Hepatic Inactivation Research Articles

Anti-TNF Thioester Glucocorticoid Antibody-Drug Conjugate Fully Inhibits Inflammation with Minimal Effect on Systemic Corticosterone Levels in a Mouse Arthritis Model.

We describe the discovery of a thioester-containing glucocorticoid receptor modulator (GRM) payload and the corresponding antibody-drug conjugate (ADC). Payload 6 was designed for rapid hepatic inactivation to minimize systemic exposure of nonconjugated GRM. Mouse PK indicated that 6 is cleared 10-fold more rapidly than a first-generation GRM payload, resulting in 10-fold lower exposure and 3-fold decrease in Cmax. The anti-mTNF conjugate ADC5 fully inhibited inflammation in mouse contact hypersensitivity with minimal effects on corticosterone, a biomarker for systemic GRM effects, at doses up to and including 100 mg/kg. Concomitant inhibition of P1NP suggests potential delivery to cells involved in the remodeling of bone, which may be a consequence of TNF-targeting or bystander payload effects. Furthermore, ADC5 fully suppressed inflammation in collagen-induced arthritis mouse model after one 10 mg/kg dose for 21 days. The properties of the anti-hTNF conjugate were suitable for liquid formulation and may enable subcutaneous dosing.

WED-423 - Hepatic inactivation of the epigenetic regulators Suv420h1-h2 mitigates NAFLD development and progression in mice

WED-423 - Hepatic inactivation of the epigenetic regulators Suv420h1-h2 mitigates NAFLD development and progression in mice

Abstract 430: Epigenome Editing Of The AGT Gene As A Therapeutic Approach For Cardiovascular Disorders

Overactivation of the renin-angiotensin system contributes to many common and rare cardiovascular diseases such as hypertension, atherosclerosis, and genetic thoracic aortopathies. Current pharmacologic therapies that target this pathway have been proven safe and effective, yet they require individuals with these conditions to adhere to daily medications. CRISPR-Cas9-mediated hepatic inactivation of the angiotensinogen ( AGT ) gene, the precursor of all angiotensin peptides, could be a promising “one and done” therapeutic approach for these disorders. However, disruption of AGT by Cas9 nuclease would result in irreversible changes to the genome and would likely have negative consequences if targeted to organs outside of the liver. CRISPRoff is a CRISPR-based epigenome editing tool consisting of catalytically inactive Cas9 fused to a DNA methyltransferase, as well as a guide RNA (gRNA) designed to target a genomic promoter of interest. Targeting to a gene promoter can result in DNA methylation and subsequent silencing of gene expression, a phenomenon that has the potential to be reversed by CRISPRon, a catalytically inactive Cas9 fused to a demethylase that could be targeted to the same site using the same gRNA. We hypothesized that CRISPRoff can be used to efficiently and durably silence AGT expression by methylation of the AGT promoter. To test this, we screened HuH-7 hepatoma cells with CRISPRoff and either individual gRNAs or dual combinations of gRNAs targeting the AGT promoter. We measured AGT mRNA expression by RT-qPCR and selected the two combinations of gRNAs that resulted in the greatest decrease in AGT expression for methylation analysis. We found that AGT expression was decreased by ≈50% in treated cells, and this correlated with substantially increased methylation throughout the AGT promoter. A long-term in vitro study to assess the durability of this methylation is underway. We are also generating a humanized AGT mouse model to test whether these CRISPRoff gRNAs can silence the human AGT gene in vivo. These results provide a proof of concept of CRISPRoff for silencing of AGT expression as a therapeutic approach for common and rare cardiovascular disorders.

Hepatic inactivation of murine Surf4 results in marked reduction in plasma cholesterol.

