Sandra Rebholz

Early Acquisition of Pneumocystis carinii in Neonatal Rats as Evidenced by PCR and Oral Swabs

ABSTRACT The complete life cycle of Pneumocystis carinii has not been defined, but accumulating evidence suggests that the mammalian host may acquire this organism early in life. In the present study, the initial time of P. carinii acquisition was determined in rats by amplification of P. carinii DNA in oral swabs from seven sets of pups and dams and from fetal tissue obtained by cesarean section of three gravid female rats. DNA extracted from all samples was amplified by using PCR primers directed to the P. carinii mitochondrial large subunit rRNA. Amplicons were produced from 80% (28 of 35) of pups within 2 h after birth; from 97% (34 of 35) after 24 h, and in all of the serially sampled pups by 48 h. No P. carinii amplicons were produced from 48 fetuses or their placentae taken by cesarean section. Thus, P. carinii is acquired almost immediately after birth, and placental transmission occurs rarely, if ever, in rats.

Widespread Occurrence of Pneumocystis carinii in Commercial Rat Colonies Detected Using Targeted PCR and Oral Swabs

ABSTRACT The genus Pneumocystis contains a family of fungal organisms that infect a wide variety of mammalian species. Although it is a cause of pneumonia in immunocompromised hosts, recent evidence suggests that these organisms colonize nonimmunosuppressed hosts. Detection of cryptic colonization withPneumocystis becomes important in animal studies when infection-free animals are necessary. Provocation by chronic immunosuppression, histology, and serology has been widely used to detect the presence of Pneumocystis in rat colonies, requiring lengthy time periods and/or postmortem tissue. We conducted a study to evaluate the use of PCR amplification of oral swabs for the antemortem detection of Pneumocystis in 12 rat groups from three commercial vendors. Sera were collected upon arrival, and the oral cavity was swabbed for PCR analysis. Ten of these groups of rats were then housed in pairs under barrier and immunosuppressed to provokePneumocystis growth. Once moribund, the rats were sacrificed, and the lungs were collected to evaluate the presence ofPneumocystis by PCR and microscopic enumeration. DNA was extracted from oral swabs and lung homogenates, and PCR was performed using primers targeting a region within the mitochondrial large-subunit rRNA of Pneumocystis carinii f. sp. carinii. Upon receipt, 64% of rats were positive for P. carinii f. sp. carinii-specific antibodies, while P. carinii f. sp. carinii DNA was amplified from 98% of oral swabs. Postmortem PCR analysis of individual lungs revealedP. carinii f. sp. carinii DNA in all rat lungs, illustrating widespread occurrence of Pneumocystis in commercial rat colonies. Thus, oral swab/PCR is a rapid, nonlethal, and sensitive method for the assessment of Pneumocystisexposure.

Highly Active Anti-Pneumocystis carinii Compounds in a Library of Novel Piperazine-Linked Bisbenzamidines and Related Compounds

ABSTRACT Trimethoprim-sulfamethoxazole and pentamidine isethionate have been used extensively for the prophylaxis and therapy of pneumonia caused by Pneumocystis jirovecii. Problems associated with toxicity and potential emerging resistance for both therapies necessitate the development of safe and effective analogs or new treatment strategies. In the present study, a library of 36 compounds was synthesized by using the pentamidine molecule as the parent compound modified by a 1,4-piperazinediyl moiety as the central linker to restrict conformation flexibility. The compounds were evaluated for anti-Pneumocystis carinii activity in a bioluminescent ATP-driven assay. Four of the compounds were highly active, with 50% inhibitory concentration (IC50) values of <0.01 μg/ml; four had very marked activity (IC50 < 0.10 μg/ml); ten had marked activity (IC50 < 1.0 μg/ml); nine had moderate activity (IC50 < 10 μg/ml); one had slight activity (IC50 = 34.1 μg/ml); and the remaining eight did not demonstrate activity in this assay system. The high level of activity was specifically associated with an alkyl chain length of five to six carbons attached to one of the nitrogens of the bisamidinium groups. None of the highly active compounds and only one of the very marked compounds exhibited any toxicity when evaluated in three mammalian cell lines. The strategy of substitution of 1,4-piperazine-linked bisbenzamidines produced compounds with the highest level of activity observed in the ATP assay and holds great promise for the development of efficacious anti-P. carinii therapy.

