Outcomes of long-term nivolumab and subsequent chemotherapy in Japanese patients with head and neck cancer: 2-year follow-up from a multicenter real-world study.

BACKGROUND: We have previously reported the effectiveness and safety of nivolumab in patients with head and neck cancer (HNC) in real-world clinical practice in Japan. Here, we report long-term outcomes from this study in the overall population and subgroups stratified by subsequent chemotherapy. METHODS: In this multicenter, retrospective observational study, Japanese patients with recurrent or metastatic (R/M) HNC receiving nivolumab were followed up for 2 years. Effectiveness endpoints included overall survival (OS), OS rate, progression-free survival (PFS), and PFS rate. Safety endpoints included the incidence of immune-related adverse events (irAEs). RESULTS: Overall, 256 patients received a median of 6.0 doses (range: 1-52) of nivolumab over a median duration of 72.5 days (range: 1-736). Median OS was 9.5 months [95% confidence interval (CI) 8.2-12.0] and median PFS was 2.1 months (95% CI 1.8-2.7). A significant difference between 2-year survivors (n = 62) and non-2-year survivors was observed by median age (P = 0.0227) and ECOG PS (P = 0.0001). Of 95 patients who received subsequent chemotherapy, 54.7% received paclitaxel ± cetuximab. The median OS and PFS from the start of paclitaxel ± cetuximab were 6.9 months (95% CI 5.9-11.9) and 3.5 months (95% CI 2.3-5.5), respectively. IrAEs were reported in 17.2% of patients. Endocrine (7.0%) and lung (4.3%) disorders were the most common irAEs; kidney disorder (n = 1) was newly identified in this follow-up analysis. CONCLUSIONS: Results demonstrated the long-term effectiveness of nivolumab and potential effectiveness of subsequent chemotherapy in patients with R/M HNC in the real-world setting. Safety was consistent with that over the 1-year follow-up.

Effectiveness and safety of nivolumab in patients with head and neck cancer in Japanese real-world clinical practice: a multicenter retrospective clinical study.

BACKGROUND: To fill the data gap between clinical trials and real-world settings, this study assessed the overall effectiveness and safety of nivolumab in patients with head and neck cancer (HNC) during Japanese real-world clinical practice. METHODS: This was a multicenter, retrospective study in Japanese patients with recurrent or metastatic HNC who received nivolumab for the first time between July and December 2017. Data on the clinical use, effectiveness, and safety of nivolumab were extracted from patient medical records. RESULTS: Overall, 256 patients were enrolled in this study. The median duration of nivolumab treatment was 72.5 days, with patients receiving a median of 6.0 (range 1-27) doses. Median overall survival (OS) was 9.5 (95% confidence interval [CI] 8.2-12.0) months and the estimated 12-month OS rate was 43.2%. The objective response rate (ORR) was 15.7% overall and 21.1%, 7.1%, and 13.6% in patients with primary nasopharynx, maxillary sinus, and salivary gland tumors, respectively, who had been excluded from CheckMate 141. Grade ≥ 3 immune-related adverse events occurred in 5.9% of patients. No new safety signals were identified compared with adverse events noted in CheckMate 141. CONCLUSIONS: The effectiveness and safety of nivolumab in real-world clinical practice are consistent with data from the CheckMate 141 clinical trial. Therapeutic response was also observed in the groups of patients excluded from CheckMate 141. TRIAL REGISTRATION NUMBER: UMIN-CTR (UMIN000032600), Clinicaltrials.gov (NCT03569436).

Effectiveness of nivolumab affected by prior cetuximab use and neck dissection in Japanese patients with recurrent or metastatic head and neck cancer: results from a retrospective observational study in a real-world setting.

