Geraldine F. Clough

Maternal high-fat feeding primes steatohepatitis in adult mice offspring, involving mitochondrial dysfunction and altered lipogenesis gene expression.

Nonalcoholic fatty liver disease (NAFLD) describes an increasingly prevalent spectrum of liver disorders associated with obesity and metabolic syndrome. It is uncertain why steatosis occurs in some individuals, whereas nonalcoholic steatohepatitis (NASH) occurs in others. We have generated a novel mouse model to test our hypothesis: that maternal fat intake contributes to the development of NAFLD in adult offspring. Female mice were fed either a high‐fat (HF) or control chow (C) diet before and during gestation and lactation. Resulting offspring were fed either a C or a HF diet after weaning, to generate four offspring groups; HF/HF, HF/C, C/HF, C/C. At 15 weeks of age, liver histology was normal in both the C/C and HF/C offspring. Kleiner scoring showed that although the C/HF offspring developed nonalcoholic fatty liver, the HF/HF offspring developed NASH. At 30 weeks, histological analysis and Kleiner scoring showed that both the HF/C and C/HF groups had NAFLD, whereas the HF/HF had a more severe form of NASH. Therefore, exposure to a HF diet in utero and during lactation contributes toward NAFLD progression. We investigated the mechanisms by which this developmental priming is mediated. At 15 weeks of age, hepatic mitochondrial electron transport chain (ETC) enzyme complex activity (I, II/III, and IV) was reduced in both groups of offspring from HF‐fed mothers (HF/C and HF/HF). In addition, measurement of hepatic gene expression indicated that lipogenesis, oxidative stress, and inflammatory pathways were up‐regulated in the 15‐week‐old HF/C and HF/HF offspring. Conclusion: Maternal fat intake contributes toward the NAFLD progression in adult offspring, which is mediated through impaired hepatic mitochondrial metabolism and up‐regulated hepatic lipogenesis. (HEPATOLOGY 2009.)

Effects of purified eicosapentaenoic and docosahexaenoic acids in nonalcoholic fatty liver disease: Results from the WELCOME* study

There is no licensed treatment for nonalcoholic fatty liver disease (NAFLD), a condition that increases risk of chronic liver disease, type 2 diabetes, and cardiovascular disease. We tested whether 15‐18 months of treatment with docosahexaenoic acid (DHA) plus eicosapentaenoic acid (EPA; Omacor/Lovaza, 4 g/day) decreased liver fat and improved two histologically validated liver fibrosis biomarker scores (primary outcomes). Patients with NAFLD were randomized in a double‐blind, placebo‐controlled trial (DHA+EPA, n = 51; placebo, n = 52). We quantified liver fat percentage by magnetic resonance spectroscopy in three liver zones. We measured liver fibrosis using two validated scores. We tested adherence to the intervention (Omacor group) and contamination (with DHA and EPA; placebo group) by measuring erythrocyte percentage DHA and EPA enrichment (gas chromatography). We undertook multivariable linear regression to test effects of (1) DHA+EPA treatment (intention‐to‐treat analyses) and (2) erythrocyte DHA and EPA enrichment (secondary analysis). Median (interquartile range) baseline and end‐of‐study liver fat percentage were 21.7 (19.3) and 19.7 (18.0) (placebo) and 23.0 (36.2) and 16.3 (22.0) (DHA+EPA). In the fully adjusted regression model, there was a trend toward improvement in liver fat percentage with DHA+EPA treatment (β = −3.64; 95% confidence interval [CI]: −8.0, 0.8; P = 0.1), but there was evidence of contamination in the placebo group and variable adherence to the intervention in the Omacor group. Further regression analysis showed that DHA enrichment was independently associated with a decrease in liver fat percentage (for each 1% enrichment: β = −1.70; 95% CI: −2.9, −0.5; P = 0.007). No improvement in fibrosis scores occurred. Conclusion: Erythrocyte DHA enrichment with DHA+EPA treatment is linearly associated with decreased liver fat percentage. Substantial decreases in liver fat percentage can be achieved with high‐percentage erythrocyte DHA enrichment in NAFLD. (Hepatology 2014;60:1211–1221)

Glycine rectifies vascular dysfunction induced by dietary protein imbalance during pregnancy