PCSK9 negatively regulates low-density lipoprotein receptor (LDLR) abundance on the cell surface, leading to decreased hepatic clearance of LDL particles and increased levels of plasma cholesterol. We previously identified SURF4 as a cargo receptor that facilitates PCSK9 secretion in HEK293T cells (Emmer et al., 2018). Here, we generated hepatic SURF4-deficient mice (Surf4fl/fl Alb-Cre+) to investigate the physiologic role of SURF4 in vivo. Surf4fl/fl Alb-Cre+ mice exhibited normal viability, gross development, and fertility. Plasma PCSK9 levels were reduced by ~60% in Surf4fl/fl Alb-Cre+ mice, with a corresponding ~50% increase in steady state LDLR protein abundance in the liver, consistent with SURF4 functioning as a cargo receptor for PCSK9. Surprisingly, these mice exhibited a marked reduction in plasma cholesterol and triglyceride levels out of proportion to the partial increase in hepatic LDLR abundance. Detailed characterization of lipoprotein metabolism in these mice instead revealed a severe defect in hepatic lipoprotein secretion, consistent with prior reports of SURF4 also promoting the secretion of apolipoprotein B (APOB). Despite a small increase in liver mass and lipid content, histologic evaluation revealed no evidence of steatohepatitis or fibrosis in Surf4fl/fl Alb-Cre+ mice. Acute depletion of hepatic SURF4 by CRISPR/Cas9 or liver-targeted siRNA in adult mice confirms these findings. Together, these data support the physiologic significance of SURF4 in the hepatic secretion of PCSK9 and APOB-containing lipoproteins and its potential as a therapeutic target in atherosclerotic cardiovascular diseases.

Bone Marrow Stroma Protects FLT3 Acute Myeloid Leukemia (AML) through CYP3A4-Mediated Drug Metabolization of FLT3 Tyrosine Kinase Inhibitors (TKIs)

IntroductionFms-like tyrosine kinase 3 internal tandem duplications (FLT3/ITD) are among the most common mutations found in AML patients. Interestingly, although initial remission rates of FLT3/ITD AML are similar to standard-risk AMLs, these AML have a high relapse rate and poor overall survival. Moreover, FLT3 TKIs have been much more successful in eliminating peripheral FLT/ITD blasts, than eradicating marrow disease and generating durable responses clinically. Studies have addressed several mechanisms underlying the FLT3 TKI resistance, including a protective role for the bone marrow (BM) microenvironment. However, the mechanisms underlying this protection remain unknown. We previously showed that human bone marrow stromal cells (BMSCs) highly express most cytochrome P450 (CYP) enzymes, and these enzymes are a major means of chemoprotection within the BM niche (Alonso et al. Oncotarget 2015). Among them, CYP3A4 is a key enzyme responsible for hepatic inactivation of many chemotherapy agents, including many FLT3 TKIs used clinically. Therefore, we hypothesized that BM stromal CYP3A4 contributes to BM microenvironment mediated FLT3 TKI resistance by FLT3/ITD AML.Methods and ResultsTo test our hypothesis in vitro, FLT3/ITD AML cell lines (MV4-11 and Molm14) were co-cultured with FLT3 TKIs with or without BMSCs (F/STRO), and their clonogenic activity was assessed. We found that 3 different clinically active FLT3 TKIs (sorafenib, quizartinib, and gilteritinib), while active against the FLT3/ITD AML in liquid culture, had little activity when co-cultured with BMSCs (Figure 1A). Moreover, when FLT3/ITD AMLs were co-cultured with BMSCs with short hairpin (sh) RNA knockdown of CYP3A4 (shCYP3A4), the activity of the FLT3 TKIs was restored (Figure 1A). To test the hypothesis in vivo, we investigated the growth of FLT3/ITD AML tumors containing control or shCYP3A4 human primary BMSCs upon FLT3 TKI treatments in a xenograft mouse model. We observed that the tumors with shCYP3A4 BMSCs were significantly more sensitive to FLT3 TKI treatments compared to those with control BMSCs.To further examine the role of CYP3A4 in BMSCs, we examined the inhibitory effects of FLT3 TKIs in the absence of stromal cellular contact with FLT3/ITD AML cells. FLT3 TKI-containing media was incubated with and without control BMSCs and shCYP3A4 BMSCs, and then incubated with FLT3/ITD AML cells. Western blot performed on the FLT3/ITD AML cells showed that FLT3 TKI media conditioned with BMSCs blocked the inhibition of FLT3 phosphorylation, and this was reversed by CYP3A4 knockdown in the BMSCs. These results demonstrated that stromal CYP3A4 protected against FLT3 TKIs even in the absence of stromal cell contact.We next studied if combining a clinically active CYP3A4 inhibitor with FLT3 TKIs would increase the FLT3/ITD AML cells' sensitivities to FLT3 TKIs in the presence of BMSCs. Clarithromycin, a clinically active CYP3A4 inhibitor, significantly reversed the protective effects of BMSCs to 3 different FLT3 TKIs (Figure 1B).ConclusionsThese data confirm the protective effects of stroma for FLT3/ITD AML against FLT3 TKIs. Further, we found for the first time that CYP3A4 expressed in BMSCs contributes to BMSC mediated FLT3/ITD AML protection against FLT3 TKIs both in vitro and in vivo mouse model. Our results also demonstrated that combining FLT3 TKIs with clinically available CYP3A4 inhibitors may become a promising strategy to overcome drug resistance in FLT3/ITD AML treatment. [Display omitted] DisclosuresLevis:Novartis: Consultancy, Honoraria, Research Funding; Daiichi Sankyo, Inc.: Consultancy, Honoraria; Astellas Pharma Us: Consultancy, Research Funding; Millennium Pharmaceuticals, Inc., a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Research Funding; FujiFilm: Research Funding.

