Acute Activation of Oxidative Pentose Phosphate Pathway as First-Line Response to Oxidative Stress in Human Skin Cells

Integrity of human skin is endangered by exposure to UV irradiation and chemical stressors, which can provoke a toxic production of reactive oxygen species (ROS) and oxidative damage. Since oxidation of proteins and metabolites occurs virtually instantaneously, immediate cellular countermeasures are pivotal to mitigate the negative implications of acute oxidative stress. We investigated the short-term metabolic response in human skin fibroblasts and keratinocytes to H2O2 and UV exposure. In time-resolved metabolomics experiments, we observed that within seconds after stress induction, glucose catabolism is routed to the oxidative pentose phosphate pathway (PPP) and nucleotide synthesis independent of previously postulated blocks in glycolysis (i.e., of GAPDH or PKM2). Through ultra-short (13)C labeling experiments, we provide evidence for multiple cycling of carbon backbones in the oxidative PPP, potentially maximizing NADPH reduction. The identified metabolic rerouting in oxidative and non-oxidative PPP has important physiological roles in stabilization of the redox balance and ROS clearance.

Stratum corneum lipidomics analysis reveals altered ceramide profile in atopic dermatitis patients across body sites with correlated changes in skin microbiome

BACKGROUND

Atopic dermatitis (AD) is driven by the interplay between a dysfunctional epidermal barrier and a skewed cutaneous immune dysregulation. As part of the complex skin barrier dysfunction, abnormalities in lipid organization and microbiome composition have been described. We set out to systematically investigate the composition of the stratum corneum lipidome, skin microbiome and skin physiology parameters at three different body sites in patients with AD and healthy volunteers.

METHODS

We analysed tape strips from different body areas obtained from 10 adults with AD and 10 healthy volunteers matched for FLG mutation status for 361 skin lipid species using the Metabolon mass spectrometry platform. 16S rRNA data were available from all probands.

RESULTS

Our study showed that the lipid composition differs significantly between body sites and between AD patients and healthy individuals. Ceramide species NS was significantly higher in AD patients compared to healthy volunteers and was also higher in AD patients with a FLG mutation compared to AD patients without a FLG mutation. The correlation analysis of skin lipid alterations with the microbiome showed that Staphylococcus colonization in AD is positively correlated with ceramide subspecies AS, ADS, NS and NDS.

CONCLUSION

This is the first study to reveal site-specific lipid alterations and correlations with the skin microbiome in AD.

Effect of adenosine versus adenine nucleotides on evoked potentials in a rat hippocampal slice preparation

A marked depression of evoked CA1 potentials was observed with the nucleotide analogues a,b-methylene ADP (AOPCP) and adenylimido-diphosphate (AIP) and with 2'-adenosine monophosphate (2'-AMP). While the depression elicited by 5'-nucleotides was completely antagonized by the action of adenosine deaminase, AOPCP and 2'-AMP were only partially antagonized. The findings indicate that nucleotides on their own are capable of modulating synaptic transmission but that the physiologically more prevalent 5'-AMP is mediating its effect via adenosine. By producing this membrane permeable compound and allowing its re-uptake, the 5'-nucleotidase may determine the time course of purinergic action.

Protein-coding variants contribute to the risk of atopic dermatitis and skin-specific gene expression

BACKGROUND

Fifteen percent of atopic dermatitis (AD) liability-scale heritability could be attributed to 31 susceptibility loci identified by using genome-wide association studies, with only 3 of them (IL13, IL-6 receptor [IL6R], and filaggrin [FLG]) resolved to protein-coding variants.

OBJECTIVE

We examined whether a significant portion of unexplained AD heritability is further explained by low-frequency and rare variants in the gene-coding sequence.

METHODS

We evaluated common, low-frequency, and rare protein-coding variants using exome chip and replication genotype data of 15,574 patients and 377,839 control subjects combined with whole-transcriptome data on lesional, nonlesional, and healthy skin samples of 27 patients and 38 control subjects.

