LPS-induced lung inflammation in marmoset monkeys - an acute model for anti-inflammatory drug testing

Marmosets as models of infectious diseases

Animal models of infectious disease often serve a crucial purpose in obtaining licensure of therapeutics and medical countermeasures, particularly in situations where human trials are not feasible, i.e., for those diseases that occur infrequently in the human population. The common marmoset (Callithrix jacchus), a Neotropical new-world (platyrrhines) non-human primate, has gained increasing attention as an animal model for a number of diseases given its small size, availability and evolutionary proximity to humans. This review aims to (i) discuss the pros and cons of the common marmoset as an animal model by providing a brief snapshot of how marmosets are currently utilized in biomedical research, (ii) summarize and evaluate relevant aspects of the marmoset immune system to the study of infectious diseases, (iii) provide a historical backdrop, outlining the significance of infectious diseases and the importance of developing reliable animal models to test novel therapeutics, and (iv) provide a summary of infectious diseases for which a marmoset model exists, followed by an in-depth discussion of the marmoset models of two studied bacterial infectious diseases (tularemia and melioidosis) and one viral infectious disease (viral hepatitis C).

Establishment of a lipopolysaccharide-induced inflammation model of human fetal colon cells

BACKGROUND

Inflammatory bowel disease (IBD) is a global health problem and there are few cell models for IBD at present. To culture a human fetal colon (FHC) cell line in vitro and establish an FHC cell inflammation model that meets the requirements for high expression of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α).

METHODS AND RESULTS

FHC cells were cultured with various concentrations of Escherichia coli lipopolysaccharide (LPS) in appropriate media for 0.5, 1, 2, 4, 8, 16 and 24 h to stimulate an inflammatory reaction. The viability of FHC cells was detected by a Cell Counting Kit-8 (CCK-8) assay. The transcriptional levels and protein expression changes of IL-6 and TNF-α in FHC cells were detected by Quantitative Real‑Time Polymerase Chain Reaction (qRT-PCR) and Enzyme‑Linked Immunosorbent Assay (ELISA), respectively. Appropriate stimulation conditions were selected (i.e., LPS concentration and treatment time), based on changes in cell survival rate, and IL-6 and TNF-α expression levels. An LPS concentration higher than 100 µg/mL or a treatment time longer than 24 h resulted in morphological changes and decreased cell survival. By contrast, expression levels of IL-6 and TNF-α significantly increased within 24 h when LPS concentration lower than 100 µg/mL and peaked at 2 h, whilst maintaining cell morphology and viability in FHC cells.

CONCLUSION

The treatment of FHC cells with 100 µg/mL LPS within 24 h was optimal in terms of stimulating IL-6 and TNF-α expression.

Tobacco product use and the risks of SARS-CoV-2 infection and COVID-19: current understanding and recommendations for future research

Heterogeneity in the clinical presentation of SARS-CoV-2 infection and COVID-19 progression underscores the urgent need to identify individual-level susceptibility factors that affect infection vulnerability and disease severity. Tobacco product use is a potential susceptibility factor. In this Personal View, we provide an overview of the findings of peer-reviewed, published studies relating tobacco product use to SARS-CoV-2 infection and COVID-19 outcomes, with most studies focusing on cigarette smoking in adults. Findings pertaining to the effects of tobacco product use on the incidence of SARS-CoV-2 infection are inconsistent. However, evidence supports a role for cigarette smoking in increasing the risk of poor COVID-19 outcomes, including hospital admission, progression in disease severity, and COVID-19-related mortality. We discuss the potential effects of tobacco use behaviour on SARS-CoV-2 transmission and infection, and highlight the pathophysiological changes associated with cigarette smoking that could promote SARS-CoV-2 infection and increased disease severity. We consider the biological mechanisms by which nicotine and other tobacco product constituents might affect immune and inflammatory responses to SARS-CoV-2 infection. Finally, we identify current knowledge gaps and suggest priorities for research to address acute and post-acute health outcomes of COVID-19 during and after the pandemic.

Oxypeucedanin relieves LPS-induced acute lung injury by inhibiting the inflammation and maintaining the integrity of the lung air-blood barrier

Introduction: Acute lung injury (ALI) is commonly accompanied by a severe inflammatory reaction process, and effectively managing inflammatory reactions is an important therapeutic approach for alleviating ALI. Macrophages play an important role in the inflammatory response, and this role is proinflammatory in the early stages of inflammation and anti-inflammatory in the late stages. Oxypeucedanin is a natural product with a wide range of pharmacological functions. This study aimed to determine the effect of oxypeucedanin on lipopolysaccharide (LPS)-induced ALI.

Methods and Results: In this study, the following experiments were performed based on LPS-induced models in vivo and in vitro. Using myeloperoxidase activity measurement, ELISA, qRT-PCR, and Western blotting, we found that oxypeucedanin modulated the activity of myeloperoxidase and decreased the expression levels of inflammatory mediators such as TNF-α, IL-6, IL-1β, MPO, COX-2 and iNOS in LPS-induced inflammation models. Meanwhile, oxypeucedanin inhibited the activation of PI3K/AKT and its downstream NF-κB and MAPK signaling pathways. In addition, oxypeucedanin significantly decreased the pulmonary vascular permeability, which was induced by LPSs, and the enhanced expression of tight junction proteins (Occludin and Claudin 3).

Conclusions: In conclusion, this study demonstrated that the anti-inflammatory mechanism of oxypeucedanin is associated with the inhibition of the activation of PI3K/AKT/NF-κB and MAPK signaling pathways and the maintenance of the integrity of the lung air-blood barrier.