BACKGROUND: To examine the effect of prior use of cetuximab and neck dissection on the effectiveness of nivolumab, we conducted a large-scale subgroup analysis in Japanese patients with recurrent/metastatic head and neck cancer. METHODS: Data on the effectiveness of nivolumab were extracted from patient medical records. All patients were analyzed for effectiveness by prior cetuximab use. In the analyses for prior neck dissection, only patients with locally advanced disease were included. RESULTS: Of 256 patients analyzed, 155 had received prior cetuximab. Nineteen of 50 patients with local recurrence underwent neck dissection. The objective response rate was 14.7 vs 17.2% (p = 0.6116), median progression-free survival was 2.0 vs 3.1 months (p = 0.0261), and median overall survival was 8.4 vs 12 months (p = 0.0548) with vs without prior cetuximab use, respectively. The objective response rate was 23.1 vs 25.9% (p = 0.8455), median progression-free survival was 1.8 vs 3.0 months (p = 0.6650), and median overall survival was 9.1 vs 9.9 months (p = 0.5289) with vs without neck dissection, respectively. CONCLUSIONS: These findings support the use of nivolumab for patients with recurrent/metastatic head and neck cancer regardless of prior cetuximab use or neck dissection history. TRIAL REGISTRATION NUMBER: UMIN-CTR (UMIN000032600), Clinicaltrials.gov (NCT03569436).

Reduction in Secretion of Very Low Density Lipoprotein-Triacylglycerol by a Matrix Metalloproteinase Inhibitor in a Rat Model of Diet-Induced Hypertriglyceridemia.

Matrix metalloproteinase inhibitors (MMPIs) reduced serum triacylglycerol (TAG) levels in streptozotocin-induced diabetic rats and Zucker fa/fa rats in our previous study. However, the mechanisms underlying TAG reduction by MMPIs remain unclear. The present study aimed to elucidate the mechanism by which F81-1144b, an MMPI, lowers serum TAG levels in an animal model of high-sucrose diet (HSD)-induced hypertriglyceridemia. F81-1144b was repeatedly administered to rats fed HSD, and its effects were evaluated on TAG levels in serum and the liver, very low density lipoprotein (VLDL) secretion, de novo fatty acid (FA) synthesis in the liver, and the expression of genes regulating the metabolism of FA, TAG, and VLDL in the liver and serum. F81-1144b lowered TAG levels in serum and the liver, VLDL-TAG secretion, de novo FA synthesis in the liver, and serum levels of insulin and glucose. F81-1144b suppressed the expression of genes related to the de novo synthesis of FA and TAG, key proteins (lipin 1 and apolipoprotein CIII) responsible for VLDL metabolism, and sterol regulatory element-binding protein-1c and carbohydrate response element-binding protein. F81-1144b little affected the expression of genes related directly to the degradation of TAG or FA, but it upregulated that of gene for uncoupling protein 2 in the liver. These results suggest that MMPIs are a novel type of therapeutic agent for the treatment of hypertriglyceridemia, because the metabolic effects of F81-1144b expected from changes in the expression of genes regulating lipid metabolism would alter metabolism differently from those induced by fibrates, niacin, or n-3 FAs.

Chronopharmacological Analysis of Antidepressant Activity of a Dual-Action Serotonin Noradrenaline Reuptake Inhibitor (SNRI), Milnacipran, in Rats.

Biological rhythms are thought to be related to the pathogenesis and therapy of various diseases including depression. Here we investigated the influence of circadian rhythms on the antidepressant activity of the dual-action serotonin-noradrenaline reuptake inhibitor (SNRI) milnacipran. Rats administered milnacipran in the morning (8:00 a.m.; zeitgeber time [ZT]1) or in the evening (8:00 p.m.; ZT13) were analyzed in a forced swim test (FST). At ZT1, the rats' immobility was reduced and the swimming was increased, whereas at ZT13, their climbing was increased. These results suggest that the serotonergic and noradrenergic systems are preferentially affected at ZT1 and ZT13, respectively by milnacipran. We analyzed the plasma and brain levels of milnacipran after administration, and there were no differences between ZT1 and ZT13. The circadian rhythm of monoamine neurotransmitters was analyzed in several brain regions. The serotonin turnover showed rhythms with a peak during ZT18-ZT22 in hippocampus. The noradrenaline turnover showed rhythms with a peak during ZT22-ZT2. There was a difference of approx. 4 h between the serotonergic and noradrenergic systems. This time difference might be one of the factors that affect the action of milnacipran and contribute to the dosing time-dependent behavioral pattern in the FST.

Time of Administration of Acute or Chronic Doses of Imipramine Affects its Antidepressant Action in Rats.

