Antibody-blocking of a tick transporter impairs Anaplasma phagocytophilum colonization in Haemaphysalis longicornis ticks.

The invasive Asian longhorned tick Haemaphysalis longicornis that vectors and transmits several animal pathogens is significantly expanding in the United States. Recent studies report that these ticks also harbor human pathogens including Borrelia burgdorferi sensu lato, Babesia microti, and Anaplasma phagocytophilum. Therefore, studies that address the interactions of these ticks with human pathogens are important. In this study, we report the characterization of H. longicornis organic anion-transporting polypeptides (OATPs) in interactions of these ticks with A. phagocytophilum. Using OATP-signature sequence, we identified six OATPs in the H. longicornis genome. Bioinformatic analysis revealed that H. longicornis OATPs are closer to other tick orthologs rather than to mammalian counterparts. Quantitative real-time PCR analysis revealed that OATPs are highly expressed in immature stages when compared to mature stages of these ticks. In addition, we noted that the presence of A. phagocytophilum upregulates a specific OATP in these ticks. We also noted that exogenous treatment of H. longicornis with xanthurenic acid, a tryptophan metabolite, influenced OATP expression in these ticks. Immunoblotting analysis revealed that antibody generated against Ixodes scapularis OATP cross-reacted with H. longicornis OATP. Furthermore, treatment of H. longicornis with OATP antibody impaired colonization of A. phagocytophilum in these ticks. These results not only provide evidence that the OATP-tryptophan pathway is important for A. phagocytophilum survival in H. longicornis ticks but also indicate OATP as a promising candidate for the development of a universal anti-tick vaccine to target this bacterium and perhaps other rickettsial pathogens of medical importance.

Novel method of measurement of in vitro drug uptake in OATP1B3 overexpressing cells in the presence of dextran.

BACKGROUND: In predictions about hepatic clearance (CLH), a number of studies explored the role of albumin and transporters in drug uptake by liver cells, challenging the traditional free-drug theory. It was proposed that liver uptake can occur for transporter substrate compounds not only from the drug's unbound form but also directly from the drug-albumin complex, a phenomenon known as uptake facilitated by albumin. In contrast to albumin, dextran does not exhibit binding properties for compounds. However, as a result of its inherent capacity for stabilization, it is widely used to mimic conditions within cells. METHODS: The uptake of eight known substrates of the organic anion-transporting polypeptide 1B3 (OATP1B3) was assessed using a human embryonic kidney cell line (HEK293), which stably overexpresses this transporter. An inert polymer, dextran, was used to simulate cellular conditions, and the results were compared with experiments involving human plasma and human serum albumin (HSA). RESULTS: This study is the first to demonstrate that dextran increases compound uptake in cells with overexpression of the OATP1B3 transporter. Contrary to the common theory that highly protein-bound ligands interact with hepatocytes to increase drug uptake, the results indicate that dextran's interaction with test compounds does not significantly increase concentrations near the cell membrane surface. CONCLUSIONS: We evaluated the effect of dextran on the uptake of known substrates using OATP1B3 overexpressed in the HEK293 cell line, and we suggest that its impact on drug concentrations in liver cells may differ from the traditional role of plasma proteins and albumin.

Humanization of SLCO2B1 in Rats Increases rCYP3A1 Protein Expression but Not the Metabolism of Erlotinib to OSI-420.