Second-generation TNFα turnover model for improved analysis of test compound interventions in LPS challenge studies

This study presents a non-linear mixed effects model describing tumour necrosis factor alpha (TNFα) release after lipopolysaccharide (LPS) provocations in absence or presence of anti-inflammatory test compounds. Inter-occasion variability and the pharmacokinetics of two test compounds have been added to this second-generation model, and the goal is to produce a framework of how to model TNFα response in LPS challenge studies in vivo and demonstrate its general applicability regardless of occasion or type of test compound. Model improvements based on experimental data were successfully implemented and provided a robust model for TNFα response after LPS provocation, as well as reliable estimates of the median pharmacodynamic parameters. The two test compounds, Test Compound A and roflumilast, showed 81.1% and 74.9% partial reduction of TNFα response, respectively, and the potency of Test Compound A was estimated to 0.166 µmol/L. Comparing this study with previously published work reveals that our model leads to biologically reasonable output, handles complex data pooled from different studies, and highlights the importance of accurately distinguishing the stimulatory effect of LPS from the inhibitory effect of the test compound.

Hordenine Protects Against Lipopolysaccharide-Induced Acute Lung Injury by Inhibiting Inflammation

Acute lung injury (ALI) is a respiratory disease that leads to death in severe cases. Hordenine (Hor), a barley-derived natural product, has various biological activities, including anti-inflammatory, and anti-oxidation activities. We investigated the effect of Hor on lipopolysaccharide-induced ALI and its potential mechanism. The anti-inflammatory effects of Hor were detected using in vivo and in vitro models by enzyme-linked immunosorbent assay, real-time polymerase chain reaction, western blotting, and molecular docking simulations. Hor inhibited increases in the levels of inflammatory factors both in vivo and in vitro, and its anti-inflammatory effect inhibited activation of protein kinase B, nuclear factor-κB, and mitogen-activated protein kinase signaling. Hor alleviated lipopolysaccharide-induced ALI by inhibiting inflammatory cytokine increases in vivo and in vitro and shows potential for preventing inflammatory disease.

Dissect the immunity using cytokine profiling and NF-kB target gene analysis in systemic inflammatory minipig model

Minipigs have remarkably similar physiology to humans, therefore, they it can be a good animal model for inflammation study. Thus, the conventional (serum chemistry, histopathology) and novel analytic tools [immune cell identification in tissue, cytokine level in peripheral blood mononuclear cells (PBMC) and serum, NF-kB target gene analysis in tissue] were applied to determine inflammation in Chicago Miniature Swine (CMS) minipig. Lipopolysaccharide (LPS)-induced acute systemic inflammation caused liver and kidney damage in serum chemistry and histopathology. Immunohistochemistry (IHC) also showed an increase of immune cell distribution in spleen and lung during inflammation. Moreover, NF-kB-target gene expression was upregulated in lung and kidney in acute inflammation and in heart, liver, and intestine in chronic inflammation. Cytokine mRNA was elevated in PBMC under acute inflammation along with elevated absolute cytokine levels in serum. Overall, LPS-mediated systemic inflammation affects the various organs, and can be detected by IHC of immune cells, gene analysis in PBMC, and measuring the absolute cytokine in serum along with conventional inflammation analytic tools.

The Effects of Insulin-Like Growth Factor I and BTP-2 on Acute Lung Injury

Acute lung injury (ALI) afflicts approximately 200,000 patients annually and has a 40% mortality rate. The COVID-19 pandemic has massively increased the rate of ALI incidence. The pathogenesis of ALI involves tissue damage from invading microbes and, in severe cases, the overexpression of inflammatory cytokines such as tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β). This study aimed to develop a therapy to normalize the excess production of inflammatory cytokines and promote tissue repair in the lipopolysaccharide (LPS)-induced ALI. Based on our previous studies, we tested the insulin-like growth factor I (IGF-I) and BTP-2 therapies. IGF-I was selected, because we and others have shown that elevated inflammatory cytokines suppress the expression of growth hormone receptors in the liver, leading to a decrease in the circulating IGF-I. IGF-I is a growth factor that increases vascular protection, enhances tissue repair, and decreases pro-inflammatory cytokines. It is also required to produce anti-inflammatory 1,25-dihydroxyvitamin D. BTP-2, an inhibitor of cytosolic calcium, was used to suppress the LPS-induced increase in cytosolic calcium, which otherwise leads to an increase in proinflammatory cytokines. We showed that LPS increased the expression of the primary inflammatory mediators such as toll like receptor-4 (TLR-4), IL-1β, interleukin-17 (IL-17), TNF-α, and interferon-γ (IFN-γ), which were normalized by the IGF-I + BTP-2 dual therapy in the lungs, along with improved vascular gene expression markers. The histologic lung injury score was markedly elevated by LPS and reduced to normal by the combination therapy. In conclusion, the LPS-induced increases in inflammatory cytokines, vascular injuries, and lung injuries were all improved by IGF-I + BTP-2 combination therapy.

Marmosets: Welfare, Ethical Use, and IACUC/Regulatory Considerations

Use of marmosets in biomedical research has increased dramatically in recent years due, in large part, to their suitability for transgenic applications and utility as models for neuroscience investigations. This increased use includes the establishment of new colonies and involvement of people new to marmoset research. To facilitate the use of the marmoset as a research model, we provide an overview of issues surrounding the ethics and regulations associated with captive marmoset research, including discussion of the history of marmosets in research, current uses of marmosets, ethical considerations related to marmoset use, issues related to importation of animals, and recommendations for regulatory oversight of gene-edited marmosets. To understand the main concerns that oversight bodies have regarding captive biomedical research with marmosets, we developed a brief, 15-question survey that was then sent electronically to academic and biomedical research institutions worldwide that were believed to house colonies of marmosets intended for biomedical research. The survey included general questions regarding the individual respondent's colony, status of research use of the colony and institutional oversight of both the colony itself and the research use of the colony. We received completed surveys from a total of 18 institutions from North America, Europe, and Asia. Overall, there appeared to be no clear difference in regulatory oversight body concerns between countries/regions. One difference that we were able to appreciate was that while biomedical research with marmosets was noted to be either stable or decreasing in Europe, use was clearly increasing elsewhere.