The pathogenesis and therapeutics of depression are linked to the operation of the circadian system. Here, we studied the chronopharmacological action of a tricyclic antidepressant, imipramine. Male adult Wistar-Hannover rats were administered imipramine acutely or chronically in the morning or in the evening. The antidepressant action of imipramine was analyzed using the forced swim test (FST). A single dose of imipramine (30 mg/kg) in the morning, but not in the evening, reduced immobility and increased climbing in the FST. The plasma concentrations of imipramine and its metabolite, desipramine, were slightly higher in the morning than in the evening, which might explain the dosing time-dependent action of imipramine. Next, we analyzed the effect of chronic imipramine treatment. Rats received imipramine in the morning or in the evening for 2 weeks. The morning treatment resulted in larger effects in the FST than the evening treatment, and was effective at a dose that was ineffective when administered acutely. The levels of brain α-adrenergic receptors tended to decrease after chronic imipramine treatment. Imipramine might interact with noradrenergic neurons, and this interaction might chronically alter receptor expression. This alteration seemed greater in the morning than in the evening, which might explain the dosing time-dependent action of imipramine.

Fatty Acid ß-Oxidation Plays a Key Role in Regulating cis-Palmitoleic Acid Levels in the Liver.

Different monounsaturated fatty acid (MUFA) species have distinct pathophysiological activities. cis-Palmitoleic acid (16:1n-7) was previously reported to improve insulin sensitivity in animal studies. The proportions of hepatic MUFAs are generally considered to reflect changes in the activities of fatty acid modifications (∆9 desaturation and fatty acid elongation). However, hepatic levels of 16:1n-7 are markedly lower than those of oleic acid (18:1n-9). Nevertheless, no convincing explanation has yet been provided for the low level of 16:1n-7. We hypothesized that fatty acid degradation plays a key role in maintaining a low 16:1n-7 proportion in the liver. In order to corroborate the link between ß-oxidation and the proportion of 16:1n-7, rats were fed a control diet, fed a fat-free diet to up-regulate fatty acid modifications, but not ß-oxidation, or treated with clofibric acid to up-regulate fatty acid modifications and ß-oxidation. The nutritional manipulation markedly increased the proportions of 16:1n-7, 18:1n-9, and cis-vaccenic acid (18:1n-7). Although the pharmacological manipulation enhanced fatty acid modifications to largely the same extent as the nutritional manipulation and markedly elevated the proportion of 18:1n-9, those of 16:1n-7 and 18:1n-7 remained largely unchanged. The oxidation rates of 16:1n-7, 18:1n-9, and 18:1n-7 in liver slices were in the following order: 16:1n-7>18:1n-7≑18:1n-9 in control livers, and were increased by the pharmacological manipulation and decreased by the nutritional manipulation. These results strongly suggest that ß-oxidation, in concert with fatty acid modifications, plays a key role in regulating the MUFA profile and is crucially involved in maintaining low 16:1n-7 levels in the liver.

Eosinophilic otitis media and eosinophilic chronic -hinosinusitis.

In Japan, eosinophilic inflammations of upper airway, eosinophilic otitis media(EOM) and eosinophilic chronic rhinosinusitis(ECRS), have been paid attention as intractable disease in recent years. The most common characteristic of EOM is the presence of highly viscous middle ear effusion enriched eosinophils, and EOM carries a high risk of hearing loss. That of ECRS is the nasal polyps with eosinophil dominant infiltration, and ECRS has a high risk of impairment of smell. In the case of the treatment of bronchial asthma, it is necessary to be careful for nasal symp- toms and aural symptoms, since EOM and ECRS were associated with bronchial asthma at high rates.

A simple and sensitive method for the determination of fibric acids in the liver by liquid chromatography.

