Medical and pathologic characteristics of fatal anaphylaxis: a Spanish nationwide 17-year series.

Forensic series on fatal anaphylaxis are scarce, probably because the diagnosis of anaphylaxis is often complex and the incidence is low. We report on the medicolegal, demographic and histopathological characteristics of a series of sudden deaths which were investigated for anaphylaxis at the Spanish National Institute of Toxicology and Forensic Sciences (INTCF) over a 17-year period (1998-2015). A total of 122 undetermined sudden deaths from a high percentage of Spanish regions (81.5% of the total population) were sent to the INTCF with anaphylaxis as the suspected cause of death for histological, biochemical, and medicolegal investigation. Two certified allergists confirmed that 46 of the 122 cases were fatal anaphylaxis. The results indicated a median age of 51 years (IQR = 29) and a male predominance (76%). The main causes of anaphylaxis were drugs (41%), hymenoptera stings (33%), and food (13%). A previous allergic event had been reported in both food anaphylaxis (67%) and drug anaphylaxis (53%). The deaths occurred in health care settings (37%), at home (22%), and outside the home (26.09%). Histopathology data were available for 40 individuals. The most frequent autopsy findings were angioedema of the upper airways (50%), pulmonary edema (47.5%), atheromatosis of coronary vessels (32.5%), and pulmonary congestion (27.5%). Our findings for fatal anaphylaxis indicated a predominance of men, older age (≥50 years) and death in a health care setting (one-third of cases). Previous episodes had occurred in two-thirds of cases of food-induced anaphylaxis and in half of the cases of drug-induced anaphylaxis.

Clinical and demographic characteristics of fatal anaphylaxis in Spain (1998-2011): A comparison between a series from the hospital system and a national forensic series.

BACKGROUND: Reports of fatal anaphylaxis remain scarce because of the rarity of the condition and the fact that information is limited to a few countries. OBJECTIVE: Our objective was to investigate clinical and demographic characteristics and the causes of fatal anaphylaxis in Spain using two databases of cases of fatal anaphylaxis. METHODS: We analysed fatal anaphylaxis in a series from the Spanish hospital system and a series from the National Institute of Toxicology and Forensic Sciences (Instituto Nacional de Toxicología y Ciencias Forenses [INTCF]), which predominantly comprise extrahospital deaths. Deaths from the Spanish hospital system were retrieved from among all deaths occurring during 1998-2011 using codes related to anaphylaxis. Deaths due to anaphylaxis in the INTCF database during the same period were retrieved by 2 allergists, who identified cases in which anaphylaxis was a possible cause of death. A logistic regression model was constructed to predict the characteristics of fatal anaphylaxis in each database. RESULTS: The incidence of death by anaphylaxis in Spain using both databases was 0.25 (95% CI, 0.24-0.26) deaths per million person-years. The most frequent causes of death in the hospital system were drugs (46.1%), unknown causes (40.0%), and foods (10.4%); in the INTCF, the most common causes of death were drugs (47.2%), insect stings (30.6%), and foods (11.1%). The logistic regression model showed that fatal anaphylaxis due to unknown causes (OR 15.2, 95% CI 1.8-129.8) was more likely in the hospital database, whereas insect stings (OR 100, 95% CI 10-833.3) and previous atopic comorbidity (OR 15.2, 95% CI 6.3-33.3) were more likely in the INTCF database. CONCLUSIONS & CLINICAL RELEVANCE: The estimated frequency of fatal anaphylaxis in Spain was among the lowest reported. Future studies of fatal anaphylaxis should use databases from different origins in order to show the considerable heterogeneity in this type of death.

Toll-like receptors-mediated pathways activate inflammatory responses in the esophageal mucosa of adult eosinophilic esophagitis.

OBJECTIVES: Esophageal microbiota and regulation of adaptive immunity are increasingly being investigated in eosinophilic esophagitis (EoE). Toll-like receptors (TLRs) play a central role in the initiation and maintenance of innate immune activity. Our objective was to characterize the esophageal and duodenal innate immune response in EoE and its modulation by dietary therapy. METHODS: Esophageal and duodenal biopsy samples were collected from 10 adults with untreated EoE, before and after effective treatment with a six-food elimination diet (SFED), and 10 controls with normal esophagus. In all cases, bacterial load (by mRNA expression of 16S), TLRs, mucins, transcription factors, interleukins, components of the NKG2D system, and innate immunity effectors were assessed by qPCR. Protein expression of TLRs were also determined by immunofluorescence. RESULTS: Bacterial load and TLR1, TLR2, TLR4, and TLR9 were overexpressed on biopsies with active EoE compared with controls. Muc1 and Muc5B genes were downregulated while Muc4 was overexpressed. Upregulation of MyD88 and NFκB was found together with IL-1ß, IL-6, IL-8, and IL-10 mediators and PER-1, iNOS, and GRZA effectors. NG-K2D components (KLRK1, IL-15, MICB) were also upregulated. In all cases, changes in active EoE were normalized following SFED and mucosal healing. Duodenal samples also showed increased expressions of TLR-1, TLR-2, and TLR-4, but not 16S or any other mediators nor effectors of inflammation. CONCLUSIONS: Esophageal TLR-dependent signaling pathways in EoE support the potential implication of microbiota and the innate immune system in the pathogenesis of this disease.

