Risk-conferring HLA variants in an epilepsy cohort: benefits of multifaceted use of whole genome sequencing in clinical practice

BACKGROUND

Whole genome sequencing is increasingly used in healthcare, particularly for diagnostics. However, its clinically multifaceted potential for individually customised diagnostic and therapeutic care remains largely unexploited. We used existing whole genome sequencing data to screen for pharmacogenomic risk factors related to antiseizure medication-induced cutaneous adverse drug reactions (cADRs), such as human leucocyte antigen HLA-B*15:02, HLA-A*31:01 variants.

METHODS

Genotyping results, generated from the Genomics England UK 100 000 Genomes Project primarily for identification of disease-causing variants, were used to additionally screen for relevant HLA variants and other pharmacogenomic variants. Medical records were retrospectively reviewed for clinical and cADR phenotypes for HLA variant carriers. Descriptive statistics and the χ2 test were used to analyse phenotype/genotype data for HLA carriers and compare frequencies of additional pharmacogenomic variants between HLA carriers with and without cADRs, respectively.

RESULTS

1043 people with epilepsy were included. Four HLA-B*15:02 and 86 HLA-A*31:01 carriers were identified. One out of the four identified HLA-B*15:02 carriers had suffered antiseizure medication-induced cADRs; the point prevalence of cADRs was 16.9% for HLA-A*31:01 carriers of European origin (n=46) and 14.4% for HLA-A*31:01 carriers irrespective of ancestry (n=83).

CONCLUSIONS

Comprehensive utilisation of genetic data spreads beyond the search for causal variants alone and can be extended to additional clinical benefits such as identifying pharmacogenomic biomarkers, which can guide pharmacotherapy for genetically-susceptible individuals.

Impact of climate change on allergic diseases in Germany

Background

Allergic diseases, especially inhalation allergies, have reached epidemic levels and environmental factors play an important role in their development. Climate change influences the occurrence, frequency, and severity of allergic diseases.

Methods

The contents of this article were selected by the authors and developed section by section according to their expertise and the current state of knowledge. The sections were then discussed and agreed upon amongst all authors.

Results

The article highlights direct and indirect effects of climate change on allergies. It goes into detail about the connections between climate change and (new) pollen allergens as well as (new) occupational inhalation allergens, explains the effects of climate change on the clinical picture of atopic dermatitis, discusses the connections between air pollutants and allergies, and provides information about the phenomenon of thunderstorm asthma.

Conclusions

There is a need for action in the field of pollen and fungal spore monitoring, allergy and sensitisation monitoring, urban planning from an allergological perspective, and changes in the working environment, among others.

Vitamin D receptor and STAT6 interactome governs oesophageal epithelial barrier responses to IL-13 signalling

OBJECTIVE

The contribution of vitamin D (VD) deficiency to the pathogenesis of allergic diseases remains elusive. We aimed to define the impact of VD on oesophageal allergic inflammation.

DESIGN

We assessed the genomic distribution and function of VD receptor (VDR) and STAT6 using histology, molecular imaging, motif discovery and metagenomic analysis. We examined the role of VD supplementation in oesophageal epithelial cells, in a preclinical model of IL-13-induced oesophageal allergic inflammation and in human subjects with eosinophilic oesophagitis (EoE).

RESULTS

VDR response elements were enriched in oesophageal epithelium, suggesting enhanced VDR binding to functional gene enhancer and promoter regions. Metagenomic analysis showed that VD supplementation reversed dysregulation of up to 70% of the transcriptome and epigenetic modifications (H3K27Ac) induced by IL-13 in VD-deficient cells, including genes encoding the transcription factors HIF1A and SMAD3, endopeptidases (SERPINB3) and epithelial-mesenchymal transition mediators (TGFBR1, TIAM1, SRC, ROBO1, CDH1). Molecular imaging and chromatin immunoprecipitation showed VDR and STAT6 colocalisation within the regulatory regions of the affected genes, suggesting that VDR and STAT6 interactome governs epithelial tissue responses to IL-13 signalling. Indeed, VD supplementation reversed IL-13-induced epithelial hyperproliferation, reduced dilated intercellular spaces and barrier permeability, and improved differentiation marker expression (filaggrin, involucrin). In a preclinical model of IL-13-mediated oesophageal allergic inflammation and in human EoE, VD levels inversely associated with severity of oesophageal eosinophilia and epithelial histopathology.

