Histamine et cellules dendritiques

Dendritic cells are professional antigen presenting cells, counceling innate and adaptative immune responses. They express all types of membrane histamine receptors, differencially according to their maturation state. Immature dendritic cells express H1R and H3R receptors. Their stimulation activates cell migration and costimulatory molecule expression. Mature dendritic cells express H2R, H3R and H4R, and their stimulation by histamine, decreases IL-12 secretion and is responsible for Th2 cytokine expression. Anti-histamines are H1R inverse agonists. In vitro and animal models suggest that these drugs may well act on the immune response. The presence of histamine receptors on dendritic cells and the better understanding of their roles may lead to new therapeutic perspectives of these drugs.     

Rôle des différentes populations de cellules dendritiques dans l'asthme allergique

Tolerance is the normal immune response to inhalation of antigen, yet type 2 T helper cell (Th2) sensitization to inhaled allergens activating dendritic cells (DCs) is possible in some individuals. Here, we were able to show that both myeloid (m) and plasmacytoid (p) DCs are present in the lung and have distinct functions. The depletion of pDCs during allergen sensitization led to development of allergic asthma characterized by production of IgE antibody, airway inflammation with eosinophilia and cytokine production by Th2 cells. Adoptive transfer of pDCs before sensitization prevented the development of the disease. On the other hand, intra-tracheal administration of mDCs induced all the features of asthma while depletion of mDCs prevented the mice from developing pulmonary inflammation. These results show that mDCs contribute to the induction and maintenance of asthma, while pDCs protect against the development of allergic asthma. Therapies aimed at exploiting the protective function of pDcs might be clinically effective in preventing the development of asthma.     

Fièvre prolongée intermittente survenant à l’effort

Introduction

Fever of unknown origin is a common reason for care in internal medicine. The wide variety of possible etiologies makes it difficult to standardize the diagnostic work-up that has to be primarily guided by the interview and physical examination.

Case report

We report a case of prolonged fever having as main characteristics to be intermittent and triggered by efforts. The diagnosis of cerebrospinal fluid shunt infection with Propionibacterium acnes was finally made. In reaching this conclusion, many tests were needed, including renal explorations with biopsy showing an aspect of shunt nephritis.

Conclusion

Prolonged fever of unknown origin in a patient having prosthetic material should raise the suspicion of prosthesis infection (especially if the fever is associated with efforts).     

Quoi de neuf en allergologie pédiatrique en 2006-2007 ? Partie 3: Allergie cutanée, alimentaire, médicamenteuse et aux insectes (une revue de la littérature internationale d’octobre 2005 à septembre 2007)

Most sensitizations in children with atopic dermatitis are non pathogenic. Thus, responses in prick-tests, specific IgE determinations and patch-tests should be carefully evaluated based on the clinical history of the children or responses in challenge tests. Moreover, although atopy patch-tests are highly specific, they have a low sensitivity. Food eviction is indicated in a few children only, since they may be responsible for anaphylactic reactions induced by accidental ingestion of the food or oral challenge tests. The predictive value of serum specific IgE to foods depends on the food investigated, the age of the children, their allergic disease (atopic dermatitis, urticaria/angioedema, anaphylaxis) and, may be, on their ethnical origin. The prevention of food-induced severe reactions is based on eviction. However, several studies suggest that oral desensitization to foods may be efficient. Most frequent reactions in children hypersensitive to antalgics, antipyretics and nonsteroidal antiinflammatory drugs are oedema (facial oedema especially) and urticaria. Usually, the severity of the reactions increases from one treatment to another one and with the dose of drug administered to the children. Diagnosis is based on a convincing clinical history or on challenge tests. Skin tests with vaccines should be performed according to a standardized procedure because they may give false positive responses. Most latex sensitizations detected by skin prick-tests and, especially, specific IgE determinations are non pathogenic. The prevention of reactions to latex is based on eviction. However, preliminary results suggest that sublingual desensitization with a latex extract is efficient and well-tolerated.     

Actualités sur les leishmanioses viscérales

During the last decade, visceral leishmaniasis has been reconsidered in its epidemiology and strategies for diagnosis, treatment and prevention. This vectorial disease, responsible for more than 50,000 deaths each year across India, East Africa, South America, the Mediterranean area, Central Asia and China, is currently spreading over new territories. This formerly rural disease has even reached cities in South America. This spreading is caused by environmental changes due to global warming or human activity, and by the movement of workers and refugees. As a consequence, the burden of HIV/Leishmania coinfection is increasing in many developing countries even though effective antiretroviral therapy has led to a marked decrease in its incidence in Europe. The disease is now handled differently than it was 10 years ago: PCR has become the most accurate tool for diagnosis and follow-up in developed countries, and field diagnostic tools have been developed (antigenuria, rK39 dipstick). While resistance to antimoniate has appeared in India and Europe, new therapies have been evaluated such as miltefosine, the first oral therapy, or short treatment with liposomal amphotericin B. In France, liposomal amphotericin B has supplanted antimoniate meglumine because of better tolerance and shorter hospitalization duration. Protecting dogs through immunization or collars impregnated with deltamethrin proved effective to prevent zoonotic leishmaniasis due to Leishmania infantum.     

