Early events in vascular injury in the rat induced by the phosphodiesterase IV inhibitor SCH 351591

Use of Rat Primary Mesenteric Cells for the Prediction of PDE4 Inhibitor Drug-Induced Vascular Injury

Drug-induced vascular injury (DIVI) in preclinical studies can delay, if not terminate, a drug development program. Clinical detection of DIVI can be very difficult as there are no definitive biomarkers known to reliably detect this disorder in all instances. The preclinical identification of DIVI requires detailed microscopic examination of a wide range of tissues although one of the most commonly affected areas in rats is the mesenteric vasculature. The reason for this predisposition of mesenteric arteries in rats as well as the exact mechanism and cell types involved in the initial development of these lesions have not been fully elucidated. We hypothesized that by using a mixed culture of cells from rat mesenteric tissue, we would be able to identify an RNA expression signature that could predict the invivo development of DIVI. Five compounds designed to inhibit Phosphodiesterase 4 activity (PDE4i) were chosen as positive controls. PDE4i's are well known to induce DIVI in the mesenteric vasculature of rats and there is microscopic evidence that this is associated, at least in part, with a proinflammatory mechanism. We surveyed, by qRT-PCR, the expression of 96 genes known to be involved in inflammation and using a Random-Forest model, identified 12 genes predictive of invivo DIVI outcomes in rats. Using these genes, we were able to cross-validate the ability of the Random-Forest modeling to predict the concentration at which PDE4i caused DIVI invivo.

Natural product HTP screening for attenuation of cytokine-induced neutrophil chemo attractants (CINCs) and NO2- in LPS/IFNγ activated glioma cells

Chronic and acute central nervous system (CNS) inflammation are contributors toward neurological injury associated with head trauma, stroke, infection, Parkinsons or Alzheimers disease. CNS inflammatory illnesses can also contribute toward risk of developing glioblastoma multiforme (GBM). With growing public interest in complementary and alternative medicines (CAMs), we conduct a high throughput (HTP) screening of >1400 natural herbs, plants and over the counter (OTC) products for anti-inflammatory effects on lipopolysaccharide (LPS)/interferon gamma (IFNγ) activated C6 glioma cells. Validation studies were performed showing a pro-inflammatory profile of [LPS 3 µg/ml/ IFNγ 3 ng/ml] consistent with greater release [>8.5 fold] of MCP-1, NO2-, cytokine-induced neutrophil chemo-attractants (CINC) 1, CINC 2a and CINC3. The data show no changes to the following, IL-13, TNF-a, fracktaline, leptin, LIX, GM-CSF, ICAM1, L-Selectin, activin A, agrin, IL-1α, MIP-3a, B72/CD86, NGF, IL-1b, MMP-8, IL-1 R6, PDGF-AA, IL-2, IL-4, prolactin R, RAGE, IL-6, Thymus Chemokine-1, CNTF,IL-10 or TIMP-1. A HTP screening was conducted, where we employ an in vitro efficacy index (iEI) defined as the ratio of toxicity (LC₅₀)/anti-inflammatory potency (IC₅₀). The iEI was precautionary to ensure biological effects were occurring in fully viable cells (ratio > 3.8) independent of toxicity. Using NO2- as a guideline molecule, the data show that 1.77% (25 of 1410 tested) had anti-inflammatory effects with iEI ratios >3.8 and IC₅₀s <250µg/ml. These include reference drugs (hydrocortisone, dexamethasone N6-(1-iminoethyl)-l-lysine and NSAIDS: diclofenac, tolfenamic acid), a histone deacetylase inhibitor (apicidin) and the following natural products; Ashwaganda (Withania somnifera), Elecampagne Root (Inula helenium), Feverfew (Tanacetum parthenium), Green Tea (Camellia sinensis), Turmeric Root (Curcuma longa) Ganthoda (Valeriana wallichii), Tansy (Tanacetum vulgare), Maddar Root (Rubia tinctoria), Red Sandle wood (Pterocarpus santalinus), Bay Leaf (Laurus nobilis, Lauraceae), quercetin, cardamonin, fisetin, EGCG, biochanin A, galangin, apigenin and curcumin. The herb with the largest iEI was Ashwaganda where the IC₅₀/LC₅₀ was 11.1/>1750.0μg/ml, and the compound with the greatest iEI was quercetin where the IC₅₀/LC₅₀ was 10.0/>363.6μg/ml. These substances also downregulate the production of iNOS expression and attenuate CINC-3 release. In summary, this HTP screening provides guideline information about the efficacy of natural products that could prevent inflammatory processes associated with neurodegenerative disease and aggressive glioma tumor growth.