In Vitro Selection and In Vivo Efficacy of Piperazine- and Alkanediamide-Linked Bisbenzamidines against Pneumocystis Pneumonia in Mice

ABSTRACT Bisbenzamidines, such as pentamidine isethionate, are aromatic dicationic compounds that are active against Pneumocystis and other microbes but are oftentimes toxic to the host. To identify potential anti-Pneumocystis agents, we synthesized bisbenzamidine derivatives in which the parent compound pentamidine was modified by a 1,4-piperazinediyl, alkanediamide, or 1,3-phenylenediamide moiety as the central linker. Several of the compounds were more active against P. carinii and less toxic than pentamidine in cytotoxicity assays. For this study, we evaluated nine bisbenzamidine derivatives representing a range of in vitro activities, from highly active to inactive, for the treatment of pneumocystosis in an immunosuppressed mouse model. Six of these in vitro-active compounds, 01, 02, 04, 06, 100, and 101, exhibited marked efficacies against infection at a dose of 10 mg/kg of body weight, and four compounds, 01, 04, 100, and 101, showed significant increases in survival versus that of untreated infected control mice. Compound 100 was highly efficacious against the infection at 20 mg/kg and 40 mg/kg, with >1,000-fold reductions in burden, and resulted in improved survival curves versus those for pentamidine-treated mice (at the same doses). All six bisbenzamidine compounds that exhibited high in vitro activity significantly decreased the infection in vivo; two compounds, 12 and 102, with marked to moderate in vitro activities had slight or no activity in vivo, while compound 31 was inactive in vitro and was also inactive in vivo. Thus, the selection of highly active compounds from in vitro cytotoxicity assays was predictive of activity in the mouse model of Pneumocystis pneumonia. We conclude that a number of these bisbenzamidine compounds, especially compound 100, may show promise as new anti-Pneumocystis drugs.

Dietary fat impacts fetal growth and metabolism: uptake of chylomicron remnant core lipids by the placenta.

The fetus requires significant energy for growth and development. Although glucose is a major source of energy for the fetus, other maternal nutrients also appear to promote growth. Thus, the goal of these studies was to determine whether triglyceride-rich remnants are taken up by the placenta and whether maternal dietary lipids, independently of adiposity, can impact fetal growth. To accomplish our first goal, chylomicron particles were duallly labeled with cholesteryl ester and triglycerides. The placenta took up remnant particles/core lipids at rates greater than adipose tissue and skeletal muscle but less than the liver. Although the placenta expresses apoE receptors, uptake of chylomicron remnants and/or core lipids can occur independently of apoE. To determine the impact of dietary lipid on fetal growth, independent of maternal adiposity, females were fed high-fat diets (HFD) for 1 mo; there was no change in adiposity or leptin levels prior to or during pregnancy of dams fed HFD. Fetal masses were greater in dams fed HFD, and mRNA levels of proteins involved in fatty acid oxidation (CPT I, PPARα), but not glucose oxidation (pyruvate kinase) or other regulatory processes (HNF-4α, LXR), were increased with maternal dietary fat. There was also no change in mRNA levels of proteins involved in placental glucose and fatty acid transport, and GLUT1 protein levels in microvillous membranes were similar in placentas of dams fed either diet. Thus, the ability of the placenta to take up chylomicron remnant core lipids likely contributes to accelerated fetal growth in females fed high fat diets.

Multiparity leads to obesity and inflammation in mothers and obesity in male offspring

Multiparity is an independent risk factor for obesity in parous females. In addition to being a health issue for the mother, offspring of multiparous females may also be at risk for obesity later in life. The aim of the current study was to establish a mouse model that mimics the human pathology of multiparity and determine the effects of multiparity-induced obesity (MIO) on offspring in adulthood. C57BL/6 mice were mated and studied when primiparous (1st pregnancy) or multiparous (4th pregnancy). Dams became obese with multiparity, an effect that was independent of the age of the dam. Multiparous dams also had increased markers of inflammation (JNK activation, cytokine expression) in adipose tissue and liver that was greater than inflammation in nulliparous females made obese with a high-fat diet. Placental inflammation was prevalent in multiparous vs. primiparous dams as well. Male offspring of the multiparous dams developed increased adiposity by 24 wk of age relative to the progeny of primiparous dams, although food consumption was similar in both groups. Lipid metabolism was altered in liver and fat in that mRNA levels of regulatory genes (PGC-1α) as well as metabolic genes (CPT I) and Akt phosphorylation were decreased in offspring of multiparous dams. Thus, in mice, as in humans, multiparity increases adiposity and is associated with hepatic and placental inflammation and abnormal glucose tolerance. Importantly, MIO leads to increased body fat and metabolic dysfunction in the offspring, suggesting a role in the propagation of obesity.

Antitumor and Anti-Pneumocystis Carinii Activities of Novel Bisbenzamidines

Among a library of 17 bisbenzamidines connected with various linkers, compounds with a flexible pentanediamide (10) or hexanediamide (12) linker were the most potent derivatives against rat Pneumocystis carinii (IC50 values of 3 and 2 nM, respectively) and had the highest selectivity index ratios (GI50 of human tumor cells/IC50 of rat P. carinii cells) of >104. Seven compounds caused 50% growth inhibition (GI50) of tumor cells at concentrations of <100 μM while the remaining ten were not cytotoxic. DNA binding affinity (ΔTm) of the tested compounds did not correlate with either their anti-P. carinii activity or cytotoxicity.

