Long-term thiazide use and risk of low-energy fractures among persons with Alzheimer's disease-nested case-control study.

We investigated the association between thiazide use and the risk of low-energy fractures among community dwellers with Alzheimer's disease. Longer use was associated with a decreased risk of low-energy fractures. This study extends the previous knowledge of reduced fracture risk of thiazides to persons with Alzheimer's disease. INTRODUCTION: To investigate the association between thiazide use and the risk of low-energy fractures (LEF), and hip fracture among community dwellers with Alzheimer's disease (AD). No prior study has evaluated the effect of thiazides on LEF risk of AD patients. METHODS: LEF cases were identified from the MEDALZ study, including all community-dwelling persons diagnosed with AD in Finland 2005-2011. During the follow-up from AD diagnoses until the end of 2015, cases with LEF (N = 10,416) and hip fracture (N = 5578) were identified. LEF cases were matched with up to three controls without LEF, according to time since AD diagnosis, age and gender. Thiazide use identified from the Prescription register data was modeled with PRE2DUP method. Current use was defined in 0-30 days' time window before the fracture/matching date, and duration of current use was assessed. The association between thiazide exposure and LEFs was assessed with conditional logistic regression. RESULTS: Current thiazide use was observed in 10.5% of LEF cases and 12.5% of controls. Current thiazide use was associated with a decreased risk of LEF (adjusted OR [aOR] 0.83, 95% CI 0.77-0.88). In terms of the duration of use, no association was observed with short-term use (< 1 year or 1-3 years), while longer use (> 3 years) was associated with a reduced risk of LEF (aOR 0.77, 95% CI 0.71-0.83) and hip fracture (aOR 0.68, 95% CI 0.60-0.78). CONCLUSIONS: Our study extends the previous knowledge of reduced fracture risk of thiazides to persons with AD, a population with significantly increased background risk of fractures.

Effects of an isocaloric healthy Nordic diet on insulin sensitivity, lipid profile and inflammation markers in metabolic syndrome -- a randomized study (SYSDIET).

BACKGROUND: Different healthy food patterns may modify cardiometabolic risk. We investigated the effects of an isocaloric healthy Nordic diet on insulin sensitivity, lipid profile, blood pressure and inflammatory markers in people with metabolic syndrome. METHODS: We conducted a randomized dietary study lasting for 18-24 weeks in individuals with features of metabolic syndrome (mean age 55 years, BMI 31.6 kg m(-2) , 67% women). Altogether 309 individuals were screened, 200 started the intervention after 4-week run-in period, and 96 (proportion of dropouts 7.9%) and 70 individuals (dropouts 27%) completed the study, in the Healthy diet and Control diet groups, respectively. Healthy diet included whole-grain products, berries, fruits and vegetables, rapeseed oil, three fish meals per week and low-fat dairy products. An average Nordic diet served as a Control diet. Compliance was monitored by repeated 4-day food diaries and fatty acid composition of serum phospholipids. RESULTS: Body weight remained stable, and no significant changes were observed in insulin sensitivity or blood pressure. Significant changes between the groups were found in non-HDL cholesterol (-0.18, mmol L(-1) 95% CI -0.35; -0.01, P = 0.04), LDL to HDL cholesterol (-0.15, -0.28; -0.00, P = 0.046) and apolipoprotein B to apolipoprotein A1 ratios (-0.04, -0.07; -0.00, P = 0.025) favouring the Healthy diet. IL-1 Ra increased during the Control diet (difference -84, -133; -37 ng L(-1) , P = 0.00053). Intakes of saturated fats (E%, beta estimate 4.28, 0.02; 8.53, P = 0.049) and magnesium (mg, -0.23, -0.41; -0.05, P = 0.012) were associated with IL-1 Ra. CONCLUSIONS: Healthy Nordic diet improved lipid profile and had a beneficial effect on low-grade inflammation.

The effect of pregnane X receptor agonists on postprandial incretin hormone secretion in rats and humans.

