STP position paper: best practice guideline for the routine pathology evaluation of the immune system

Intermittent rapamycin feeding recapitulates some effects of continuous treatment while maintaining lifespan extension

OBJECTIVE

Rapamycin, a powerful geroprotective drug, can have detrimental effects when administered chronically. We determined whether intermittent treatment of mice can reduce negative effects while maintaining benefits of chronic treatment.

METHODS

From 6 months of age, male and female C3B6F1 hybrid mice were either continuously fed with 42 mg/kg rapamycin, or intermittently fed by alternating weekly feeding of 42 mg/kg rapamycin food with weekly control feeding. Survival of these mice compared to control animals was measured. Furthermore, longitudinal phenotyping including metabolic (body composition, GTT, ITT, indirect calorimetry) and fitness phenotypes (treadmil, rotarod, electrocardiography and open field) was performed. Organ specific pathology was assessed at 24 months of age.

RESULTS

Chronic rapamycin treatment induced glucose intolerance, which was partially ameliorated by intermittent treatment. Chronic and intermittent rapamycin treatments increased lifespan equally in males, while in females chronic treatment resulted in slightly higher survival. The two treatments had equivalent effects on testicular degeneration, heart fibrosis and liver lipidosis. In males, the two treatment regimes led to a similar increase in motor coordination, heart rate and Q-T interval, and reduction in spleen weight, while in females, they equally reduced BAT inflammation and spleen weight and maintained heart rate and Q-T interval. However, other health parameters, including age related pathologies, were better prevented by continuous treatment.

CONCLUSIONS

Intermittent rapamycin treatment is effective in prolonging lifespan and reduces some side-effects of chronic treatment, but chronic treatment is more beneficial to healthspan.

Twelve-month in utero safety assessment of gardenia blue, a natural food colorant

Toxicity assessment of the food colorant Gardenia jasminoides Ellis at dietary exposures of 0.0%, 0.1%, 0.5%, 1.5%, 3.0% and 5.0% included measures of T-cell- dependent antibody response, neurotoxicity, and clinical and anatomic pathology in Sprague Dawley rats during mating, gestation, lactation, postnatal development, and following weaning for up to 12 months including 3- and 6-month interim evaluations. Blue coloration of the gastrointestinal tract, mesenteric lymph nodes and kidneys was present in treated rats only at necropsy with minimal blue coloration at the lowest dose and without histopathological correlates in any of the tissues. There was good survival with no consistent treatment-related changes in hematology, clinical chemistry, enhanced evaluation of lymphoid tissues, or tissue histopathology at interim and final time points. T-cell dependent antibody response and neurotoxicity screening were negative in treated rats. The no-observed-adverse-effect level (NOAEL) was determined to be 5.0% gardenia blue (2,854.5 and 3,465.4 mg/kg/day in parental males and females, respectively, prior to mating; 3,113.5 and 4,049.6 mg/kg/day in male and female offspring, respectively, following up to 12 months of exposure.

Chronic toxicity and carcinogenicity study of dietary gardenia blue in Sprague Dawley rats

In this combined chronic toxicity/carcinogenicity study of gardenia blue as a natural food color additive, Sprague Dawley rats were administered 0.5%, 2.5%, or 5.0% gardenia blue via the feed or carrier diet (0.0% gardenia blue) for 12 (chronic toxicity cohort) or 24 (carcinogenicity cohort) months. No abnormal clinical, ophthalmological, neurotoxicity or clinical pathology changes were attributed to treatment, and there was no increase in mortality due to gardenia blue exposure. The only treatment-related change was grossly observed blue discoloration of the stomach, intestines, and mesenteric lymph nodes as well as reversible dark discoloration of the kidneys all without associated histopathology. The no-observed-adverse-effect level (NOAEL) for gardenia blue exposure via the diet for one or two years was determined to be 5.0% (2175.3 mg/kg body weight/day in male rats and 3075.4 mg/kg body weight/day in female rats).

Effect of zinc supplementation on immunotoxicity induced by subchronic oral exposure to glyphosate-based herbicide (GOBARA®) in Wistar rats

OBJECTIVES

To evaluate the effect of zinc supplementation on immunotoxicity induced by subchronic oral exposure to glyphosate-based herbicide (GBH).

METHODS

Sixty adult male Wistar rats randomly divided equally into six groups were exposed to GBH by gavage daily for 16 weeks with or without zinc pretreatment. Group DW rats received distilled water (2 mL/kg), group Z rats received zinc (50 mg/kg), and group G1 and G2 rats received 187.5 and 375 mg/kg GBH, respectively. Group ZG1 and ZG2 rats were pretreated with 50 mg/kg zinc before exposure to 187.5 and 375 mg/kg GBH, respectively. Tumor necrosis factor alpha (TNF-α) and immunoglobulin (IgG, IgM, IgE) levels were measured by enzyme-linked immunosorbent assay. Spleen, submandibular lymph node, and thymus samples were processed for histopathology.

RESULTS

Exposure to GBH (G1 and G2) significantly increased serum TNF-α concentrations and significantly decreased serum IgG and IgM concentrations compared with the control levels. Moderate-to-severe lymphocyte depletion occurred in the spleen, lymph nodes, and thymus in the GBH-exposed groups. Zinc supplementation mitigated the immunotoxic effects of GBH exposure.

CONCLUSIONS

GBH exposure increased pro-inflammatory cytokine responses, decreased immunoglobulin production, and depleted lymphocytes in lymphoid organs in rats, but zinc supplementation mitigated this immunotoxicity.