Fibrates are used in biochemical and pharmacological studies as bioactive tools. Nevertheless, most studies have lacked information concerning the concentrations of fibric acids working inside tissues because a simple and sensitive method is not available for their quantitation. This study aimed to develop a simple and sensitive bioanalytical method for the quantitation of clofibric, bezafibric and fenofibric acids in samples of very small portions of tissues. Fibric acids were extracted into n-hexane-ethyl acetate from tissue homogenates (10 mg of liver, kidney or muscle) or serum (100 µL) and were derivatized with 4-bromomethyl-6,7-dimethoxycoumarin, followed by HPLC with fluorescence detection. These compounds were separated isocratically on a reversed phase with acetonitrile-water. Standard analytical curves were linear over the concentration range of 0.2-20 nmol/10 mg of liver. Precision and accuracy were within acceptable limits. Recovery from liver homogenates ranged from 93.03 to 112.29%. This method enabled the quantitation of fibric acids in 10 mg of liver from rats treated with clofibric acid, bezafibric acid or fenofibrate. From these analytical data, it became clear that there was no large difference in ratio of acyl-CoA oxidase 1 (Acox1) mRNA level to fibric acid content in the liver among the three fibric acids, suggesting that these three fibric acids have similar potency to increase expression of the Acox1 gene, which is a target of peroxisome proliferator-activated receptor α. Thus, the proposed method is a simple, sensitive and reliable tool for the quantitation of fibric acids working in vivo inside livers.

Diabetes can increase the prevalence of EBV infection and worsen the prognosis of nasopharyngeal carcinoma.

Epstein‒Barr virus (EBV) infection is a primary oncogenic factor of nasopharyngeal carcinoma (NPC) that elicits epithelial-mesenchymal transition (EMT). Although diabetic patients are more susceptible to various infectious diseases, the pathological association with virus-related NPC has not yet been clarified. Herein, we evaluated the influence of diabetes on the clinicopathological changes of 70 patients with NPC. Disease-specific survival (DSS) modified by viral infection was also analysed. The proportion of NPC patients with diabetes was 32.9% (23/70 cases), and 91.3% (21/23 cases) were infected with EBV detected by EBER-I in situ hybridisation. NPC with diabetes showed an effect on EMT evaluated by immunostaining for E-cadherin and vimentin, which was correlated with HbA1c levels. Receiver operating characteristic (ROC) curve analysis determined a HbA1c level of 6.5% as the cut-off value for primary disease death at 2 years [area under the curve (AUC) 0.76; sensitivity 0.64; and specificity 0.81]. High HbA1c levels (≥6.5%) significantly increased the number of lymph node metastases in NPC compared to low HbA1c levels (<6.5%, p<0.01). Diabetic NPC patients had a significantly poorer prognosis than all non-diabetic patients (DSS, 72 months vs not reached, p<0.05). Diabetic EBV-positive NPC patients had a significantly poorer prognosis than non-diabetic EBV-positive patients (DSS, 35 months vs not reached, p<0.01). Multivariate analysis using the Cox proportional hazards model also suggested that HbA1c ≥6.5% was a significant factor in poor prognosis, with a hazard ratio of 6.84 (p<0.05). Collectively, our results revealed for the first time a high prevalence of EBV infection, poor prognosis and the importance of proper glycaemic control in diabetic NPC patients.

Fibrates reduce triacylglycerol content by upregulating adipose triglyceride lipase in the liver of rats.

Hepatic triacylglycerol (TAG) homeostasis is maintained by carefully regulated balance between its synthesis and disposal. Impairment in this balance causes steatosis. The aims of this study were i) to uncover whether fibrates control TAG concentration through the action of adipose triglyceride lipase (ATGL) and ii) to compare the potency of the effects on ATGL expression and TAG concentration among fenofibrate, bezafibrate, and clofibric acid in the liver of rats. Treatments of rats with the three fibrates induced ATGL and concomitantly decreased hepatic TAG concentration. The upregulation of ATGL was likely mediated through the activation of peroxisome proliferator-activated receptor α. Fibrates also expanded capacity of fatty acid ß-oxidation. Importantly, three fibric acids (fenofibric, bezafibric, and clofibric acids) that are active metabolites formed in the liver exhibited almost the same potency to elevate ATGL expression in vivo, despite the fact that there were considerable differences in this regard among fenofibrate, bezafibrate, and clofibric acid when compared on the basis of their dosage. These results suggest that ATGL represents a potential therapeutic target for ameliorating hepatic steatosis and that fibric acids are promising agents to ameliorate and/or protect against hepatic steatosis.