Bronchoconstriction: a potential missing link in airway remodelling

In asthma, progressive structural changes of the airway wall are collectively termed airway remodelling. Despite its deleterious effect on lung function, airway remodelling is incompletely understood. As one of the important causes leading to airway remodelling, here we discuss the significance of mechanical forces that are produced in the narrowed airway during asthma exacerbation, as a driving force of airway remodelling. We cover in vitro, ex vivo and in vivo work in this field, and discuss up-to-date literature supporting the idea that bronchoconstriction may be the missing link in a comprehensive understanding of airway remodelling in asthma.

Use of precision cut lung slices as a translational model for the study of lung biology

Animal models remain invaluable for study of respiratory diseases, however, translation of data generated in genetically homogeneous animals housed in a clean and well-controlled environment does not necessarily provide insight to the human disease situation. In vitro human systems such as air liquid interface (ALI) cultures and organ-on-a-chip models have attempted to bridge the divide between animal models and human patients. However, although 3D in nature, these models struggle to recreate the architecture and complex cellularity of the airways and parenchyma, and therefore cannot mimic the complex cell-cell interactions in the lung. To address this issue, lung slices have emerged as a useful ex vivo tool for studying the respiratory responses to inflammatory stimuli, infection, and novel drug compounds. This review covers the practicality of precision cut lung slice (PCLS) generation and benefits of this ex vivo culture system in modeling human lung biology and disease pathogenesis.

Phosphodiesterases as therapeutic targets for respiratory diseases

Chronic respiratory diseases, such as chronic obstructive pulmonary disease (COPD) and asthma, affect millions of people all over the world. Cyclic adenosine monophosphate (cAMP) which is one of the most important second messengers, plays a vital role in relaxing airway smooth muscles and suppressing inflammation. Given its vast role in regulating intracellular responses, cAMP provides an attractive pharmaceutical target in the treatment of chronic respiratory diseases. Phosphodiesterases (PDEs) are enzymes that hydrolyze cyclic nucleotides and help control cyclic nucleotide signals in a compartmentalized manner. Currently, the selective PDE4 inhibitor, roflumilast, is used as an add-on treatment for patients with severe COPD associated with bronchitis and a history of frequent exacerbations. In addition, other novel PDE inhibitors are in different phases of clinical trials. The current review provides an overview of the regulation of various PDEs and the potential application of selective PDE inhibitors in the treatment of COPD and asthma. The possibility to combine various PDE inhibitors as a way to increase their therapeutic effectiveness is also emphasized.

Evaluation of inflammatory and immune responses in long-term cultured human precision-cut lung slices

The development of systems that are more accurate and time-efficient in predicting safety and efficacy of target products in humans are critically important in reducing the cost and duration of pharmaceutical development. To circumvent some of the limitations imposed by the use of animal models, ex vivo systems, such as precision-cut lung slices (PCLS), have been proposed as an alternative for evaluating safety, immunogenicity and efficacy of vaccines and pharmaceuticals. In this study, we have established a human PCLS system and methodology for PCLS cultivation that can provide long-term viability and functionality in culture. Using these techniques, we found that cultured PCLS remained viable for at least 14 d in culture and maintained normal metabolic activity, tissue homeostasis and structural integrity. To investigate whether cultured PCLS remained functional, lipopolysaccharide (LPS) was used as a target stimulating compound. We observed that after an 18-hour incubation with LPS, cultured PCLS produced a set of pro-inflammatory cytokines, including TNF-α, IL-1β, IL-6 and IL-10 as well as the enzyme COX-2. Furthermore, cultured PCLS were shown to be capable of generating re-call immune responses, characterized by cytokine production, against antigens commonly found in routine vaccinations against influenza virus and tetanus toxoid. Taken together, these results suggest that human PCLS have the potential to be used as an alternative, high-throughput, ex vivo system for evaluating the safety, and potentially immunogenicity, of vaccines and pharmaceuticals.

Artemisia argyi attenuates airway inflammation in lipopolysaccharide induced acute lung injury model

Artemisia argyi is used as a health supplement, tea, and food source in Korea. This study aimed to evaluate the effect of Artemisia argyi (AA) and its active compound, dehydromatricarin A (DA), on the attenuation of airway inflammation in a murine model of lipopolysaccharide (LPS)-induced acute lung injury (ALI). The C57BL/6 mice were administered AA (50 mg/kg or 100 mg/kg) and DA (10 mg/kg or 20 mg/kg) by oral gavage from day 0 to 7 days and LPS treated by intranasal instillation 48 hours before the sacrifice. The treatment of AA and DA markedly decreased inflammatory cells in the bronchoalveolar lavage fluid (BALF) compared with that in ALI-induced mice, which was accompanied by a significant reduction in the levels of tumor necrosis factor (TNF)-α and interleukin (IL)-6 in BALF. Furthermore, the administration of AA and DA clearly decreased inducible nitric oxide synthase (iNOS) expression and nuclear factor kappa B (NF-κB) phosphorylation in comparison with that in the ALI-induced mice. The histological examination of the lung tissue revealed that the administration of AA and DA suppressed the inflammatory cell infiltration into the peribronchial and alveolar lesions induced by LPS instillation. Collectively, our results indicated that AA and DA effectively decreased the airway inflammatory response induced by LPS instillation. Therefore, AA and DA may offer a potential therapy for airway inflammatory disease.