Functional analysis of ABCB4 mutations relates clinical outcomes of progressive familial intrahepatic cholestasis type 3 to the degree of MDR3 floppase activity.

OBJECTIVE: Progressive familial intrahepatic cholestasis type 3 (PFIC3) is a potentially lethal autosomal recessive liver disease associated with mutations in ABCB4, the gene encoding the canalicular translocator of phosphatidylcholine MDR3. While some affected children benefit from ursodeoxycholic acid (UDCA) therapy, others evolve to end-stage liver disease. We aimed to evaluate whether these different outcomes are related to the impact of ABCB4 mutations. DESIGN: Six children with PFIC3 were investigated by sequencing of ABCB4 exons and flanking intron-exon boundaries and by immunohistochemistry. ABCB4 missense mutations were phenotyped in vitro by assessing their effects on MDR3 expression, subcellular localisation, and phosphatidylcholine-translocating activity. The resulting data were contrasted with the clinical outcomes. RESULTS: Eight distinct ABCB4 mutations were identified: one nonsense, one splicing and six missense mutations, four of which (G68R, T201M, P479L, D459H) affected MDR3 expression level. G68R and D459H also led to retention of the protein in endoplasmic reticulum. Phosphatidylcholine efflux assays indicated that T201M, P479L, S978P and E1118K mutations impaired MDR3 activity to variable degrees. Three children with mutations that caused a total loss of MDR3 expression/function manifested progressive liver disease refractory to UDCA treatment. This was also the case in a patient carrying two different mutations that, in combination, resulted in a 90% reduction in total MDR3 activity. A favourable response to UDCA was achieved in two patients with estimated MDR3 activities of 50% and 33%, respectively. CONCLUSIONS: These data provide experimental evidence of the correlation between the degree of MDR3 floppase activity and the clinical outcomes of PFIC3.

Recurrence of bile salt export pump deficiency after liver transplantation.

Severe bile salt export pump (BSEP) deficiency is a hereditary cholestatic condition that starts in infancy and leads to end-stage liver disease. Three children who underwent orthotopic liver transplantation for severe BSEP deficiency had post-transplantation episodes of cholestatic dysfunction that mimicked the original disease. Remission of all episodes was achieved by intensifying the immunosuppressive regimen. The phenotypic recurrence of the disease correlated with the presence of circulating high-titer antibodies against BSEP that inhibit transport by BSEP in vitro. When administered to rats, these antibodies targeted the bile canaliculi and impaired bile acid secretion.

Knockdown of ATP8B1 expression leads to specific downregulation of the bile acid sensor FXR in HepG2 cells: effect of the FXR agonist GW4064.

Farnesoid X receptor (FXR) is a bile acid-sensing nuclear receptor that controls bile acid homeostasis. It has been suggested that downregulation of FXR contributes to the pathogenesis of an inherited disorder of bile secretion caused by mutations in ATP8B1. We have investigated the relationship between ATP8B1 knockdown and FXR downregulation in the human hepatoblastoma cell line HepG2. Transfection of HepG2 cells with ATP8B1 small interfering RNA (siRNA) duplexes led to a 60% reduction in the endogenous levels of ATP8B1 mRNA and protein and a concomitant decrease in FXR mRNA and protein content, as well as in FXR phosphorylation. This decrease was accompanied by a marked reduction in mRNA levels of a subset of FXR targets, such as bile salt export pump (ABCB11), small heterodimer partner, and uridine 5'-diphosphate-glucuronosyltransferase. ATP8B1 inhibition specifically targeted FXR since mRNA expression of other prominent nuclear receptors, such as pregnane X receptor and constitutive androstane receptor, or liver-enriched transcription factors, such as hepatocyte nuclear factor 1alpha (HNF-1alpha) and HNF-4alpha, was not altered. The expression of other key genes involved in bile acid synthesis, detoxification, and transport also remained unchanged upon ATP8B1 knockdown. Supporting the specificity of the effect, siRNA-mediated silencing of ABCB11, whose defect is associated with another inherited disorder of bile secretion, did not affect FXR expression. Treatment with the synthetic FXR agonist GW4064 was able to partially neutralize ATP8B1 siRNA-mediated FXR downregulation and fully counteract inhibition of FXR target genes. Collectively these findings indicate that ATP8B1 knockdown specifically downregulates FXR, and this action can be circumvented by treatment with FXR agonists.

Molecular basis of cholestatic diseases of surgical interest.

Cholestasis constitutes one of the most common and severe manifestations of acquired or inherited liver disease. When manifest in early infancy, it is often life-threatening and usually requires surgical management. In many cases, liver transplantation is the only effective therapy. Extensive knowledge about the molecular mechanisms underlying several pediatric cholestatic disorders has been gained in recent years from studies in both experimental models and clinical forms. In this review, we focus on recent contributions to the knowledge of molecular basis of main pediatric cholestatic disorders, such as biliary atresia, Alagille syndrome, and familial intrahepatic cholestasis. For some of them, putative targets of therapeutic interest, such as interferon-gamma and Farnesoid X receptor, have been proposed.