Clostridium paraputrificum Bacteremia in a Patient with Rectal Cancer after Receiving Antibiotic Therapy for Acute Pharyngolaryngitis.

Clostridium paraputrificum bacteremia is very rare, and its clinical importance is poorly understood. An 86-year-old man was receiving lascufloxacin therapy for acute pharyngolaryngitis before presenting to our emergency department with a recurrent fever. Two sets of blood cultures on admission revealed C. paraputrificum. A stool culture showed a reduced presence of intestinal commensal bacteria. After admission, the patient's fever resolved without antibiotics. Colonoscopy revealed a rectal tumor. Rectal tumor and microbial substitutions caused by antibiotics may have led to bacteremia. When treating C. paraputrificum bacteremia, physicians should be mindful of coexisting gastrointestinal disorders and a history of antibiotic administration.

Impairment of heme biosynthesis induces short circadian period in body temperature rhythms in mice.

It has been demonstrated that the function of mammalian clock gene transcripts is controlled by the binding of heme in vitro. To examine the effects of heme on biological rhythms in vivo, we measured locomotor activity (LA) and core body temperature (T(b)) in a mouse model of porphyria with impaired heme biosynthesis by feeding mice a griseofulvin (GF)-containing diet. Mice fed with a 2.0% GF-containing diet (GF2.0) transiently exhibited phase advance or phase advance-like phenomenon by 1-3 h in terms of the biological rhythms of T(b) or LA, respectively (both, P < 0.05) while mice were kept under conditions of a light/dark cycle (12 h:12 h). We also observed a transient, ~0.3 h shortening of the period of circadian T(b) rhythms in mice kept under conditions of constant darkness (P < 0.01). Interestingly, the observed duration of abnormal circadian rhythms in GF2.0 mice lasted between 1 and 3 wk after the onset of GF ingestion; this finding correlated well with the extent of impairment of heme biosynthesis. When we examined the effects of therapeutic agents for acute porphyria, heme, and hypertonic glucose on the pathological status of GF2.0 mice, it was found that the intraperitoneal administration of heme (10 mg·kg(-1)·day(-1)) or glucose (9 g·kg(-1)·day(-1)) for 7 days partially reversed (50%) increases in urinary δ-aminolevulinic acids levels associated with acute porphyria. Treatment with heme, but not with glucose, suppressed the phase advance (-like phenomenon) in the diurnal rhythms (P < 0.05) and restored the decrease of heme (P < 0.01) in GF2.0 mice. These results suggest that impairments of heme biosynthesis, in particular a decrease in heme, may affect phase and period of circadian rhythms in animals.

Characterization of fatty acid profile in the liver of SHR/NDmcr-cp (cp/cp) rats, a model of the metabolic syndrome.

The fatty acid profile of hepatic lipid in spontaneously hypertensive rats (SHR)/NDmcr-cp (cp/cp) rats (SHR/NDcp), which offer an animal model of the metabolic syndrome, was characterized by comparing those in Wistar Kyoto rats (WKY), SHR, stroke-prone spontaneously hypertensive rats (SHRSP) and SHR/NDmcr-cp (+/+) rats (SHR/ND+) . Hierarchical clustering analysis revealed that SHR/NDcp and the other four strains and/or substrains of rats were clearly disparate in fatty acid profile of hepatic lipid and that the disparity observed was due to the drastic increases in the mass of monounsaturated fatty acids, especially palmitoleic acid and oleic acid, in the liver of SHR/NDcp. Activities of stearoyl-CoA desaturase (SCD) and palmitoyl-CoA chain elongase in hepatic microsomes of SHR/NDcp were markedly higher than those of WKY, SHR, SHRSP and SHR/ND+. Activities of palmitoleoyl-CoA chain elongase in the liver of SHR/NDcp were also higher, but to a lesser extent. mRNA levels of SCD1 and elongation of very long-chain fatty acids (Elovl6), but not Elovl5, in the liver of SHR/NDcp were remarkably higher than those of the other four groups of rats. These results suggest that the enhanced expressions of SCD1 and Elovl6 induced abnormalities in fatty acid profile in the liver of SHR/NDcp.