RESULTS

An additional 12.56% (SE, 0.74%) of AD heritability is explained by rare protein-coding variation. We identified docking protein 2 (DOK2) and CD200 receptor 1 (CD200R1) as novel genome-wide significant susceptibility genes. Rare coding variants associated with AD are further enriched in 5 genes (IL-4 receptor [IL4R], IL13, Janus kinase 1 [JAK1], JAK2, and tyrosine kinase 2 [TYK2]) of the IL13 pathway, all of which are targets for novel systemic AD therapeutics. Multiomics-based network and RNA sequencing analysis revealed DOK2 as a central hub interacting with, among others, CD200R1, IL6R, and signal transducer and activator of transcription 3 (STAT3). Multitissue gene expression profile analysis for 53 tissue types from the Genotype-Tissue Expression project showed that disease-associated protein-coding variants exert their greatest effect in skin tissues.

CONCLUSION

Our discoveries highlight a major role of rare coding variants in AD acting independently of common variants. Further extensive functional studies are required to detect all potential causal variants and to specify the contribution of the novel susceptibility genes DOK2 and CD200R1 to overall disease susceptibility.

Relationship between atopic dermatitis, depression and anxiety: a two-sample Mendelian randomization study

BACKGROUND

Growing evidence suggests that atopic dermatitis (AD) is associated with an increased risk of depressive disorders and anxiety. However, existing studies were observational and may have uncovered correlations but could not easily disentangle noncausal or reverse-causal associations because these associations could be confounded and may not reflect true causal relationships.

OBJECTIVES

To examine, in a two-sample Mendelian randomization study, the potential effect of AD on the risk of depressive disorders and anxiety.

METHODS

Genetic instruments from the largest available genome-wide association study (GWAS) for AD (10 788 cases and 30 047 controls) were used to investigate the relationship to broad depression (170 756 cases and 329 443 controls), major depressive disorder (MDD; 30 603 cases and 143 916 controls) and anxiety (5580 cases and 11 730 controls). A set of complementary approaches were carried out to assess horizontal pleiotropy and related potential caveats occurring in MR studies.

RESULTS

We observed no causal impact of AD on the risk of depressive disorders and anxiety, with close-to-zero effect estimates. The inverse weighted method revealed no associations of AD on broad depression [odds ratio (OR) 1·014; P = 0·431], probable MDD (OR 1·002; P = 0·568), International Classification of Diseases, Ninth/Tenth Revision-based MDD (OR 1·001; P = 0·466) or anxiety (OR 1·097; P = 0·180).

CONCLUSIONS

This MR study does not support a causal effect of AD on depression and anxiety.

Effects of lithium on electrical activity and potassium ion distribution in the vertebrate central nervous system

Three different regions of the vertebrate central nervous system maintained in vitro (frog spinal cord, guinea pig olfactory cortex and hippocampus) have been used to investigate how Li+ influences membrane potential, membrane resistance, action potentials, synaptic potentials and the transmembrane K+-distribution of neurons and glial cells. In view of the therapeutic action of Li+ in manic-depressive disease, a special effort was made to determine the threshold concentration for the actions of Li+ on the parameters described above. It was observed that Li+ induced a membrane depolarization of both neurons and glial cells, a decrease of action potential amplitudes, a facilitation of monosynaptic excitatory postsynaptic potentials and a depression of polysynaptic reflexes. The membrane resistance of neurons was not altered. Li+ also induced an elevation of the free extracellular potassium concentration and a decrease of the free intracellular potassium concentration. Furthermore, in the presence of Li+ a slowing of the recovery of the membrane potential of neurons and glial cells, and of the extracellular potassium concentration after repetitive synaptic stimulation was observed. The threshold concentrations for the effects of Li+ were below 5 mmol/l in the frog spinal cord and below 2 mmol/l in the guinea pig olfactory cortex and hippocampus. The basic mechanism underlying the action of Li+ may be an interaction with the transport-function of the Na+/K+ pump.

Plasma membrane associated location of sulfonated meso-tetraphenylporphyrins of different hydrophilicity probed by total internal reflection fluorescence spectroscopy

