Building confidence in skin sensitisation potency assessment using new approach methodologies: report of the 3rd EPAA Partners Forum, Brussels, 28th October 2019.

Skin sensitising substances that induce contact allergy and consequently risk elicitation of allergic contact dermatitis (ACD) remain an important focus regarding the replacement of animal experimentation. Current in vivo methods, notably the local lymph node assay (LLNA) refined and reduced animal usage and led to a marked improvement in hazard identification, characterisation and risk assessment. Since validation, regulatory confidence in the LLNA approach has evolved until it became the first choice assay in most regulated sectors. Currently, hazard identification using the LLNA is being actively replaced by a toolbox of non-animal approaches. However, there remains a need to increase confidence in the use of new approach methodologies (NAMs) as replacements for LLNA sensitiser potency estimation. The EPAA Partners Forum exchanged the current state of knowledge on use of NAMs in various industry sectors and regulatory environments. They then debated current challenges in this area and noted several ongoing needs. These included a requirement for reference standards for potency, better characterisation of applicability domains/technical limitations of NAMs, development of a framework for weight of evidence assessments, and an increased confidence in the characterisation of non-sensitisers. Finally, exploration of an industry/regulator cross-sector user-forum on skin sensitisation was recommended.

Toward a comparative retrospective analysis of rat and rabbit developmental toxicity studies for pharmaceutical compounds.

Based on a proposal made at the ICH Workshop in Tallinn, Estonia (2010), the value of the rabbit embryo-fetal development (EFD) versus the rodent EFD was examined by the HESI DART group. A cross-industry data survey provided anonymised EFD and toxicokinetic data from EFD studies on over 400 marketed and unmarketed drugs (over 800 studies) that were entered by experts at RIVM into US EPA's ToxRefDB style database. The nature and severity of findings at the lowest observed adverse effect level (LOAEL) are being reviewed to quantitate the frequency with which lesser signs of embryo-fetal effects (e.g., delays in ossification, minor changes in frequency of variants) are driving the LOAELs. Interpretation was based on exposure rather than administered dose. This paper provides an update of this ongoing project as discussed during a workshop of the European Teratology Society in Ispra, Italy (2013). This was the first presentation of the initial data set, allowing debate on future directions, to provide a better understanding of the implications of either delaying a rabbit EFD or waiving the need in particular circumstances.

Treacher Collins syndrome with multiple congenital heart defects after paroxetine exposure: case report.

Treacher Collins syndrome is an autosomal dominant disorder of craniofacial development with an incidence of I in 40,000 to in 70,000 live births. It is characterized by abnormalities of the pinnae which are frequently associated with atresia of the external auditory canals and anomalies of the middle ear ossicles. Rarely congenital heart defects can be present. Prenatal paroxetine exposure may enhance the risks of major malformation, particularly cardiac defects. This article reports a newborn, whose mother used paroxetine during pregnancy, presenting with multiple congenital heart defects associated to typical physical characteristics of Treacher Collins syndrome.

A novel mutation of laminin ß-2 gene in Pierson syndrome manifested with nephrotic syndrome in the early neonatal period.

Pierson syndrome is a rare autosomal recessive disorder which is mainly characterized by congenital nephrotic syndrome (CNS), diffuse mesangial sclerosis (DMS) and distinct ocular abnormalities, including microcoria. Most affected children exhibit early onset of chronic renal failure, neurodevelopmental deficits, and blindness. It is caused by a homozygous or compound heterozygous mutation in the gene encoding laminin beta2 (LAMB2) on chromosome 3p21. In this article, we report on a patient with CNS, bilateral megalocornea and microcoria. The patient had developed renal failure at very early postnatal period and died of septic shock. A novel homozygous donor splice mutation (IVS4 + 2T > C) in LAMB2 gene was identified in the patient.

Crisponi syndrome: a new mutation in CRLF1 gene associated with moderate outcome.

SUMMARY: Crisponi syndrome (CS) is a rare, autosomal recessive disorder, characterized by hyperthermia, extensive muscular contractions in the face after even minimal stimuli or crying, hypertonia, opisthotonus, camptodactyly, and typical facial features. Recently, it has been demonstrated that CRLF1 (cytokine receptor-like factor 1) gene mutation is associated with CS. Here we report a case of CS with a new mutation in the CRLF1 gene associated with moderate clinical phenotype.

Papillorenal syndrome with de novo reciprocal translocation t(2;15) (q31; q26).