The organic anion transporting polypeptide (OATP)2B1 [(gene: solute carrier organic anion transporter family member 2B1 (SLCO2B1)] is an uptake transporter that facilitates cellular accumulation of its substrates. Comparison of SLCO2B1+/+ knockin and rSlco2b1-/- knockout rats showed a higher expression of rCYP3A1 in the humanized animals. We hypothesize that humanization of OATP2B1 not only affects cellular uptake but also metabolic activity. To further investigate this hypothesis, we used SLCO2B1+/+ and rSlco2b1-/ - rats and the OATP2B1 and rCYP3A1 substrate erlotinib, which is metabolized to OSI-420, for in vivo and ex vivo experiments. One hour after administration of a single dose of erlotinib, the knockin rats exhibited significantly lower erlotinib serum levels, but no change was observed in metabolite concentration or the OSI-420/erlotinib ratio. Similar results were obtained for liver tissue levels comparing SLCO2B1+/+ and rSlco2b1-/- rats. Liver microsomes isolated from the erlotinib-treated animals were characterized ex vivo for rCYP3A activity using testosterone, showing higher activity in the knockin rats. The contrary was observed when microsomes isolated from treatment-naïve animals were assessed for the metabolism of erlotinib to OSI-420. The latter is in contrast to the higher rCYP3A1 protein amount observed by western blot analysis in rat liver lysates and liver microsomes isolated from untreated rats. In summary, rats humanized for OATP2B1 showed higher expression of rCYP3A1 in liver and reduced serum levels of erlotinib but no change in the OSI-420/erlotinib ratio despite a lower OSI-420 formation in isolated liver microsomes. Studies with CYP3A-specific substrates are warranted to evaluate whether humanization affects not only rCYP3A1 expression but also metabolic activity in vivo. SIGNIFICANCE STATEMENT: Humanization of rats for the organic anion transporting polypeptide (OATP)2B1 increases rCYP3A1 expression and activity in liver. Using the OATP2B1/CYP3A-substrate erlotinib to assess the resulting phenotype, we observed lower erlotinib serum and liver concentrations but no impact on the liver/serum ratio. Moreover, there was no difference in the OSI-420/erlotinib ratio comparing humanized and knockout rats, suggesting that OSI-420 is not applicable to monitor differences in rCYP3A1 expression as supported by data from ex vivo experiments with rat liver microsomes.

Non-targeted metabolomics for the identification of plasma metabolites associated with organic anion transporting polypeptide 1B1 function.

Our aim was to evaluate biomarkers for organic anion transporting polypeptide 1B1 (OATP1B1) function using a hypothesis-free metabolomics approach. We analyzed fasting plasma samples from 356 healthy volunteers using non-targeted metabolite profiling by liquid chromatography high-resolution mass spectrometry. Based on SLCO1B1 genotypes, we stratified the volunteers to poor, decreased, normal, increased, and highly increased OATP1B1 function groups. Linear regression analysis, and random forest (RF) and gradient boosted decision tree (GBDT) regressors were used to investigate associations of plasma metabolite features with OATP1B1 function. Of the 9152 molecular features found, 39 associated with OATP1B1 function either in the linear regression analysis (p < 10-5) or the RF or GBDT regressors (Gini impurity decrease > 0.01). Linear regression analysis showed the strongest associations with two features identified as glycodeoxycholate 3-O-glucuronide (GDCA-3G; p = 1.2 × 10-20 for negative and p = 1.7 × 10-19 for positive electrospray ionization) and one identified as glycochenodeoxycholate 3-O-glucuronide (GCDCA-3G; p = 2.7 × 10-16). In both the RF and GBDT models, the GCDCA-3G feature showed the strongest association with OATP1B1 function, with Gini impurity decreases of 0.40 and 0.17. In RF, this was followed by one GDCA-3G feature, an unidentified feature with a molecular weight of 809.3521, and the second GDCA-3G feature. In GBDT, the second and third strongest associations were observed with the GDCA-3G features. Of the other associated features, we identified with confidence two representing lysophosphatidylethanolamine 22:5. In addition, one feature was putatively identified as pregnanolone sulfate and one as pregnenolone sulfate. These results confirm GCDCA-3G and GDCA-3G as robust OATP1B1 biomarkers in human plasma.

Roles of breast cancer resistance protein and organic anion transporting polypeptide 2B1 in gastrointestinal toxicity induced by SN-38 under inflammatory conditions.

Drug transporters are among the factors that determine the pharmacokinetic profiles after drug administration. In this study, we investigated the roles of drug transporters involved in transport of SN-38, which is an active metabolite of irinotecan, in the intestine under inflammatory conditions in vitro and determined their functional consequences. The expression alterations of breast cancer resistance protein (BCRP) and organic anion transporting polypeptide (OATP) 2B1 were determined at the mRNA and protein levels, and the subsequent functional alterations were evaluated via an accumulation study with the representative transporter substrates [prazosin and dibromofluorescein (DBF)] and SN-38. We also determined the cytotoxicity of SN-38 under inflammatory conditions. Decreased BCRP expression and increased OATP2B1 expression were observed under inflammatory conditions in vitro, which led to altered accumulation profiles of prazosin, DBF, and SN-38, and the subsequent cytotoxic profiles of SN-38. Treatment with rifampin or novobiocin supported the significant roles of BCRP and OATP2B1 in the transport and cytotoxic profile of SN-38. Collectively, these results suggest that BCRP and OATP2B1 are involved in the increased cytotoxicity of SN-38 under inflammatory conditions in vitro. Further comprehensive research is warranted to completely understand SN-38-induced gastrointestinal cytotoxicity and aid in the successful treatment of cancer with irinotecan.

