Regulated LC-MS/MS bioanalysis technology for therapeutic antibodies and Fc-fusion proteins using structure-indicated approach

In recent studies, the development of bioanalysis technologies using liquid chromatography-tandem mass spectrometry (LC-MS/MS) has attracted attention. Our developed nano-surface and molecular-orientation limited (nSMOL) proteolysis enables Fab-specific proteolysis and is optimal for LC-MS/MS analysis of antibody drugs and Fc-fusion proteins in biological samples. In this nSMOL method, antibodies and Fc-fusion proteins are held in pores of the particle and the subsequent proteolysis is carried out with protease-immobilized nanoparticles. The Fab of antibodies or fused region of Fc-fusion protein can be held to orient toward the reaction solution. The access of the immobilized protease is limited to a part in the structure of protein substrate on the particle surface. Thus, nSMOL proteolysis reacts selectively at the Fab complementarity-determining region of antibodies or N-terminal specific domain of Fc-fusion proteins and can be applied to both types of drugs. We have already evaluated drug concentrations in biological samples pretreated with nSMOL proteolysis using LC-MS/MS for more than twenty drugs, of which ten drugs have been fully validated and published. In this review, we discuss the development and application of LC-MS/MS bioanalysis, which enables the bioanalysis of therapeutic antibodies and Fc-fusion proteins by focusing on a structure-based approach.     

Reduced variability in tacrolimus pharmacokinetics following intramuscular injection compared to oral administration in cynomolgus monkeys: Investigating optimal dosing regimens

Tacrolimus is one of the most commonly used immunosuppressive agents in animal models of transplantation. However, in these models, oral administration is often problematic due to the lowered compliance associated with highly invasive surgery and due to malabsorption in the intestinal tract. Therefore, we carried out a study to determine the pharmacokinetics of tacrolimus after intramuscular (IM) injection and to determine the optimal IM dosing regimens in primate models. Six male cynomolgus monkeys (Macaca fascicularis) were used in the study. Doses of 0.1 mg/kg and 5 mg were administered via IM injection and oral administration, respectively, once to determine single-dose pharmacokinetics and once daily for 5 days to determine multiple-dose pharmacokinetics. According to pharmacokinetic model estimates, the inter- and intra-individual variabilities in bioavailability following IM injection were remarkably reduced compared with those following oral administration. Monte Carlo simulations revealed that C_peak, C_trough and AUC would also have less variability following IM injection compared with oral administration. In this study, we found that the pharmacokinetic characteristics of tacrolimus were more constant following IM injection compared with oral administration. These results suggest that IM injection can be an alternative route of administration fin non-human primate model studies.     

基于LC-MS/MS分析鹿角方的入血移行成分

目的：研究鹿角方的入血移行成分及规律,初步阐明其药效物质基础。方法：通过LC-MS/MS法分析大鼠含药血清,明确鹿角方的原型入血成分;及不同给药剂量下各移行成分相对峰面积与剂量的关系,解析移行规律。结果：通过与标准品保留时间、离子碎片信息的比对,鉴定鹿角方中13种成分（马钱苷、柚皮苷、橙皮苷、朝霍定A、朝霍定B、朝霍定C、淫羊藿苷、补骨脂素、异补骨脂素、宝霍苷Ⅰ、红景天苷、莫诺苷、特女贞苷）均能以原型入血;随给药剂量上升,柚皮苷、橙皮苷、补骨脂素、异补骨脂素、特女贞苷的相对峰面积与剂量呈线性关系,而马钱苷、莫诺苷、红景天苷、宝霍苷Ⅰ呈非线性关系,其中马钱苷、莫诺苷、补骨脂素、异补骨脂素、宝霍苷Ⅰ、红景天苷易入血。结论：马钱苷、莫诺苷、补骨脂素、异补骨脂素、宝霍苷Ⅰ、红景天苷可能是鹿角方体内直接作用的主要物质,实验结果为鹿角方药效物质基础的研究提供借鉴。     

藤茶中杨梅素、二氢杨梅素及其乙酰化衍生物在SD大鼠体内药动学研究

目的：建立LC-MS/MS法测定SD大鼠血浆中杨梅素（myricetin,MY）和二氢杨梅素（dihydromyricetin,DMY）的浓度,将其运用到药动学研究,并评价DMY乙酰化衍生物是否改善生物利用度。方法：SD大鼠随机分为4组,分别灌胃DMY （100 mg·kg^-1,相当于9 375.0 μmo·L^-1）的0.5%羧甲基纤维素钠生理盐水溶液,以及等摩尔剂量的DMY-1、DMY-2、MY。于给药前0.0 h和给药后0.08,0.17,0.25,0.33,0.50,0.75,1.0,2.0,4.0,6.0,8.0,12.0 h尾静脉断尾采血200 μL,血浆样品经0.1%甲酸-乙腈沉淀蛋白,内标法定量,DAS3.0和SPSS统计分析得到药动学参数和曲线。结果：低、中、高的质控样品日内、日间精密度RSD均小于10.2%;DMY和MY的基质效应分别为98.3%~105.5%、98.0%~108.1%;萃取回收率分别为99.4%~103.0%、95.0%~99.7%,均符合生物样品分析检测的要求;DMY-2和DMY-1组相比于DMY组,相对生物利用度分别为47.22%,10.70%,表明口服灌胃给药DMY相对生物利用度要高出乙酰化衍生物组。结论：本研究建立测定大鼠血浆中DMY和MY的LC-MS/MS法,具有灵敏度高、准确性高、重复性好等优点,能够满足生物样品分析检测的要求,可应用于MY、DMY及其衍生物的药动学研究,也可为DMY结构修饰和新药开发提供参考依据。     