Renal hypoplasia is a congenital anomaly, the etiology of which is not yet fully known. Genetic studies have shown that certain genes, in utero environmental factors and molecular mechanisms have a role in the identification ofnephron formation and kidney size. The coexistence of bilateral renal hypoplasia and optic disc coloboma is observed in papillorenal syndrome, which caused by the mutation of the PAX2 gene. In the case presented in this article, bilateral renal hypoplasia and optic disc coloboma have been detected to coexist. The analysis of the PAX2 gene, which was carried out with an eye to the papillorenal syndrome, did not reveal any mutations. However, de novo t(2;15) (q31; q26) (reciprocal translocation) was detected in chromosome analysis. As far as we know, there are not any publications focusing on the clinical importance of this type of translocation. In cases with renal hypoplasia and optic disc coloboma, the possibility of a de novo translocation between chromosomes 2 and 15 should be considered.

Prevalence of iron deficiency at the first age of the infants hospitalized in neonatal period.

Iron deficiency (ID) is a global health problem. We aimed to determine the prevalence of ID at the first year of life in infants who were hospitalized in our neonatal intensive care unit (NICU) and investigate the effects of various factors on iron status. One year follow-up data of 219 infants who were discharged from NICU was retrospectively evaluated. ID anemia and ID without anemia were detected in fifteen infants (6.8%) and five (2.3%) infants, respectively. We concluded that, due to prophylactic iron treatment and close follow-up, hospitalization in neonatal period did not have any adverse effect on iron status at first year of life.

A neonatal case of left ventricular noncompaction associated with trisomy 18.

A neonatal case of left ventricular non-compaction associated with trisomy 18: Left ventricular noncompaction (LVNC) is a rare congenital cardiomyopathy and exact etiology is still unknown. Trisomy 18 is the second most common autosomal trisomy in live-born infants. LVNC has been described in association with other dysmorphic features, association with trisomy 18 has not been reported previously in a neonate. LVNC broadens the cardiac anomalies associated with trisomy 18.

Performance and microbial analysis of defined and non-defined inocula for the removal of dimethyl sulfide in a biotrickling filter.

The performance and microbial communities of three differently inoculated biotrickling filters removing dimethyl sulfide (DMS) were compared. The biotrickling filters were inoculated with Thiobacillus thioparus TK-m (THIO), sludge (HANDS) and sludge + T. thioparus TK-m + Hyphomicrobium VS (HANDS++), respectively. The criteria investigated were length of the start-up period, the maximum elimination capacity, and the effects of intermittent loading rates, low pH, peak loading and very low loading rate on the DMS removal efficiency. The HANDS++ reactor exhibited the best performance considering all treatments. HANDS performed almost equally well as HANDS++, except during the determination of the EC(max), while THIO was generally the least efficient. During stable DMS loading at concentrations of 20 ppmv or lower, all reactors exhibited similar and high removal efficiencies (>99%). Denaturing gradient gel electrophoresis (DGGE) analysis showed the establishment of T. thioparus in the biofilm of all reactors, but not of Hyphomicrobium VS. Quantitative monitoring of the introduced bacterial strains was performed with a newly developed real-time PCR protocol. Initially, the inoculated strains were exclusively found in the reactors in which they were added. Afterwards, however, both strains developed in the biofilm of all three reactors, although T. thioparus attained higher cell densities than Hyphomicrobium. The presence of T. thioparus in THIO was related with the DMS loading rates that were applied, in the sense that intermittent DMS loading and very low DMS loading rates (0.5 ppmv) induced a decrease in gene copy numbers. Real-time PCR and DGGE both gave consistent results regarding the presence of Hyphomicrobium VS and Thiobacillus thioparus TK-m in the reactors. Only real-time PCR could be used to detect bacteria comprising of less than 1.4% of the total bacterial community ( approximately 10(5) copies ring(-1)).

Effects of L-proline on phase I and phase II xenobiotic biotransformation capacities of rat and human hepatocytes in long-term collagen gel cultures.