Update on the diagnosis and management of neonatal intrahepatic cholestasis caused by citrin deficiency: Expert review on behalf of the Asian Pan-Pacific Society for Pediatric Gastroenterology, Hepatology, and Nutrition.

Citrin deficiency is an autosomal recessive metabolic liver disease caused by mutations in the SLC25A13 gene. The disease typically presents with cholestasis, elevated liver enzymes, hyperammonemia, hypercitrullinemia, and fatty liver in young infants, resulting in a phenotype known as "neonatal intrahepatic cholestasis caused by citrin deficiency" (NICCD). The diagnosis relies on clinical manifestation, biochemical evidence of hypercitrullinemia, and identifying mutations in the SLC25A13 gene. Several common mutations have been found in patients of East Asian background. The mainstay treatment is nutritional therapy in early infancy utilizing a lactose-free and medium-chain triglyceride formula. This approach leads to the majority of patients recovering liver function by 1 year of age. Some patients may remain asymptomatic or undiagnosed, but a small proportion of cases can progress to cirrhosis and liver failure, necessitating liver transplantation. Recently, advancements in newborn screening methods have improved the age of diagnosis. Early diagnosis and timely management improve patient outcomes. Further studies are needed to elucidate the long-term follow-up of NICCD patients into adolescence and adulthood.

Building a Predictive PBPK Model for Human OATP Substrates: a Strategic Framework for Early Evaluation of Clinical Pharmacokinetic Variations Using Pitavastatin as an Example.

To select a drug candidate for clinical development, accurately and promptly predicting human pharmacokinetic (PK) profiles, assessing drug-drug interactions (DDIs), and anticipating potential PK variations in disease populations are crucial steps in drug discovery. The complexity of predicting human PK significantly increases when hepatic transporters are involved in drug clearance (CL) and volume of distribution (Vss). A strategic framework is developed here, utilizing pitavastatin as an example. The framework includes the construction of a monkey physiologically-based PK (PBPK) model, model calibration to obtain scaling factors (SF) of in vitro-in vivo extrapolation (IVIVE) for various clearance parameters, human model development and validation, and assessment of DDIs and PK variations in disease populations. Through incorporating in vitro human parameters and calibrated SFs from the monkey model of 3.45, 0.14, and 1.17 for CLint,active, CLint,passive, and CLint,bile, respectively, and together with the relative fraction transported by individual transporters obtained from in vitro studies and the optimized Ki values for OATP inhibition, the model reasonably captured observed pitavastatin PK profiles, DDIs and PK variations in human subjects carrying genetic polymorphisms, i.e., AUC within 20%. Lastly, when applying the functional reduction based on measured OATP1B biomarkers, the model adequately predicted PK changes in the hepatic impairment population. The present study presents a strategic framework for early-stage drug development, enabling the prediction of PK profiles and assessment of PK variations in scenarios like DDIs, genetic polymorphism, and hepatic impairment-related disease states, specifically focusing on OATP substrates.

First case report of dichorionic diamniotic twins with chronic enteropathy associated with the SLCO2A1 gene.

We report the case of twins diagnosed with chronic enteropathy associated with the SLCO2A1 gene (CEAS) based on characteristic ulcer findings, which required 8 years to diagnose. Both twins had similar symptoms, including anemia and growth failure but the gastrointestinal tract was not evaluated initially because of mild symptoms that were considered consistent with psychological etiology. The endoscopic findings of the firstborn child showed spiral ulcer scars and pseudodiverticulum formation without Helicobacter pylori infection or eosinophilic infiltration in the duodenum. Since the twins presented with ulcers of an unknown cause simultaneously and the first-born child had a spiral ulcer, CEAS was suspected. Genetic analysis and high levels of prostaglandin E major urinary metabolites in the urine led to a definitive diagnosis of CEAS.