Ameliorative Effects of Bovine Lactoferrin on Benzene-Induced Hematotoxicity in Albino Rats

Benzene (Bz) is one of the major products of the petrochemical industry globally, which induces aplastic anemia and leukemia in humans and animals. This study aimed to investigate the modulatory effects of bovine lactoferrin (bLf) on Bz-induced hematotoxicity in albino rats. Eighty male rats were randomly divided into eight groups: corn oil group [2 mL/kg body weight (BW)], bLf groups (100, 200, and 300 mg/kg BW), Bz group (Bz 2 mL/kg BW; corn oil 2 mL/kg BW), and Bz + bLf groups (Bz 2 mL/kg BW; corn oil 2 mL/kg BW; bLf 100, 200, and 300 mg/kg BW). Hematobiochemical results exhibited marked pancytopenia, a significant decrease in total protein, albumin, α2- and γ-globulin, ferritin, serum iron, and total iron-binding capacity (TIBC), and an increase in serum bioactivities of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase (ALP), lactate dehydrogenase (LDH), and erythropoietin hormone levels in Bz-treated rats. Histopathological examination revealed a marked reduction in all hematopoietic cell lines in the bone marrow (BM), necrosis in the white pulp of the spleen and cytosolic hydrops, and apoptosis of hepatocytes in the Bz-treated group. Rats treated with bLf (300 mg/kg BW) revealed marked increases in total protein, albumin, α2- and γ-globulin, ferritin, serum iron, and TIBC levels and decreases both in ALP and LDH bioactivities and erythropoietin hormone levels compared with the Bz-treated group. Histopathological results were concomitant with hematobiochemical parameters in rats treated with bLf (300 mg/kg BW), almost showing restoration of the normal cellularity of BM, the architecture of red and white pulps of the spleen, and even the normal hypertrophy of hepatocytes compared with the control groups. To conclude, bLf (300 mg/kg BW) can be recommended to treat Bz-induced hematotoxicity.

Preclinical Activity and Pharmacokinetic/Pharmacodynamic Relationship for a Series of Novel Benzenesulfonamide Perforin Inhibitors

Perforin is a key effector of lymphocyte-mediated cell death pathways and contributes to transplant rejection of immunologically mismatched grafts. We have developed a novel series of benzenesulfonamide (BZS) inhibitors of perforin that can mitigate graft rejection during allogeneic bone marrow/stem cell transplantation. Eight such perforin inhibitors were tested for their murine pharmacokinetics, plasma protein binding, and their ability to block perforin-mediated lysis in vitro and to block the rejection of major histocompatibility complex (MHC)-mismatched mouse bone marrow cells. All compounds showed >99% binding to plasma proteins and demonstrated perforin inhibitory activity in vitro and in vivo. A lead compound, compound 1, that showed significant increases in allogeneic bone marrow preservation was evaluated for its plasma pharmacokinetics and in vivo efficacy at multiple dosing regimens to establish a pharmacokinetic/pharmacodynamic (PK/PD) relationship. The strongest PK/PD correlation was observed between perforin inhibition in vivo and time that total plasma concentrations remained above 900 μM, which correlates to unbound concentrations similar to 3× the unbound in vitro IC₉₀ of compound 1. This PK/PD relationship will inform future dosing strategies of BZS perforin inhibitors to maintain concentrations above 3× the unbound IC₉₀ for as long as possible to maximize efficacy and enhance progression toward clinical evaluation.

Effect of Bacillus subtilis on the microarchitectural development of the immune system in Salmonella-challenged broiler chickens

The effect of Bacillus subtilis on the immune responses and morphometry of the immune organs was evaluated in broilers challenged with S. gallinarum. For this purpose, Salmonella-free birds (n = 240) were split into four groups with six replicates of ten birds each. Groups included an NC (negative control, non-infected + non-medicated), a PC-S (positive control, Salmonella-infected + non-medicated), an AT-S (Salmonella-infected + medicated with enrofloxacin), and a BS-S (Salmonella-infected + B. subtilis (2.0 × 1010 cfu/g; 0.1 g/kg) group. On day 21, the thickness of the thymus cortex and medulla, germinal centre area of the spleen, bursal follicular length and bursal follicular area increased (P < 0.05) in the BS-S when compared to the NC and PC-S groups. On day 35, the BS-S group exhibited a higher (P < 0.05) antibody titre against the Newcastle disease virus (NDV), and cortex of the thymus was thicker (P < 0.05) compared to the other groups. A decrease in the thymus medulla thickness, germinal area of the spleen and bursal follicular number were noted in the PC-S group when compared to the other treatment groups. In conclusion, the prophylactic use of B. subtilis type probiotics alleviated the stress resulting from a Salmonella gallinarum infection and improved the immune organs development and function in infected broilers.

Novel Nanoparticle-Based Cancer Treatment, Effectively Inhibits Lung Metastases and Improves Survival in a Murine Breast Cancer Model

Sarah Nanoparticles (SaNPs) are unique multicore iron oxide-based nanoparticles, developed for the treatment of advanced cancer, following standard care, through the selective delivery of thermal energy to malignant cells upon exposure to an alternating magnetic field. For their therapeutic effect, SaNPs need to accumulate in the tumor. Since the potential accumulation and associated toxicity in normal tissues are an important risk consideration, biodistribution and toxicity were assessed in naïve BALB/c mice. Therapeutic efficacy and the effect on survival were investigated in the 4T1 murine model of metastatic breast cancer. Toxicity evaluation at various timepoints did not reveal any abnormal clinical signs, evidence of alterations in organ function, nor histopathologic adverse target organ toxicity, even after a follow up period of 25 weeks, confirming the safety of SaNP use. The biodistribution evaluation, following SaNP administration, indicated that SaNPs accumulate mainly in the liver and spleen. A comprehensive pharmacokinetics evaluation, demonstrated that the total percentage of SaNPs that accumulated in the blood and vital organs was ~78%, 46%, and 36% after 4, 13, and 25 weeks, respectively, suggesting a time-dependent clearance from the body. Efficacy studies in mice bearing 4T1 metastatic tumors revealed a 49.6% and 70% reduction in the number of lung metastases and their relative size, respectively, in treated vs. control mice, accompanied by a decrease in tumor cell viability in response to treatment. Moreover, SaNP treatment followed by alternating magnetic field exposure significantly improved the survival rate of treated mice compared to the controls. The median survival time was 29 ± 3.8 days in the treated group vs. 21.6 ± 4.9 days in the control, p-value 0.029. These assessments open new avenues for generating SaNPs and alternating magnetic field application as a potential novel therapeutic modality for metastatic cancer patients.

International Harmonization of Nomenclature and Diagnostic Criteria (INHAND): Non-proliferative and Proliferative Lesions of the Non-human Primate (M. fascicularis)

The INHAND (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions Project (www.toxpath.org/inhand.asp) is a joint initiative of the Societies of Toxicologic Pathology from Europe (ESTP), Great Britain (BSTP), Japan (JSTP) and North America (STP) to develop an internationally accepted nomenclature for proliferative and nonproliferative lesions in laboratory animals. The purpose of this publication is to provide a standardized nomenclature for classifying microscopic lesions observed in most tissues and organs from the nonhuman primate used in nonclinical safety studies. Some of the lesions are illustrated by color photomicrographs. The standardized nomenclature presented in this document is also available electronically on the internet (http://www.goreni.org/). Sources of material included histopathology databases from government, academia, and industrial laboratories throughout the world. Content includes spontaneous lesions as well as lesions induced by exposure to test materials. Relevant infectious and parasitic lesions are included as well. A widely accepted and utilized international harmonization of nomenclature for lesions in laboratory animals will provide a common language among regulatory and scientific research organizations in different countries and increase and enrich international exchanges of information among toxicologists and pathologists.