Sampling the Rat Mesenteric Artery

Vascular injury can be induced by different classes of drug candidates, and it can affect the mesenteric vasculature. Sampling of the mesenteric vessels in the rat is crucial for proper assessment of potential adverse or pharmacologic effects of drugs in nonclinical rodent studies. To date, several sampling and processing techniques for the histopathologic evaluation of the mesenteric artery in rodents have been described and used in studies with candidate drugs that may affect the vascular system. However, most of those techniques require a significant amount of time and effort. A less labor-intensive, time-consuming, and expensive technique that allows examination of the mesentery vasculature with abundant longitudinal and cross sections of the vessels when examined microscopically was developed and presented here.

An in vivo and in vitro study: High-dosage Danshen injection induces peripheral vascular endothelial cells injury

Danshen injection, a pharmaceutical dosage form of Danshen, has been widely used in the treatment of coronary heart diseases, myocardial infarction, and hypertension. With more and more adverse drug reactions linked with Danshen injection, its safety comes under suspicion. To evaluate its safety, mice were divided into four groups: vehicle, low-, middle-, and high-Danshen group, and each group was intravenously administered with Danshen injection at a dose of 0, 0.64, 1.55, and 5.76 g/kg/day for 5 days, respectively (the low dosage was the recommended clinical dosage, the middle dosage was the most commonly used higher dosage, and the high dosage was the highest dosage used in clinic). Peripheral vascular toxicity wasn't observed in the low-dosage group, elevated serum endothelin-1 (ET-1) was observed in the middle-dosage group; and more peripheral vascular toxicities like increased vascular leakage, elevated serum nitrate and ET-1, and vascular endothelial cells apoptosis were detected in the high-dosage group. In vitro study, low-concentration Danshen injection showed protective effect to human umbilical vein endothelial cells (HUVECs), while high concentration displayed strong cytotoxic effects, including increase in nitric oxide and ET-1 production, inhibition of cell viability, and apoptosis induction. Further, the HUVECs' apoptosis induced by high-concentration Danshen injection was found along with the induction of reactive oxygen species. In conclusion, these results suggest that Danshen injection is nontoxic in its recommended clinical dosage, and the 2.4-fold as the recommended clinical dosage might be the highest safety dosage in clinic treatment. In addition, Danshen injection is a potential vascular toxic drug in its high dosage and shouldn't be used far beyond its recommended dosage in clinic treatment.

Scientific and Regulatory Policy Committee Points-to-consider Paper*

Drug-induced vascular injury (DIVI) is a recurrent challenge in the development of novel pharmaceutical agents. Although DIVI in laboratory animal species has been well characterized for vasoactive small molecules, there is little available information regarding DIVI associated with biotherapeutics such as peptides/proteins or antibodies. Because of the uncertainty about whether DIVI in preclinical studies is predictive of effects in humans and the lack of robust biomarkers of DIVI, preclinical DIVI findings can cause considerable delays in or even halt development of promising new drugs. This review discusses standard terminology, characteristics, and mechanisms of DIVI associated with biotherapeutics. Guidance and points to consider for the toxicologist and pathologist facing preclinical cases of biotherapeutic-related DIVI are outlined, and examples of regulatory feedback for each of the mechanistic types of DIVI are included to provide insight into risk assessment.

Proceedings of the 2014 National Toxicology Program Satellite Symposium

The 2014 annual National Toxicology Program (NTP) Satellite Symposium, entitled "Pathology Potpourri" was held in Washington, D.C., in advance of the Society of Toxicologic Pathology's 33rd annual meeting. The goal of this annual NTP Symposium is to present current diagnostic pathology or nomenclature issues to the toxicologic pathology community. This article presents summaries of the speakers' presentations, including diagnostic or nomenclature issues that were presented, along with select images that were used for audience voting and discussion. Some lesions and topics covered during the symposium included a pulmonary mucinous adenocarcinoma in a male B6C3F1 mouse; plexiform vasculopathy in Wistar Han (Crl:WI[Han]) rats; staging of the estrous cycle in rats and mice; peri-islet fibrosis, hemorrhage, lobular atrophy and inflammation in male Sprague-Dawley (SD) rats; retinal dysplasia in Crl:WI[Han] rats and B6C3F1 mice; multicentric lymphoma with intravascular microemboli and tumor lysis syndrome, and 2 cases of myopathy and vascular anomaly in Tg.rasH2 mice; benign thymomas in Crl:WI[Han] rats; angiomatous lesions in the mesenteric lymph nodes of Crl:WI[Han] rats; an unusual foveal lesion in a cynomolgous monkey; and finally a series of nomenclatures challenges from the endocrine International Harmonization of Nomenclature and Diagnostic Criteria (INHAND) Organ Working Group (OWG).