Sulfonated meso-tetraphenylporphyrins of different hydrophilicity were microspectrofluorimetrically examined in endothelial cells using total internal reflection (TIR) illumination or epi-illumination. Since the penetration depth of the evanescent field during TIR illumination is limited to a few hundred nanometers, photosensitizers were almost selectively examined in close vicinity to the plasma membrane. Pronounced fluorescence signals during TIR illumination were observed for the hydrophilic compounds meso-tetraphenylporphyrin tetrasulfonate (TPPS4) and meso-tetraphenylporphyrin trisulfonate (TPPS3), whereas the more lipophilic compounds meso-tetraphenylporphyrin disulfonate (TPPS2a) and meso-tetraphenylporphyrin monosulfonate (TPPS1) could only be detected under epi-illumination. Irradiation of TPPS1 and TPPS2a in the Soret band led to an increase in fluorescence intensity and formation of a photoproduct with an emission maximum around 610 nm, which was limited to intracellular compartments. In contrast, fluorescence spectra of TPPS3 and TPPS4 obtained by TIR and epi-illumination remained almost unchanged after irradiation in the Soret band. Extralysosomal location of TPPS3 and TPPS4 in close proximity to the plasma membrane was deduced from experiments with the lysosomal markers acridine orange (AO) or lysotracker yellow (LY), which were not detectable under TIR illumination. In conclusion, these results provide for the first time direct evidence for a plasma membrane-associated fraction of the hydrophilic compounds TPPS3 and TPPS4 in living cells.

Kindlin-1 protects cells from oxidative damage through activation of ERK signalling

Kindlin-1 is a FERM domain containing adaptor protein that is found predominantly at cell-extracellular matrix adhesions where it binds to β-integrin subunits and is required for integrin activation. Loss of function mutations in the FERMT1 gene which encodes Kindlin-1 leads to the development of Kindler Syndrome (KS) an autosomal recessive skin disorder characterized by skin blistering, photosensitivity, and predisposition to aggressive squamous cell carcinoma (SCC). Here we show that loss of Kindlin-1 sensitizes both SCC cells and keratinocytes to oxidative stress: Kindlin-1 deficient cells have higher levels of reactive oxygen species, decreased viability and increased DNA damage after treatment with either hydrogen peroxide (H₂O₂) or irradiation with UVA. We show that Kindlin-1 is required to fully activate ERK signalling after oxidative damage, and that activation of ERK protects cells from DNA damage following oxidative stress: inhibition of ERK activation sensitizes Kindlin-1 expressing cells, but not Kindlin-1 deficient cells to oxidative stress. Finally we demonstrate that the Kindlin-1 dependent activation of ERK and protection from DNA damage following oxidative stress depends on the ability of Kindlin-1 to bind integrins. Thus loss of Kindlin-1 leads to an imbalance in the cellular oxidative state, which renders Kindlin-1 deficient cells more prone to the effects of ROS generated in response to oxidative stress. We propose that Kindlin-1 dependent activation of ERK signalling is a key molecular mechanism that renders KS keratinocytes more sensitive to oxidative damage and contributes to the increased photosensitivity in KS patients.

Host traits, lifestyle and environment are associated with human skin bacteria

BACKGROUND

The human skin offers diverse ecosystems for microbial symbionts. However, the factors shaping skin-microbiome interactions are still insufficiently characterized. This contrasts with the broader knowledge about factors influencing gut microbiota.

OBJECTIVES

We aimed to investigate major patterns of association of host traits, lifestyle and environmental factors with skin bacteria in two German populations.

METHODS

This is a cross-sectional study with 647 participants from two population-based German cohorts, PopGen (n = 294) and KORA FF4 (n = 353), totalling 1794 skin samples. The V1-V2 regions of the 16S ribosomal RNA (rRNA) gene were sequenced. Associations were tested with two bacterial levels, community (beta diversity) and 16S rRNA gene amplicon sequence variants (ASVs).

RESULTS

We validated known associations of the skin microbiota with skin microenvironment, age, body mass index and sex. These factors were associated with beta diversity and abundance of ASVs in PopGen, which was largely replicated in KORA FF4. Most intriguingly, dietary macronutrients and total dietary energy were associated with several ASVs. ASVs were also associated with smoking, alcohol consumption, skin pH, skin type, transepidermal water loss, education and several environmental exposures, including hours spent outdoors. Associated ASVs included members of the genera Propionibacterium, Corynebacterium and Staphylococcus.

CONCLUSIONS

We expand the current understanding of factors associated with the skin bacterial community. We show the association of diet with skin bacteria. Finally, we hypothesize that the skin microenvironment and host physiology would shape the skin bacterial community to a greater extent compared with a single skin physiological feature, lifestyle and environmental exposure.