Induction of 1-acylglycerophosphocholine acyltransferase genes by fibrates in the liver of rats.

The effect of fibrates (clofibric acid, bezafibrate and fenofibrate) on the gene expression and activity of 1-acylglycerophosphocholine acyltransferase (LPCAT) was investigated. The administration of 0.1% (w/w) clofibric acid, bezafibrate or fenofibrate in diet for 14 d to rats induced LPCAT activity in hepatic microsomes in the following order: fenofibrate>bezafibrate>clofibric acid. The LPCAT induced by fenofibrate preferred to arachidonoyl-CoA and linoleoyl-CoA to a greater extent than did LPCAT in control microsomes. The treatment with the fibrates resulted in upregulation of the relative expression of mRNAs encoding LPCAT3 and LPCAT4 in the following order: fenofibrate>bezafibrate>clofibric acid. The administration of fibrates did not change the expression of genes encoding either LPCAT1 or LPCAT2. The treatment with fibrates elevated relative levels of both mRNAs encoding Δ6 desaturase (Fads2) and Δ5 desaturase (Fads1) in the order of fenofibrate>bezafibrate>clofibric acid, and the extent of the increase in the level of Δ6 desaturase mRNA was greater than that of Δ5 desaturase. Fatty acid profile in hepatic phosphatidylcholine (PC) was significantly changed by the treatments with fibrates. These results suggest (i) that fibrates induce LPCAT activity in hepatic microsomes by elevating the expression of genes encoding LPCAT3 and LPCAT4, (ii) that the changes in fatty acid profile of hepatic PC are, in part, due to the elevated expression of two isoforms, LPCAT3 and LPCAT4, and (iii) that the ability of fibrates to induce these changes are in the order of fenofibrate>bezafibrate>clofibric acid.

Differential induction of stearoyl-CoA desaturase 1 and 2 genes by fibrates in the liver of rats.

The administration of fibrates (fenofibrate, bezafibrate and clofibric acid) to rats induced stearoyl-CoA desaturase (SCD) in the liver, and increased relative expression of mRNAs encoding SCD1 and SCD2 in dose- and time-dependent manners. The magnitudes of the increases in SCD2 mRNA level caused by fenofibrate and clofibric acid were much higher than those of SCD1 at relatively higher doses of the fibrates, and a relatively long time (7 or 14 d) was required for significant induction of SCD2 mRNA expression compared with that of SCD1. Although the absolute number of transcripts for SCD2 was 1,800 times lower than that of SCD1 in the control liver, it was strikingly increased by fibrates. These results suggest that differential regulations operate for the gene expression between SCD1 and SCD2, and that the physiological significance of SCD2 is distinct from that of SCD1 in the liver.

Major basic protein deposited at intra mucosal epithelium with probable eosinophilic chronic rhinosinusitis.

Background: Eosinophilic chronic rhinosinusitis (ECRS) is diagnosed by Japanese Epidemiological Survey of Refractory Eosinophilic Chronic Rhinosinusitis (JESREC) scoring system and histopathological eosinophil counts of dissected nasal polyps. Patients with low JESREC score and small number of tissue eosinophils are diagnosed with non-ECRS (NECRS). Due to the 2 parameters of this diagnostic system, chronic rhinosinusitis is to be divided to 4 groups and some patients fall into the 2 groups other than ECRS and NECRS: probable ECRS (pECRS) and probable non-ECRS (pNECRS). We attempted to clarify clinical and histopathological similarities and differences, especially concerning major basic protein (MBP), among those groups. Methods: One hundred twenty-eight patients treated by endoscopic sinus surgery was included. Clinical characteristics were compared among each group, and immunohistological analysis for MBP was performed to 35 randomly selected patients. MBP deposition at intra mucosal epithelium was evaluated by semiquantificational approach. Results: ECRS patients showed significantly higher comorbidity rate with allergic rhinitis (36 patients, 78.3%), asthma (36 patients, 78.3%) compared with other groups. Also, percentage of the patients complaining olfactory dysfunction (42 patients, 91.3%) was significantly higher (p < 0.001). Lund-Mackay score (mean, 14.5; 6-24) and recurrence rate (27 patients, 61.4%) was the highest in ECRS patients. Regarding pECRS, the number of patients with olfactory dysfunction (5 patients, 55.6%) was higher than pNECRS and NECRS groups. Also, comorbidity of asthma and percentage of blood eosinophils tended to be higher than those 2 groups. MBP score of pECRS group was significantly higher than NECRS (p < 0.05), despite of smaller tissue eosinophil counts. Conclusion: pECRS might share some characteristics with ECRS although tissue eosinophil count was significantly smaller compared with ECRS. The results of this study have shown that MBP score in pECRS nasal polyps was significantly higher than NECRS patients and close to ECRS. That might suggest that eosinophils have existed in the nasal polyps of pPECRS patients at some point before surgery.