Nonclinical Safety Biomarkers of Drug-induced Vascular Injury

Better biomarkers are needed to identify, characterize, and/or monitor drug-induced vascular injury (DIVI) in nonclinical species and patients. The Predictive Safety Testing Consortium (PSTC), a precompetitive collaboration of pharmaceutical companies and the U.S. Food and Drug Administration (FDA), formed the Vascular Injury Working Group (VIWG) to develop and qualify translatable biomarkers of DIVI. The VIWG focused its research on acute DIVI because early detection for clinical and nonclinical safety monitoring is desirable. The VIWG developed a strategy based on the premise that biomarkers of DIVI in rat would be translatable to humans due to the morphologic similarity of vascular injury between species regardless of mechanism. The histomorphologic lexicon for DIVI in rat defines degenerative and adaptive findings of the vascular endothelium and smooth muscles, and characterizes inflammatory components. We describe the mechanisms of these changes and their associations with candidate biomarkers for which advanced analytical method validation was completed. Further development is recommended for circulating microRNAs, endothelial microparticles, and imaging techniques. Recommendations for sample collection and processing, analytical methods, and confirmation of target localization using immunohistochemistry and in situ hybridization are described. The methods described are anticipated to aid in the identification and qualification of translational biomarkers for DIVI.

Translation Strategy for the Qualification of Drug-induced Vascular Injury Biomarkers

Drug-induced vascular injury (DIVI) is a common preclinical toxicity usually characterized by hemorrhage, vascular endothelial and smooth muscle damage, and inflammation. DIVI findings can cause delays or termination of drug candidates due to low safety margins. The situation is complicated by the absence of sensitive, noninvasive biomarkers for monitoring vascular injury and the uncertain relevance to humans. The Safer And Faster Evidence-based Translation (SAFE-T) consortium is a public–private partnership funded within the European Commission’s Innovative Medicines Initiative (IMI) aiming to accelerate drug development by qualifying biomarkers for drug-induced organ injuries, including DIVI. The group is using patients with vascular diseases that have key histomorphologic features (endothelial damage, smooth muscle damage, and inflammation) in common with those observed in DIVI, and has selected candidate biomarkers associated with these features. Studied populations include healthy volunteers, patients with spontaneous vasculitides and other vascular disorders. Initial results from studies with healthy volunteers and patients with vasculitides show that a panel of biomarkers can successfully discriminate the population groups. The SAFE-T group plans to seek endorsement from health authorities (European Medicines Agency and Food and Drug Administration) to qualify the biomarkers for use in regulatory decision-making processes.

The role of eNOS phosphorylation in causing drug-induced vascular injury

Previously we found that regulation of eNOS is an important part of the pathogenic process of Drug-induced vascular injury (DIVI) for PDE4i. The aims of the current study were to examine the phosphorylation of eNOS in mesentery versus aorta at known regulatory sites across DIVI-inducing drug classes and to compare changes across species. We found that phosphorylation at S615 in rats was elevated 35-fold 2 hr after the last dose of CI-1044 in mesentery versus 3-fold in aorta. Immunoprecipitation studies revealed that many of the upstream regulators of eNOS activation were associated with eNOS in 1 or more signalosome complexes. Next rats were treated with drugs from 4 other classes known to cause DIVI. Each drug was given alone and in combination with SIN-1 (NO donor) or L-NAME (eNOS inhibitor), and the level of eNOS phosphorylation in mesentery and aorta tissue was correlated with the extent of vascular injury and measured serum nitrite. Drugs or combinations produced altered serum nitrite levels as well as vascular injury score in the mesentery. The results suggested that phosphorylation of S615 may be associated with DIVI activity. Studies with the species-specific A2A adenosine agonist CI-947 in rats versus primates showed a similar pattern.