Examining the Association of Rare Allelic Variants in Urate Transporters SLC22A11, SLC22A13, and SLC17A1 with Hyperuricemia and Gout.

Genetic variations in urate transporters play a significant role in determining human urate levels and have been implicated in developing hyperuricemia or gout. Polymorphism in the key urate transporters, such as ABCG2, URAT1, or GLUT9 was well-documented in the literature. Therefore in this study, our objective was to determine the frequency and effect of rare nonsynonymous allelic variants of SLC22A11, SLC22A13, and SLC17A1 on urate transport. In a cohort of 150 Czech patients with primary hyperuricemia and gout, we examined all coding regions and exon-intron boundaries of SLC22A11, SLC22A13, and SLC17A1 using PCR amplification and Sanger sequencing. For comparison, we used a control group consisting of 115 normouricemic subjects. To examine the effects of the rare allelic nonsynonymous variants on the expression, intracellular processing, and urate transporter protein function, we performed a functional characterization using the HEK293A cell line, immunoblotting, fluorescent microscopy, and site directed mutagenesis for preparing variants in vitro. Variants p.V202M (rs201209258), p.R343L (rs75933978), and p.P519L (rs144573306) were identified in the SLC22A11 gene (OAT4 transporter); variants p.R16H (rs72542450), and p.R102H (rs113229654) in the SLC22A13 gene (OAT10 transporter); and the p.W75C variant in the SLC17A1 gene (NPT1 transporter). All variants minimally affected protein levels and cytoplasmic/plasma membrane localization. The functional in vitro assay revealed that contrary to the native proteins, variants p.P519L in OAT4 (p ≤ 0.05), p.R16H in OAT10 (p ≤ 0.05), and p.W75C in the NPT1 transporter (p ≤ 0.01) significantly limited urate transport activity. Our findings contribute to a better understanding of (1) the risk of urate transporter-related hyperuricemia/gout and (2) uric acid handling in the kidneys.

Genotype and phenotype characterization of primary hypertrophic osteoarthropathy type 2 and chronic enteropathy associated with SLCO2A1: Report of two cases and literature review.

Autosomal recessive type 2 primary hypertrophic osteoarthropathy (PHOAR2) and chronic enteropathy associated with SLCO2A1 (CEAS) are two entities caused by pathogenic variants (PVs) in the SLCO2A1 gene that can coexist or occur independently from one another. We report two cases of PHOAR2 in Mexico with concomitant CEAS and conducted a review of the literature of the reported cases of PHOAR2 and/or CEAS to analyze the relationship between their genotype and phenotype presentation. The patients from our Institution with classical PHOAR2 phenotype and CEAS, harbored SLCO2A1 c.547G > A and c.1768del variants. We reviewed 232 cases, of which 86.6% were of Asian origin, and identified 109 different variants in SLCO2A1. Intron 7, exon 13, and exon 4 were predominantly affected. The two most common PVs were c.940 + 1G > A and c.1807C > T. We found a statistically significant association between SLCO2A1 variants located in intron 7, exons 12, and 13 and the development of CEAS. Missense variants were more frequent in isolated PHOAR2, while a greater proportion of protein-truncating variants (PTVs) were found in CEAS. Further investigation is imperative to elucidate the underlying pathophysiological mechanisms associated with CEAS, thereby facilitating the identification of effective therapeutic interventions.

Clinical and genetic analysis of 26 Chinese patients with neonatal intrahepatic cholestasis due to citrin deficiency.

BACKGROUND: Neonatal intrahepatic cholestasis due to citrin deficiency (NICCD) is an autosomal recessive disorder caused by SLC25A13 genetic mutations. We retrospectively analyzed 26 Chinese infants with NICCD (years 2014-2022) in Quanzhou City. METHODS: The plasma citrulline (CIT) concentration analyzed by tandem mass spectrometry (MS/MS), biochemical parameters and molecular analysis results are presented. RESULTS: Twelve genotypes were discovered. The relationship between the CIT concentration and genotype is uncertain. In total, 8 mutations were detected, with 4 variations, c.851_854delGTAT, c.615 + 5G > A, c.1638_1660dup and IVS16ins3kb, constituting the high-frequency mutations. Specifically, we demonstrated 2 patients with NICCD combined with another inborn errors of metabolism (IEM). Patient No. 22 possessed compound heterozygous mutations of c.615 + 5G > A and c.790G > A in the SLC25A13 gene accompanied by compound heterozygous variations of c.C259T and c.A155G in the PTS gene. Additionally, Patient No. 26 carried c.51C > G and c.760C > T in the SLC22A5 gene as well as c.615 + 5G > A and IVS16ins3kb in the SLC25A13 gene. CONCLUSIONS: We report a case of the simultaneous occurrence of primary carnitine deficiency (PCD) and NICCD.