Clofibric acid increases the formation of oleic acid in endoplasmic reticulum of the liver of rats.

The effects of 2-(4-chlorophenoxy)-2-methylpropionic acid (clofibric acid) on the formation of oleic acid (18:1) from stearic acid (18:0) and utilization of the 18:1 formed for phosphatidylcholine (PC) formation in endoplasmic reticulum in the liver of rats were studied in vivo. [¹4C]18:0 was intravenously injected into control Wistar male rats and rats that had been fed on a diet containing 0.5% (w/w) clofibric acid for 7 days; and the distribution of radiolabeled fatty acids among subcellular organelles, microsomes, peroxisomes, and mitochondria, was estimated on the basis of correction utilizing the yields from homogenates of marker enzymes for these organelles. The radioactivity was mostly localized in microsomes and the radiolabeled fatty acids present in microsomes were significantly increased by the treatment of rats with clofibric acid. The formation of radiolabeled 18:1 in microsomes markedly increased and incorporations of the formed [¹4C]18:1 into PC and phosphatidylethanolamine in microsomes were augmented in response to clofibric acid. The [¹4C]18:1 incorporated into PC was mostly located at the C-2 position, but not the C-1 position, of PC, and the radioactivity in 18:1 at the C-2 position of PC was strikingly increased by clofibric acid. These results obtained from the in vivo experiments directly link the findings that clofibric acid treatment induces microsomal stearoyl-CoA desaturase and 1-acylglycerophosphocholine acyltransferase in the liver and the findings that the treatment with the drug elevated absolute mass and mass proportion of 18:1 at the C-2 position, but not the C-1 position, of PC in the liver together.

Effects of perfluorinated fatty acids with different carbon chain length on fatty acid profiles of hepatic lipids in mice.

Alterations by perfluorinated fatty acids (PFCAs) with a chain length of 6-9 carbons in the fatty acid profile of hepatic lipids of mice were investigated. The characteristic changes caused by all the PFCAs examined were increases in the contents and proportions of oleic acid (18 : 1), palmitoleic acid (16 : 1) and 8,11,14-eicosatrienoic acid (20 : 3) in hepatic lipids. Hepatic contents of palmitic acid were also increased by the treatments with the PFCAs. These effects were almost dependent on the hepatic concentrations of PFCA molecules regardless of their carbon chain length. Perfluorooctanoic acid elevated the expressions of mRNA encoding acetyl-CoA carboxylase, fatty acid synthase, malic enzyme, stearoyl-CoA desaturase (SCD) (SCD1 and 2), chain elongase (ELOVL5), Δ6 desaturase (Fads2), 1-acylglycerophosphocholine acyltransferase (LPCAT) (LPCAT3). The four PFCAs examined induced microsomal SCD and LPCAT in hepatic concentration-dependent manners regardless of carbon chain length. One linear regression line was confirmed between LPCAT activity and hepatic concentration of PFCA at wide range of the concentration, whereas the induction of SCD was saturable at relatively low concentration of PFCAs. These results suggest (i) that PFCAs with a chain length of 6-9 carbons change the fatty acid profile of hepatic lipids by increasing contents and proportions of 16 : 1, 18 : 1 and 20 : 3, (ii) that these alterations in fatty acid profile are caused by up-regulation of SCD, de novo fatty acid synthesis, chain elongase and Δ6 desaturase and (iii) that the mechanism underlying SCD induction is, in part, mediated through peroxisome proliferator-activated receptor α.