International Harmonization of Nomenclature and Diagnostic Criteria (INHAND): Nonproliferative and Proliferative Lesions of the Minipig

The INHAND (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions) Project (www.toxpath.org/inhand.asp) is a joint initiative of the Societies of Toxicologic Pathology from Europe (ESTP), Great Britain (BSTP), Japan (JSTP), and North America (STP) to develop an internationally accepted nomenclature for proliferative and nonproliferative lesions in laboratory animals. The purpose of this publication is to provide a standardized nomenclature for classifying microscopic lesions observed in most tissues and organs from the minipig used in nonclinical safety studies. Some of the lesions are illustrated by color photomicrographs. The standardized nomenclature presented in this document is also available electronically on the internet (http://www.goreni.org/). Sources of material included histopathology databases from government, academia, and industrial laboratories throughout the world. Content includes spontaneous lesions as well as lesions induced by exposure to test materials. Relevant infectious and parasitic lesions are included as well. A widely accepted and utilized international harmonization of nomenclature for lesions in laboratory animals will provide a common language among regulatory and scientific research organizations in different countries and increase and enrich international exchanges of information among toxicologists and pathologists.

International Harmonization of Nomenclature and Diagnostic Criteria (INHAND): Nonproliferative and Proliferative Lesions of the Dog

The INHAND (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions) Project (www.toxpath.org/inhand.asp) is a joint initiative of the societies of toxicologic Pathology from Europe (ESTP), Great Britain (BSTP), Japan (JSTP), and North America (STP) to develop an internationally accepted nomenclature for proliferative and nonproliferative lesions in laboratory animals. The purpose of this publication is to provide a standardized nomenclature for classifying lesions observed in most tissues and organs from the dog used in nonclinical safety studies. Some of the lesions are illustrated by color photomicrographs. The standardized nomenclature presented in this document is also available electronically on the internet (http://www.goreni.org/). Sources of material included histopathology databases from government, academia, and industrial laboratories throughout the world. Content includes spontaneous lesions, lesions induced by exposure to test materials, and relevant infectious and parasitic lesions. A widely accepted and utilized international harmonization of nomenclature for lesions in laboratory animals will provide a common language among regulatory and scientific research organizations in different countries and increase and enrich international exchanges of information among toxicologists and pathologists.

A one-generation reproductive toxicity study of the mycotoxin ochratoxin A in Fischer rats

Ochratoxin A (OTA) is a mycotoxin produced by Aspergillus and Penicillium molds. Grain-based foods account for most human dietary exposures to OTA. OTA is a teratogen, but its reproductive and developmental effects are poorly understood. A one-generation reproductive toxicity study was conducted with groups of 16 male and 16 female Fischer rats exposed to 0, 0.026, 0.064, 0.16, 0.4 or 1.0 mg OTA/kg in diet. Dams exposed to 1.0 mg OTA/kg diet had statistically significant F1 pup losses between implantation and postnatal day (PND 4). Delays in preputial separation (PPS) and vaginal opening (VO) were indicative of delayed puberty in F1 rats. Mild renal lesions in nursing pups indicated that exposure prior to weaning impacted the kidneys. The developing kidney was more susceptible to OTA than the adult kidney. Significant increases in multi-oocyte follicles (MOFs) and proportional changes in resting and growing follicles were observed in F1 female ovaries. Plasma testosterone was reduced in F0 males, and there were negative effects on sperm quality in F0 and F1 male rats. The results confirm that continuous dietary exposure to OTA causes post-implantation fetotoxicity in dams, and renal and reproductive toxicity in their male and female offspring.

The sentinel node invasion level (SNIL) as a prognostic parameter in melanoma

Sentinel lymph node (SN) tumor burden is becoming increasingly important and is likely to be included in future N classifications in melanoma. Our aim was to investigate the prognostic significance of melanoma infiltration of various anatomically defined lymph node substructures. This retrospective cohort study included 1250 consecutive patients with SN biopsy. The pathology protocol required description of metastatic infiltration of each of the following lymph node substructures: intracapsular lymph vessels, subcapsular and transverse sinuses, cortex, paracortex, medulla, and capsule. Within the SN with the highest tumor burden, the SN invasion level (SNIL) was defined as follows: SNIL 1 = melanoma cells confined to intracapsular lymph vessels, subcapsular or transverse sinuses; SNIL 2 = melanoma infiltrating the cortex or paracortex; SNIL 3 = melanoma infiltrating the medulla or capsule. We classified 338 SN-positive patients according to the non-metric SNIL. Using Kaplan-Meier estimates and Cox models, recurrence-free survival (RFS), melanoma-specific survival (MSS) and nodal basin recurrence rates were analyzed. The median follow-up time was 75 months. The SNIL divided the SN-positive population into three groups with significantly different RFS, MSS, and nodal basin recurrence probabilities. The MSS of patients with SNIL 1 was virtually identical to that of SN-negative patients, whereas outgrowth of the metastasis from the parenchyma into the fibrous capsule or the medulla of the lymph node indicated a very poor prognosis. Thus, the SNIL may help to better assess the benefit-risk ratio of adjuvant therapies in patients with different SN metastasis patterns.

The Key Characteristics of Carcinogens: Relationship to the Hallmarks of Cancer, Relevant Biomarkers, and Assays to Measure Them

The key characteristics (KC) of human carcinogens provide a uniform approach to evaluating mechanistic evidence in cancer hazard identification. Refinements to the approach were requested by organizations and individuals applying the KCs. We assembled an expert committee with knowledge of carcinogenesis and experience in applying the KCs in cancer hazard identification. We leveraged this expertise and examined the literature to more clearly describe each KC, identify current and emerging assays and in vivo biomarkers that can be used to measure them, and make recommendations for future assay development. We found that the KCs are clearly distinct from the Hallmarks of Cancer, that interrelationships among the KCs can be leveraged to strengthen the KC approach (and an understanding of environmental carcinogenesis), and that the KC approach is applicable to the systematic evaluation of a broad range of potential cancer hazards in vivo and in vitro We identified gaps in coverage of the KCs by current assays. Future efforts should expand the breadth, specificity, and sensitivity of validated assays and biomarkers that can measure the 10 KCs. Refinement of the KC approach will enhance and accelerate carcinogen identification, a first step in cancer prevention.See all articles in this CEBP Focus section, "Environmental Carcinogenesis: Pathways to Prevention."