Early acquisition of Pneumocystis carinii in neonatal rats using targeted PCR and oral swabs.

Members of the Pnewnocysris genus are fungal pathogens that infect mammals with mmpromised immune systems, including humans. To date, the life cycle of Pnewnocystis is incomplete, and has been examined cmly within the confines of the mammalian lung. This deficit of information on the life cycle has complicated the study, diagnosis, and treatment of Pnewnocystis-related disease, and is primarily due to the lack of a robust method for long-term in vitro cultivation of these organisms. Humans became seropositive for Pnewnocystis antibodies within the first three years of life [24, 301, but there is increasing evidence that acquisition is earlier than previously expected. Some investigators have nported pneumocystasis in infants as young as three months of age [5. 21,27-291, whereas others have reported the presence of Pnewnocystis organisms in the lungs of neonates and stillborn infants [12. 231. Previous studies in rodents have suggested transplacental transport of Pneumocystis as a potential mode of transmission [8, 11, 17. 19. 211. Unfortunately these data have been difficult to reproduce and warrant further investigation. This study sought to define the time of initial acquisition of Pnewnocystis in rats by use of oral swab/PCR analysis, as well as PCR analysis of homogenized fetal tissue taken by cesarean section. We recently determined that the presence of Pneumocystis-specific DNA in the oral cavities of nonimmunosuppressed rats was highly predictive for Pnewnocystis exposure [18]. This technique was used in the present study. Determination of the initial contact with Pneumocystis will be useful for studies of its life cycle and transmission in humans.

Mapping Atheroprotective Functions and Related Proteins/Lipoproteins in Size Fractionated Human Plasma

HDL has been shown to possess a variety of cardio-protective functions, including removal of excess cholesterol from the periphery, and inhibition of lipoprotein oxidation. It has been proposed that various HDL subparticles exist, each with distinct protein and lipid compositions, which may be responsible for HDLs many functions. We hypothesized that HDL functions will co-migrate with the operational lipoprotein subspecies when separated by gel filtration chromatography. Plasma from 10 healthy male donors was fractionated and the protein composition of the phospholipid containing fractions was analyzed by mass spectrometry (MS). Each fraction was evaluated for its proteomic content as well as its ability to promote cholesterol efflux and protect low density lipoprotein (LDL) from free radical oxidation. For each function, several peaks of activity were identified across the plasma size gradient. Neither cholesterol efflux or LDL antioxidation activity correlated strongly with any single protein across the fractions. However, we identified multiple proteins that had strong correlations (r values >0.7, p < 0.01) with individual peaks of activity. These proteins fell into diverse functional categories, including those traditionally associated with lipid metabolism, as well as alternative complement cascade, innate immunity and clotting cascades and immunoglobulins. Additionally, the phospholipid and cholesterol concentration of the fractions correlated strongly with cholesterol efflux (r = 0.95 and 0.82 respectively), whereas the total protein content of the fractions correlated best with antioxidant activity across all fractions (r = 0.746). Furthermore, two previously postulated subspecies (apoA-I, apoA-II and apoC-1; as well as apoA-I, apoC-I and apoJ) were found to have strong correlations with both cholesterol efflux and antioxidation activity. Up till now, very little has been known about how lipoprotein composition mediates functions like cholesterol efflux and antioxidation.

Hypercholesterolemia with consumption of PFOA-laced Western diets is dependent on strain and sex of mice.

Perfluorooctanoic acid (PFOA) is a man-made surfactant with a number of industrial applications. It has a long half-life environmentally and biologically. Past studies suggest a direct relationship between plasma cholesterol and PFOA serum concentrations in humans and an inverse one in rodents fed standard rodent chow, making it difficult to examine mechanisms responsible for the potential PFOA-induced hypercholesterolemia and altered sterol metabolism. To examine dietary modification of PFOA-induced effects, C57BL/6 and BALB/c mice were fed PFOA in a fat- and cholesterol-containing diet. When fed these high fat diets, PFOA ingestion resulted in marked hypercholesterolemia in male and female C57BL/6 mice and less robust hypercholesterolemia in male BALB/c mice. The PFOA-induced hypercholesterolemia appeared to be the result of increased liver masses and altered expression of genes associated with hepatic sterol output, specifically bile acid production. mRNA levels of genes associated with sterol input were reduced only in C57BL/6 females, the mice with the greatest increase in plasma cholesterol levels. Strain-specific PFOA-induced changes in cholesterol concentrations in mammary tissues and ovaries paralleled changes in plasma cholesterol levels. mRNA levels of sterol-related genes were reduced in ovaries of C57BL/6 but not in BALB/c mice and not in mammary tissues. Our data suggest that PFOA ingestion leads to hypercholesterolemia in mice fed fat and cholesterol and effects are dependent upon the genetic background and gender of the mice with C57BL/6 female mice being most responsive to PFOA.