Manual and automated leukocyte differentiation in bronchoalveolar lavage fluids from rodent models of pulmonary inflammation

Influence of toll-like receptor-4 antagonist on bacterial load of asthma in Swiss albino mice: targeting TLR4/MD2 complex pathway

Air pollution and environmental issues significantly impact life, resulting in the emergence and exacerbation of allergic asthma and other chronic respiratory infections. The main objective of this study is to suppress allergic asthma by TAK-242 from lipopolysaccharide-induced airway inflammation primarily stimulating toll-like receptor-4, and also to determine the potential mechanism of asthma eradication. The TAK-242 anti-allergic action was assured through the ovalbumin murine model of asthma via bronchial hyperresponsiveness and inflammation of the respiration tract in a pre-existing allergic inflammation paradigm. Swiss albino mice were sensitized and then challenged by ovalbumin and lipopolysaccharide for 5 days straight. TAK-242 reaction was assessed by inflammatory cytokines, and inflammatory cell count was determined from blood serum and bronchoalveolar lavage fluid, as well as group-wise regular weight assessments. After ovalbumin, lipopolysaccharide infusion, toll-like receptor-4 agonists caused a substantial increase in airway hyperresponsiveness, specific cellular inflammation, histological alterations, and immune mediator synthesis, as well as dose-related body-weight variations. A decrease in lipopolysaccharide-induced leukocyte count and Th1/Th17 related cytokines, TNF-α, and IL-6 expression through the ELISA study was particularly noticeable. Finally in treated groups, TAK-242, a TLR4/MD2 complex inhibitor, reduced airway inflammation and histopathological changes, cytokine expression, and body-weight management. TAK-242 has been found in an ovalbumin allergic asthma model to be a potential inhibitor of lipopolysaccharide-induced respiratory infection.

Research-Relevant Clinical Pathology Resources: Emphasis on Mice, Rats, Rabbits, Dogs, Minipigs, and Non-Human Primates

Clinical pathology testing for investigative or biomedical research and for preclinical toxicity and safety assessment in laboratory animals is a distinct specialty requiring an understanding of species specific and other influential variables on results and interpretation. This review of clinical pathology principles and testing recommendations in laboratory animal species aims to provide a useful resource for researchers, veterinary specialists, toxicologists, and clinical or anatomic pathologists.

Myeloid Protease-Activated Receptor-2 Contributes to Influenza A Virus Pathology in Mice

Background

Innate immune responses to influenza A virus (IAV) infection are initiated in part by toll-like receptor 3 (TLR3). TLR3-dependent signaling induces an antiviral immune response and an NFκB-dependent inflammatory response. Protease-activated receptor 2 (PAR2) inhibits the antiviral response and enhances the inflammatory response. PAR2 deficiency protected mice during IAV infection. However, the PAR2 expressing cell-types contributing to IAV pathology in mice and the mechanism by which PAR2 contributes to IAV infection is unknown.

Methods

IAV infection was analyzed in global (Par2-/-), myeloid (Par2fl/fl;LysMCre+) and lung epithelial cell (EpC) Par2 deficient (Par2fl/fl;SPCCre+) mice and their respective controls (Par2+/+ and Par2fl/fl). In addition, the effect of PAR2 activation on polyinosinic-polycytidylic acid (poly I:C) activation of TLR3 was analyzed in bone marrow-derived macrophages (BMDM). Lastly, we determined the effect of PAR2 inhibition in wild-type (WT) mice.

Results

After IAV infection, Par2-/- and mice with myeloid Par2 deficiency exhibited increased survival compared to infected controls. The improved survival was associated with reduced proinflammatory mediators and reduced cellular infiltration in bronchoalveolar lavage fluid (BALF) of Par2-/- and Par2fl/fl;LysMCre+ 3 days post infection (dpi) compared to infected control mice. Interestingly, Par2fl/fl;SPCCre+ mice showed no survival benefit compared to Par2fl/fl. In vitro studies showed that Par2-/- BMDM produced less IL6 and IL12p40 than Par2+/+ BMDM after poly I:C stimulation. In addition, activation of PAR2 on Par2+/+ BMDM increased poly I:C induction of IL6 and IL12p40 compared to poly I:C stimulation alone. Importantly, PAR2 inhibition prior to IAV infection protect WT mice.

Conclusion

Global Par2 or myeloid cell but not lung EpC Par2 deficiency was associated with reduced BALF inflammatory markers and reduced IAV-induced mortality. Our study suggests that PAR2 may be a therapeutic target to reduce IAV pathology.

Comparison of different autoanalyzers for the determination of lymphocyte and neutrophil counts in mouse blood

OBJECTIVES

Autoanalyzers are used in clinical haematology for analysis of blood samples in clinical as well as in nonclinical studies. The results from these analyzers vary from machine to machine. In this study, we compared the lymphocyte and neutrophil count of mouse blood between ADVIA 2120i, Horiba Yumizen H2500 and CellaVision analyzers against manual counting as gold standard.

METHODS

Blood samples from 28 female BALB/c mice were collected and analyzed. Agreement between different autoanalyzers and manual counting were determined by Bland-Altman method.

RESULTS

A high level of agreement was found between CellaVision and manual technique for lymphocyte (Bias=4.75, 95% limits of agreement -14 to 24) and neutrophil count (Bias=0.68 (-17 to 19)). Agreement in lymphocyte count was also observed between ADVIA and manual counting, but to a lesser extent compared to CellaVision (Bias=13.9 (-10.45 to 38.27)). However, no agreement was observed for ADVIA (Neutrophils), Horiba (lymphocytes and neutrophils) with manual counting.

CONCLUSIONS

Our data suggests that CellaVision could be used for the differential counting of neutrophil and lymphocytes in mouse blood sample.