CONCLUSIONS

Collectively, these findings identify VD as a natural IL-13 antagonist with capacity to regulate the oesophageal epithelial barrier functions, providing a novel therapeutic entry point for type 2 immunity-related diseases.

Update on basic and clinical aspects of eosinophilic oesophagitis

The identification of a distinct syndrome, designated eosinophilic oesophagitis (EoE), with its own clinical and histopathological characteristics, was first described in the early 1990s. Meanwhile intense research has uncovered many molecular, immunological and clinical aspects of this chronic-inflammatory disorder. This article focuses exclusively on basic and clinical insights of EoE gathered during the last few years. Regarding aetiopathogenesis it has become clear that EoE is a food-triggered disease with milk and wheat as the dominant culprit food categories. However, it is still debated whether a disturbed mucosal integrity allowing allergens to cross the mucosal barrier, or changes in wheat and milk manufacturing might induce these inflammatory responses. Furthermore, basic science and clinical studies have accordingly confirmed that a chronic eosinophilic inflammation leads to a remodelling of the oesophagus with micro- and macro-morphological alterations, ending in a strictured oesophagus with impaired function. Fortunately, long-term therapeutic trials, using either topical corticosteroids or dietary allergen avoidance, have demonstrated that this sequela can be prevented or even reversed. This finding is of clinical relevance as it supports the initiation of a consistent anti-inflammatory therapy. Nevertheless, EoE is still an enigmatic disease and the long list of unanswered questions will certainly stimulate further research.

The effect of cortisone on the Shwartzman reaction; the production of lesions resembling the dermal and generalized Shwartzman reactions by a single injection of bacterial toxin in cortisone-treated rabbits

1. Cortisone, in a dose of 25 mg. daily and with a pretreatment period of 3 days, in rabbits weighing 1 to 1.5 kilos, did not inhibit the dermal Shwartzman reaction produced by meningococcal or S. marcescens toxin. 2. In cortisone-treated rabbits, a single intradermal injection of toxin produced a primary reaction of hemorrhage and necrosis in the skin at the injected site. This lesion resembled the Shwartzman reaction in its gross and histological appearance. 3. Like the Shwartzman reaction, the primary hemorrhagic reaction in cortisone-treated rabbits was prevented by nitrogen mustard, and the preventive effect of nitrogen mustard was partly eliminated when the femoral marrow was protected against the latter agent. 4. A single intravenous injection of meningococcal or S. marcescens toxin, in cortisone-treated rabbits, was followed by bilateral cortical necrosis of the kidneys in the majority of instances. The renal lesions, as well as hemorrhages in the lungs, spleen, liver, and gastrointestinal tract, resembled the lesions of the generalized Shwartzman reaction. Histologically, the glomerular capillaries in both types appeared to be occluded by homogeneous, eosinophilic material which showed a strongly positive Schiff reaction. 5. The renal lesion following a single injection of toxin in cortisone-treated animals, and that following two intravenous injections in the generalized Shwartzman reaction, were both completely prevented by nitrogen mustard. This effect of nitrogen mustard was inhibited when the femoral marrow was protected against the latter agent. 6. The injection of S. marcescens toxin into the skin of normal rabbits did not cause systemic symptoms, nor was it possible to provoke the generalized Shwartzman reaction by this route. In cortisone-treated rabbits, a similar intradermal injection was regularly followed by the development of bilateral cortical necrosis of the kidneys, indicating that absorption of toxin from the skin occurred in these animals. 7. Possible mechanisms to account for the observations are discussed. The authors are obliged to Professor James R. Dawson for many helpful suggestions during the course of this investigation.