Use of nonhuman primates in obstructive lung disease research - is it required?

In times of increasing costs for health insurances, obstructive lung diseases are a burden for both the patients and the economy. Pulmonary symptoms of asthma and chronic obstructive pulmonary disease (COPD) are similar; nevertheless, the diseases differ in pathophysiology and therapeutic approaches. Novel therapeutics are continuously developed, and nonhuman primates (NHPs) provide valuable models for investigating novel biologicals regarding efficacy and safety.

This review discusses the role of nonhuman primate models for drug development in asthma and COPD and investigates whether alternative methods are able to prevent animal experiments.

Assessment of long-term cultivated human precision-cut lung slices as an ex vivo system for evaluation of chronic cytotoxicity and functionality

Background

Investigation of basic chronic inflammatory mechanisms and development of new therapeutics targeting the respiratory tract requires appropriate testing systems, including those to monitor long- persistence. Human precision-cut lung slices (PCLS) have been demonstrated to mimic the human respiratory tract and have potential of an alternative, ex-vivo system to replace or augment in-vitro testing and animal models. So far, most research on PCLS has been conducted for short cultivation periods (≤72 h), while analyses of slowly metabolized therapeutics require long-term survival of PCLS in culture. In the present study, we evaluated viability, physiology and structural integrity of PCLS cultured for up to 15 days.

Methods

PCLS were cultured for 15 days and various parameters were assessed at different time points.

Results

Structural integrity and viability of cultured PCLS remained constant for 15 days. Moreover, bronchoconstriction was inducible over the whole period of cultivation, though with decreased sensitivity (EC₅₀1d = 4 × 10⁻⁸ M vs. EC₅₀15d = 4 × 10⁻⁶ M) and reduced maximum of initial airway area (1d = 0.5% vs. 15d = 18.7%). In contrast, even though still clearly inducible compared to medium control, LPS-induced TNF-α secretion decreased significantly from day 1 to day 15 of culture.

Conclusions

Overall, though long-term cultivation of PCLS need further investigation for cytokine secretion, possibly on a cellular level, PCLS are feasible for bronchoconstriction studies and toxicity assays.

Electronic supplementary material

The online version of this article (doi:10.1186/s12995-017-0158-5) contains supplementary material, which is available to authorized users.

Spontaneous lung pathology in a captive common marmoset colony (Callithrix jacchus)

Data on spontaneous pathology are substantially scarce for common marmosets, compared to other laboratory animals, but is essential for the interpretation of histological findings in the context of toxicological and experimental studies. Especially if common marmosets are used as experimental animals in respiratory research, detailed knowledge on the spectrum, occurrence, and incidence of spontaneous histopathological pulmonary lesions in this non-human primate species is required. In this study, lung tissue of 638 common marmosets from the marmoset colony of the German Primate Center was examined histologically. The analysis revealed a high incidence of predominantly mild and multifocal interstitial pneumonia (32.99 %) of unknown etiology in most cases. Only few marmosets exhibited lobar pneumonia (1.41 %) and bronchopneumonia (0.94), which were mainly caused by bacterial pathogens such as Bordetella bronchiseptica and Klebsiella pneumoniae. Lung immaturity and atelectasis were common histological findings in newborn marmosets. Typical background lesions included anthracosis (8.15 %), hemosiderosis (1.72 %), extramedullary hematopoiesis (11.6 %), mineralization (10.97 %), and inflammatory cell foci (10.34 %). In addition, three cases of pulmonary arteriopathy (0.47 %) and 1 case of foreign-body granuloma (0.16 %) were detected in the marmoset study cohort. The high prevalence of circulatory disturbances (congestion, edema, hemorrhage) and changes in air content (secondary atelectasis, alveolar emphysema) could partly be explained by euthanasia-related artifacts or agonal changes. The present study provides a comprehensive overview of the range and incidence of spontaneous pulmonary histopathology in common marmosets, serving as valuable reference data for the interpretation of lung lesions in toxicological and experimental marmoset studies.

Polymorphism of the 3'-UTR of the dopamine transporter gene (DAT) in New World monkeys

Genetic polymorphism in the 3'-untranslated region (3'-UTR) of the dopamine transporter (DAT) gene has been reported in both human and nonhuman primates, and the variable number of tandem repeats (VNTR) polymorphism has been related to several neurological and psychiatric disorders. As New World primates have been employed as models in biomedical research in these fields, in the present study we assessed genetic variation in the DAT gene in 25 robust capuchin monkeys (Sapajus spp.) and 39 common marmosets (Callithrix jacchus). Using enzymatic amplification followed by sequencing of amplified fragments, a VNTR polymorphism in the 3'-UTR region of the DAT gene was identified in both robust capuchins and common marmosets. The polymorphic tandem repeat of 40-bp basic units is similar to the human VNTR consensus sequence, with size variants composed of 9, 10, and 11 units in marmosets and 8, 9, 13, and 17 basic units in capuchins. We found behavioral evidence that carrying the 10-repeat DAT allele promotes flexible choice and maximization of foraging in marmosets tested in an operant choice paradigm. Moreover, in an intertemporal choice task, capuchins with longer repeat variants show less self-controlled choices than capuchins with at least one short repeat variant. Future research should focus on the relationship between these DAT polymorphisms, dopamine reuptake via the dopamine transporter, and behavioral and cognitive variation across New World monkey individuals.