We recently showed that pregnane X receptor (PXR) agonists cause hyperglycaemia during oral glucose tolerance test (OGTT) in rats and healthy volunteers (Rifa-1 study). We now aimed to determine if the secretion of incretin hormones, especially glucagon-like peptide-1 (GLP-1) and gastric inhibitory polypeptide (GIP), are affected by PXR agonists since these gut-secreted hormones are major regulators of postprandial glucose metabolism. The Rifa-2 study had a one-phase, open-label design. Twelve subjects were given 600 mg of rifampicin a day for a week. OGTT with glucose, insulin, and incretin hormone measurements was performed before and after the rifampicin dosing. Incretins and insulin were analysed in previously collected rat OGTT samples after pregnenolone 16α-carbonitrile (PCN) or control treatment for 4 days. Rifampicin treatment did not affect glucose, insulin, GLP-1, GIP, glucagon, and peptide YY levels statistically significantly. Incremental AUCs (AUCincr) of glucose and insulin tended to increase (41% increase in glucose AUCincr, P = 0.21, 95% confidence interval (CI) of the difference -47, 187; 24% increase in insulin AUCincr, P = 0.084, CI of the difference -110, 1493). Glucagon AUC was increased in women (53% increase, P = 0.028) and decreased in men (19% decrease, P < 0.001) after rifampicin dosing. In combined analysis of human Rifa-1 and Rifa-2 studies, glucose AUCincr was elevated by 63% (P = 0.010) and insulin AUCincr by 37% (P = 0.011). PCN increased rat insulin level at 60 min time point but did not affect incretin and insulin AUCs statistically significantly. In conclusion, PXR agonists do not affect the secretion of incretin hormones. The regulation of glucagon secretion by PXR may be sexually dimorphic in humans. The mechanism of disrupted glucose metabolism induced by PXR activation requires further study.

Experimental hematogenous endophthalmitis due to Cryptococcus neoformans.

New Zealand white female rabbits injected with 6 X 10(7) to 5.5 X 10(8) CFU of Cryptococcus neoformans into the right carotid artery developed three types of clinically detectable eye lesions. These eye manifestations included: (1) iritis that had distinctive 1-3 mm white nodules; (2) white vitreous lesions with ill-defined borders, and (3) focal and diffusely infiltrative lesions of the optic nerve radiations. Most of the eye lesions appeared between 1 to 3 weeks after intracarotid injection and resolved almost completely by 10 weeks. Their clinical appearance resembled some of the eye lesions described from human cases. Predominantly a mononuclear leukocyte response with scattered cryptococcal organisms were seen in the iris and optic nerve lesions. Serial quantitative cultures from eye tissues, brain, and kidney indicated that the clearance of viable cryptococci was slowest from the eye tissues. Among the three diagnostic techniques (India Ink mount, culture, and cryptococcal polysaccharide antigen (CPA) determination), the CPA determination was the most sensitive test to detect C. neoformans in the aqueous and vitreous humors of clinically involved eyes. This rabbit model may be useful for further studies on hematogenous cryptococcal endophthalmitis.

Expression of xenobiotic-metabolizing cytochrome P450 forms in human full-term placenta.

The expression of individual xenobiotic-metabolizing cytochrome P450 (CYP) genes in human placenta was studied at the mRNA level by reverse transcriptase-polymerase chain reaction (RT-PCR). mRNAs of CYP1A1, CYP2E1, CYP2F1, CYP3A3/4, CYP3A5, and CYP4B1 were detected by RT-PCR, and CYP1A2, CYP2A6/7, CYP2B6/7, CYp2C8-19, CYP2D6, and CYp3A7 were not detected. Several enzyme activity assays and immunoblasts were used to further characterize expression of forms producing detectable mRNA transcripts. The catalytic activities of 7-ethoxycoumarin O-deethylase (ECOD), 7-ethoxyresorufin O-deethylase (EROD) and aryl hydrocarbon hydroxylase (AHH) were substantially increased in response to maternal cigarette smoking, and paralleled the amount of CYP1A1 mRNA and protein. Aromatase activities were slightly lower in placentas exposed to cigarette smoke compared with nonexposed placentas. These data show that several xenobiotic-metabolizing CYP genes are expressed in human placenta at a low level. The significant of such low-level expression is unknown, but it may have local physiological or toxic consequences.