L-Proline supplementation of the medium for collagen gel cultures of hepatocytes has been shown to improve albumin secretion. A study was made as to whether L-proline is also essential for the maintenance of xenobiotic biotransformation capacities in collagen gel sandwich and immobilisation cultures of rat and human hepatocytes. Key phase I (cytochrome P450-dependent monooxygenase [CYP)] and microsomal epoxide hydrase [mEH]) and phase II (glutathione S-transferase [GST]) biotransformation enzyme activities and the secretion of albumin in the culture medium were assessed in the absence and presence of L-proline. CYP and mEH activities were not affected by the addition of L-proline, whereas phase II alpha-Class GST activity of rat hepatocytes in collagen cultures was decreased. Species differences were demonstrated, as human hepatocytes showed a better maintenance of GST activities than their rat counterparts in the presence of L-proline. Albumin secretion, often considered to be a marker for differentiated cell function, does not parallel the biotransformation capacities of the hepatocytes in culture. Additional results demonstrated an L-proline-mediated enhancement of the proliferation rate of contaminating stellate cells in conventional monolayer culture. Transdifferentiation of stellate cells to proliferating myofibroblasts, along with an increased albumin secretion and collagen synthesis, are characteristic of fibrotic liver. Since the last two phenomena have been observed in L-proline-supplemented collagen gel cultures, it can be concluded that when stable collagen gel cultures of rat hepatocytes are needed for long-term pharmacotoxicological studies, it is preferable to use an L-proline-free culture medium. Further studies on medium optimisation are required for hepatocytes from species other than rat.

Glutathione transferase activities in renal carcinomas and adjacent normal renal tissues: factors influencing renal carcinogenesis induced by xenobiotics.

In general, the biological activation of nephrocarcinogenic chlorinated hydrocarbons proceeds via conjugation with glutathione. It has mostly been assumed that the main site of initial conjugation is the liver, followed by a mandatory transfer of intermediates to the kidney. It was therefore of interest to study the enzyme activities of subgroups of glutathione transferases (GSTs) in renal cancers and the surrounding normal renal tissues of the same individuals (n = 21). For genotyping the individuals with respect to known polymorphic GST isozymes the following substrates with differential specificity were used: 1-chloro-2,4-dinitrobenzene for overall GST activity (except GST theta); 7-chloro-4-nitrobenzo-2-oxa- 1,3-diazole for GST alpha; 1,2-dichloro-4-nitro-benzene for GST mu; ethacrynic acid and 4-vinylpyridine for GST pi; and methyl chloride for GST theta. In general, the normal tissues were able to metabolize the test substrates. A general decrease in individual GST enzyme activities was apparent in the course of cancerization, and in some (exceptional) cases individual activities, expressed in the normal renal tissue, were lost in the tumour tissue. The GST enzyme activities in tumours were independent of tumour stage, or the age and gender of the patients. There was little influence of known polymorphisms of GSTM1, GSTM3 and GSTP1 upon the activities towards the test substrates, whereas the influence of GSTT1 polymorphism on the activity towads methyl chloride was straightforward. In general, the present findings support the concept that the initial GST-dependent bioactivation step of nephrocarcinogenic chlorinated hydrocarbons may take place in the kidney itself. This should be a consideration in toxicokinetic modelling.

Effects of extracellular matrix on the expression of peroxisomes in primary rat hepatocyte cultures.

BACKGROUND/AIMS: Peroxisomes in wild-type cells vary between tissues and developmental stages. In the liver of some peroxisomal deficiency disorder patients, rare parenchymal cells express normal peroxisomes (mosaics); the mechanism is unknown. Our aim was to find factors regulating peroxisome expression. METHODS: Liver-specific as well as peroxisome characteristics were studied in three types of primary rat hepatocyte cultures. RESULTS: Total glutathione S-transferase activity and albumin secretion both increased in the collagen I sandwich and immobilization gel cultures. In contrast, in monolayers cultured on plastic, total glutathione S-transferase activity decreased and albumin secretion was only 30-40% compared to the collagen cultures. Glycogen rosettes typical of liver parenchymal cells were always abundant. Laminin and collagen IV-producing stellate cells were numerous in the monolayer but almost absent in the sandwich cultures. In 6-day-monolayer cultures, the number of liver-specific peroxisomes had decreased while atypical small or elongated peroxisomes appeared. Immunolabeling density for catalase and three beta-oxidation enzymes was decreased compared to adult rat liver; catalase specific activity in homogenates had dropped to 15% and 4% in the sandwich and monolayer cultures, respectively. In 17-day-sandwich cultures, some peroxisomes showed a very weak catalase reaction; total activity was 5%. Supplementation of the collagen type I cultures with several extracellular matrix factors could not prevent peroxisome dedifferentiation. CONCLUSION: The presence of these extracellular matrix components is not sufficient for normal peroxisome expression. It is suggested that hepatocyte-specific and peroxisomal features are regulated differently. The sandwich preserves hepatocyte differentiation better than the monolayer.