Aspiration and Inspiration: Using Bronchoalveolar Lavage for Toxicity Assessment

Bronchoalveolar lavage (BAL) is a simple procedure that is used to investigate drug efficacy or lung toxicity. It is sensitive to lung changes and less invasive than histological evaluation. It can be performed repeatedly at interim time points or as a terminal procedure. Airborne contaminants and purposely inhaled compounds, resident and inflammatory cells, as well as different cellular soluble products can be harvested in bronchoalveolar fluid (BALF) and measured. Bronchoalveolar lavage can also be an important tool to understand drug exposure and its metabolism in the lung, although it should be rigorously performed and interpreted with caution, especially in the context of regulated toxicology studies. This review focuses on the methods and uses of BAL in animal research, primarily in the pharmaceutical industry, as well as for the assessment of drugs, pollutants, and chemical lung toxicity. Methods of collecting and analyzing BALF and parameters affecting variability are discussed in detail. Improved automated methods for cell counting and analysis of the inflammatory cellular differential using hematology analyzers, common markers of lung injury, and new methodologies are described. Correlation between BALF and histological evaluation should not be considered as repetitive but as complementary assessments in the context of efficacy and toxicity studies.

Btk Inhibitor RN983 Delivered by Dry Powder Nose-only Aerosol Inhalation Inhibits Bronchoconstriction and Pulmonary Inflammation in the Ovalbumin Allergic Mouse Model of Asthma

BACKGROUND

In allergen-induced asthma, activated mast cells start the lung inflammatory process with degranulation, cytokine synthesis, and mediator release. Bruton's tyrosine kinase (Btk) activity is required for the mast cell activation during IgE-mediated secretion.

METHODS

This study characterized a novel inhaled Btk inhibitor RN983 in vitro and in ovalbumin allergic mouse models of the early (EAR) and late (LAR) asthmatic response.

RESULTS

RN983 potently, selectively, and reversibly inhibited the Btk enzyme. RN983 displayed functional activities in human cell-based assays in multiple cell types, inhibiting IgG production in B-cells with an IC50 of 2.5 ± 0.7 nM and PGD2 production from mast cells with an IC50 of 8.3 ± 1.1 nM. RN983 displayed similar functional activities in the allergic mouse model of asthma when delivered as a dry powder aerosol by nose-only inhalation. RN983 was less potent at inhibiting bronchoconstriction (IC50(RN983) = 59 μg/kg) than the β-agonist salbutamol (IC50(salbutamol) = 15 μg/kg) in the mouse model of the EAR. RN983 was more potent at inhibiting the antigen induced increase in pulmonary inflammation (IC50(RN983) = <3 μg/kg) than the inhaled corticosteroid budesonide (IC50(budesonide) = 27 μg/kg) in the mouse model of the LAR.

CONCLUSIONS

Inhalation of aerosolized RN983 may be effective as a stand-alone asthma therapy or used in combination with inhaled steroids and β-agonists in severe asthmatics due to its potent inhibition of mast cell activation.

Best practices for veterinary toxicologic clinical pathology, with emphasis on the pharmaceutical and biotechnology industries

The purpose of this paper by the Regulatory Affairs Committee (RAC) of the American Society for Veterinary Clinical Pathology (ASVCP) is to review the current regulatory guidances (eg, guidelines) and published recommendations for best practices in veterinary toxicologic clinical pathology, particularly in the pharmaceutical and biotechnology industries, and to utilize the combined experience of ASVCP RAC to provide updated recommendations. Discussion points include (1) instrumentation, validation, and sample collection, (2) routine laboratory variables, (3) cytologic laboratory variables, (4) data interpretation and reporting (including peer review, reference intervals and statistics), and (5) roles and responsibilities of clinical pathologists and laboratory personnel. Revision and improvement of current practices should be in alignment with evolving regulatory guidance documents, new technology, and expanding understanding and utility of clinical pathology. These recommendations provide a contemporary guide for the refinement of veterinary toxicologic clinical pathology best practices.

Bleomycin induced lung fibrosis increases work of breathing in the mouse

Bleomycin induces a transient lung fibrosis in mice that has been used to investigate mechanisms related to idiopathic pulmonary fibrosis. Our aim was to determine a sensitive method for assessing lung function in bleomycin treated mice that correlated with the degree of lung fibrosis as measured by collagen immunohistochemistry. Bleomycin (2 U/kg) or saline was intratracheally microsprayed to male C57BL/6 mice under isoflurane anesthesia. Lung function (single compartment model, constant phase model, and work of breathing) was assessed using the flexiVent system, and after euthanasia lungs were inflated with formalin in situ for histological analysis. The lung fibrosis histopathology score for the bleomycin treated animals on day 21 was indicative of mild-to-moderate fibrosis (Saline treated control: 0 ± 0, Bleomycin treated: 4.9 ± 0.4). There were at least three large areas of fibrosis in the peribronchial alveolar regions of the lung, but less than 50% of each lung was affected by fibrosis. Although changes in lung function were less obvious, volume normalized dynamic work of breathing measured at 30 ml/kg tidal volume (Saline treated control: 9.2 ± 0.1 J/l, Bleomycin treated: 10.6 ± 0.3 J/l) and the oscillatory mechanics constant phase model parameter tissue elastance (H; Saline treated control: 31 ± 2 cm H(2)O/ml, Bleomycin treated: 38 ± 3 cm H(2)O/ml) were significantly increased on day 21. The work of breathing (r = 0.83) correlated slightly better with fibrosis histopathology score than H (r = 0.64). Work of breathing can detect decrements in lung function due to pulmonary fibrosis, correlates well with the amount of collagen in the lungs, and may be a more sensitive quantitative measure of efficacy for drugs being developed to treat pulmonary fibrosis.