Skin microbiota analysis in human 3D skin models-"Free your mice"

In the May issue of Experimental Dermatology 2018, we published a review article focusing on human 3D skin models in the context of microbiota research. The principal intention was to provide an overview of present and future concepts to use skin models in microbiota analyses. With the present viewpoint, we would like to draw the reader's attention again to the use of human skin models in microbiota research with the aim to highlight the benefits and necessity of human skin models to analyse the human skin-microbiota interaction. This is accompanied by a critical view on mice models that often are not suitable to analyse the functional impact of the human skin microbiota. In addition, we present novel and future concepts highlighting the benefits of human 3D skin models in microbiota research.

Host genetic factors related to innate immunity, environmental sensing and cellular functions are associated with human skin microbiota

Despite the increasing knowledge about factors shaping the human microbiome, the host genetic factors that modulate the skin-microbiome interactions are still largely understudied. This contrasts with recent efforts to characterize host genes that influence the gut microbiota. Here, we investigated the effect of genetics on skin microbiota across three different skin microenvironments through meta-analyses of genome-wide association studies (GWAS) of two population-based German cohorts. We identified 23 genome-wide significant loci harboring 30 candidate genes involved in innate immune signaling, environmental sensing, cell differentiation, proliferation and fibroblast activity. However, no locus passed the strict threshold for study-wide significance (P < 6.3 × 10-10 for 80 features included in the analysis). Mendelian randomization (MR) analysis indicated the influence of staphylococci on eczema/dermatitis and suggested modulating effects of the microbiota on other skin diseases. Finally, transcriptional profiles of keratinocytes significantly changed after in vitro co-culturing with Staphylococcus epidermidis, chosen as a representative of skin commensals. Seven candidate genes from the GWAS were found overlapping with differential expression in the co-culturing experiments, warranting further research of the skin commensal and host genetic makeup interaction.

Inhibition of cyclin-dependent kinase activity exacerbates H2 O2 -induced DNA damage in Kindler syndrome keratinocytes

Kindler syndrome (KS) is an autosomal recessive skin disorder characterized by skin blistering and photosensitivity. KS is caused by loss of function mutations in FERMT1, which encodes Kindlin-1. Kindlin-1 is a FERM domain containing adaptor protein that is found predominantly at cell-extracellular matrix adhesions where it binds to integrin β subunits and is required for efficient integrin activation. Using keratinocytes derived from a patient with KS, into which wild-type Kindlin-1 (Kin1WT) has been expressed, we show that Kindlin-1 binds to cyclin-dependent kinase (CDK)1 and CDK2. CDK1 and CDK2 are key regulators of cell cycle progression, however, cell cycle analysis showed only small differences between the KS and KS-Kin1WT keratinocytes. In contrast, G2/M cell cycle arrest in response to oxidative stress induced by hydrogen peroxide (H₂ O₂ ) was enhanced in KS keratinocytes but not KS-Kin1WT cells, following inhibition of CDK activity. Furthermore, KS keratinocytes were more sensitive to DNA damage in response to H₂ O₂ and this was exacerbated by treatment with the CDK inhibitor roscovitine. Thus, in Kindlin-1 deficient keratinocytes, CDK activity can further regulate oxidative damage induced cell cycle arrest and DNA damage. This provides further insight into the key pathways that control sensitivity to oxidative stress in KS patients.

Effects of Early Emollient Use in Children at High Risk of Atopic Dermatitis: A German Pilot Study

Several small studies have indicated that daily emollient use from birth might delay, suppress or prevent atopic dermatitis (AD). Two larger trials did not confirm this; however, a recent smaller study indicated a protective effect if daily emollient use is used in the first 2 months of life. Further research is needed to evaluate the effect of emollient use on development of AD. The current study randomly assigned 50 newborns who were at high risk of developing AD (1:1) to receive general infant skin-care advice (control group), or skin-care advice plus emollient with advice to apply emollient at least once daily until 1 year of age (intervention group). Repeated skin examinations, skin physiology measurements and skin microbiome profiling were performed. Of the children in the intervention and control groups, 28% and 24%, respectively, developed AD (adjusted Relative Risk (RR) 1.19, p = 0.65, adjusted risk difference 0.05). Skin pH decreased and transepidermal water loss and stratum corneum hydration increased over time in both groups with no significant differences. In the intervention group skin microbiome alpha diversity increased earlier, and the abundance of Streptococcus and Staphylococcus species were significantly reduced at month 1. Daily early emollient use in children with high risk of AD was safe, but it did not significantly reduce the risk of developing AD or impact skin physiology development.