Protein restriction in rat pregnancy programmes the development of elevated systolic blood pressure and vascular dysfunction in the offspring. A recent study has shown that hypertension is reversed by maternal glycine supplementation. Whether this protective effect is exerted directly on the embryo and fetus, or indirectly via effects on the mother, is unknown although we have previously shown abnormalities in the maternal vasculature. We tested the hypothesis that dietary glycine repletion would reverse endothelial dysfunction in protein‐restricted pregnant rat dams using wire myography. Impaired acetylcholine‐ (P < 0.01) and isoprenaline‐induced (P < 0.05) vasodilatation in isolated mesenteric arteries (MA) from protein‐restricted pregnant dams was accompanied by reduced vascular nitric oxide (NO) release (P < 0.05). Dietary glycine supplementation reversed vascular dysfunction in MA (P < 0.05) and improved NO release thus potentially protecting the maternal circulation. The impaired NO release in the MA of low protein diet dams was not accompanied by reduced eNOS mRNA expression, suggesting that eNOS activity was altered. Protein restriction did not alter the vascular function of a conduit artery, the thoracic aorta. These results provide evidence that adequate provision of glycine, a conditionally essential amino acid in pregnancy, may play a role in the vascular adaptations to pregnancy, protecting the fetus from abnormal programming of the cardiovascular system.

A microdialysis method for the recovery of IL-1β, IL-6 and nerve growth factor from human brain in vivo

Intracerebral microdialysis is used extensively as a research tool in the investigation of the neurochemical and metabolic changes that occur following acute brain injury. Microdialysis has enabled elucidation of intra-cerebral levels of substances such as lactate, pyruvate and glycerol but, as yet, has not been used effectively to recover macromolecules from the human brain. Traumatic brain injury is known to result in the generation of cytokines and neurotrophins into extracellular fluid compartment of the brain, with effects on neuronal damage and repair. We have developed a technique of in vivo sampling of the interstitial fluid of the brain of patients with severe head injuries which has allowed the measurement of IL-1beta, IL-6 and nerve growth factor. This report confirms the safety and effectiveness of this modified microdialysis method in the clinical setting of a neurological intensive care unit. The technique provides a timely addition to the armamentarium of the clinical scientist and will potentially lead to a greater understanding of neuroinflammation following acute traumatic brain injury.

Microdialysis of large molecules

Microdialysis has been used in many tissues, including skin, brain, adipose tissue, muscle, kidney, and gastrointestinal tract, to recover low-molecular mass endogenous mediators, metabolites, and xenobiotics from the interstitial space. Recently, molecules of larger molecular mass, such as plasma proteins, cytokines, growth factors, and neuropeptides, have also been recovered successfully using largerpore membranes. Microdialysis recovery of large molecules offers the opportunity to identify patterns of protein expression in a variety of tissue spaces and to evaluate clinically useful biomarkers of disease. From this may develop a better understanding of the disease process and its diagnosis and more targeted approaches to therapy.

The soluble form of a disintegrin and metalloprotease 33 promotes angiogenesis : Implications for airway remodeling in asthma

BACKGROUND A disintegrin and metalloprotease (ADAM)-33 is a susceptibility gene for asthma and chronic obstructive pulmonary disease whose function remains unknown. OBJECTIVE Because asthmatic bronchoalveolar lavage fluid contains high levels of soluble ADAM33 (sADAM33), which includes the catalytic domain, we postulated that its release from cell membranes might play functional roles in airway remodeling by promoting angiogenesis. METHODS The proangiogenic activity of the highly purified catalytic domain of ADAM33 or a catalytically inactive mutant was studied in vitro (Matrigel assay), ex vivo (human embryonic/fetal lung explants) and in vivo (chorioallantoic membrane assay). The regulation of sADAM33 release from cells overexpressing full-length ADAM33 and its biological activity were characterized. RESULTS We show that the purified catalytic domain of ADAM33, but not its inactive mutant, causes rapid induction of endothelial cell differentiation in vitro, and neovascularization ex vivo and in vivo. We also show that TGF-beta(2) enhances sADAM33 release from cells overexpressing full-length ADAM33 and that this truncated form is biologically active. CONCLUSION The discovery that sADAM33 promotes angiogenesis defines it as a tissue remodeling gene with potential to affect airflow obstruction and lung function independently of inflammation. As TGF-beta(2) enhances sADAM33 release, environmental factors that cause epithelial damage may synergize with ADAM33 in asthma pathogenesis, resulting in a disease-related gain of function. This highlights the potential for interplay between genetic and environmental factors in this complex disease.