Genotype and Phenotype of Renal Hypouricemia: A Single-Center Study from China.

BACKGROUND: Renal hypouricemia (RHUC), a rare inherited disorder characterized by impaired uric acid reabsorption and subsequent profound hypouricemia, occurs mainly due to variants in SLC22A12 or SLC2A9. Only anecdotal cases and one small-scale RHUC screening study have been reported in the Chinese population. METHODS: A total of 19 patients with RHUC from 17 unrelated families were recruited from our center. The medical history, clinical manifestations, biochemical exam, and clinical outcomes were collected. Next-generation sequencing-based targeted gene sequencing or whole exon sequencing was performed. RESULTS: A total of 22 variants in SLC22A12 or SLC2A9 were found in 19 patients. The variant c.944G>A (p.W315X) in SLC2A9 was identified in three patients. Three variants c.165C>A (p.D55E), c.1549_1555delGAGACCC (p.E517Rfs*17), and c.1483T>C (p.W495R) in SLC22A12 and three variants c.1215+1G>A (splicing variant), c.643A>C (p.T215P), and c.227C>A (p.S76X) in SLC2A9 were novel. A proportion of 10 out of 19 patients presented with exercise-induced acute kidney injury (EIAKI). The renal outcome was favorable. Five patients had nephrolithiasis, in whom three had hypercalciuria. CONCLUSION: The current study reported six novel variants in SLC22A12 and SLC2A9 genes of Chinese patients with RHUC. The variant c.944G>A (p.W315X) in SLC2A9 may be common in Chinese patients. EIAKI is the main clinical phenotype associated with RHUC in our cohort, with a favorable outcome. Hypercalciuria presented in some RHUC patients is a new finding.

SLCO1B3 and SLCO2B1 genotypes, androgen deprivation therapy, and prostate cancer outcomes: a prospective cohort study and meta-analysis.

Solute carrier organic anion (SLCO) transporters (OATP transporters) are involved in cellular uptake of drugs and hormones. Germline variants in SLCO1B3 and SLCO2B1 have been implicated in prostate cancer progression and therapy response, including to androgen deprivation and statin medications, but results have appeared heterogeneous. We conducted a cohort study of five single-nucleotide polymorphisms (SNPs) in SLCO1B3 and SLCO2B1 with prior evidence among 3208 men with prostate cancer who participated in the Health Professionals Follow-up Study or the Physicians' Health Study, following participants prospectively after diagnosis over 32 years (median, 14 years) for development of metastases and cancer-specific death (lethal disease, 382 events). Results were suggestive of, but not conclusive for, associations between some SNPs and lethal disease and differences by androgen deprivation and statin use. All candidate SNPs were associated with SLCO mRNA expression in tumor-adjacent prostate tissue. We also conducted a systematic review and harmonized estimates for a dose-response meta-analysis of all available data, including 9 further studies, for a total of 5598 patients and 1473 clinical events. The A allele of the exonic SNP rs12422149 (14% prevalence), which leads to lower cellular testosterone precursor uptake via SLCO2B1, was associated with lower rates of prostate cancer progression (hazard ratio per A allele, 0.80; 95% confidence interval, 0.69-0.93), with little heterogeneity between studies (I2, 0.27). Collectively, the totality of evidence suggests a strong association between inherited genetic variation in SLCO2B1 and prostate cancer prognosis, with potential clinical use in risk stratification related to androgen deprivation therapy.

Effect of food and polymorphisms in SLCO2B1, CYP3A4 and UGT1A4 on pharmacokinetics of abiraterone and its metabolites in Chinese volunteers.

