Urticaria papular y sus agentes causales en Colombia / Papular urticaria: A review of causal agents in Colombia

Resumen La urticaria papular es una enfermedad alérgica causada por la picadura de insectos, la cual predomina en el trópico. El objetivo de esta revisión fue profundizar en sus aspectos epidemiológicos e inmunológicos, particularmente con base en datos publicados en Latinoamérica. Se hizo una revisión no sistemática mediante la búsqueda electrónica de artículos sobre la epidemiología de la urticaria papular, las características entomológicas de los agentes causales y los mecanismos inmunológicos asociados. Según los diversos reportes de centros médicos de Latinoamérica la urticaria papular es frecuente; el único estudio de prevalencia publicado indica que afecta a una cuarta parte de los niños escolares de Bogotá. Hay información sobre la relación causal entre la exposición domiciliaria a la pulga, la pobreza y la urticaria papular en Bogotá, una ciudad representativa de las altitudes andinas. No hay estudios que indaguen directamente sobre los insectos causales en zonas cálidas, aunque se sospecha clínicamente de los mosquitos Aedes aegypti y Culex quinquefasciatus. En cuanto a su patogenia, se destaca la participación de mecanismos celulares que involucran las células colaboradoras Th2, lo cual explica que sea una condición de hipersensibilidad retardada. El papel de la inmunoglobulina E (IgE) en la urticaria papular no está tan claro. Se desconocen los antígenos derivados de los insectos que causan la enfermedad, aunque se plantea que existen moléculas comunes de reacción cruzada entre los insectos, tales como el alérgeno Cte f 2 en la pulga, y sus homólogos en los mosquitos. La urticaria papular es una condición frecuente en Latinoamérica que debe investigarse en profundidad. La caracterización inmunológica de los componentes moleculares que causan esta condición puede resolver interrogantes sobre su etiología y su patogenia.

Abstract Papular urticaria is a chronic allergic reaction induced by insect bites, which is common in the tropics. The objective of this review was to deepen on epidemiological and immunological aspects of this disease, focused on data published in Latin American countries. We conducted a non-systematic review of the literature through electronic search on the epidemiology of papular urticaria, the entomological characteristics of the causative agents and associated immunological mechanisms. Several reports from medical centers suggest that papular urticaria is common in Latin America. Only one epidemiological survey designed to estimate prevalence of papular urticaria has been published, reporting that about a quarter of children under six years of age is affected by this condition in Bogotá. There is evidence on the causal relationship among exposure to indoor fleas, poverty and papular urticaria in Bogotá, a representative city of the Andean altitudes. Information about causal insects in tropical warmer areas is scarce, although from clinical reports Aedes aegypti and Culex quienquefasciatus appear to be the most common. Th2 cellular-mediated mechanisms are involved in its pathogenesis, which explains its delayed hypersensitivity. The role of immunoglobulin E is not clear in this disease. Insect-derived antigens directly involved in papular urticaria etiology are unknown. However, it is possible that common molecules among causal insects mediate cross-reactive reactions, such as Cte f 2 allergen, found in cat fleas, and its counterparts in mosquitoes. Papular urticaria is a frequent disease in Latin America that should be further investigated. Immunological characterization of the molecular components that cause this condition may solve questions about its pathogenesis.

Linkage and haplotype analysis for chemokine receptors clustered on chromosome 3p21.3 and transmitted in family pedigrees with asthma and atopy

Genomic scan analyses have suggested that the chemokine receptor cluster [CCR2, CCR3, CCR5 <300 kb span] on the short arm of chromosome 3 may contribute to susceptibility to HIV-1 infection and to the expression of a number of inflammatory diseases. Two single nucleotide polymorphisms [SNP] and a deletion in these chemokine receptors have also been found in case-control studies to be associated with susceptibility for asthma and related phenotypes. We extended these case-control studies by establishing whether these polymorphisms were in linkage and linkage disequilibrium with asthma and related phenotypes using linkage and haplotype analyses. We genotyped 154 nuclear families identified through two child probands with physician-diagnosed asthma [453 unrelated individuals] including 303 unrelated parents and 150 unrelated children. Atopy was defined as a positive skin prick test [SPT 3 mm] to a panel of common inhaled allergens. From a panel often known SNPs, only three polymorphisms: -G190A in CCR2, -T51C in CCR3, and a 32 bp deletion in CCR5 were found to occur at clinically relevant frequencies. All 154 families were used for haplotype analysis but only 12 nuclear families were eligible for linkage analysis. Both analyses confirmed that the mutations were in linkage with asthma, but not with atopy. The chemokine receptor genes on 3p21.3 are significantly plausible candidate genes that can influence the expression of asthma. The previous association of the CCR5delta32 deletion with protection from childhood asthma appears to be explained by linkage disequilibrium with the -G190A mutation in the CCR2 receptor gene