Interactions between microvascular and macrovascular disease in diabetes: pathophysiology and therapeutic implications

Convention partitions the complications of diabetes into two main subtypes. First are the diabetes‐specific microvascular complications of retinopathy, nephropathy and neuropathy; second are the atherothrombotic macrovascular complications that account for the majority of premature deaths. Pathological interactions between microvascular and macrovascular complications, for example, nephropathy and macrovascular disease, are common. Similar mechanisms and shared risk factors drive the development and progression of both small and large vessel disease. This concept has therapeutic implications. Mounting evidence points to the need for multifactorial strategies to prevent vascular complications in subjects with diabetes and/or the metabolic syndrome. We advocate a combined therapeutic approach that addresses small and large vessel disease. Preferential use should be made of drug regimens that (i) maximize vascular protection, (ii) reduce the risk of iatrogenic vascular damage and (iii) minimize the increasing problem of polypharmacy.

Role of nitric oxide in the regulation of microvascular perfusion in human skin in vivo

1 Nitric oxide (NO) concentrations were measured in dialysate from healthy human skin, in vivo, both at rest and during the inflammatory response to intradermal histamine or bradykinin. Changes in dialysate NO concentration, measured by electrochemical detection, were related to changes in dermal vascular perfusion, measured using scanning laser Doppler imaging. 2 Basal NO concentration in dermal microdialysate was 0·60 ± 0·14 μM (mean ± s.e.m.). Following the intradermal injection of histamine, a transient, time‐dependent increase in NO concentration was measured in areas of skin incorporating the weal and in others incorporating the flare. The increase in NO concentration was associated with an increase in dialysate cGMP concentration in both the weal and flare areas. 3 Addition of NG‐nitro‐l‐arginine‐methyl ester (L‐NAME, 5 mM) to the probe perfusate resulted in an inhibition of the histamine‐induced increase in NO and cGMP. Moreover, the reduction in dialysate NO concentration was associated with a reduction in dermal vascular flux, both under basal conditions and within the weal and flare response. 4 These results demonstrate, by the use of microdialysis, that vasoactive mediators can be measured in healthy human skin in vivo. They provide direct evidence that endogenous concentration of NO increases during the inflammatory weal and flare response to histamine and that the increase in dermal NO concentration is associated with increases in cGMP concentration and dermal vascular perfusion, thus confirming a role for NO in vasoregulation in human skin.

How Minimally Invasive is Microdialysis Sampling? A Cautionary Note for Cytokine Collection in Human Skin and other Clinical Studies

It is common to refer to microdialysis as a minimally invasive procedure, likening it to insertion of an artificial capillary. While a comparison of this type allows the process to be easily visualized by those outside the field, it tends to provide a false impression of the localized perturbation of the tissue space that is caused by catheter insertion. With the increased acceptance of microdialysis sampling as a viable in vivo sampling method, many researchers have begun to use the technique to explore inflammatory and immune-mediated diseases in the skin and other organs. Unfortunately, many of the molecules of interest, particularly chemokines and cytokines, are known to be generated during the inflammatory response to wounding and the subsequent cellular events leading to wound repair. With more than 11,000 reports citing the use of microdialysis sampling, only a few researchers have sought to assess the tissue damage that is incurred by probe insertion. For this reason, caution is warranted when collecting these molecules and inferring a role for them in clinical disease states. This commentary seeks to remind the research community of the confounding effects that signaling molecules related to the wounding response will have on clinical studies. Proper controls must be incorporated into all studies in order to assess whether or not particular molecules are truly related to the disease state under investigation or have been generated as part of the tissue response to the wound incurred by microdialysis catheter implantation.

Comparison of the effects of levocetirizine and loratadine on histamine-induced wheal, flare, and itch in human skin

Background: This randomized, double‐blind, crossover study compared the effects of the R‐enantiomer of cetirizine, levocetirizine, with those of loratadine on the wheal, flare, and itch response to histamine in human skin.