complex (MHC) class II and B7, but induced an up-regulation of CD25, CD31 and vascular endothelial (VE)-cadherin expression and a down-regulation of Mac-1 expression, by LC. Importantly, LPG treatment inhibited the migratory activity of LC, as it reduced their efflux from skin explants and their migration in transwell cultures. These results suggest that Leishmania LPG impairs LC migration out of the skin and thus may modulate their immunostimulatory functions, which require LC translocation from skin to lymph nodes.

Treatment of two patients with diffuse cutaneous leishmaniasis caused by Leishmania mexicana modifies the immunohistological profile but not the disease outcome.

Two patients with diffuse cutaneous leishmaniasis caused by Leishmania mexicana were treated with two leishmanicidal drugs (pentamidine and allopurinol) combined with recombinant interferon-gamma restoring Th-1 favouring conditions in the patients. Parasites decreased dramatically in the lesions and macrophages diminished concomitantly, while IL-12-producing Langerhans cells and interferon-gamma- producing NK and CD8 + lymphocytes increased in a reciprocal manner. The CD4+/CD8 + ratio in the peripheral blood normalized. During exogenous administration of interferon-gamma the parasites' capacity to inhibit the oxidative burst of the patients' monocytes was abolished. Even though Th-1-favouring conditions were restored, both patients relapsed two months after therapy was discontinued. We conclude that the tendency to develop a disease-promoting Th-2 response in DCL patients is unaffected by, and independent of, parasite numbers. Even though intensive treatment in DCL patients induced Th-1 disease restricting conditions, the disease-promoting immunomodulation of few persistent Leishmania sufficed to revert the immune response.

Los bloqueadores de canales ionicos inhiben la invasion de macrofagos por leishmania SP / Blockers of channels ionics inhibit the invasion of macrophage by leishmania SP

En este trabajo hemos evaluado la interacción de Leishmania con su célula hospedera e macrofagos peritoneales de ratones BALB/c preincubados con inhibidores de canales ionicos. Demostramos que solo la glibenclamida disminuye significativamente la incorporación de los parásitos a su célula hospedera. adicionalmente, la tasa de infección y la carga parasitaria de macrófagos infectados con Leishmania e incubados durante 72 h en presencia de 4-aminopiridina, glibenclamida o amilorida disminuyó significativamente. Al explorar el mecanismo molecular del efecto de la glibenclamida, encontramos que la ausencia de Ca2+ extracelualr revierte la disminución d ela fagocitosis encontrada en los viales experimentales. Este hecho sugiere que parte de los efectos de esta droga s edeben a una acción directa sobre la célula hispedera. Por su parte, la reducción de la tasa de infección y de la carga parasitaria evidenciada a las 72 horas no es revertida por la ausencia del Ca extracelular ni por aumentos intracelulares de Ca2+ de las organelas intracelulares. Este hecho sugiere que los efectos a largo plazo de la glibenciamida pudieran ser debidos a acciones directas de la droga sobre el parásito intracelular. Estos resultados sugieren que el funcionamiento de las estructuras sensibles a estos inhibidores de canales iónios son fundamentales para el mantenimiento de la homeostasis y la supervivencia del parásito en los diferentes ambientes en los cuales se lleva a cabo su ciclo de vida. es importante el hecho de que los amastigotes son particularmente sensibles a algunas de las drogas como la glibenclamida, que en otros tejidos y organismos modula el funcionamiento de canales de potasio cuya función esta intrínsecamente relacionada con el estado metabólico de la célula

The duration of febrile seizures and peripheral leukocytosis.

In 203 consecutive children with febrile seizures, no clear association (odds ratio = 1.0 [95% CI, 0.9-1.1], P = .59) was found between seizure duration and blood leukocytosis (> or = 15.0 x 10(9) cells/L). Increased leukocyte counts may be misinterpreted because of seizure duration. In children with febrile seizures, leukocyte counts should be used to evaluate the underlying cause of fever.

Leishmania sp.: growth and survival are impaired by ion channel blockers.

In the present work we examined the effect of ion transport blockers on the growth and viability of Leishmania sp. and on the infection of macrophages by the parasite. 4-aminopyridine and glibenclamide block voltage-dependent and K+ ATP channels, respectively; amiloride is used to detect Na+ channels and Na+/H+ antiporters; and anthracene-9-carboxylic acid affects chloride channels. The EC50 for promastigote cultures of three strains of the Leishmania subgenus, namely, Leishmania (Leishmania) NR, Leishmania (Leishmania) amazonensis LTB0016, and Leishmania (Leishmania) major, at their stationary phase of growth, were, respectively, 39, 46, and 464 microM for 4-aminopyridine; 7, 0.8, and 10 microM for glibenclamide and 66, 170, and 10 microM for anthracene-9-carboxylic acid. The amiloride EC50 for NR was 264 microM and 10 microM for L. (L.) major, but was never reached for LTB0016. Higher concentrations of the drugs impaired the exponential growth of Leishmania promastigotes. These results suggest the susceptibility of Leishmania sp. to blockers associated with K+ and Cl- and to Na+ or Na+/H+ transport systems. Blockade of such systems might have impaired the survival of the parasites as promastigotes. In addition, it affected the persistence of parasites in host cells. Although the infection of the macrophage cell line J774 and peritoneal-exudate macrophages was not significantly decreased by concentrations of the drugs around the promastigotes' EC50, the survival of intracellular parasites decreased significantly in the presence of these drugs without affecting the viability of the macrophages. Some blockers consistently gave small EC50 and significantly decreased the infection process as well as the survival of intracellular parasites. Thus, elucidation of their mechanism of action in Leishmania is relevant, since they could represent a potential subject for the development of leishmanicidal drugs.

Sensitivity of Leishmania spp. to glibenclamide and 4-aminopyridine: a tool for the study of drug resistance development.

We have demonstrated that Leishmania spp. grown as promastigotes, are sensitive to the K+ channel inhibitors 4-aminopyridine and glibenclamide. Their host cells, the macrophages, are not affected by similar concentrations of the drugs. We have also initiated the molecular characterization of the mechanisms involved in the development of drug resistance to glibenclamide by the parasite. Therefore, we have selected experimentally and begun to characterize the Venezuelan Leishmania (Leishmania) strain, NR resistant to glibenclamide [NR(Gr)]. The analysis of genomic DNA evidenced the existence of a fragment which apparently is amplified in NR(Gr). The fragment recognized by the pgpA probe, related to the Leishmania P-glycoprotein family and which was originally isolated from L. tarentolae, showed a size polymorfism between the sensitive and the resistant strain. These results suggest that the development of resistance to glibenclamide in the strain NR(Gr) might be associated with the amplification of the ltpgpA or related gene(s).