Algunos aspectos de la prevención primaria y secundaria en alergia y asma / Strategies for primary and secondary prevention of asthma and allergy

Existe un aumento en la prevalencia de las enfermedades alérgicas y el asma. Dicho incremento es más notable en la población urbana de los países occidentales más industrializados. Enfermedades como el eczema atópico, la alergia a alimentos, la rinoconjuntivitis alérgica y el asma bronquial, entre otras, además de generar costos millonarios a los distintos estados, afectan notablemente la calidad de vida de la población que las padece, reflejándose en un gran ausentismo escolar y laboral entre otros aspectos. Las enfermedades alérgicas y el asma surgen de la interacción de factores genéticos y factores ambientales. Dicha interacción que provocará la sensibilización atópica y posteriormente el desarrollo de las distintas enfermedades, comienza en la vida fetal intrauterina, siendo clave el primer, y tal vez el segundo año de vida. Se describen diversas estrategias de prevención primaria para evitar la sensibilización, entre las que se destacan, el control ambiental para evitar o disminuir el contacto a diversos aeroalérgenos interiores, la manipulación en la dieta fomentando lactancia materna exclusiva hasta los 4 a 6 meses, utilizando en niños de riesgo fórmulas hidrolizadas como suplemento, evitar el tabaquismo en la embarazada y el pasivo en los niños pequeños. Entre las estrategias en la prevención secundaria, es decir, el evitar el desarrollo de una enfermedad alérgica después de la sensibilización, se destaca nuevamente el control ambiental (se mencionan distintos consejos de la OMS), la inmunoterapia con alérgenos y la farmacoterapia (antihistamínicos). Por último, se mencionan la influencia de la polución ambiental y el potencial papel de la terapia génica.

There has been an increase in the prevalence of asthma and allergic diseases, more notably in urban population of western developed countries diseases such as atopic eczema, food allergy, allergic rhinoconjunctivitis and bronchial asthma, among other, not only generate millionaire costs to the different states, but also considerably affect the quality of life of the population suffering them, which is reflected in a great work and school absence, among other aspects. Allergic diseases and asthma develop from the interaction between genes and environment. Such an interaction will cause allergic sensitization and lately the development of different diseases. It starts in fetal life and becomes more important in the first, and perhaps second, year of life. Different strategies for primary prevention are described to avoid atopic sensitization, such as allergen avoidance of indoor allergens, diet manipulation to avoid cow's milk protein with exclusive breast feeding until four to six months of life; use of hydrolyzed milk formulae as a replacement for or supplement to breast-feeding, late introduction of solid food, avoidance of active smoking among pregnant women and passive smoking in children. Among other strategies for secondary prevention, this is to avoid the development of an allergic disease after sensitization has occurred, again allergen avoidance is mentioned (with advice measures by WHO), allergen immunotherapy and medication (antihistamines). At last, the influence of air pollution and the potential use of gene therapy are also considered.

TAP1 and TAP2 Gene Polymorphisms in Korean Patients with Allergic Rhinitis

Antigen peptides are actively transported across the endoplasmic reticulum by the transporters associated with antigen presentation (TAP). TAP genes polymorphism could influence the selection process that determines which antigen peptides play a role in the pathogenesis of allergic rhinitis. The aim of this study was to investigate the association of TAP genes polymorphism with allergic rhinitis. TAP1 and TAP2 genotyping were performed on 110 allergic rhinitis patients and 107 healthy controls. TAP1 polymorphic residues at codons 333 and 637, and TAP2 polymorphic residues at codons 379, 565, 651, and 665 were analyzed by the amplification refractory mutation system-polymerase chain reaction (ARMS-PCR). Analysis of TAP1 gene polymorphism demonstrated decreased frequencies of Ile/Val genotype at codon 333, Asp/Gly genotype at codon 637, and haplotype A and B in allergic rhinitis patients when compared to controls (p<0.05). However, there was no significant difference in the genotype, phenotype, or allele frequencies at four TAP2 codons between controls and allergic rhinitis patients. In conclusion, TAP1 gene polymorphism may be an important factor contributing to the genetic susceptibility in the development of allergic rhinitis in the Korean population.