AIMS: Abiraterone acetate, a prodrug of abiraterone (ABI), provides an efficient therapeutic option for metastatic castration-resistant prostate cancer patients. ABI undergoes extensive metabolism in vivo and is transformed into active metabolites Δ4 -abiraterone and 3-keto-5α-abiraterone as well as inactive metabolites abiraterone sulfate and abiraterone N-oxide sulfate. We aimed to examine the effect of polymorphisms in SLCO2B1, CYP3A4 and UGT1A4 on the pharmacokinetics of ABI and its metabolites. METHODS: In this study, 81 healthy Chinese subjects were enrolled and divided into 2 groups for fasted (n = 45) and fed (n = 36) studies. Plasma samples were collected after administering a 250 mg abiraterone acetate tablet followed by liquid chromatography-tandem mass spectrometry analysis. Genotyping was performed on a MassARRAY system. The association between SLCO2B1, CYP3A4, UGT1A4 genotype and pharmacokinetic parameters of ABI and its metabolites was assessed. RESULTS: Food effect study demonstrated high fat meal remarkedly increased systemic exposure of ABI and its metabolites. The geometric mean ratio and 90% confidence interval of area under the plasma concentration-time curve from time 0 to the time of the last quantifiable concentration (AUC0-t ) and maximum plasma concentration (Cmax ) of ABI in fed state vs. fasted state were 351.64% (286.86%-431.04%) and 478.45% (390.01%-586.94%), respectively, while the corresponding results were ranging from 145.11% to 269.42% and 150.10% to 478.45% for AUC0-t and Cmax of ABI metabolites in fed state vs. fasted state, respectively. The SLCO2B1 rs1077858 had a significant influence on AUC0-t and Cmax , while 7 other SLCO2B1 variants prolonged half-life of ABI under both fasted and fed conditions. As for ABI metabolites, the systemic exposure of Δ4 -abiraterone, abiraterone sulfate and abiraterone N-oxide sulfate as well as the elimination of 3-keto-5α-abiraterone were significantly affected by SLCO2B1 polymorphisms. Polymorphisms in CYP3A4 and UGT1A4 did not significantly affect pharmacokinetics of ABI and its metabolites. CONCLUSION: Polymorphisms in SLCO2B1 were significantly related to the pharmacokinetic variability of ABI and its metabolites under both fasted and fed conditions.

Influence of Slco2b1-knockout and SLCO2B1-humanization on coproporphyrin I and III levels in rats.

BACKGROUND AND PURPOSE: Coproporphyrin (CP) I and III are byproducts of haem synthesis currently investigated as biomarkers for drug-drug interactions involving hepatic organic anion transporting polypeptide (OATP) 1B transporters. Another hepatically expressed OATP-member is OATP2B1. The aim of this study was to test the impact of OATP2B1, which specifically transports CPIII, on CP serum levels, applying novel rat models. EXPERIMENTAL APPROACH: CPIII transport kinetics and the interplay between OATP2B1 and multidrug resistance-associated proteins (MRPs) were determined in vitro using the vTF7 expression system. Novel rSlco2b1-/- and SLCO2B1+/+ rat models were characterized for physiological parameters and for CP serum levels. Hepatic and renal expression of transporters involved in CP disposition were determined by real-time qPCR, Western blot analysis, and immunohistochemistry. KEY RESULTS: In vitro experiments revealed differences in transport kinetics comparing human and rat OATP2B1 and showed a consistent, species-specific interplay with hMRP3/rMRP3. Deletion of rOATP2B1 was associated with a trend towards lower CPI serum levels compared with wildtype rats, while CPIII remained unchanged. Comparing SLCO2B1+/+ with knockout rats revealed an effect of sex: only in females the genetic modification influenced CP serum levels. Analysis of hepatic and renal transporters revealed marginal, but in part, statistically significant differences in rMRP2 abundance, which may contribute to the observed changes in CP serum levels. CONCLUSION AND IMPLICATIONS: Our findings support that factors other than OATP1B transporters are of relevance for basal CP levels. Only in female rats, humanization of SLCO2B1 affects basal CPI and CPIII serum levels, despite isomer selectivity of OATP2B1.

Physiologically based pharmacokinetic (PBPK) modeling of pitavastatin in relation to SLCO1B1 genetic polymorphism.