Morphology and staining behavior of neutrophilic and eosinophilic granulocytes of the common marmoset (Callithrix jacchus)

Common marmosets (Callithrix jacchus) are frequently used as translational animal models for human diseases. However, a comparative study of cytological and histochemical detection methods as well as morphometric and ultrastructural characterization of neutrophils and eosinophils in this species is lacking. Blood samples of house dust mite sensitized and allergen challenged as well as lipopolysaccharide (LPS) challenged marmosets were analyzed with different cytological and histological staining methods. Furthermore, cell size and number of nuclear segments were compared between neutrophils and eosinophils. Electron microscopy was performed to characterize the ultrastructure of granulocytes. Of all applied cytological stains, three allowed differentiation of eosinophils and neutrophils and, thus, reliable quantification in blood smears: May-Grünwald-Giemsa stain, Congo Red and Naphthol AS-D Chloroacetate-Esterase. For histology, Hematoxylin-Eosin (H&E) could not demonstrate clear differences, whereas Sirius Red, Congo Red, and Naphthol AS-D Chloroacetate Esterase showed capable results for identification of eosinophils or neutrophils in lung tissue. Morphometry revealed that marmoset neutrophils have more nuclear segments and are slightly larger than eosinophils. Ultrastructurally, eosinophils presented with large homogeneous electron-dense granules without crystalloid cores, while neutrophils were characterized by heterogeneous granules of different size and density. Additionally, sombrero-like vesicles were detected in tissue eosinophils of atopic marmosets, indicative for hypersensitivity-related piecemeal degranulation. In conclusion, we provide a detailed overview of marmoset eosinophils and neutrophils, important for phenotypic characterization of marmoset models for human airway diseases.

8,9-Dehydrohispanolone-15,16-lactol diterpene prevents LPS-triggered inflammatory responses by inhibiting endothelial activation

Endothelial activation contributes to lung inflammatory disorders by inducing leucocyte recruitment to pulmonary parenchyma. Consequently, vascular-targeted therapies constitute promising strategies for the treatment of inflammatory pathologies. In the present study, we evaluated the effect of 8,9-dehydrohispanolone-15,16-lactol diterpene (DT) on lung endothelium during inflammation. Lung endothelial cells pre-treated with DT and activated with lipopolysaccharide (LPS) or tumour necrosis factor-α (TNF-α) exhibited reduced expression of the pro-inflammatory cytokines Cxcl10, Ccl5 and Cxcl1, whereas the anti-inflammatory molecules IL1r2 and IL-10 were induced. Consistent with this result, DT pre-treatment inhibited nuclear factor κB (NF-κB) nuclear translocation, by interfering with IκBα phosphorylation, and consequently NF-κB transcriptional activity in endothelium activated by LPS or TNF-α. Furthermore, DT, probably through p38 signalling, induced transcriptional activation of genes containing activator protein 1 (AP-1)-binding elements. Inhibition of p38 prevented IL1r2 mRNA expression in endothelium incubated with DT alone or in combination with LPS or TNF-α. Accordingly, conditioned medium (CM) from these cells failed to stimulate leucocytes as measured by a reduction in adhesive ability of the leucocyte cell line J774 to fibronectin (FN). Additionally, DT reduced the expression of the endothelial adhesion molecules E-selectin, vascular cell adhesion molecule 1 (VCAM-1) and intercellular adhesion molecule 1 (ICAM-1) after activation. Similarly, expression of VCAM-1 and ICAM-1 molecules on the lung endothelial layer of C57/BL6 mice pre-treated with DT and challenged with LPS were unchanged. Finally, inhibition of vascular adhesion molecule expression by DT decreased the interaction of J774 cells with lung endothelial cells in an inflammatory environment. Our findings establish DT as a novel endothelial inhibitor for the treatment of inflammatory-related diseases triggered by Gram-negative bacteria or by the associated cytokine TNF-α.

From the working group "Experimental Pathology" to the department "Pathology Unit" – historical development in retrospect

Abstract. The Pathology Unit of the German Primate Center started as the working group of Experimental Pathology in 1992. This small group with one veterinary pathologist and a technician was founded based on an idea of Prof. Dr. Kuhn, who wanted to strengthen the pathology research activities and to establish a centralized electron microscopy laboratory. Later on, experimental pathology, veterinary services and primate husbandry were integrated as the Department of Veterinary Medicine and Primate Husbandry but subsequently again separated. Prof. Dr. Franz-Josef Kaup, the head of the previously integrated department, remained in his capacity as the leader of the different units. Over the years, the research activities have changed from SIV-associated pathology to other infectious diseases. Today, the main research focus is on the pathogenesis of orthopoxvirus infection, primate pathology, neglected tropical diseases and nonhuman primates as models for chronic respiratory diseases. This paper gives an overview of the historical development and aspects of research activities.

Mouse lung slices: An ex vivo model for the evaluation of antiviral and anti-inflammatory agents against influenza viruses

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Mouse lung slices stay alive for at least 5 days ex vivo.

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Influenza viruses can replicate in mouse lung slices and trigger robust cytokine and chemokine responses.

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A positive correlation in cytokine and chemokine responses between ex vivo and in vivo exists.

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Neuraminidase and IP-10 can serve as readouts for antiviral and anti-inflammation activities, respectively.

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This ex vivo model may predict efficacy of drug candidates in antiviral and anti-inflammation activities in vivo.