Effect of epidermal growth factor in collagen gel cultures of rat hepatocytes.

Collagen gel cultures of hepatocytes represent a promising in vitro model in pharmaco-toxicology. Epidermal growth factor (EGF) is usually added to the culture medium, although one could question its value in a culture model aiming at maintaining a maximum of differentiated functional capacities. In this study, the effects of EGF (20 ng/ml) on albumin secretion, morphology and pentoxyresorufin O-depentylase (PROD), ethoxyresorufin O-deethylase (EROD) and glutathione S-transferase (GST) activities have been examined in both collagen gel sandwich and immobilization gel cultures of adult rat hepatocytes. Transmission electron microscopy did not show an obvious influence of epidermal growth factor (EGF) on the intracellular organization of organelles of the rat hepatocytes. It was found that EGF addition had no effect on albumin secretion in both culture models. On the contrary, the presence of EGF in the culture medium provoked in collagen gel sandwich cultures, after 7 days, significant decreases of 66% and 25% in EROD and PROD activities, respectively. On GST activities, no effect of EGF could be observed in both collagen gel cultures. Removal of EGF from the culture medium seemed to have a positive effect on the maintenance of the phase 1 biotransformation capacity of rat hepatocytes. Its addition should therefore be avoided in collagen gel cultures used in pharmaco-toxicology.

Effect of Extracellular Matrix Composition on the Expression of Glutathione S-transferase Isoenzymes in Organotypical Hepatocyte Cultures.

Collagen gel sandwich and immobilization cultures of hepatocytes, using hydrated collagen type I as extracellular matrix (ECM), have been proposed as long-term in vitro models in pharmaco-toxicology. The in vivo ECM composition in the space of Disse is, however, much more complex. As a differentiated hepatocyte phenotype is thought to be highly dependent on ECM composition and biophysical characteristics, we modulated the ECM to mimic the in vivo situation. Moreover, commercially available collagen type I (Boehringer-Ingelheim) was compared to the one prepared in the laboratory from rat tails. ECM composition had no effect on albumin secretion or hepatocyte morphology in both collagen gel sandwich and immobilization cultures. Total, Alpha and Mu class GST activities in organotypical cultures with a complex or a simple collagen type I ECM were similar. The Pi class GST activity increased as a function of culture time in all culture models. Thus, mimicking the in vivo composition of the ECM did not improve the changes in GST expression that were observed in simple collagen gel cultures. The collagen type I matrix is therefore assumed to confer sufficient protection to help the hepatocytes to maintain their differentiated phenotype to a certain extent. Moreover, we hypothesize that the collagen gel matrix may act as a scaffold to keep newly synthesized ECM components in the proximity of the basolateral surfaces of the hepatocytes.

Cell morphology, albumin secretion and glutathione S-Transferase expression in collagen gel sandwich and immobilization cultures of rat hepatocytes.

In order to investigate whether collagen gel sandwich and immobilization cultures of rat hepatocytes are suitable in vitro models for long-term pharmaco-toxicological studies, the expression of the key phase II biotransformation enzyme, glutathione S-transferase (GST, EC 2.5.1.18), has been studied in the presence or absence of l-proline (60mug/ml) in the culture medium. Additionally, hepatocytes morphology was followed and albumin secretion into the medium measured. As judged by inverse phase light microscopy and transmission electron microscopy, cells cultured in both organotypical models remained viable and well differentiated for at least 14 days. Albumin secretion increased 2.5-fold after 7 days of culture, in comparison with the values found after 2 days, and remained thereafter relatively constant. When l-proline was added to the medium of sandwich and immobilization gel cultures, steady-state secretion levels of 7.1 and 5.1 mug albumin/hr, respectively, were already obtained after 4 days of culture. Total, Mu, Alpha and Pi class GST activities were determined using a general substrate and isoenzyme specific substrates, respectively. After 7 days of culture, total GST activities were decreased as compared with the values obtained for freshly isolated cells. On the contrary, Mu class GST activities were kept at a constant level. Alpha class GSTs were maintained at a 50% activity level and GST 7-7 activity was shown to be slightly induced. l-proline prevented an initial decline in total and Mu class GST activities in both culture models. The GST subunit pattern, measured after affinity chromatography by reversed phase HPLC, reflected the GST activity results.