Pitavastatin, a potent 3-hydroxymethylglutaryl coenzyme A reductase inhibitor, is indicated for the treatment of hypercholesterolemia and mixed dyslipidemia. Hepatic uptake of pitavastatin is predominantly occupied by the organic anion transporting polypeptide 1B1 (OATP1B1) and solute carrier organic anion transporter family member 1B1 (SLCO1B1) gene, which is a polymorphic gene that encodes OATP1B1. SLCO1B1 genetic polymorphism significantly alters the pharmacokinetics of pitavastatin. This study aimed to establish the physiologically based pharmacokinetic (PBPK) model to predict pitavastatin pharmacokinetics according to SLCO1B1 genetic polymorphism. PK-Sim® version 10.0 was used to establish the whole-body PBPK model of pitavastatin. Our pharmacogenomic data and a total of 27 clinical pharmacokinetic data with different dose administration and demographic properties were used to develop and validate the model, respectively. Physicochemical properties and disposition characteristics of pitavastatin were acquired from previously reported data or optimized to capture the plasma concentration-time profiles in different SLCO1B1 diplotypes. Model evaluation was performed by comparing the predicted pharmacokinetic parameters and profiles to the observed data. Predicted plasma concentration-time profiles were visually similar to the observed profiles in the non-genotyped populations and different SLCO1B1 diplotypes. All fold error values for AUC and Cmax were included in the two fold range of observed values. Thus, the PBPK model of pitavastatin in different SLCO1B1 diplotypes was properly established. The present study can be useful to individualize the dose administration strategy of pitavastatin in individuals with various ages, races, and SLCO1B1 diplotypes.

ASSOCIATION OF SOLUTE CARRIER ORGANIC ANION TRANSPORTER 1B1 GENE POLYMORPHISM WITH RESPONSE TO ATORVASTATIN AND ASSOCIATED MYOPATHY IN IRAQI DYSLIPIDEMIA PATIENTS.

OBJECTIVE: Aim: The study aims to investigate the effect of solute carriers organic anions transporters 1B1 (SLCO1B1) gene polymorphisms rs4149056, rs2306283, rs55901008, and rs729559745 in a sample of patients with dyslipidemia, and relate it to atorvastatin response and associated myopathy. PATIENTS AND METHODS: Materials and Methods: A cross sectional enrolled 200 patients both males and females of Arabic race, Iraqi nationality aged between 30-65 years. The patients were divided into two groups: Group 1 (Atorvastatin responders and tolerant), Group 2 (Atorvastatin non responder and intolerant). Blood samples collected from the patients for biochemical studies and analyzed statistically by Student T-test and Chi-square, and DNA extracted for polymerase chains reactions (PCR). RESULTS: Results: The results showed insignificant association P≥0.05 between the demographic characteristics of the study population with different genotypes, and significant difference P<0.05 in the biochemical parameters regarding (T-cholesterol, triglycerides, low density lipoproteins, and Creatine kinase-MM) when comparing the two groups. Odds ratio (OR) with confidence intervals CI (95%) used to evaluate the risk association to develop myopathy and poor response to atorvastatin therapy show relevant association for CC and CT genotype of rs4149056, while rs2306283 GG genotype show low association, also rs55901008 show low association for CC genotype, and moderate association for rs72559745 genotypes GG, AG. CONCLUSION: Conclusions: The mutant allele's genotypes of rs4149056, rs55901008, and rs72559745, and the wild allele genotype of rs2306283 show significant association with the development of poor response to atorvastatin and elevated the level of CK-MM plasma concentration.

Citrin deficiency due to SLC25A13 exon deletion in a Chinese infant: A case report.