Receptor-Mediated ER Export of Lipoproteins Controls Lipid Homeostasis in Mice and Humans

Efficient delivery of specific cargos invivo poses a major challenge to the secretory pathway, which shuttles products encoded by ∼30% of the genome. Newly synthesized protein and lipid cargos embark on the secretory pathway via COPII-coated vesicles, assembled by the GTPase SAR1 on the endoplasmic reticulum (ER), but how lipid-carrying lipoproteins are distinguished from the general protein cargos in the ER and selectively secreted has not been clear. Here, we show that this process is quantitatively governed by the GTPase SAR1B and SURF4, a high-efficiency cargo receptor. While both genes are implicated in lipid regulation in humans, hepatic inactivation of either mouse Sar1b or Surf4 selectively depletes plasma lipids to near-zero and protects the mice from atherosclerosis. These findings show that the pairing between SURF4 and SAR1B synergistically operates a specialized, dosage-sensitive transport program for circulating lipids, while further suggesting a potential translation to treat atherosclerosis and related cardio-metabolic diseases.

Electrophilic fatty acid nitroalkenes are systemically transported and distributed upon esterification to complex lipids

Electrophilic nitro-fatty acids [NO2-FAs (fatty acid nitroalkenes)] showed beneficial signaling actions in preclinical studies and safety in phase 1 clinical trials. A detailed description of the pharmacokinetics (PK) of NO2-FAs is complicated by the capability of electrophilic fatty acids to alkylate thiols reversibly and become esterified in various complex lipids, and the instability of the nitroalkene moiety during enzymatic and base hydrolysis. Herein, we report the mechanism and kinetics of absorption, metabolism, and distribution of the endogenously detectable and prototypical NO2-FA, 10-nitro-oleic acid (10-NO2-OA), in dogs after oral administration. Supported by HPLC-high-resolution-MS/MS analysis of synthetic and plasma-derived 10-NO2-OA-containing triacylglycerides (TAGs), we show that a key mechanism of NO2-FA distribution is an initial esterification into complex lipids. Quantitative analysis of plasma free and esterified lipid fractions confirmed time-dependent preferential incorporation of 10-NO2-OA into TAGs when compared with its principal metabolite, 10-nitro-stearic acid. Finally, new isomers of 10-NO2-OA were identified in vivo, and their electrophilic reactivity and metabolism characterized. Overall, we reveal that NO2-FAs display unique PK, with the principal mechanism of tissue distribution involving complex lipid esterification, which serves to shield the electrophilic character of this mediator from plasma and hepatic inactivation and thus permits efficient distribution to target organs.

Inactivating hepatic follistatin alleviates hyperglycemia.

Unsuppressed hepatic glucose production (HGP) contributes significantly to glucose intolerance and diabetes, which can be modeled by genetic inactivation of hepatic insulin receptor substrate (Irs) 1 and Irs2 (LDKO-mice). We previously showed that glucose intolerance in LDKO-mice is resolved by hepatic inactivation of the transcription factor FoxO1 (i.e., LTKO-mice)—even though the liver remains insensitive to insulin. Here, we report that insulin sensitivity in the white adipose tissue (WAT) of LDKO-mice is also impaired, but is restored in LTKO-mice in conjunction with normal suppression of HGP by insulin. To establish the mechanism by which WAT insulin signaling and HGP were regulated by hepatic FoxO1, we identified putative hepatokines—including excess follistatin (Fst)—that were dysregulated in LDKO-mice but normalized in LTKO-mice. Knockdown of hepatic Fst in the LDKO-liver restored glucose tolerance, WAT insulin signaling, and the suppression of HGP by insulin; however, expression of Fst in the liver of healthy LTKO-mice had the opposite effect. Of potential clinical significance, knockdown of Fst also improved glucose tolerance in high-fat fed obese mice, and serum FST was reduced in parallel with glycated hemoglobin in obese individuals with diabetes who underwent therapeutic gastric bypass surgery. We conclude that follistatin is a pathological hepatokine that might be targeted for diabetes therapy during hepatic insulin resistance.