The Impact of Endogenous Breast Cancer Resistance Protein on Human P-Glycoprotein-Mediated Transport Assays Using LLC-PK1 Cells Transfected With Human P-Glycoprotein

Lilly Laboratories cell porcine kidney 1 (LLC-PK1) cells transfected with human P-glycoprotein (LLC-PK1-P-gp) are widely used in transport assays to identify drug candidates that function as substrates of this efflux transporter. Endogenous transporters expressed in LLC-PK1 cells may complicate the interpretation of findings from P-gp-mediated transport assays. We investigated the impact of porcine breast cancer resistance protein (Bcrp) in P-gp-mediated transport assays in LLC-PK1 cells. Porcine Bcrp mRNA was detected in both LLC-PK1 wildtype (WT) and LLC-PK1-P-gp cells by quantitative RT-PCR. To investigate the activity and impact of porcine Bcrp, we conducted transport assays using 6 typical BCRP substrates in LLC-PK1 cells. Efflux ratios (ER) of the 6 BCRP substrates in LLC-PK1 WT cells were >2, and were reduced in the presence of the BCRP inhibitor Ko143. The efflux activities of the 6 BCRP substrates were confirmed using MDCKII cells transfected with human BCRP. Net ERs of prazosin and fluvastatin, dual substrates of P-gp and BCRP, determined by dividing ERs in LLC-PK1-P-gp cells by those in LLC-PK1 WT cells, were <2, but increased to >2 in the presence of Ko143. These results indicated that endogenous Bcrp in LLC-PK1 cells was involved in the transport of BCRP substrates and may interfere with the identification of P-gp substrates.     

A fish-based diet intervention improves endothelial function in postmenopausal women with type 2 diabetes mellitus: A randomized crossover trial

Objective

The beneficial effects of fish and n-3 polyunsaturated fatty acids (PUFAs) consumption on atherosclerosis have been reported in numerous epidemiological studies. However, to the best of our knowledge, the effects of a fish-based diet intervention on endothelial function have not been investigated. Therefore, we studied these effects in postmenopausal women with type 2 diabetes mellitus (T2DM).

Materials/Methods

Twenty-three postmenopausal women with T2DM were assigned to two four-week periods of either a fish-based diet (n-3 PUFAs ≧ 3.0 g/day) or a control diet in a randomized crossover design. Endothelial function was measured with reactive hyperemia using strain-gauge plethysmography and compared with the serum levels of fatty acids and their metabolites. Endothelial function was determined with peak forearm blood flow (Peak), duration of reactive hyperemia (Duration) and flow debt repayment (FDR).

Results

A fish-based dietary intervention improved Peak by 63.7%, Duration by 27.9% and FDR by 70.7%, compared to the control diet. Serum n-3 PUFA levels increased after the fish-based diet period and decreased after the control diet, compared with the baseline (1.49 vs. 0.97 vs. 1.19 mmol/l, p < 0.0001). There was no correlation between serum n-3 PUFA levels and endothelial function. An increased ratio of epoxyeicosatrienoic acid/dihydroxyeicosatrienoic acid was observed after a fish-based diet intervention, possibly due to the inhibition of the activity of soluble epoxide hydrolase.

Conclusions

A fish-based dietary intervention improves endothelial function in postmenopausal women with T2DM. Dissociation between the serum n-3 PUFA concentration and endothelial function suggests that the other factors may contribute to this phenomenon.     

DNA methylation is altered in B and NK lymphocytes in obese and type 2 diabetic human

Objective

Obesity is associated with low-grade inflammation and the infiltration of immune cells in insulin-sensitive tissues, leading to metabolic impairment. Epigenetic mechanisms control immune cell lineage determination, function and migration and are implicated in obesity and type 2 diabetes (T2D). The aim of this study was to determine the global DNA methylation profile of immune cells in obese and T2D individuals in a cell type-specific manner.

Material and methods

Fourteen obese subjects and 11 age-matched lean subjects, as well as 12 T2D obese subjects and 7 age-matched lean subjects were recruited. Global DNA methylation levels were measured in a cell type-specific manner by flow cytometry. We validated the assay against mass spectrometry measures of the total 5-methylcytosine content in cultured cells treated with the hypomethylation agent decitabine (r = 0.97, p < 0.001).