Comparison of tris(2-ethylhexyl) phosphate and di(2-ethylhexyl) phosphoric acid toxicities in a rat 28-day oral exposure study

Tris(2-ethylhexyl) phosphate (TEHP, CAS no. 78-42-2) is a plasticizer and a flame retardant, while di(2-ethylhexyl) phosphoric acid (DEHPA, CAS no. 298-07-7) is an oil additive and extraction solvent. Publicly-available information on repeated exposure to these two related organophosphate compounds is fragmentary. Hence, adult male and female Fischer rats were exposed to TEHP (300, 1000 and 3000 mg/kg body weight [BW]/day) or DEHPA (20, 60 and 180 mg/kg BW/day) by gavage for 28 consecutive days, to assess and compare their toxicities. Although significantly impaired BW gains and evidence of TEHP enzymatic hydrolysis to DEHPA were observed only in males, exposures to the highest TEHP and DEHPA doses often resulted in similar alterations of hematology, serum clinical chemistry and liver enzymatic activities in both males and females. The squamous epithelial hyperplasia and hyperkeratosis observed in the non-glandular forestomach of rats exposed to the middle and high DEHPA doses were most likely caused by the slightly corrosive nature of this chemical. Although tubular degeneration and spermatid retention were observed only in the testes of males exposed to the highest TEHP dose, numerous periodic acid-Schiff stained crystalline inclusions were observed in testis interstitial cells at all TEHP dose levels. No-observed-adverse-effect levels for TEHP and DEHPA are proposed, but the lower serum pituitary hormone levels resulting from TEHP and DEHPA exposures and the perturbations of testicular histology observed in TEHP-treated males deserve further investigation. Improved characterization of the toxicity of flame retardants will contribute to better informed substitution choices for legacy flame retardants phased-out over health concerns.

Genotoxicity and subchronic toxicological study of a novel ginsenoside derivative 25-OCH3-PPD in beagle dogs

Background

Ginsenosides have been widely used clinically for many years and were regarded as very safe. However, a few researches on the toxicities of these kinds of agents showed that some ginsenosides may have side-effect on the rats or dogs. So it is extremely necessary to further clarify the potential toxicity of ginsenosides. This study was carried out to investigate long-term toxicity and genotoxicity of 25-methoxydammarane-3, 12, 20-triol (25-OCH₃-PPD), a new derivative of ginsenoside, in beagle dogs.

Methods

Twenty-four beagle dogs were divided randomly into four treatment groups and repeatedly orally administered with 25-OCH₃-PPD capsule at 60, 120, and 240 mg/kg/day for 91 consecutive days. Ames, micronucleus, and chromosomal aberration tests were established to analyze the possible genotoxicity of 25-OCH₃-PPD.

Results

There was no 25-OCH₃-PPD–induced systemic toxicity in beagle dogs at any doses. The level of 25-OCH₃-PPD at which no adverse effects were observed was found to be 240 mg/kg/day. The result of Ames test showed that there was no significant increase in the number of revertant colonies of 25-OCH₃-PPD administrated groups compared to the vehicle control group. There were also no significant differences between 25-OCH₃-PPD administrated groups at all dose levels and negative group in the micronucleus test and chromosomal aberration assay.

Conclusion

The highest dose level of 25-OCH₃-PPD at which no adverse effects were observed was found to be 240 mg/kg per day, and it is not a genotoxic agent either in somatic cells or germs cells. 25-OCH₃-PPD is an extremely safe candidate compound for antitumor treatment.

Scientific and Regulatory Policy Committee Points to Consider*: Approaches to the Conduct and Interpretation of Vaccine Safety Studies for Clinical and Anatomic Pathologists

The design and execution of toxicology studies supporting vaccine development have some unique considerations relative to those supporting traditional small molecules and biologics. A working group of the Society of Toxicologic Pathology Scientific and Regulatory Policy Committee conducted a review of the scientific, technical, and regulatory considerations for veterinary pathologists and toxicologists related to the design and evaluation of regulatory toxicology studies supporting vaccine clinical trials. Much of the information in this document focuses on the development of prophylactic vaccines for infectious agents. Many of these considerations also apply to therapeutic vaccine development (such as vaccines directed against cancer epitopes); important differences will be identified in various sections as appropriate. The topics addressed in this Points to Consider article include regulatory guidelines for nonclinical vaccine studies, study design (including species selection), technical considerations in dosing and injection site collection, study end point evaluation, and data interpretation. The intent of this publication is to share learnings related to nonclinical studies to support vaccine development to help others as they move into this therapeutic area. [Box: see text].

Strain differences in histopathological features of lymphoid tissues of SD and F344 rats in a T cell-dependent antibody response assay of cyclophosphamide

When conducting histopathological evaluation of lymphoid tissues, it is necessary to know the variability and strain differences in histological features of different sites of lymphoid tissues. To investigate in detail the variability of lymphoid tissues and strain differences of control rats as well as those of immune reactivity and sensitivity to immunosuppression, we performed a histopathological analysis of various lymphoid tissues in conjunction with the evaluation of immune function in a T cell-dependent antibody response (TDAR) assay with cyclophosphamide (CP) in Sprague Dawley (SD) and F344 rats. Six-week-old male SD and F344 rats were orally treated with CP at 0 (control) or 4 mg/kg/day for 28 days; keyhole limpet hemocyanin (KLH) was introduced intravenously on Days 14 and 23, and the serum concentrations of anti-KLH antibodies were measured. HE staining and immunohistochemistry for T-cell (CD3) and B-cell (CD45RA) markers were performed using tissues from the spleen, thymus, and various lymph nodes. In CP-treated rats of both strains, decreased concentrations of anti-KLH antibodies were observed. Histopathological analysis revealed decreased lymphocytes mainly in the B-cell area, and these changes induced by CP treatment were more prominent in the F344 rats than in the SD rats. The present study also demonstrated that some of the lymphoid tissues of the control F344 rats were less developed than those of the control SD rats, suggesting that F344 rats might be easily affected by CP-induced immunosuppression. This information concerning rat strain differences in lymphoid tissues will be useful in histopathological evaluation for drug-induced immunotoxicity.