The in vitro effects of a novel estradiol analog on cell proliferation and morphology in human epithelial cervical carcinoma

BackgroundThe majority of novel chemotherapeutics target the cell cycle, aiming to effect arrest and cause apoptosis. One such agent, 2-methoxyestradiol (2ME), has been shown to possess anticancer properties against numerous cancer types, both in vitro and in vivo. Despite its promise, 2ME has exhibited limitations, including low oral bioavailability and rapid hepatic enzymatic inactivation in vivo. A novel sulphamoylated estrogen analog, 2-ethyl-3-O-sulphamoyl-estra-1,3,5(10)16-tetraene (ESE-16), was in silico-designed in our laboratory to overcome these issues. It was then synthesized by a pharmaceutical company and used in an in vitro antiproliferative effect study on a human cervical carcinoma (HeLa) cell line.ResultsCell proliferation data obtained from the crystal violet assay and real-time cell analysis demonstrated that 0.2 μM of ESE-16 had a significant inhibitory effect on the HeLa cells 24 h post-exposure. Immunofluorescence showed that ESE-16 is a microtubule disruptor that causes cells to undergo a mitotic block. Qualitative morphological studies using polarization-optical transmitted light differential interference contrast (PlasDIC) and light microscopy revealed a decrease in cell density and an increase in the number of cells arrested in metaphase. After ESE-16 exposure, hallmarks of apoptosis were also observed, including membrane blebbing, chromatin condensation and the presence of apoptotic bodies. Flow cytometry provided quantitative results from cell cycle progression analysis, indicating cells undergoing apoptosis and cells in the G2/M phase of the cell cycle, confirming cell cycle arrest in metaphase after ESE-16 treatment. Quantification of the ESE-16-mediated upregulation of cyclin B in HeLa cells and spectrophotometric and flow cytometric confirmation of cell death via apoptosis further confirmed the substance’s impact.ConclusionESE-16 exerts its antiproliferative effects through microtubule disruption, which induces a mitotic block culminating in apoptosis. This research provided information on ESE-16 as a potential antitumor agent and on cellular targets that could aid in the design of prospective microtubule-disrupting compounds. Further in vitro and in vivo investigations of this novel compound are needed.

Hepatic mTORC1 Opposes Impaired Insulin Action to Control Mitochondrial Metabolism in Obesity

Dysregulated mitochondrial metabolism during hepatic insulin resistance may contribute to pathophysiologies ranging from elevated glucose production to hepatocellular oxidative stress and inflammation. Given that obesity impairs insulin action but paradoxically activates mTORC1, we tested whether insulin action and mammalian target of rapamycin complex 1 (mTORC1) contribute to altered invivo hepatic mitochondrial metabolism. Loss of hepatic insulin action for 2weeks caused increased gluconeogenesis, mitochondrial anaplerosis, tricarboxylic acid (TCA) cycle oxidation, and ketogenesis. However, activation of mTORC1, induced by the loss of hepatic Tsc1, suppressed these fluxes. Only glycogen synthesis was impaired by both loss of insulin receptor and mTORC1 activation. Mice with a double knockout of the insulin receptor and Tsc1 had larger livers, hyperglycemia, severely impaired glycogen storage, and suppressed ketogenesis, as compared to those with loss of the liver insulin receptor alone. Thus, activation of hepatic mTORC1 opposes the catabolic effects of impaired insulin action under some nutritional states.