The influenza A virus is notoriously known for its ability to cause recurrent epidemics and global pandemics. Antiviral therapy is effective when treatment is initiated within 48 h of symptom onset, and delaying treatment beyond this time frame is associated with decreased efficacy. Research on anti-inflammatory therapy to ameliorate influenza-induced inflammation is currently underway and seems important to the impact on the clinical outcome. Both antiviral and anti-inflammatory drugs with novel mechanisms of action are urgently needed. Current methods for evaluating the efficacy of anti-influenza drugs rely mostly on transformed cells and animals. Transformed cell models are distantly related to physiological and pathological conditions. Although animals are the best choices for preclinical drug testing, they are not time- or cost-efficient. In this study, we established an ex vivo model using mouse lung slices to evaluate both antiviral and anti-inflammatory agents against influenza virus infection. Both influenza virus PR8 (H1N1) and A/Human/Hubei/3/2005 (H3N2) can replicate efficiently in mouse lung slices and trigger significant cytokine and chemokine responses. The induction of selected cytokines and chemokines were found to have a positive correlation between ex vivo and in vivo experiments, suggesting that the ex vivo cultured lung slices may closely resemble the lung functionally in an in vivo configuration when challenged by influenza virus. Furthermore, a set of agents with known antiviral and/or anti-inflammatory activities were tested to validate the ex vivo model. Our results suggested that mouse lung slices provide a robust, convenient and cost-efficient model for the assessment of both antiviral and anti-inflammatory agents against influenza virus infection in one assay. This ex vivo model may predict the efficacy of drug candidates’ antiviral and anti-inflammatory activities in vivo.

The expression and secretion of vimentin in the progression of non-alcoholic steatohepatitis

The pathogenesis of non-alcoholic steatohepatitis (NASH) is not fully understood. In the present study, both in vitro and in vivo vimentin expression and secretion in NASH were investigated. The exposure of palmitate and lipopolysaccharide (LPS) to HepG2 cells enhanced caspase-3 activity and vimentin expression, respectively. The combined effects of both treatments on vimentin expression and caspase-3 activation appeared to be synergic. In contrast, blockade of caspase-3 activity by zVADfmk resulted in a significant reduction of cleaved vimentin and secreted vimentin into the culture supernatant. Similarly, lipid accumulation and inflammation occurred in mice fed a methionine-choline-deficient diet; thus, vimentin expression and serum cleaved vimentin levels were increased. However, vimentin was not significantly upregulated, and no cleavage occurred in mice fed a high-fat diet. It was conclusively determined that lipid accumulation in hepatocytes induces apoptosis through a caspase-3 dependent pathway; whereas, LPS stimulates vimentin expression, leading to its cleavage and secretion. Increased vimentin fragment levels indicated the existence of substantial hepatocellular death via an apoptotic mechanism. [BMB Reports 2014; 47(8): 457-462]

Exploring the innate immunological response of an alternative nonhuman primate model of infectious disease; the common marmoset

The common marmoset (Callithrix jacchus) is increasingly being utilised as a nonhuman primate model for human disease, ranging from autoimmune to infectious disease. In order to fully exploit these models, meaningful comparison to the human host response is necessary. Commercially available reagents, primarily targeted to human cells, were utilised to assess the phenotype and activation status of key immune cell types and cytokines in naive and infected animals. Single cell suspensions of blood, spleen, and lung were examined. Generally, the phenotype of cells was comparable between humans and marmosets, with approximately 63% of all lymphocytes in the blood of marmosets being T cells, 25% B-cells, and 12% NK cells. The percentage of neutrophils in marmoset blood were more similar to human values than mouse values. Comparison of the activation status of cells following experimental systemic or inhalational infection exhibited different trends in different tissues, most obvious in cell types active in the innate immune response. This work significantly enhances the ability to understand the immune response in these animals and fortifies their use as models of infectious disease.

Cyclic nucleotide-based therapeutics for chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) defines a group of chronic inflammatory disorders of the airways that are characterised by a progressive and largely irreversible decline in expiratory airflow. Drugs used to treat COPD through actions mediated by cyclic AMP (cAMP) are restricted to long-acting and short-acting β2-adrenoceptor agonists and, in a subset of patients with chronic bronchitis, a phosphodiesterase 4 inhibitor, roflumilast. These agents relax airway smooth muscle and suppress inflammation. At the molecular level, these effects in the airways are mediated by two cAMP effectors, cAMP-dependent protein kinase and exchange proteins activated by cAMP. The pharmacology of newer agents, acting through these systems, is discussed here with an emphasis on their potential to interact and increase therapeutic effectiveness.

Airway hyper-responsiveness in lipopolysaccharide-challenged common marmosets (Callithrix jacchus)

Animal models with a high predictive value for human trials are needed to develop novel human-specific therapeutics for respiratory diseases. The aim of the present study was to examine lung-function parameters in marmoset monkeys (Callithrix jacchus) that can be used to detect pharmacologically or provocation-induced AHR (airway hyper-responsiveness). Therefore a custom-made lung-function device that allows application of defined aerosol doses during measurement was developed. It was hypothesized that LPS (lipopolysaccharide)-challenged marmosets show AHR compared with non-challenged healthy subjects. Invasive plethysmography was performed in 12 anaesthetized orotracheally intubated and spontaneously breathing marmosets. Pulmonary data of R_L (lung resistance), C_dyn (dynamic compliance), EF₅₀ (mid-expiratory flow), P_oes (oesophageal pressure), MV (minute volume), respiratory frequency (f) and V_T (tidal volume) were collected. Measurements were conducted under baseline conditions and under MCh (methacholine)-induced bronchoconstriction. The measurement was repeated with the same group of animals after induction of an acute lung inflammation by intratracheal application of LPS. PDs (provocative doses) of MCh to achieve a certain increase in R_L were significantly lower after LPS administration. AHR was demonstrated in the LPS treated compared with the naïve animals. The recorded lung-function data provide ground for pre-clinical efficacy and safety testing of anti-inflammatory substances in the common marmoset, a new translational NHP (non-human primate) model for LPS-induced lung inflammation.