The mechanism of action of 17-hydroxy-11-dehydrocorticosterone (compound E) and of the adrenocorticotropic hormone in experimental hypersensitivity in rabbits

The concurrent administration of compound E at a daily dosage of 2 mg. per kg. to rabbits receiving daily intracutaneous injections of crystalline egg albumin markedly inhibited the development of anaphylactic hypersensitivity of the Arthus type. ACTH, when given at a similar dosage, produced a much less marked effect. Both hormones suppressed circulating antibody and as with the Arthus reaction, the suppression produced by compound E was much greater than that obtained with ACTH. When treatment with compound E was started following sensitization, there was a rapid decline in circulating antibody and, if the pretreatment serum antibody was low, there was also a progressive decrease in skin reactivity, becoming negative after 5 days of treatment. When the pretreatment serum antibody concentration was great, so that by the termination of treatment the antibody concentration was still above the level ordinarily sufficient for a maximal skin response, the Arthus reaction was unaffected by treatment. These considerations as well as the failure of compound E to inhibit the systemic passive Arthus reaction suggest that the inhibitory effect of compound E and ACTH on the development of experimental hypersensitivity results from the hormonal reduction of circulating antibody. Treatment with compound E had no effect on the rate of disappearance of circulating antibody in the passively immunized rabbit. This finding suggests that ACTH and compound E reduce circulating antibody by inhibiting antibody formation rather than by promoting antibody destruction. The question is raised as to whether the marked lymphoid atrophy produced by these hormones may be related to the interference with antibody production.

Studies on the mechanism of hypersensitivity phenomena. III. The participation of complement in the formation of anaphylatoxin

The interaction of fresh rat and guinea pig serum with washed preformed immune aggregates has been studied with respect to the loss in hemolytic potency of the serum, diminution of the C'₃; activity, and appearance of anaphylatoxin. It has been found that the formation of anaphylatoxin, as judged by its effect on capillary permeability and smooth muscle contraction, is coincident with or subsequent to the fixation of all the known C' components. Less anaphylatoxin is formed by aggregates formed with excess antigen than those in equivalence ratio combination. C' fixation, as well as anaphylatoxin production, may be inhibited by chelation of the divalent cations, presumably by interfering with the fixation of C'₁, C'₄, and C'₂. Phlorizin suppresses the utilization of C'₃ in immune hemolysis, C' fixation by antigen-antibody aggregates, and the production of anaphylatoxin. The biological activities associated with the fixation of C' are not manifest unless C'₃ participates in this process at 37°C. It is concluded that the formation of anaphylatoxin may be regarded as a product of C' fixation.

The specificity of allergic reactions. VI. Unresponsiveness to simple chemicals

"Gastric feeding" of adult guinea pigs with dinitrochlorobenzene (DCB) resulted in a specific unresponsiveness to sensitization with the specific contact hapten. The more DCB gastric-fed to a guinea pig, the more complete the unresponsiveness to the hapten. When mycobacteria were incorporated into the sensitizing emulsion, the state of unresponsiveness to the dinitrophenyl (DNP) group was less apparent. When animals gastric-fed with DCB were later sensitized with an in vitro conjugate of the hapten combined with a heterologous protein such as dinitrophenyl-hen egg albumin (DNP.HEA), an immune response similar to that in the controls occurred both to the hapten and to the protein carrier. However, when the tolerant animals were sensitized with a conjugate containing a homologous protein carrier such as dinitrophenyl guinea pig serum (DNP.GPS), they showed diminished immune responses in comparison with those in the non-tolerant controls. The presence of circulating anti-DNP antibodies from sensitization with DNP-HEA did not affect the unresponsiveness to the specific contact hapten, regardless of whether these antibodies are present before or after induction of tolerance. Sensitization with picryl chloride (PiCl) (a cross-reacting hapten), either before or after gastric feeding of DCB, did not affect the state of unresponsiveness to DNP. Similarly when the DNP-tolerant animal was sensitized with PiCl, the subsequent immune response was similar to that in the controls; cross-reactions with the DNP group both in the contact and circulating antibody phase occurred at a rate similar to that in the controls. The foregoing relationships can be explained by presuming that, upon the gastric feeding of DCB, an in vivo conjugate is formed with a somatic protein, which determines the basic specificity of the tolerance. Acquired tolerance seems to manifest an immunologic specificity similar to that of delayed hypersensitivity, a relationship not unexpected if delayed hypersensitivity is an early phase of the immune response.