Enhanced Histopathology Evaluation of Lymphoid Organs

Enhanced histopathology is a tool that the pathologist can use as a screening test to identify immunomodulatory compounds. This assessment is based on the assumption that chemically induced alterations may result in qualitative or quantitative changes in the histology of the lymphoid organs. It involves the histological evaluation of various lymphoid organs and their respective tissue compartments to identify specific cellular and architectural changes. Although this methodology cannot directly measure immune function, it does have the potential to determine whether or not a specific chemical causes suppression or enhancement of the immune system. As with all screening tests, evaluation of and comparison with control tissues are crucial in order to establish the range of normal tissue changes for a particular group of animals. Laboratory animals include species other than rat and mouse; therefore, recognition of species differences in the structure and function of the immune system should be noted as well as identification of which differences are biologically relevant for the endpoint being considered. Consideration should also be given to the nutritional status, antigen load, age, spontaneous lesions, steroid hormone status, and stress for each strain and group of animals. General guidelines for the examination of each of the lymphoid organs are provided in this chapter.

Pathology Study Design, Conduct, and Reporting to Achieve Rigor and Reproducibility in Translational Research Using Animal Models

In translational research, animal models are an important tool to aid in decision-making when taking potential therapies into human clinical trials. Recently, there have been a number of papers that have suggested limited concordance of preclinical animal experiments with subsequent human clinical experience. Assessments of preclinical animal studies have led to concerns about the reproducibility of data and have highlighted the need for an emphasis on rigor and quality in the planning, conduct, analysis, and reporting of such studies. The incorporation of a wider role for the comparative pathologist using pathology best practices in the planning and conduct of animal model-based research is one way to increase the quality and reproducibility of data. The use of optimal design and planning of tissue collection, incorporation of pathology methods into written protocols, conduct of pathology procedures using accepted best practices, and the use of optimal pathology analysis and reporting methods enhance the quality of the data acquired from many types of preclinical animal models and studies. Many of these pathology practices are well established in the discipline of toxicologic pathology and have a proven and useful track record in enhancing the data from animal-based studies used in safety assessment of human therapeutics. Some of this experience can be adopted by the wider community of preclinical investigators to increase the reproducibility of animal study data.

Variability of Spleen and Mesenteric Lymph Node in Control Cynomolgus Monkeys ( Macaca fascicularis) from Nonclinical Safety Studies: A Retrospective Assessment

We assessed the variability of spleen and mesenteric lymph node (MLN) microscopic observations and the correlations of these observations with other study data from 478 control cynomolgus monkeys from 53 routine nonclinical safety studies. Spleen weight parameters (absolute and relative to body or brain weights) were highly variable both within a control group on an individual study (up to 5.11-fold) and among animals with the same light microscopic observation. Grades for microscopic observations were also highly variable. The most frequent microscopic observations for spleen were changes in the size and number of germinal centers (58%), acidophilic (hyaline) material in lymphoid follicles (52%), and compound lymphoid follicles (20%). The most frequent microscopic observations in the MLN were eosinophil infiltrates (90%), changes in size and number of germinal centers (42%), and brown pigment (21%). The only meaningful relationships ( r² > 0.3) were positive correlations between reticuloendothelial hyperplasia and malarial pigment in the spleen and between each of these observations and spleen weight parameters. We conclude that determination of test article-related effects on the immune system in routine monkey toxicology studies requires careful consideration and a weight-of-evidence approach due to the low numbers of animals/group, the inherent variability in spleen and MLN parameters, and the infrequent correlation among immune system-related end points.

Proof of Concept for an Automated Image Analysis Method to Quantify Rat Bone Marrow Hematopoietic Lineages on H&E Sections

The bone marrow is an important site for assessment of the hematopoietic toxicity of new drug candidates. Here, we extended our previous work, where we developed a computer algorithm to automatically quantitate overall bone marrow cell density by analyzing digitized images of standard hematoxylin and eosin (H&E) slides of rat bone marrow and further evaluated the capability to quantify myeloid: erythroid + lymphoid (M:EL) ratio and megakaryocyte cell density. We tested the algorithm in a toxicity study, where rats were dosed with two molecules known to affect bone marrow composition, monomethyl auristatin E, and a Bcl-xL inhibitor. The image analysis method detected significant changes in M:EL and megakaryocyte number that were either not found or semiquantitatively described by manual microscopic observation of the same slides. The image analysis results were consistent with other more established but time-consuming methods that measure changes in bone marrow cell composition: smear cytology, flow cytometry, and microscopic assessment. Our work demonstrates the feasibility of a rapid and more quantitative assessment of changes in bone marrow cell lineage composition using a computer algorithm compared to microscopic examination of H&E-stained bone marrow sections.

An Automated Image Analysis Method to Quantify Veterinary Bone Marrow Cellularity on H&E Sections

Bone marrow toxicity is a common finding when assessing safety of drug candidate molecules. Standard hematoxylin and eosin (H&E) marrow tissue sections are typically manually evaluated to provide a semiquantitative assessment of overall cellularity. Here, we developed an automated image analysis method that allows quantitative assessment of changes in bone marrow cell population in sternal bone. In order to test whether the method was repeatable and sensitive, we compared the automated method with manual subjective histopathology scoring of total cellularity in rat sternal bone marrow samples across 17 independently run studies. The automated method was consistent with manual scoring methodology for detecting altered bone marrow cellularity and, in multiple cases, identified changes at lower doses. The image analysis method allows rapid and more quantitative assessment of bone marrow toxicity compared to manual examination of H&E slides, making it an excellent tool to aid detection of bone marrow cell depletion in preclinical toxicologic studies.

Effects of ICOS+ T cell depletion via afucosylated monoclonal antibody MEDI-570 on pregnant cynomolgus monkeys and the developing offspring

MEDI-570 is a fully human afucosylated monoclonal antibody (MAb) against Inducible T-cell costimulator (ICOS), highly expressed on CD4+ T follicular helper (T_FH) cells. Effects of MEDI-570 were evaluated in an enhanced pre-postnatal development toxicity (ePPND) study in cynomolgus monkeys. Administration to pregnant monkeys did not cause any abortifacient effects. Changes in hematology and peripheral blood T lymphocyte subsets in maternal animals and infants and the attenuated infant IgG immune response to keyhole limpet hemocyanin (KLH) were attributed to MEDI-570 pharmacology. Adverse findings included aggressive fibromatosis in one dam and two infant losses in the high dose group with anatomic pathology findings suggestive of atypical lymphoid hyperplasia. The margin of safety relative to the no observed adverse effect level (NOAEL) for the highest planned clinical dose in the Phase 1a study was 7. This study suggests that women of child bearing potential employ effective methods of contraception while being treated with MEDI-570.