Efficacy and safety of RPL554, a dual PDE3 and PDE4 inhibitor, in healthy volunteers and in patients with asthma or chronic obstructive pulmonary disease: findings from four clinical trials

BACKGROUND

Many patients with asthma or chronic obstructive pulmonary disease (COPD) routinely receive a combination of an inhaled bronchodilator and anti-inflammatory glucocorticosteroid, but those with severe disease often respond poorly to these classes of drug. We assessed the efficacy and safety of a novel inhaled dual phosphodiesterase 3 (PDE3) and PDE4 inhibitor, RPL554 for its ability to act as a bronchodilator and anti-inflammatory drug.

METHODS

Between February, 2009, and January, 2013, we undertook four proof-of-concept clinical trials in the Netherlands, Italy, and the UK. Nebulised RPL554 was examined in study 1 for safety in 18 healthy men who were randomly assigned (1:1:1) to receive an inhaled dose of RPL554 (0·003 mg/kg or 0·009 mg/kg) or placebo by a computer-generated randomisation table. Subsequently, six non-smoking men with mild allergic asthma received single doses of RPL554 (three received 0·009 mg/kg and three received 0·018 mg/kg) in an open-label, adaptive study, and then ten men with mild allergic asthma were randomly assigned to receive placebo or RPL554 (0·018 mg/kg) by a computer-generated randomisation table for an assessment of safety, bronchodilation, and bronchoprotection. Study 2 examined the reproducibility of the bronchodilator response to a daily dose of nebulised RPL554 (0·018 mg/kg) for 6 consecutive days in a single-blind (patients masked), placebo-controlled study in 12 men with clinically stable asthma. The safety and bronchodilator effect of RPL554 (0·018 mg/kg) was assessed in study 3, an open-label, placebo-controlled crossover trial, in 12 men with mild-to-moderate COPD. In study 4, a placebo-controlled crossover trial, the effect of RPL554 (0·018 mg/kg) on lipopolysaccharide-induced inflammatory cell infiltration in induced sputum was investigated in 21 healthy men. In studies 3 and 4, randomisation was done by computer-generated permutation with a block size of two for study 3 and four for study 4. Unless otherwise stated, participants and clinicians were masked to treatment assignment. Analyses were by intention to treat. All trials were registered with EudraCT, numbers 2008-005048-17, 2011-001698-22, 2010-023573-18, and 2012-000742-34.

FINDINGS

Safety was a primary endpoint of studies 1 and 3 and a secondary endpoint of studies 2 and 4. Overall, RPL554 was well tolerated, and adverse events were generally mild and of equal frequency between placebo and active treatment groups. Efficacy was a primary endpoint of study 2 and a secondary endpoint of studies 1 and 3. Study 1 measured change in forced expiratory volume in 1 s (FEV1) and provocative concentration of methacholine causing a 20% fall in FEV1 (PC20MCh) in participants with asthma. RPL554 produced rapid bronchodilation in patients with asthma with an FEV1 increase at 1 h of 520 mL (95% CI 320-720; p<0·0001), which was a 14% increase from placebo, and increased the PC20MCh by 1·5 doubling doses (95% CI 0·63-2·28; p=0·004) compared with placebo. The primary endpoint of study 2 was maximum FEV1 reached during 6 h after dosing with RPL554 in patients with asthma. RPL554 produced a similar maximum mean increase in FEV1 from placebo on day 1 (555 mL, 95% CI 442-668), day 3 (505 mL, 392-618), and day 6 (485 mL, 371-598; overall p<0·0001). A secondary endpoint of study 3 (patients with COPD) was the increase from baseline in FEV1. RPL554 produced bronchodilation with a mean maximum FEV1 increase of 17·2% (SE 5·2). In healthy individuals (study 4), the primary endpoint was percentage change in neutrophil counts in induced sputum 6 h after lipopolysaccharide challenge. RPL554 (0·018 mg/kg) did not significantly reduce the percentage of neutrophils in sputum (80·3% in the RPL554 group vs 84·2% in the placebo group; difference -3·9%, 95% CI -9·4 to 1·6, p=0·15), since RPL554 significantly reduced neutrophils (p=0·002) and total cells (p=0·002) to a similar degree.

INTERPRETATION

In four exploratory studies, inhaled RPL554 is an effective and well tolerated bronchodilator, bronchoprotector, and anti-inflammatory drug and further studies will establish the full potential of this new drug for the treatment of patients with COPD or asthma.

FUNDING

Verona Pharma.

The repertoire of MHC class I genes in the common marmoset: evidence for functional plasticity

In humans, the classical antigen presentation function of major histocompatibility complex (MHC) class I molecules is controlled by the human leukocyte antigen HLA -A, HLA-B and HLA-C loci. A similar observation has been made for great apes and Old World monkey species. In contrast, a New World monkey species such as the cotton-top tamarin (Saguinus oedipus) appears to employ the G locus for its classical antigen presentation function. At present, little is known about the classical MHC class I repertoire of the common marmoset (Callithrix jacchus), another New World monkey that is widely used in biomedical research. In the present population study, no evidence has been found for abundant transcription of classical I class genes. However, in each common marmoset, four to seven different G-like alleles were detected, suggesting that the ancestral locus has been subject to expansion. Segregation studies provided evidence for at least two G-like genes present per haplotype, which are transcribed by a variety of cell types. The alleles of these Caja-G genes cluster in separate lineages, suggesting that the loci diversified considerably after duplication. Phylogenetic analyses of the introns confirm that the Caja-G loci cluster in the vicinity of HLA-G, indicating that both genes shared an ancestor. In contrast to HLA-G, Caja-G shows considerable polymorphism at the peptide-binding sites. This observation, together with the lack of detectable transcripts of A and B-like genes, indicates that Caja-G genes have taken over the function of classical class I genes. These data highlight the extreme plasticity of the MHC class I gene system.