226 The Mechanism of Hepatic Stellate Cell Inactivation During Reversal of Liver Fibrosis

226 The Mechanism of Hepatic Stellate Cell Inactivation During Reversal of Liver Fibrosis

Interplay between FGF21 and insulin action in the liver regulates metabolism

The hormone FGF21 regulates carbohydrate and lipid homeostasis as well as body weight, and increasing FGF21 improves metabolic abnormalities associated with obesity and diabetes. FGF21 is thought to act on its target tissues, including liver and adipose tissue, to improve insulin sensitivity and reduce adiposity. Here, we used mice with selective hepatic inactivation of the IR (LIRKO) to determine whether insulin sensitization in liver mediates FGF21 metabolic actions. Remarkably, hyperglycemia was completely normalized following FGF21 treatment in LIRKO mice, even though FGF21 did not reduce gluconeogenesis in these animals. Improvements in blood sugar were due in part to increased glucose uptake in brown fat, browning of white fat, and overall increased energy expenditure. These effects were preserved even after removal of the main interscapular brown fat pad. In contrast to its retained effects on reducing glucose levels, the effects of FGF21 on reducing circulating cholesterol and hepatic triglycerides and regulating the expression of key genes involved in cholesterol and lipid metabolism in liver were disrupted in LIRKO mice. Thus, FGF21 corrects hyperglycemia in diabetic mice independently of insulin action in the liver by increasing energy metabolism via activation of brown fat and browning of white fat, but intact liver insulin action is required for FGF21 to control hepatic lipid metabolism.

Oral Beclomethasone Dipropionate: A Critical Review of its Use in the Management of Ulcerative Colitis and Crohn’s Disease

Crohn's disease and ulcerative colitis are inflammatory bowel diseases characterised by a chronic relapsing course. Corticosteroids represent the mainstay of medical treatment of inflammatory bowel disease for the induction of remission. Despite the high efficacy of systemic steroids, their use is limited by the high incidence of potentially serious adverse effects. The topically acting steroids are synthetic compounds characterised by high anti-inflammatory activity and low systemic effects by virtue of efficient first-pass hepatic inactivation. Budesonide and Beclomethasone Dipropionate are the two most studied topically acting steroids in inflammatory bowel disease. Oral Budesonide has been extensively studied in the treatment of mild to moderate ileo-caecal Crohn's disease but few data are available concerning oral Beclomethasone Dipropionate. This review focuses on the available evidence of efficacy and safety of oral Beclomethasone Dipropionate in the management of ulcerative colitis and Crohn's disease and a possible role of this steroid in clinical practice is suggested.

Kupffer-cell activity is essential for thyroid hormone rat liver preconditioning

We studied the role of Kupffer cell functioning in T3 liver preconditioning against ischemia-reperfusion (IR) injury using the macrophage inactivator gadolinium chloride (GdCl3) previous to T3 treatment. Male Sprague-Dawley rats given a single i.p. dose of 0.1 mg T3/kg were subjected to 1 h ischemia followed by 20 h reperfusion, in groups of animals pretreated with 10 mg GdCl3/kg i.v. 72 h before T(3) or with the respective vehicles. IR resulted in significant enhancement of serum aspartate aminotransferase (3.3-fold increase) and tumor necrosis factor-alpha (93% increase) levels, development of liver damage, and diminished nuclear factor-kappaB DNA binding over control values. These changes, which were suppressed by the T3 administration prior to IR, persisted in animals given GdCl3 before T3 treatment, under conditions of complete elimination of ED2+ Kupffer cells achieved in a time window of 72 h. It is concluded that Kupffer cell functioning is essential for T3 liver preconditioning, assessed in a warm IR injury model by hepatic macrophage inactivation.

Quantification of cortisol inactivation in cirrhosis of the liver.

Impaired cortisol inactivation in patients with cirrhosis of the liver has been described, but precise data are limited and the pathophysiological significance of this finding has to be elucidated. Therefore, we assessed the main urinary cortisol metabolites using capillary gas chromatography and urinary free cortisol using an enzyme immunoassay in 20 consecutive patients with cirrhosis of the liver and in 28 healthy controls; ratios of cortisol inactivation were calculated (cortisol metabolites/cortisone metabolites, and sum of tetrahydrogenated cortisol metabolites/free urinary cortisol). In patients with cirrhosis free urinary cortisol was normal, whereas the sum of cortisol metabolites was significantly reduced; therefore, cortisol synthesis seems to be adequately adapted to the decreased hepatic inactivation (conjugation, ring A-reduction). A significantly reduced ratio of cortisol metabolites to cortisone metabolites indicating impaired renal 11beta-hydroxysteroid dehydrogenase activity was only found in a subgroup of patients with ascites.