Incidence of spontaneous lymphomas in non-experimental NOD/Shi-scid, IL-2Rγnull (NOG) mice

Severely immunodeficient NOD/Shi-scid, IL-2Rγ^null (NOG) mice provide an in vivo model for human cell/tissue transplantation studies. NOG mice were established by combining interleukin-2 receptor-γ chain knockout mice and NOD/Shi-scid mice. They exhibit a high incidence of thymic lymphomas and immunoglobulin (Ig) leakiness. In this study, we assessed the incidence of malignant lymphomas and the occurrence of leakiness in 2,184 non-experimental NOG retired breeder mice aged 16-40 weeks. We established that the total incidence of lymphomas was only 0.60% (13/2,184). Most lymphomas (10/13) occurred in female mice by the age of around 25 weeks. No mice developed Ig leakiness. All lymphomas were derived from the thymus, and consisted mainly of CD3-positive and CD45R-negative lymphoblastic-like cells. Therefore, based on the absence of Ig leakiness and a very low incidence of lymphomas, including thymic lymphomas, NOG mice may be useful in regeneration medicine for xenotransplantation of human embryonic stem (ES) cells or induced pluripotent stem (iPS) cells, and in transplantation experiments involving tumor cells.

Impacts of Bisphenol A and Ethinyl Estradiol on Male and Female CD-1 Mouse Spleen

The endocrine disruptor bisphenol A (BPA) and the pharmaceutical 17α-ethinyl estradiol (EE) are synthetic chemicals with estrogen-like activities. Despite ubiquitous human exposure to BPA, and the wide-spread clinical use of EE as oral contraceptive adjuvant, the impact of these estrogenic endocrine disrupting chemicals (EDCs) on the immune system is unclear. Here we report results of in vivo dose response studies that analyzed the histology and microstructural changes in the spleen of adult male and female CD-1 mice exposed to 4 to 40,000 μg/kg/day BPA or 0.02 to 2 μg/kg/day EE from conception until 12–14 weeks of age. Results of that analysis indicate that both BPA and EE have dose- and sex-specific impacts on the cellular and microanatomical structures of the spleens that reveal minor alterations in immunomodulatory and hematopoietic functions. These findings support previous studies demonstrating the murine immune system as a sensitive target for estrogens, and that oral exposures to BPA and EE can have estrogen-like immunomodulatory affects in both sexes.

The lymphoid system: a review of species differences

While an understanding of the structure and function of a generically described immune system is essential in contemporary biomedicine, it is clear that a one-size-fits-all approach applied across multiple species is fraught with contradictions and inconsistencies. Nevertheless, the breakthroughs achieved in immunology following the application of observations in murine systems to that of man have been pivotal in the advancement of biology and human medicine. However, as additional species have been used to further address biologic and safety assessment questions relative to the structure and function of the immune system, it has become clear that there are differences across species, gender, age and strain that must be considered. The meaningfulness of these differences must be determined on a case-by-case basis. This review article attempts to collect, consolidate and discuss some of these species differences thereby aiding in the accurate placement of new observations in a proper immunobiological and immunopathological perspective.

A maternal diet high in saturated fat impairs offspring hippocampal function in a sex-specific manner

While a maternal diet high in saturated fat is likely to affect foetal brain development, whether the effects are the same for male and female offspring is unclear. As a result, we randomly assigned female, Sprague-Dawley rats to either a control, or high-fat diet (HFD; 45% of calories from saturated fat) for 10 weeks. A range of biometrics were collected, and hippocampal function was assessed at both the tissue level (by measuring synaptic plasticity) and at the behavioural level (using the Morris water maze; MWM). Subsequently, a subset of animals was bred and remained on their respective diets throughout gestation and lactation. On post-natal day 21, offspring were weaned and placed onto the control diet; biometrics and spatial learning and memory were then assessed at both adolescence and young adulthood. Although the HFD led to changes in the maternal generation consistent with an obese phenotype, no impairments were noted at the level of hippocampal synaptic plasticity, or MWM performance. Unexpectedly, among the offspring, a sexually dimorphic effect upon MWM performance became apparent. In particular, adolescent male offspring displayed a greater latency to reach the platform during training trials and spent less time in the target quadrant during the probe test; notably, when re-examined during young adulthood, the performance deficit was no longer present. Overall, our work suggests the existence of sexual dimorphism with regard to how a maternal HFD affects hippocampal-dependent function in the offspring brain.

Evaluation of Organ Weights for Rodent and Non-Rodent Toxicity Studies: A Review of Regulatory Guidelines and a Survey of Current Practices

The Society of Toxicologic Pathology convened a working group to evaluate current practices regarding organ weights in toxicology studies. A survey was distributed to pharmaceutical, veterinary, chemical, food/nutritional and consumer product companies in Europe, North America, and Japan. Responses were compiled to identify organs routinely weighed for various study types in rodent and non-rodent species, compare methods of organ weighing, provide perspectives on the value of organ weights and identify the scientist(s) responsible for organ weight data interpretation. Data were evaluated as a whole as well as by industry type and geographic location. Regulatory guidance documents describing organ weighing practices are generally available, however, they differ somewhat dependent on industry type and regulatory agency. While questionnaire respondents unanimously stated that organ weights were a good screening tool to identify treatment-related effects, opinions varied as to which organ weights are most valuable. The liver, kidneys, and testes were commonly weighed and most often considered useful by most respondents. Other organs thatbreak were commonly weighed included brain, adrenal glands, ovaries, thyroid glands, uterus, heart, and spleen. Lungs, lymph nodes, and other sex organs were weighed infrequently in routine studies, but were often weighed in specialized studies such as inhalation, immunotoxicity, and reproduction studies. Organ-to-body weight ratios were commonly calculated and were considered more useful when body weights were affected. Organ to brain weight ratios were calculated by most North American companies, but rarely according to respondents representing veterinary product or European companies. Statistical analyses were generally performed by most respondents. Pathologists performed interpretation of organ weight data for the majority of the industries.