Results

Global DNA methylation in peripheral blood mononuclear cells, monocytes, lymphocytes or T cells was not altered in obese or T2D subjects. However, analysis of blood fractions from lean, obese, and T2D subjects showed increased methylation levels in B cells from obese and T2D subjects and in natural killer cells from T2D patients. In these cell types, DNA methylation levels were positively correlated with insulin resistance, suggesting an association between DNA methylation changes, immune function and metabolic dysfunction.

Conclusions

Both obesity and T2D are associated with an altered epigenetic signature of the immune system in a cell type-specific manner. These changes could contribute to the altered immune functions associated with obesity and insulin resistance.     

Measurement of Sterigmatocystin Concentrations in Urine for Monitoring the Contamination of Cattle Feed

This study aimed (1) at determining the levels of the fungal toxin sterigmatocystin (STC) in the feed and urine of cattle and (2) at evaluating the effects of supplementing the feed with a mycotoxin adsorbent (MA) on STC concentrations in urine. Two herds of female Japanese Black cattle were used in this study. The cattle in each herd were fed a standard ration containing rice straw from different sources and a standard concentrate; two groups of cattle from each herd (n = six per group) received the commercial MA, mixed with the concentrate or given as top-dressing, whereas a third group received no supplement and served as control. Urine and feed samples were collected at various time points throughout the experiment. STC concentrations were measured using liquid chromatography-tandem mass spectrometry (LC-TMS). STC concentrations in straw were higher in Herd 1 (range 0.15–0.24 mg/kg DM) than in Herd 2 (range <0.01–0.06 mg/kg DM). In Herd 1, STC concentrations in urine significantly declined 2 weeks after replacing the contaminated feed, whereas MA supplementation had no effect. In conclusion, mycotoxins in urine samples are useful biological markers for monitoring the systemic exposure of cattle to multiple mycotoxins, as well as evaluating the effectiveness of interventions.     

Simultaneous quantitation of four androgens and 17-hydroxyprogesterone in polycystic ovarian syndrome patients by LC-MS/MS

BackgroundDue to the low concentration of androgens in women and the limitation of immunoassays, it remains a challenge to accurately determine the levels of serum androgens in polycystic ovary syndrome (PCOS) patients for clinical laboratories. In this report, a liquid chromatography‐tandem mass spectrometry (LC‐MS/MS) method was developed and validated for simultaneous quantitation of testosterone (T), androstenedione (A4), dehydroepiandrosterone sulfate (DHEAS), dihydrotestosterone (DHT), and 17‐hydroxyprogesterone (17‐OHP) that are associated with PCOS.MethodsThe serum samples were processed by protein precipitation and solid phase extraction before analysis with the in‐house developed LC‐MS/MS. The chromatographic separation was achieved with a C18 column, using a linear gradient elution with two mobile phases: 0.02% formic acid in water (phase A) and 0.1% formic acid in methanol (phase B). The separated analytes were detected by positive or negative electrospray ionization mode under multiple reaction monitoring (MRM).ResultsThe assay for all the five analytes was linear, stable, with imprecision less than 9% and recoveries within ±10%. The lower limits of quantification were 0.05, 0.05, 5, 0.025, and 0.025 ng/mL for T, A4, DHEAS, DHT, and 17‐OHP, respectively. In the receiver operating characteristic curve (ROC) analyses with the PCOS (n = 63) and healthy (n = 161) subjects, the AUC of the four‐androgen combined was greater than that of any single androgen tested in PCOS diagnosis.ConclusionsThe LC‐MS/MS method for the four androgens and 17‐OHP showed good performance for clinical implementation. More importantly, simultaneous quantitation of the four androgens provided better diagnostic power for PCOS.     

Nitrosamine Contamination in Pharmaceuticals: Threat,Impact, and Control

Nitrosamine-contaminated medicinal products have raised safety concerns towards the use of various drugs, not only valsartan and all tetrazole-containing angiotensin II receptor blockers, but also ranitidine, metformin, and other medicines, many of which have been recalled and prone to shortage. At any stages, from drug substance synthesis throughout each product's lifetime, these impurities may evolve if an amine reacts with a nitrosating agent coexisting under appropriate conditions. Consequently, drug regulatory authorities worldwide have established stringent guidelines on nitrosamine contamination for all drug products in the market. This review encompasses various critical elements contributing to successful control measures against current and upcoming nitrosamine issues, ranging from accumulated knowledge of their toxicity concerns and potential root causes, precise risk evaluation, as well as suitable analytical techniques with sufficient sensitivity for impurity determination. With all these tools equipped, the impact of nitrosamine contamination in pharmaceuticals should be mitigated. An evaluation aid to tackle challenges in risk identification, as well as suitable industry-friendly analytical techniques to determine nitrosamines and other mutagenic impurities, are among unmet needs that will significantly simplify the risk assessment process.