Expression of CYP2A genes in human liver and extrahepatic tissues.

Members of the human cytochrome P450 2A (CYP2A) subfamily are known to metabolize several promutagens, procarcinogens, and pharmaceuticals. In this study, the expression of the three genes found in the human CYP2A gene cluster was investigated in the liver and several extrahepatic tissues by gene-specific reverse transcriptase-polymerase chain reaction (RT-PCR). All three transcripts (CYP2A6, CYP2A7, and CYP2A13) were found to be present in liver. Quantitative RT-PCR analysis showed that CYP2A6 and CYP2A7 mRNAs were present at roughly equal levels in the liver, while CYP2A13 was expressed at very low levels. Two putative splicing variants of CYP2A7 were found in the liver. Nasal mucosa contained a low level of CYP2A6 and a relatively high level of CYP2A13 transcripts. Kidney, duodenum, lung, alveolar macrophages, peripheral lymphocytes, placenta, and uterine endometrium were negative for all transcripts. This survey gives a comprehensive picture of the expression pattern of CYP2A genes in liver and extrahepatic tissues and constitutes a basis for a search for functional CYP2A forms and their roles in chemical toxicity in liver and nasal mucosa.

New evidence for active sodium transport from fluid-filled rat lungs.

The hypothesis that fluid reabsorption from the air spaces is mediated at least in part by active transport of Na+ was investigated in six sets of experiments conducted in isolated fluid-filled rat lungs. Fluid reabsorption was monitored by following the changes in the air space concentration of labeled albumin. We found that incorporation of bicarbonate rather than a nonvolatile buffer (N-2-hydroxy-ethylpiperazine-N'-2-ethanesulfonic acid) in the air space solution more than doubled the rate of fluid reabsorption. Addition of 10(-4) M amiloride to the air space solution reduced the rate of fluid reabsorption over a 2-h experiment from 1.2 +/- 0.1 to 0.7 +/- 0.1 ml and decreased reabsorption of both labeled and unlabeled Na+ from the air spaces. To show that Na+ could be reabsorbed from the air spaces even if the concentrations of Na+ in the perfusate increased above those in the air space, mannitol (150 mM) was added to the perfusate and air space solutions and the concentrations of Na+ and Cl- were reduced to 90 and 60 mM, respectively. Mannitol diffuses across the pulmonary epithelium very slowly, and it osmotically restrained the movement of water out of the air spaces. Na+ concentrations in the perfusate increased by 10 +/- 2 mM, but concentrations in the air space remained unchanged. Despite an increasingly unfavorable concentration gradient for Na+, 0.2 mmol Na+ and 0.6 ml water were reabsorbed from the air spaces in 2 h. Ouabain (10(-4) M) did not appear to slow fluid reabsorption in the presence of mannitol, but it reduced K+ secretion into the air spaces and increased K+ appearance in the perfusate in a manner consistent with inhibition of Na+-K+-adenosinetriphosphatase at the basolateral surface of the epithelial cells. Fluid reabsorption was not altered when the lungs were exposed to a hypotonic solution (185 mM), but secretion of K+ into the air spaces was accelerated and K+ was lost from the perfusate. These experiments are consistent with active Na+ transport from the air spaces.

Protein concentrations have little effect on reabsorption of fluid from isolated rat lungs.