Low-dose endotoxin inhalation in healthy volunteers--a challenge model for early clinical drug development

BACKGROUND

Inhalation of endotoxin (LPS) induces a predominantly neutrophilic airway inflammation and has been used as model to test the anti-inflammatory activity of novel drugs. In the past, a dose exceeding 15-50 μg was generally needed to induce a sufficient inflammatory response. For human studies, regulatory authorities in some countries now request the use of GMP-grade LPS, which is of limited availability. It was therefore the aim of this study to test the effect and reproducibility of a low-dose LPS challenge (20,000 E.U.; 2 μg) using a flow- and volume-controlled inhalation technique to increase LPS deposition.

METHODS

Two to four weeks after a baseline sputum induction, 12 non-smoking healthy volunteers inhaled LPS on three occasions, separated by at least 4 weeks. To modulate the inflammatory effect of LPS, a 5-day PDE4 inhibitor (Roflumilast) treatment preceded the last challenge. Six hours after each LPS inhalation, sputum induction was performed.

RESULTS

The low-dose LPS inhalation was well tolerated and increased the mean percentage of sputum neutrophils from 25% to 72%. After the second LPS challenge, 62% neutrophils and an increased percentage of monocytes were observed. The LPS induced influx of neutrophils and the cumulative inflammatory response compared with baseline were reproducible. Treatment with Roflumilast for 5 days did not have a significant effect on sputum composition.

CONCLUSION

The controlled inhalation of 2 μg GMP-grade LPS is sufficient to induce a significant neutrophilic airway inflammation in healthy volunteers. Repeated low-dose LPS challenges potentially result in a small shift of the neutrophil/monocyte ratio; however, the cumulative response is reproducible, enabling the use of this model for "proof-of-concept" studies for anti-inflammatory compounds during early drug development.

Distribution and morphology of Clara cells in common marmosets (Callithrix jacchus)

BACKGROUND

The objective of this investigation was to define the phenotype and spatial distribution of Clara cells within the respiratory tract of common marmosets and to distinguish them from other non-ciliated cells (goblet cells, mixed type secretory cells).

METHODS

Non-ciliated cells were identified immunohistochemically using antibodies against Clara cell secretory protein and mucin 5AC. Transmission electron microscopy and scanning electron microscopy were performed to characterize Clara cells ultrastructurally.

RESULTS

Clara cells were present throughout the tracheobronchial tree, with lowest numbers in the trachea and highest numbers in bronchioles. Goblet cells and mixed type cells were scarce in the upper conducting airways and virtually absent within bronchioles. Ultrastructurally, Clara cells showed typical apical electron-dense granules and a prominent granular endoplasmatic reticulum.

CONCLUSIONS

Clara cells of common marmosets have species-specific morphological characteristics, which suggest grouping the common marmoset phenotypically between primates and rodents.

Assessment of immunotoxicity using precision-cut tissue slices

1.When the immune system encounters incoming infectious agents, this generally leads to immunity. The evoked immune response is usually robust, but can be severely perturbed by potentially harmful environmental agents such as chemicals, pharmaceuticals and allergens. 2.Immunosuppression, hypersensitivity and autoimmunity may occur due to changed immune activity. Evaluation of the immunotoxic potency of agents as part of risk assessment is currently established in vivo with animal models and in vitro with cell lines or primary cells. 3.Although in vivo testing is usually the most relevant situation for many agents, more and more in vitro models are being developed for assessment of immunotoxicity. In this context, hypersensitivity and immunosuppression are considered to be a primary focus for developing in vitro methods. Three-dimensional organotypic tissue models are also part of current research in immunotoxicology. 4.In recent years, there has been a revival of interest in organotypic tissue models. In the context of immunotoxicity testing, precision-cut lung slices in particular have been intensively studied. Therefore, this review is very much focused on pulmonary immunotoxicology. Respiratory hypersensitivity and inflammation are further highlighted aspects of this review. Immunotoxicity assessment currently is of limited use in other tissue models, which are therefore described only briefly within this review.

Upregulation of Mer receptor tyrosine kinase signaling attenuated lipopolysaccharide-induced lung inflammation

Mer receptor tyrosine kinase (Mer) signaling plays a central role in the intrinsic inhibition of the inflammatory response to Toll-like receptor activation. Previously, we found that lung Mer protein expression decreased after lipopolysaccharide (LPS) treatment due to enhanced Mer cleavage. The purpose of the present study was to examine whether pharmacologically restored membrane-bound Mer expression upregulates the Mer signaling pathways and suppresses lung inflammatory responses. Pretreatment with the ADAM17 (a disintegrin and metalloproteinase-17) inhibitor TAPI-0 (tumor necrosis factor alpha protease inhibitor-0) reduced LPS-induced production of soluble Mer protein in bronchoalveolar lavage (BAL) fluid, restored membrane-bound Mer expression, and increased Mer activation in alveolar macrophages and lungs after LPS treatment. TAPI-0 also enhanced Mer downstream signaling, including phosphorylation of protein kinase b, focal adhesion kinase, and signal transducer and activator of transcription 1. As expected from enhanced Mer signaling, TAPI-0 also augmented suppressor of cytokine signaling-1 and -3 mRNA and protein levels and inhibited nuclear factor κB activation at 4 and 24 hours after LPS treatment. TAPI-0 suppressed LPS-induced inflammatory cell accumulation, total protein level elevation in BAL fluid, and production of inflammatory mediators, including tumor necrosis factor-α, interleukin-1β, and macrophage inflammatory protein-2. Additionally, the effects of TAPI-0 on the activation of Mer signaling and the production of inflammatory responses could be reversed by cotreatment with specific Mer-neutralizing antibody. Restored Mer protein expression by treatment with TAPI-0 efficiently prevents the inflammatory cascade during acute lung injury.