Glucose utilization during chromatolysis: a 14C deoxyglucose study

After transection of the facial and hypoglossal nerves, rats were injected with 14C 2-deoxyglucose. Contact-autoradiographs of histological sections showed increased radioactivity in the motor nuclei of the operated side between 1 and 28 days post operation. This suggests an increase of glucose utilization and thus an enhanced energy supply to the facial and hypoglossal nuclei during the process of axonal reaction.

Stratum corneum and microbial biomarkers precede and characterize childhood atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is the most common paediatric inflammatory skin disease. There are currently no robust biomarkers that could reliably predict its manifestation, and on the molecular level, it is less well characterized than adult AD.

OBJECTIVES

This study aimed to extend previous findings and provide evidence for distinct changes of the epidermal proteome and microbiome preceding the onset of AD as well as characterizing early AD.

METHODS

We longitudinally analysed epidermal biomarker levels and microbial profiles in a cohort of 50 neonates at high risk for AD, who had participated in a randomized controlled trial on early emollient use for AD prevention.

RESULTS

About 26% of the infants developed AD until month 24 with an average age of 10 month at disease onset. In children with later AD, IL-1Ra, TNFβ, IL-8, IL-18, IL-22, CCL2, TARC, TSLP and VEGFa showed increased levels prior to disease manifestation with levels of IL-1Ra, TNFβ and VEGFa already increased shortly after birth. Further, children with later AD displayed a delayed maturation and differentially composed skin microbiome prior to AD onset. At manifestation, levels of multiple Th2, Th17/22 and Th1-associated biomarkers as well as innate immunity markers were elevated, and abundances of commensal Streptococcus species were reduced in favour of Staphylococcus epidermidis.

CONCLUSIONS

Our results indicate that elevations of proinflammatory stratum corneum biomarkers and alterations of the skin microbiome precede paediatric AD and characterize the disease at onset.

Zugang und Inanspruchnahme psychosomatischer Versorgung aus ärztlicher Sicht: Eine qualitative Interviewstudie

Hintergrund Chronisch entzündliche Hauterkrankungen sind häufig mit psychosozialen Beeinträchtigungen und einer reduzierten Lebensqualität vergesellschaftet. Ziel dieser Studie war es zu erfassen, wie spezialisiertes medizinisches Personal eines universitären Haut-Entzündungszentrums die Zugangswege und die Inanspruchnahme psychosomatischer Sondierungsgespräche oder Kurzzeitinterventionen bei PatientInnen mit chronisch entzündlichen Hauterkrankungen wahrnimmt.

Methoden Es wurden qualitative Erhebungen in Form von 10 Einzelinterviews mit medizinischem Personal durchgeführt, das zum Zeitpunkt der Befragung im Zentrum für entzündliche Hauterkrankungen der Uni-Hautklinik tätig war. Die Daten wurden inhaltsanalytisch mithilfe einer qualitativen Analysesoftware ausgewertet.

Ergebnisse Die Ergebnisse aus den geführten Einzelinterviews ergaben, dass die Einbindung einer psychosomatischen Versorgung innerhalb eines dermatologischen Entzündungszentrums vom ärztlichen Personal als durchweg positiv bewertet wurde. Die Option auf ein zeit- und zentrumsnahes Gesprächsangebot nimmt dabei eine besondere Rolle ein. Experten fühlen sich mit der ortsnahen Einbindung psychosomatischer Expertise sicherer im Umgang mit belasteten Patient*innen. Der holistische Ansatz scheint einen positiven Einfluss auf die individuelle Behandlung und die Beziehungsgestaltung mit den Patient*innen zu nehmen. Dabei zeigten sich keine wesentlichen Unterschiede im Geschlecht und über verschiedene Altersgruppen hinweg.

Diskussion Die Möglichkeit zur zentrumsnahen Anbindung von belasteten Patient*innen in Form von zusätzlichen psychosomatischen Sondierungsgesprächen wie auch dem Einsatz von adaptierten Kurzzeitinterventionen trägt zur holistischen Behandlung bei, scheint einen günstigen Einfluss auf den somatischen Behandlungsverlauf zu nehmen und unterstützt Ärzt*innen in ihrer Behandlung.