A study was conducted to determine whether differences in the concentrations of large molecules between the air space and perfusate solutions altered the rates at which fluid was reabsorbed from isolated fluid-filled perfused rat lungs. Four groups of experiments were conducted: 1) 5 g/dl albumin in the air spaces and perfusate, 2) 15 g/dl albumin in the air space and 5 g/dl albumin in the perfusate, 3) 5 g/dl albumin in the air space and 15 g/dl albumin in the perfusate, and 4) a mixture of 5 g/dl albumin and 7 g/dl Dextran 70 in the air spaces and 5 g/dl albumin in the perfusate. Fluid reabsorption was determined by following the concentration of albumin labeled with Evans blue (T-1824) in the air space and perfusate compartments. Because leakage of protein between the air space and perfusate compartments is very slow, increases in T-1824 concentrations in the air spaces indicated loss of fluid from this compartment, whereas decreases in these concentrations in the perfusate compartment provided evidence of fluid transport into the vasculature. Approximately 30% of the air space fluid was reabsorbed in a 2-h period, and virtually all of this fluid reached the perfusate compartment. Despite oncotic differences that ranged from -65 to 65 Torr, variations in air space or perfusate albumin concentrations did not have a significant effect on this process. A 30% decrease in fluid reabsorption was observed when dextran was in the air space solution, but this decrease did not appear to be due to the oncotic properties of this solution because albumin did not have a measurable effect on reabsorption.(ABSTRACT TRUNCATED AT 250 WORDS)

Pulmonary epithelial sieving of small solutes in rat lungs.

Transport and consumption of glucose from the air spaces of isolated, fluid-filled lungs can result in significantly lower glucose concentrations in the air spaces than in the perfusate compartment (11). This concentration difference could promote the osmotic movement of water from the air spaces to the perfusate, but the rate of fluid extraction from the air spaces would then be limited by the rates of electrolyte transport through the epithelium. In the present study, measurements were made of solute and water losses from the air spaces of fluid-filled rat lungs and the transport of these solutes and water into the vasculature after addition of hypertonic glucose or sucrose to the perfusate. Increases in the concentrations of Na+, Cl-, K+, and labeled mannitol in the air space were initially comparable to those of albumin labeled with Evans blue. Similarly, decreases in electrolyte concentrations in the perfusate were comparable to those of labeled albumin, indicating that very little solute accompanied the movement of water out of the lungs. Nor was evidence found that exposure of the vasculature to hypertonic glucose resulted in an increase in the rate at which fluid was reabsorbed from the air spaces over a 1-h interval, aside from an initial, abrupt loss of solute-free water from the lungs. These observations suggest that perfusion of fluid-filled lungs with hypertonic solutions of small solutes results in the extraction of water from the air spaces and pulmonary parenchyma across membranes that resist the movement of electrolytes and other lipophobic solutes.

Exchange of labeled bicarbonate and carbon dioxide with erythrocytes suspended in an elutriator.

An elutriator was used to study exchange of labeled CO2 and bicarbonate with erythrocytes. Rabbit erythrocytes were suspended by centrifugation in a stream of fluid and exposed to transient injections of an extracellular indicator (125I-albumin or 22Na+), a water indicator (3H2O), and H14CO3- and/or 14CO2. Diffusion of indicators into erythrocytes was judged by comparison of initial concentrations of diffusible and extracellular indicators in the elutriator outflow. It was possible to conduct these experiments at normal hematocrits because any carbonic anhydrase released from erythrocytes by hemolysis was washed away in the elutriator flow, and ambient pH, PO2, and PCO2 were kept constant by the inflow of fresh fluid. Equilibration of HCO3- with erythrocytes was complete during the 7- to 10-s transit time through the chamber. After this exchange was irreversibly inhibited by the anion exchange inhibitor, DIDS (4,4'-diisothiocyanostilbene-2,2'-disulfonic acid), addition of carbonic anhydrase (100 mg/dl) accelerated exchange, but acetazolamide (20 mg/dl) was without effect. These observations were consistent with the absence of carbonic anhydrase on the surface of the erythrocytes.

Solute concentrations of the pulmonary epithelial lining fluid of anesthetized rats.