Unique genetic responses revealed in RNA-seq of the spleen of chickens stimulated with lipopolysaccharide and short-term heat

Climate change and disease have large negative impacts on poultry production, but little is known about the interactions of responses to these stressors in chickens. Fayoumi (heat and disease resistant) and broiler (heat and disease susceptible) chicken lines were stimulated at 22 days of age, using a 2x2x2 factorial design including: breed (Fayoumi or broiler), inflammatory stimulus (lipopolysaccharide (LPS) or saline), and temperature (35°C or 25°C). Transcriptional changes in spleens were analyzed using RNA-sequencing on the Illumina HiSeq 2500. Thirty-two individual cDNA libraries were sequenced (four per treatment) and an average of 22 million reads were generated per library. Stimulation with LPS induced more differentially expressed genes (DEG, log₂ fold change ≥ 2 and FDR ≤ 0.05) in the broiler (N = 283) than the Fayoumi (N = 85), whereas heat treatment resulted in fewer DEG in broiler (N = 22) compared to Fayoumi (N = 107). The double stimulus of LPS+heat induced the largest numbers of changes in gene expression, for which broiler had 567 DEG and Fayoumi had 1471 DEG of which 399 were shared between breeds. Further analysis of DEG revealed pathways impacted by these stressors such as Remodelling of Epithelial Adherens Junctions due to heat stress, Granulocyte Adhesion and Diapedesis due to LPS, and Hepatic Fibrosis/Hepatic Stellate Cell Activation due to LPS+heat. The genes and pathways identified provide deeper understanding of the response to the applied stressors and may serve as biomarkers for genetic selection for heat and disease tolerant chickens.

Society of Toxicologic Pathology Position Paper: Organ Weight Recommendations for Toxicology Studies

The evaluation of organ weights in toxicology studies is an integral component in the assessment of pharmaceuticals, chemicals, and medical devices. The Society of Toxicologic Pathology (STP) has created recommendations for weighing organs in GLP general toxicology studies lasting from 7 days to 1 year. The STP recommends that liver, heart, kidneys, brain, testes, and adrenal glands be weighed in all multidose general toxicology studies. Thyroid gland and pituitary gland weights are recommended for all species except mice. Spleen and thymus should be weighed in rodent studies and may be weighed in non-rodent studies. Weighing of reproductive organs is most valuable in sexually mature animals. Variability in age, sexual maturity, and stage of cycle in non-rodents and reproductive senescence in female rodents may complicate or limit interpretation of reproductive organ weights. The STP recommends that testes of all species be weighed in multidose general toxicology studies. Epididymides and prostate should be weighed in rat studies and may be weighed on a case-by-case basis in non-rodent and mouse studies. Weighing of other organs including female reproductive organs should be considered on a case-by-case basis. Organ weights are not recommended for any carcinogenicity studies including the alternative mouse bioassays. Regardless of the study type or organs evaluated, organ weight changes must be evaluated within the context of the compound class, mechanism of action, and the entire data set for that study.

Chronic Ingestion of Coal Fly-Ash Contaminated Prey and Its Effects on Health and Immune Parameters in Juvenile American Alligators (Alligator mississippiensis)

Coal-burning power plants supply approximately 37 % of the electricity in the United States. However, incomplete combustion produces ash wastes enriched with toxic trace elements that have historically been disposed of in aquatic basins. Organisms inhabiting such habitats may accumulate these trace elements; however, studies investigating the effects on biota have been primarily restricted to shorter-lived, lower-trophic organisms. The American alligator (Alligator mississippiensis), a long-lived, top-trophic carnivore, has been observed inhabiting these basins, yet the health or immune effects of chronic exposure and possible accumulation remains unknown. In this study, we investigated how chronic dietary ingestion of prey contaminated with coal combustion wastes (CCWs) for 25 months, and subsequent accumulation of trace elements present in CCWs, affected juvenile alligator immune function and health. Alligators were assigned to one of four dietary-treatment groups including controls and those fed prey contaminated with CCWs for one, two, or three times a week. However, no effect of Dietary Treatment (p > 0.05) was observed on any immune parameter or hematological or plasma analyte we tested. Our results suggest that neither exposure to nor accumulation of low doses of CCWs had a negative effect on certain aspects of the immune and hematological system. However, future studies are required to elucidate this further.

Histopathology of Bone Marrow

As a major hematopoietic and lymphoid organ, morphological evaluation of the bone marrow is an important component of toxicity or safety assessment studies. While definitive characterization of bone marrow lesions often requires cytological aspirates or smears, assessment of histological bone marrow sections provides information regarding tissue architecture and hematopoietic status that is relevant for the detection of direct or indirect responses to chemical exposure. A variety of lesions have been observed in bone marrow. For example, lesions involving disturbances in growth, degenerative changes, inflammatory changes and neoplasia have been described. Lesions identified in hematoxylin and eosin-stained sections typically represent changes in the hematopoietic cell lineage and/or stromal cells since definitive identification of lymphoid cells is difficult except in cases of lymphoma. This review provides a descriptive and pictorial representation of a wide range of bone marrow lesions. Since large animal-to-animal variation may exist and there can be collection site- and age-related differences, it is imperative that the pathologist reviews all potential treatment-related findings against appropriate concurrent controls.

Tissue Sampling Guides for Porcine Biomedical Models

This article provides guidelines for organ and tissue sampling adapted to porcine animal models in translational medical research. Detailed protocols for the determination of sampling locations and numbers as well as recommendations on the orientation, size, and trimming direction of samples from ∼50 different porcine organs and tissues are provided in the Supplementary Material. The proposed sampling protocols include the generation of samples suitable for subsequent qualitative and quantitative analyses, including cryohistology, paraffin, and plastic histology; immunohistochemistry;in situhybridization; electron microscopy; and quantitative stereology as well as molecular analyses of DNA, RNA, proteins, metabolites, and electrolytes. With regard to the planned extent of sampling efforts, time, and personnel expenses, and dependent upon the scheduled analyses, different protocols are provided. These protocols are adjusted for (I) routine screenings, as used in general toxicity studies or in analyses of gene expression patterns or histopathological organ alterations, (II) advanced analyses of single organs/tissues, and (III) large-scale sampling procedures to be applied in biobank projects. Providing a robust reference for studies of porcine models, the described protocols will ensure the efficiency of sampling, the systematic recovery of high-quality samples representing the entire organ or tissue as well as the intra-/interstudy comparability and reproducibility of results.