Role of CYP3A enzymes in fluticasone biotransformation

Fluticasone propionate (FLU) is a synthetic, trifluorinated glucocorticoid with potent anti-inflammatory action that is commonly used in patients with asthma. After oral or intranasal administration, FLU undergoes rapid hepatic inactivation to a single metabolite, a 17β-carboxylic acid derivative (M1). M1 formation has been attributed largely to cytochrome P450 (CYP) 3A4, however, there are no published data that confirm this assertion. Hence, in vitro studies were conducted to determine the role that human CYPs play in the metabolism of FLU. Consistent with in vivo data, human liver microsomes (HLM) catalyzed the formation of a single metabolite (M1) at low substrate concentrations (<1 μM; mean plasma Cmax = 1 nM). At FLU concentrations <1 μM, the kinetics of M1 formation in HLM were consistent with those of a single enzyme (Km ≅800 nM). M1 formation correlated significantly (r>0.95) with CYP3A4/5 activities in a panel of HLM (n=14) and was markedly impaired by the CYP3A inhibitor, ketoconazole, (>94%), but not by inhibitors of other CYPs (<10%). Studies with a panel of cDNA-expressed enzymes revealed that M1 formation was catalyzed solely by CYP3A enzymes at FLU concentrations <1 μM. M1 formation was catalyzed by CYPs 3A4, 3A5 and 3A7, however CYP3A5 was ~4-fold less active than CYP3A4 or 3A7. These results suggest that at pharmacologically relevant concentrations of FLU, biotransformation of FLU to M1 is mediated predominantly by CYPs 3A4 and 3A7. Clinical Pharmacology & Therapeutics (2004) 75, P84–P84; doi: 10.1016/j.clpt.2003.11.320

Is 11β-Hydroxysteroid Dehydrogenase Type 1 a Therapeutic Target? Effects of Carbenoxolone in Lean and Obese Zucker Rats

In liver and adipose tissue, 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) regenerates glucocorticoids from inactive 11-keto metabolites. Pharmacological inhibition or transgenic disruption of 11beta-HSD1 attenuates glucocorticoid action and increases insulin sensitivity. Increased adipose 11beta-HSD1 may also contribute to the metabolic complications of obesity. Here, we examine the effects of inhibition of 11beta-HSDs with carbenoxolone in obese insulin-resistant Zucker rats, a strain in which tissue-specific dysregulation of 11beta-HSD1 (increased in adipose, decreased in liver) mirrors changes in human obesity. Six-week-old male rats were treated orally with carbenoxolone (50 mg/kg/day) or water (1 ml/kg/day) for 3 weeks. Carbenoxolone inhibited 11beta-HSD1 activity in liver (25 +/- 3 versus 52 +/- 2% conversion in lean; 18 +/- 3 versus 35 +/- 3% in obese; p < 0.01) but not in adipose tissue or skeletal muscle. Carbenoxolone had no effect on weight gain or food intake, did not affect plasma glucose during an oral glucose tolerance test, and increased the plasma insulin response to glucose. However, high-density lipoprotein cholesterol was increased by carbenoxolone in obese animals (1.52 +/- 0.24 versus 1.21 +/- 0.26 mM; p < 0.03). Carbenoxolone did not inhibit hepatic inactivation of glucocorticoid by 5beta-reductase and had no significant effect on plasma corticosterone levels. In conclusion, carbenoxolone provides a model for liver-specific inhibition of 11beta-HSD1, which results in improved lipid profile, in Zucker obese rats. Failure to inhibit 11beta-HSD1 in adipose tissue and/or skeletal muscle may explain the lack of effect on glucose tolerance and obesity. Inhibition of adipose 11beta-HSD1 is probably necessary to gain the maximum benefit of an 11beta-HSD1 inhibitor.

Safety of inhaled corticosteroids in children.