Uncertainty persists concerning the best method of estimating the volume and solute concentrations of the pulmonary epithelial lining fluid (ELF) recovered during bronchoalveolar lavage (BAL). In the present study, measurements were made of the BAL-to-plasma concentration ratios of a variety of solutes in an anesthetized rat model. One minute after an intravenous injection of labeled Na+ and urea, 5 ml of isotonic mannitol, saline, or glucose were injected into the trachea and an initial aliquot of the BAL was immediately removed. Initial BAL-to-plasma concentration ratios of urea, Na+, Cl-, Ca2+, and total protein were similar (ranging from 0.013 to 0.017) after BAL with mannitol, but albumin and transferrin ratios were approximately 60% lower and K+ ratios were five times greater. Lavage with saline yielded BAL-to-plasma urea concentration ratios similar to those obtained with mannitol lavage. The BAL-to-plasma specific activity of urea was about twice that of Na+, indicating that urea diffused into the ELF more rapidly than Na+ during the 70 s that elapsed between the time the radioactive urea and Na+ were injected into the circulation and the time when lavage was complete. Subsequent lavage samples also indicated that urea rapidly diffuses into the fluid-filled lungs. These experiments suggest that isotonic mannitol may be a useful solution for lavage, because it allows use of Na+ and perhaps Cl- as additional indicators of ELF dilution by BAL.(ABSTRACT TRUNCATED AT 250 WORDS)

Movement of ions and small solutes across endothelium and epithelium of perfused rabbit lungs.

In situ and isolated fluid-filled rabbit lungs were used to study the transport of indicators between the air space and vascular compartments. These indicators were placed in either the perfusate or air spaces and samples were collected from the perfusate at intervals during a 1-h perfusion period. At the end of the hour, fluid was pumped out of the air space compartment into serial tubes and indicator concentrations were determined in both the air space and perfusion fluids. One hour after introducing the indicators into the air space, the relative decreases in solute concentration were (arranged from the greatest to the least decline): [14C]urea greater than 36Cl- = 125I- greater than 22Na+ greater than [3H]mannitol. The relative rates at which the indicators appeared in the perfusate were similar. When the indicators were placed in the perfusate, a similar relationship was observed in the increase in air space concentrations, but the loss of 22Na+ from the perfusate was similar to those of 36Cl- and 125I-. Losses of all indicators from the perfusate were two or more times those from the air spaces, and although the loss of [3H]mannitol from the perfusate was similar to that of 22Na+ for about 30 min, subsequent loss was much slower. Very little 125I-albumin traversed the tissue barrier, and the small changes in the concentrations of 125I-albumin in the air spaces suggested that little fluid movement had occurred. These studies suggest that the epithelium is less permeable to solutes than the endothelium and permits passage of anions at a faster rate than 22Na+.(ABSTRACT TRUNCATED AT 250 WORDS)

Expression of xenobiotic-metabolizing CYPs in human pulmonary tissue.

The pattern of expression of individual cytochrome P450 (CYP) forms participating in the metabolism of xenobiotics is being increasingly well characterised in the human pulmonary tissue. Recent studies using methods having increased sensitivity and specificity, such as the reverse transcriptase-polymerase chain reaction (RT-PCR) analysis, have revealed constitutive and inducible expression of several CYP forms in different cell types of the human lung. These studies have revealed the presence of mRNA of several procarcinogen-activating CYP forms in whole lung tissue and alveolar macrophages, including CYP1A1, CYP2B6/7, CYP2E1, and CYP3A5. The results of several studies on CYP2D6 expression have yielded contradictory results. Immunohistochemical analysis shows that CYP3A5 protein is present in all lung samples studied, and is localized in the ciliated and mucous cells of the bronchial wall, bronchial glands, bronchiolar ciliated and terminal cuboidal epithelium, type I and type II alveolar epithelium, vascular and capillary endothelium, and alveolar macrophages. Also CYP3A4 protein is found in some cell types in a minority (about 20%) of lung samples. Primary cultures of freshly isolated broncho-alveolar macrophages as well as a continuously growing bronchial carcinoma cell line (A-549) are being used for CYP induction studies in our laboratory. The results indicate that CYP1 family members are inducible in these cells by polycyclic aromatic hydrocarbon (PAH) inducers, and that CYP3A5, but not CYP3A4, is present constitutively. The results of these studies indicate that several different xenobiotic-metabolizing CYPs are present in the human lung and lung-derived cell lines, possibly contributing to in situ activation of pulmonary procarcinogens. Interindividual differences in the expression of these CYPs may contribute to the risk of developing lung cancer and possibly other pulmonary diseases initiated by agents that require metabolic activation.