INTRODUCTION: Citrin is a calcium-bound aspartate-glutamate carrier protein encoded by the gene SLC25A13, mutations of which can cause citrin deficiency, an autosomal recessive disorder. The manifestations of citrin deficiency include neonatal intrahepatic choledeposits caused by citrin deficiency (NICCD: OMIM#605814), intermediate growth disorders and dyslipidemia caused by citrin deficiency, and citrullinemia type II (OMIM#603471) in adults. NICCD is a classical metabolic disorder that causes cholestasis in newborns. PATIENT CONCERN AND CLINICAL FINDINGS: Here, we present the case of a 2-month-old male patient treated in our hospital on March 20, 2023, due to "postnatal skin xanthochromia and transaminases higher than normal values". Since birth, the child's skin had yellowed all over the body, and his condition did not improve after multiple medical treatments. DIAGNOSIS/INTERVENTION/OUTCOMES: The child underwent full exome gene testing at the age of 2 months and 13 days, and the results indicated heterozygous deletion of exon 3 of the SLC25A13 gene, while genetic testing of the parents revealed no gene mutations. The variant was preliminarily judged as being pathogenic according to the ACMG guidelines, and the patient was diagnosed with "citrin deficiency". Skin yellowing eventually subsided, and liver function returned to normal without special treatment. CONCLUSIONS: Here, we report a rare case of citrin deficiency caused by a heterozygous deletion of the SLC25A13 gene. This case increases the clinical phenotypic profile of NICCD, suggesting that clinicians must be vigilant regarding such genetic metabolic diseases in the clinic for early diagnosis and treatment. NICCD should always be considered in the differential diagnosis of neonatal cholestasis.

Recurrent exercise-induced acute kidney injury associated with hypouricemia: a case report and literature review.

BACKGROUND: Hereditary renal hypouricemia (RHUC) is a heterogenous disorder characterized by defective uric acid (UA) reabsorption resulting in hypouricemia and increased fractional excretion of UA. RHUC is an important cause of exercise-induced acute kidney injury (EIAKI), nephrolithiasis and posterior reversible encephalopathy syndrome (PRES). We present here an unusual case of a patient with RHUC who presented with recurrent EIAKI and had two heterozygous mutations in the SLC2A9 gene. CASE PRESENTATION: A 43-year old man was admitted to our clinic because of bilateral loin pain, nausea and sleeplessness for 3 days after strenuous exercise. The laboratory results revealed increased levels of blood urea nitrogen (BUN) (15 mmol/l) and serum creatinine (Scr) (450 µmol/l), while the UA level was extremely low at 0.54 mg/dl, and his fractional excretion of urate (FE-UA) was 108%. The patient had an episode of acute kidney injury after playing soccer approximately 20 years ago, and on routine physical examination, his UA was less than 0.50 mg/dl. In view of the marked hypouricemia and high FE-UA, a diagnosis of RHUC was suspected, which led us to perform mutational screening of the SLC22A12 and SLC2A9 genes. DNA sequencing revealed no mutation in SLC22A12 gene, but two heterozygous mutations in the SLC2A9 gene. CONCLUSIONS: This is a rare report of a patient with RHUC2 due to the mutation of SLC2A9. And this unique symptom of EIAKI and decreased or normal serum concentrations of UA warrant more attention as an early cue of RHUC.

[Analysis of clinical and genetic variation in neonatal intrahepatic cholestasis caused by citrin deficiency].

Objective: To investigate the clinical phenotype and gene variation conditions in neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD), so as to provide a basis for genetic counseling and clinical diagnosis and treatment of the family. Methods: 11 cases of neonatal intrahepatic cholestasis who visited the Children's Hospital Affiliated to Zhengzhou University between February 2019 and March 2021 were selected as the study subjects. High-throughput sequencing technology was used to detect the gene variation condition in 11 neonatal patients and 100 normal control neonates. The suspicious loci and family members were verified by Sanger sequencing and QPCR technology. Results: All 11 children with NICCD had different degrees of jaundice and liver damage symptoms, combined with coagulation dysfunction and anemia (n = 7), cardiac malformation (n = 2), elevated myocardial enzymes (n = 4), hyperlipidemia (n = 1), hyperkalemia (n = 1), persistent diarrhea (n = 3), developmental delay (n = 1). A total of 10 different types of SLC25A13 gene mutations were detected in 11 cases, including three frameshift mutations, two splicing changes, two missense mutations, one intron insertion, one nonsense mutation, and one heterozygous deletion. After reviewing literature and databases, c.1878delG(p.I627Sfs*73) and exon11 deletion were novel mutations that had not been reported at home or abroad. Conclusion: The clinical features of NICCD are non-specific, and genetic testing aids in the early and accurate diagnosis of the disease, providing an important basis for clinical treatment and genetic counseling for family members. In addition, the detection of novel mutation sites has enriched the SLC25A13 gene variation spectrum.