Inhaled corticosteroids (ICS) are now first-line therapy for persistent asthma in children. The major safety concerns of long-term ICS therapy for childhood asthma are potential effects on adrenal function, growth, and bone mass. Dosage, type of inhaler device, and individual drug characteristics influence systemic effects of ICS. Sensitive measures of basal adrenal function can show statistically significant changes during ICS therapy, but these do not accurately predict clinically meaningful adrenal axis suppression. Adrenal insufficiency is rare and confined to children receiving high doses of ICS. Dose-related inhibition of growth has been seen in some short- and intermediate-term studies, but long-term studies have found no detrimental effect on final height. ICS therapy has not been associated with significant changes in measurements of bone and bone biomarkers, but more studies of high doses and of therapy in adolescents are needed. Overall, although ICS are the most effective anti-inflammatory treatment available for asthma, high doses of ICS in children are still of concern. The risk of high doses is compounded in children with concomitant allergic conditions that require multiple forms of topical corticosteroids. Benefits of ICS clearly outweigh potential adverse effects and risks associated with poorly controlled asthma. Risk can be minimized by using the lowest effective ICS dose, limiting systemic availability of the drug through proper technique to minimize swallowed drug, and selection of agents with efficient first-path hepatic inactivation of swallowed drug. Adjuvant treatments can reduce the dose of ICS required for asthma control, allowing a reduction in overall systemic exposure for most children with mild-to-moderate persistent asthma. Therefore, these agents should be added to, but should not replace, ICS therapy.

Biochemical evidence of the functional recovery and regeneration of adrenal autotransplants in the rat spleen.

Adrenal transplantation may restore adrenal function after bilateral adrenalectomy or when adrenal function is lost. Thus, animal experiments could provide useful information before clinical application of adrenal transplantation. Using an experimental model of autotransplantion of a complete adrenal gland in the spleen of adrenalectomized rats, several biochemical and hormonal parameters were studied to evaluate the function of transplanted adrenal tissue compared to control and adrenalectomized animals. Three weeks after surgery, the animals were sacrificed and plasma and tissue samples were obtained for biochemical studies. In the autotransplanted rats, plasma glucose, hepatic glycogen, plasma, and hepatic proteins, which were decreased in adrenalectomized rats, increased to values close to those of the control group; whereas muscle and thymus proteins, which were increased in adrenalectomized animals, decreased and reached normal levels. Corticosterone plasma levels in autotransplanted rats showed a 50% recovery compared to control animals, whereas plasma aldosterone concentrations were low, with similar values to those of the adrenalectomized group. These results provide evidence that the adrenal grafts secrete corticosterone in quantities enough to overcome hepatic inactivation. On the other hand, aldosterone plasma concentrations remain very low, plasma potassium levels are increased, and plasma sodium levels are decreased in animals with intrasplenic adrenal grafts, indicating that aldosterone production is insufficient to avoid hypoaldosteronism.

Systemic effects of intranasal steroids: An endocrinologist’s perspective

Intranasal steroids (INSs) are established as first-line treatment for allergic rhinitis. Extensive use of INSs with few reported adverse events supports the safety of these medications. Nevertheless, the prescription of more potent INSs for consistent and more prolonged use to younger and older patients, often in combination with inhaled corticosteroids, justifies the careful examination of their potential adverse systemic effects. Systemic bioavailability of INSs, by way of nasal and intestinal absorption, can be substantial; but current INSs vary significantly in their degree of first-pass hepatic inactivation and clearance from the body of the swallowed drug. For safety studies of INSs, distinguishing detectable physiologic perturbations from important adverse events is aided by an understanding of normal endocrine physiology and the methods used to test these systems. A review of available information indicates that (1) sensitive tests can measure the effects of INSs on biologic feedback systems, but they do not accurately predict clinically relevant adverse effects; (2) the primary factors that influence the relationship between therapeutic and adverse systemic effects of INSs are dosing frequency and efficiency of hepatic inactivation of swallowed drug; (3) INS treatment in recommended doses does not cause clinically significant hypothalamic-pituitary-adrenal axis suppression; (4) growth suppression can occur with twice-daily administration of certain INSs but does not appear to occur with once-daily dosing or with agents with more complete first-pass hepatic inactivation; (5) harmful effects of INSs on bone metabolism have not yet been adequately studied but would not be expected with the use of an INS dose and dosing frequency that do not suppress basal hypothalamic-pituitary-adrenal axis function or growth; and (6) these conclusions apply to INS treatment alone and in recommended doses-the risk of adverse effects in individual patients who are treated with INSs is increased by excessive dosing or concomitant inhaled corticosteroid or other topical corticosteroid therapy. (J Allergy Clin Immunol 2000;106:S179-90.)