Pregnane X receptor agonists impair postprandial glucose tolerance.

We conducted a randomized, open, placebo-controlled crossover trial to investigate the effects of the pregnane X receptor (PXR) agonist rifampin on an oral glucose tolerance test (OGTT) in 12 healthy volunteers. The subjects were administered 600 mg rifampin or placebo once daily for 7 days, and OGTT was performed on the eighth day. The mean incremental glucose and insulin areas under the plasma concentration-time curves (AUC(incr)) increased by 192% (P = 0.008) and 45% (P = 0.031), respectively. The fasting glucose, insulin, and C-peptide, and the homeostasis model assessment for insulin resistance, were not affected. The glucose AUC(incr) during OGTT was significantly increased in rats after 4-day treatment with pregnenolone 16α-carbonitrile (PCN), an agonist of the rat PXR. The hepatic level of glucose transporter 2 (Glut2) mRNA was downregulated by PCN. In conclusion, both human and rat PXR agonists elicited postprandial hyperglycemia, suggesting a detrimental role of PXR activation on glucose tolerance.

Expression of xenobiotic-metabolizing enzymes in human pulmonary tissue: possible role in susceptibility for ILD.

The lung is a major target for all inhaled toxicants. Many inhaled chemicals are not hazardous as such, but are biotransformed to reactive intermediates. Therefore, the pathogenesis of interstitial and other lung diseases is intimately linked to exposure to environmental and other chemicals, which may be causative or modifying factors in the cellular pathways and mechanisms mediating oxidative stress and cell protection in the pulmonary tissue. Several different xenobiotic-metabolizing cytochrome P450 (CYP) and phase II enzymes (i.e. conjugation enzymes including several transferases) are present in the human lung and lung-derived cell lines, possibly contributing to in situ activation and inactivation of chemical toxicants. This paper describes the expression and localization of individual CYP-forms in the lung. Interindividual differences in the expression of these enzymes may contribute to the risk of developing interstitial and other lung diseases initiated by agents that require metabolic activation.

Reabsorption of solutes and water from fluid-filled rabbit lungs.

Uncertainty persists concerning the mechanisms responsible for fluid clearance from the lungs after the air spaces become flooded in severe pulmonary edema. In this study, solute and water fluxes were investigated in an isolated, fluid-filled, perfused rabbit lung preparation. These lungs were perfused with physiologic 1.0 or 5.0 g/dl albumin solutions, and the air spaces were flushed and filled with the same solutions. Samples were obtained at intervals from the perfusate, and at the end of 1 or 2 h, fluid was pumped from the trachea into collection tubes. Concentrations of albumin (labeled with Evans blue) in the air space increased by 2.4 +/- 0.7% (SEM) at 1 h and by 7.0 +/- 0.8% at 2 h. Approximately half of the increase at 2 h could be attributed to dehydration (as judged by increases in perfusate and air-space Na+ concentration). Because previous studies have indicated that the movement of labeled protein between these compartments is very slow in this preparation, it can be concluded that fluid is being reabsorbed from the air spaces. However, reabsorption appears to be slower in rabbits than in rats and it is not stimulated by terbutaline, an effect observed in other species. Under control conditions, potassium concentrations in the air-space fluid fell from 4.01 +/- 0.05 (SEM) mEq/L to 3.37 +/- 0.14 mEq/L at 1 h. Concentrations of K+ in the perfusate rose during this interval from 3.95 +/- 0.05 mEq/L to 4.39 +/- 0.08 mEq/L.(ABSTRACT TRUNCATED AT 250 WORDS)

Fluid reabsorption and glucose consumption in edematous rat lungs.