Corticothérapie prolongée et alimentation

In order to prevent adverse effects of long lasting treatments by glucocorticoids, some dietetic measures are underlined. If one was to strictly follow all these recommendations i.e., no salt, little glucose intake, high level of proteins, low calories diet, sufficient potassium intake and supplementation with calcium and vitamin D3, it would hardly be possible. The most common practice from doctors and patients is a salt-less diet, followed by calcium and vitamin D supplementation. Literature analysis on the opportunity of all these dietetic measures is surprisingly very poor, knowing that these drugs have been on the market for over fifty years. Only because osteoporosis has been on the front of the scene those past years a little more is known about calcium and vitamin D. It seems there are plenty opportunities on more studies on the subject.     

Maladie de Lyme avec hépatite et corticothérapie : à propos d’une observation

Introduction

Abnormalities of liver function tests have been occasionally described in large series of Lyme disease, but only one case of hepatitis directly related to infection have been described in literature.

Case report

A 78-year-old-man, with a past medical history of polymyalgia rheumatica (PMR) who had discontinued corticosteroids two years before, presented a transient acute fever and liver cholestasis and cytolysis after an exposure to tick bites. A few days later, cervical pain occurred and corticosteroids were resumed as a PMR relapse was suspected. Hematogenous dissemination with acute meningoradiculitis and multiple erythema migrans led to conclude to a stage 2 Lyme disease.

Conclusion

Although hepatitis complicating the course of Lyme disease has been described in literature, the marked inflammation in our patient led us to investigate the possibility of a co-infection. Also, we discuss the responsibility of corticosteroids in clinical worsening of Lyme disease if they are prescribed without concomitant antibiotics.     

Axes de recherche en allergologie alimentaire : hypoallergénicité et vaccins

The frequency of food allergy in the pediatric population (8%), as well as the worrying increase of prevalence of severe anaphylaxis boost the research for means of prevention and for therapeutics alternative to the sole eviction of foods. Oral desensitization and sublingual immunotherapy, being the main part of the present clinical research are not in the scope of this review. Future trends of research focus on hypoallergenicity and vaccines. The definition of hypoallergenicity is limited to a lesser reactivity because of a lesser binding of specific IgE to modified food allergens, since the conditions of the immunogenicity leading to sensitization remain unknown. Different ways for patients, alimentary industry and agronomical research are detailed: heating and cooking, enzymatic and chemical treatment of natural foods, physical treatments (texturization, ultrafiltration,…), screening of natural varieties in order to characterize some of them with a lower level or an absence of major allergens. Bioengineering of plants with a reduced level of major allergens, and site-directed mutagenesis on B epitopes could be helpful for a safer nutrition and vaccines. Possible molecular forms aimed at vaccines are considered: recombinant natural allergens, modified recombinant allergens by dimerisation, site-directed mutagenesis, fusion with other molecules, long peptides,… Associated considerations are the choice of adjuvants promoting a Th1 response, as well as vectors for the expression of recombinant food allergens: bacteria, probiotic ones, or poorly allergenic plants. Mucosal vaccines could be especially interesting for food allergens in order to add specific mechanisms of tolerance arising in the intestinal mucosa to the reorientation towards a Th1 and TREG response. Plasmidic DNA vaccines and anti-IgE vaccines are an object of research without any application in the near future. Therapeutic vaccines for food allergens might be substituted to oral desensitization and could be applied first to peanut allergy and to cross allergy between pollens and fruit or vegetable linked to panallergens. Prophylactic vaccines might be a second step for atopic infants, insofar as more knowledge could be obtained of mechanisms and enhancing factors of oral tolerance to food allergens and the “opportunity window” for the establishment of oral tolerance.     

Arthrite réactionnelle dans les suites d’une infection urinaire à Escherichia coli

Reactive arthritis following Escherichia coli urinary tract infection is very rare. We report a 25-year-old woman with acute oligoarthritis associated with bilateral anterior uveitis after an episode of urinary tract infection due to E. coli. The diagnosis of reactive arthritis was considered and the patient treated with non-steroidal anti-inflammatory agents. Disease course was rapidly successful and at 6-month follow-up the patient was asymptomatic. Reactive arthritis is associated with intestinal infection but also with common urinary tract infection.     

Allergies cyprès-pêche : allergie croisée ou simple coïncidence ?

Recently, a cross reactivity between cypress pollens and peach has been published. In this paper, we have tried to confirm this possibility in 33 patients suffering from cypress pollen allergy. The analysis of the collected patients data lead to the following classification of them into two groups: nine patients (27.3%) had a sensitivity to peach (four patients were allergic to peach and five patients were only sensitised to this fruit but could eat it without experiencing any symptoms), the second group of 24 patients were allergic to cypress pollens, but not sensitive to peach. These results clearly confirm that the cypress-peach syndrome exists together with the apple-birch syndrome. Other analysis on these patients will enable to characterise the cross-reacting allergens.