Toxicology of 3-epi-deoxynivalenol, a deoxynivalenol-transformation product by Devosia mutans 17-2-E-8

Microbial detoxification of deoxynivalenol (DON) represents a new approach to treating DON-contaminated grains. A bacterium Devosia mutans 17-2-E-8 was capable of completely transforming DON into a major product 3-epi-DON and a minor product 3-keto-DON. Evaluation of toxicities of these DON-transformation products is an important part of hazard characterization prior to commercialization of the biotransformation application. Cytotoxicities of the products were demonstrated by two assays: a MTT bioassay assessing cell viability and a BrdU assay assessing DNA synthesis. Compared with DON, the IC50 values of 3-epi-DON and 3-keto-DON were respectively 357 and 3.03 times higher in the MTT bioassay, and were respectively 1181 and 4.54 times higher in the BrdU bioassay. Toxicological effects of 14-day oral exposure of the B6C3F1 mouse to DON and 3-epi-DON were also investigated. Overall, there were no differences between the control (free of toxin) and the 25 mg/kg bw/day or 100 mg/kg bw/day 3-epi-DON treatments in body and organ weights, hematology and organ histopathology. However, in mice exposed to DON (2 mg/kg bw/day), white blood cell numbers and serum immunoglobulin levels were altered relative to controls, and lesions were observed in adrenals, thymus, stomach, spleen and colon. Taken together, in vitro and in vivo studies indicate that 3-epi-DON is substantially less toxic than DON.

The transferability from rat subacute 4-week oral toxicity study to translational research exemplified by two pharmaceutical immunosuppressants and two environmental pollutants with immunomodulating properties

Exposure to chemicals may have an influence on the immune system. Often, this is an unwanted effect but in some pharmaceuticals, it is the intended mechanism of action. Immune function tests and in depth histopathological investigations of immune organs were integrated in rodent toxicity studies performed according to an extended OECD test guideline 407 protocol. Exemplified by two immunosuppressive drugs, azathioprine and cyclosporine A, and two environmental chemicals, hexachlorobenzene and benzo[a]pyrene, results of subacute rat studies were compared to knowledge in other species particular in humans. Although immune function has a high concordance in mammalian species, regarding the transferability from rodents to humans various factors have to be taken into account. In rats, sensitivity seems to depend on factors such as strain, sex, stress levels as well as metabolism. The two immunosuppressive drugs showed a high similarity of effects in animals and humans as the immune system was the most sensitive target in both. Hexachlorobenzene gave an inconsistent pattern of effects when considering the immune system of different species. In some species pronounced inflammation was observed, whereas in primates liver toxicity seemed more obvious. Generally, the immune system was not the most sensitive target in hexachlorobenzene-treatment. Immune function tests in rats gave evidence of a reaction to systemic inflammation rather than a direct impact on immune cells. Data from humans are likewise equivocal. In the case of benzo[a]pyrene, the immune system was the most sensitive target in rats. In the in vitro plaque forming cell assay (Mishell-Dutton culture) a direct comparison of cells from different species including rat and human was possible and showed similar reactions. The doses in the rat study had, however, no realistic relation to human exposure, which occurs exclusively in mixtures and in a much lower range. In summary, a case by case approach is necessary when testing immunotoxicity. Improvements for the translation from animals to humans related to immune cells can be expected from in vitro tests which offer direct comparison with reactions of human immune cells. This may lead to a better understanding of results and variations seen in animal studies.

Biocompatibility and Immunophenotypic Characterization of a Porcine Cholecyst–derived Scaffold Implanted in Rats

Comparative histomorphological assessment of local response to implanted reference biomaterial, also called biocompatibility testing/evaluation, in an appropriate animal model is a widely practiced safety evaluation procedure performed on biomaterials before clinical use. Standardized protocols and procedures, originally designed for testing synthetic materials, available for the testing/evaluation do not account for the immunogenic potential of a candidate biomaterial. Therefore, it is appropriate to supplement the routine biocompatibility test reports with adjunct data that may provide insight into the immunogenic potential of candidate biomaterials, especially when testing biomaterials that are derived from mammalian sources. This article presents expanded safety evaluation data of a porcine cholecyst–derived scaffold (CDS) intended as a xenogeneic graft. The biocompatibility was tested in rat subcutaneous model in comparison with a reference material and the CDS was found biocompatible. However, when studied by immunohistochemistry and real-time reverse transcription polymerase chain reaction for the number and/or polarization of M1 macrophage, M2 macrophage, cytotoxic T-cell, helper T cell, TH1 cell, and TH2 cell, the CDS appeared to induce a differential local immunopathological tissue reaction despite the similarity in biocompatibility with the reference material. The adjunct data collected were useful for objectively assessing the safety of CDS as a xenograft.

In vivo and in vitro toxicological evaluation of the hydroalcoholic leaf extract of Ageratum conyzoides L. (Asteraceae)

ETHNOPHARMACOLOGICAL RELEVANCE

In African traditional medicine, Ageratum conyzoides has been used as purgative, febrifuge, anti-ulcer and wound dressing. To date there is no safety information about long term use of Ageratum conyzoides which contains pyrrolizidine alkaloids, a class of hepatotoxic and carcinogenic phytochemicals. This study aims to evaluate the 90 days subchronic toxicity and in vitro toxicity of Ageratum conyzoides.

MATERIALS AND METHODS

Three groups of 8 rats (4 males and 4 females) received distilled water (control), 500 and 1000 mg/kg of the extract daily for 90 consecutive days by oral gavage. The animals were observed daily for abnormal clinical signs and death. Body weight, relative organ weight, haematological and biochemical parameters of blood as well as heart, kidney, liver and spleen tissues histology were evaluated.

RESULTS

After 90 days administration, Ageratum conyzoides increased significantly (p<0.05) the relative weight of the liver, the spleen and kidney as compared to control group. Ageratum conyzoides increased also significantly (p<0.05) ALP, ALT, AST and blood glucose. Furthermore, an increase in the number of platelets associated with a normocytic and normochromic anaemia was observed. The cytotoxicity, determined by the MTT test and neutral red assay, has shown that the cytotoxicity of hydroalcoholic extract of Ageratum conyzoides and its total alkaloids was very close.

CONCLUSIONS

Our results have shown that Ageratum conyzoides at 500 and 1000 mg/kg can induce liver, kidney and haematological disorders. These toxics effects can be attributed to its total alkaloids especially to pyrrolizidine alkaloids which are present in this plant.