Selective examination of plasma membrane-associated photosensitizers using total internal reflection fluorescence spectroscopy: correlation between photobleaching and photodynamic efficacy of protoporphyrin IX

Fluorescence spectra, fluorescence decay kinetics, photobleaching kinetics and photodynamic efficacy of protoporphyrin IX (PP) were investigated in endothelial cells in vitro after different incubation times. Fluorescence spectra and photobleaching kinetics were determined during total internal reflection (TIR) illumination or epi-illumination. Because penetration depth of the excitation light during TIR illumination was limited to about 100 nm, plasma membrane-associated PP was almost selectively examined. Spectra obtained by TIR fluorescence spectroscopy (FS) showed a very low background, whereas spectra obtained by epi-illumination exhibited considerable background by autofluorescence and scattered light. For photobleaching kinetics during TIR illumination after 1 h or 24 h incubation, a biexponential fluorescence decrease was observed with a rapidly and a slowly bleaching portion. After 1 h incubation, the rapidly bleaching portion was the predominant fraction, whereas after 24 h incubation comparable relative amounts of the rapidly and slowly bleaching portion were determined. The rapidly and slowly bleaching portion were assigned to PP monomers and aggregated species in close vicinity to the plasma membrane. Fluorescence decay measurements after epi-illumination support the decrease of PP monomers within the whole cell with increasing incubation time. In contrast to TIR illumination, photobleaching of PP during epi-illumination was characterized by slow monoexponential fluorescence decrease after 1 h or 24 h incubation. Photodynamic efficacy of PP using epi-illumination was found to depend strongly on incubation time. Considerable cell inactivation was determined for short incubation times (1 h or 3 h), whereas photodynamic efficacy was diminished for longer incubation times. Reduced photodynamic efficacy after long incubation times was assigned to the lower amount of photodynamically active monomers determined close to the plasma membrane as well as within the whole cell. In conclusion, TIRFS measurements are suggested to be an appropriate tool for the examination of the plasma membrane-associated photosensitizer fraction in living cells.

Type 2 Cytokine-Dependent Skin Barrier Regulation in Personalized 2-Dimensional and 3-Dimensional Skin Models of Atopic Dermatitis: A Pilot Study

Keratinocytes (KCs) from healthy donors stimulated with type 2 cytokines are often used to experimentally study atopic dermatitis (AD) inflammatory responses. Owing to potential intrinsic alterations, it seems favorable to use KCs from patients with AD. KCs isolated from hair follicles offer a noninvasive approach to investigate AD-derived KCs. To evaluate whether such AD-derived KCs are suitable to mimic AD inflammatory responses, we compared hair follicle-derived KCs from healthy donors with those from patients with AD in a type 2 cytokine environment. Stimulation of AD-derived KCs with IL-4 and IL-13 induced higher expression changes of AD-associated markers than that of healthy KCs. The combination of IL-4 and IL-13 generally induced highest expression changes, but IL-13 alone also induced significant changes of AD-specific markers. Similar to the 2-dimensional cultures, IL-4/IL-13 stimulation of 3-dimensional skin models generated with AD-derived KCs modulated the expression of several AD-relevant factors. Whole-transcriptome analysis revealed that IL-4 and IL-13 acted similarly on these 3-dimensional skin models. Histologically, IL-13 alone and in combination with IL-4 increased epidermal spongiosis, a histological hallmark of AD skin. Taken together, our pilot study suggests that hair follicle-derived KCs from patients with AD represent a useful model system to study AD-related inflammation in a personalized in vitro model.

Current Developments of Clinical Sequencing and the Clinical Utility of Polygenic Risk Scores in Inflammatory Diseases

In this mini-review, we highlight selected research by the Deutsche Forschungsgemeinschaft (DFG) Cluster of Excellence “Precision Medicine in Chronic Inflammation” focusing on clinical sequencing and the clinical utility of polygenic risk scores as well as its implication on precision medicine in the field of the inflammatory diseases inflammatory bowel disease, atopic dermatitis and coronary artery disease. Additionally, we highlight current developments and discuss challenges to be faced in the future. Exemplary, we point to residual challenges in detecting disease-relevant variants resulting from difficulties in the interpretation of candidate variants and their potential interactions. While polygenic risk scores represent promising tools for the stratification of patient groups, currently, polygenic risk scores are not accurate enough for clinical setting. Precision medicine, incorporating additional data from genomics, transcriptomics and proteomics experiments, may enable the identification of distinct disease pathogeneses. In the future, data-intensive biomedical innovation will hopefully lead to improved patient stratification for personalized medicine.