Alergia en la infancia: ¿existen realmente? / Allergy in childhood: exist?

Las enfermedades alérgicas constituyen un grupo heterogéneo de enfermedades asociadas clásicamente a una reacción de hipersensibilidad tipo I, en cuya respuesta inmune, mediada principalmente por IgE, participan diversas clases de celulas como linfocitos, especialmente los CD4 polarizados a Th2, linfocitos B antígeno específicos, mastocitos, basófilos y finalmente citoquinas. Durante la última década se ha observado un incremento de la incidencia de las enfermedades alérgicas en los países occidentales, especialmente en niños. Este artículo resume y expone aspectos básicos para comprender la existencia de la alergia en la infancia. Así mismo, se expone la opinión de Comités de expertos internacionales en el área de alergia, quienes han propuesto una nueva nomenclatura para estas enfermedades, según la reacción de hipersensibilidad involucre o no un mecanismo inmune, y esté o no mediada por IgE.

Atopia: ¿genética o medio ambiente? / Atopic: genetics or environment?

El origen de la alegria responde a diversos factores y depende de la interacción de situaciones ambientales en individuos genéticamente susceptibles. El riesgo de contraer un padecimiento alérgico y la tendencia a desarrollar alergía en forma temprana, están fuertemente influidos por factores genéticos e historia familiar de padecimientos alérgicos. La genética de la atopia, sin embargo, no se ha comprendido totalmente. Aunque se asocie con aberraciones bioquímicas e inmunológicas junto con genes en los cromosomas, 5 y 11, los factores del medio ambiente juegan un papel principal en el desarrollo del padecimiento alérgico. Los mecanismos de éstos en forma individual son desconocidos, y se necesita más información sobre la dinámica de producción y de contaminantes en interiores, tasas de descomposición y factores ambientales que favorecen o crean las fuentes de contaminación del aire en interiores

Bee venom hypersensitivity and its management: patients perception of venom desensitisation.

The objectives of the study were to review bee venom immunotherapy from the patient's perspective: in particular its benefits and its problems, and to investigate any genetic tendency for bee venom hypersensitivity. A self administered, 9 item questionnaire was sent to 219 patients who had undergone either inpatient or outpatient bee venom immunotherapy at Flinders Medical Center. The clinic records of these patients were also reviewed. The controls for the genetic study were sought from patients, staff and students at Flinders University and Flinders Medical Centre. One hundred and forty-six questionnaires (some incomplete and anonymous) were received. The female to male ratio was 1:2.5. The age at the time of the initial anaphylactic reaction to a bee sting ranged between 2 to 59 years, with 67% of patients being less then 20 years old. Forty percent of patients underwent venom immunotherapy for a period less than 2 years with only 11% maintaining therapy for the recommended period of 5 years or more. Thirty three percent of patients stopped their therapy on their own accord. Bee stings occurring during bee venom immunotherapy (n = 56) were generally well tolerated except in 8 subjects, 7 of whom had not reached the maintenance dose. The reduction in systemic reactions to subsequent bee stings was significantly better in the study group receiving bee venom than in an historic control group treated with whole bee extract (p = 0.03). Fear of bee stings and restricted life styles were improved during or after venom immunotherapy. The frequency of a positive family history of systemic reactions to bee stings in the patient cohort was 31%, whereas in controls it was 15% (p = 0.013). Bee venom immunotherapy has dual benefits: patients are protected from subsequent sting anaphylaxis and there is reduced psychological morbidity. However, to be effective, venom immunotherapy requires a prolonged period of carefully supervised treatment and each venom injection can cause local and systemic side effects. Genetic factors appear to be present in those patients who develop immediate hypersensitivity to be stings.