Solute and water uptake were studied in isolated perfused rat lungs with airspaces filled with the perfusion fluid. The albumin in this solution was labelled with Evans blue (T-1824), and uptake of fluid from the airspaces was documented by an increase in T-1824 concentration in airway fluid of 6.5 +/- 1.6% (n = 5, SEM) at 1 hour and 12.2 +/- 0.9% (n = 10) at 2 hours. The only detectable osmotic force that could have contributed to a loss of fluid from the alveolar fluid was a decrease in airspace glucose concentrations, which fell much more rapidly (from 150 mg/dl to 58.7 +/- 7.1 mg/dl, n = 10, after 2 hours) than plasma glucose (from 150 mg/dl to 128.9 +/- 3.7 mg/dl). Addition of 5 X 10(-5) M terbutaline to the perfusate and airspace solutions nearly doubled fluid reabsorption at 1 hour, an effect that was inhibited by propranolol and did not appear to be related to glucose consumption. Exposure to terbutaline for 2 hours increased epithelial permeability to 3H-mannitol and 22Na+. These observations suggest that active sodium transport and epithelial metabolism or transport of glucose in airway fluid may each play a role in the reabsorption of edema fluid.

Detection of mRNA encoding xenobiotic-metabolizing cytochrome P450s in human bronchoalveolar macrophages and peripheral blood lymphocytes.

Human pulmonary tissue are known to contain enzymes mediating procarcinogen activation. Peripheral blood lymphocytes and bronchoalveolar macrophages (BAMs) have been used as surrogates for the lung in studies involving cytochrome P450 (CYP) parameters, including CYP1A1 inducibility in relation to susceptibility to lung cancer. In this study, a comprehensive view of the expression patterns of xenobiotic-metabolizing CYP forms in human BAMs and peripheral blood lymphocytes was obtained by using gene-specific reverse transcriptase-polymerase chain reaction analysis. These patterns were compared with that in the whole lung. mRNAs of CYP2B6/7, CYP2C, CYP2E1, CYP2F1, CYP3A5, and CYP4B1 were detected in all seven BAM samples studied; however, only the mRNA of CYP2E1 was found consistently in all eight lymphocyte samples. The amounts of amplification products of CYP2B6/7, CYP2C, CYP3A5, and CYP4B1 were low and inconsistent, indicating low levels of expression in lymphocytes. Consistent with previous knowledge, mRNAs of CYP1A1, CYP2B6/7, CYP2E1, CYP2F1, CYP3A5, and CYP4B1 were detected in whole-lung tissue. These results give an overall picture of the expression of CYP genes in the xenobiotic-metabolizing families CYP1, CYP2, and CYP3 in BAMs, peripheral blood lymphocytes, and whole-lung tissue and will aid in directing future studies on the respective protein products. The differences in the CYP gene expression patterns between lung and lymphocytes cast additional doubt on the use of lymphocytes as a surrogate for the lung.

Expression of xenobiotic-metabolizing cytochrome P450s in human pulmonary tissues.

The purpose of the study was to obtain a comprehensive picture of the expression of cytochrome P450s (CYP) in the human lung, broncho-alveolar macrophages (BAM), and peripheral blood lymphocytes. The methods used were reverse transcriptase-polymerase chain reaction (RT-PCR) with gene-specific primers and immunohistochemistry with specific anti-peptide antibodies. In RT-PCR, CYPs 1A1, 2B6/7, 2E1, 2F1, 3A5 and 4B1 were detected in cDNA prepared from whole lung tissue. BAMs expressed CYPs 1B1, 2B6/7, 2C, 2E1, 2F1, 3A5 and 4B1. These tissues lacked CYPs 1A2, 2A6, 2D6, and 3A7. In peripheral blood lymphocytes, only CYP1B1 and CYP2E1 mRNAs were consistently detected. In immunohistochemistry with anti-CYP3A antibodies, epithelial staining of CYP3A5 was observed in 100% of individuals, while only about 20% exhibited CYP3A4 staining. CYP3A5 protein was localized in the bronchial wall, bronchial glands, bronchiolar epithelium, alveolar epithelium, vascular endothelium and alveolar macrophages. The results indicate that several different xenobiotic-metabolizing CYPs are present in the human lung, possibly contributing to in situ activation of pulmonary procarcinogens.