Harnessing opportunities in non-animal asthma research for a 21st-century science

Animals in Respiratory Research

The respiratory barrier, a thin epithelial barrier that separates the interior of the human body from the environment, is easily damaged by toxicants, and chronic respiratory diseases are common. It also allows the permeation of drugs for topical treatment. Animal experimentation is used to train medical technicians, evaluate toxicants, and develop inhaled formulations. Species differences in the architecture of the respiratory tract explain why some species are better at predicting human toxicity than others. Some species are useful as disease models. This review describes the anatomical differences between the human and mammalian lungs and lists the characteristics of currently used mammalian models for the most relevant chronic respiratory diseases (asthma, chronic obstructive pulmonary disease, cystic fibrosis, pulmonary hypertension, pulmonary fibrosis, and tuberculosis). The generation of animal models is not easy because they do not develop these diseases spontaneously. Mouse models are common, but other species are more appropriate for some diseases. Zebrafish and fruit flies can help study immunological aspects. It is expected that combinations of in silico, in vitro, and in vivo (mammalian and invertebrate) models will be used in the future for drug development.

Poor Translatability of Biomedical Research Using Animals - A Narrative Review

The failure rate for the translation of drugs from animal testing to human treatments remains at over 92%, where it has been for the past few decades. The majority of these failures are due to unexpected toxicity - that is, safety issues revealed in human trials that were not apparent in animal tests - or lack of efficacy. However, the use of more innovative tools, such as organs-on-chips, in the preclinical pipeline for drug testing, has revealed that these tools are more able to predict unexpected safety events prior to clinical trials and so can be used for this, as well as for efficacy testing. Here, we review several disease areas, and consider how the use of animal models has failed to offer effective new treatments. We also make some suggestions as to how the more human-relevant new approach methodologies might be applied to address this.

Human-specific approaches to brain research for the 21st century: a South American perspective

The 21st century paradigm in toxicology, which emphasizes mechanistic understanding and species-relevant modeling of human biology and pathophysiology, is gaining traction in the wider biosciences through a global workshop series organized by the BioMed21 Collaboration. The second of this series, entitled Emerging Technology Toward Pathway-Based Human Brain Research, was held in Brazil in 2017, bringing together leading South American and international scientists, research funders and other stakeholders. The aims were to foster strategic scientific dialogue and identify actionable consensus recommendations as a first step toward a roadmap for 21st century, human-specific health research and funding in the region.

Towards a 21st-century roadmap for biomedical research and drug discovery: consensus report and recommendations

Decades of costly failures in translating drug candidates from preclinical disease models to human therapeutic use warrant reconsideration of the priority placed on animal models in biomedical research. Following an international workshop attended by experts from academia, government institutions, research funding bodies, and the corporate and non-governmental organisation (NGO) sectors, in this consensus report, we analyse, as case studies, five disease areas with major unmet needs for new treatments. In view of the scientifically driven transition towards a human pathways-based paradigm in toxicology, a similar paradigm shift appears to be justified in biomedical research. There is a pressing need for an approach that strategically implements advanced, human biology-based models and tools to understand disease pathways at multiple biological scales. We present recommendations to help achieve this.

A look into the future of ALS research

Although amyotrophic lateral sclerosis (ALS), also referred as 'Lou Gehrig's Disease,' was first described in 1869 and the first disease-associated gene was discovered almost 20 years ago, the disease etiology is still not fully understood and treatment options are limited to one drug approved by the US Food and Drug Administration (FDA). The slow translational progress suggests that current research models are not ideal to study such a complicated disease and need to be re-examined. Progress will require greater insight into human genes and biology involved in ALS susceptibility, as well as a deeper understanding of disease phenotype at the histological and molecular levels. Improving human disease outcome will require directing focus toward improved assessment technologies and innovative approaches.

Human Reconstituted Nasal Epithelium, a promising in vitro model to assess impacts of environmental complex mixtures

Considering the impact of respiratory diseases around the world, appropriate experimental tools to help understand the mechanisms involved in such diseases are becoming essential. Our aim was to investigate the cellular and morphological reactivity of a human Reconstituted Nasal Epithelium (hRNE) to evaluate the impact of environmental complex mixture (ECM), with tobacco smoke as a model, after three weeks of repeated exposures. Staining of hRNE showed a multilayered ciliated epithelium, with a regular cilia beats, and a mucus production. When hRNE was exposed to ECM for 5 min once or twice a week, during 3 weeks, significant changes occurred: IL-8 production significantly increased 24h after the first exposure compared with Air-exposure and only during the first week, without any loss of tissue integrity. Immunostaining of F-actin cytoskeleton showed a modification in cellular morphology (number and diameter). Taken together our results indicate that hRNE is well suited to study the cellular and morphological effects of repeated exposures to an environmental complex mixture. Human reconstituted epithelium models are currently the best in vitro representation of human respiratory tract physiology, and also the most robust for performing repeated exposures to atmospheric pollutants.

A model of human nasal epithelial cells adapted for direct and repeated exposure to airborne pollutants

Airway epithelium lining the nasal cavity plays a pivotal role in respiratory tract defense and protection mechanisms. Air pollution induces alterations linked to airway diseases such as asthma. Only very few in vitro studies to date have succeeded in reproducing physiological conditions relevant to cellular type and chronic atmospheric pollution exposure. We therefore, set up an in vitro model of human Airway Epithelial Cells of Nasal origin (hAECN) close to real human cell functionality, specifically adapted to study the biological effects of exposure to indoor gaseous pollution at the environmental level. hAECN were exposed under air-liquid interface, one, two, or three-times at 24 h intervals for 1 h, to air or formaldehyde (200 μg/m(3)), an indoor air gaseous pollutant. All experiments were ended at day 4, when both cellular viability and cytokine production were assessed. Optimal adherence and confluence of cells were obtained 96 h after cell seeding onto collagen IV-precoated insert. Direct and repeated exposure to formaldehyde did not produce any cellular damage or IL-6 production change, although weak lower IL-8 production was observed only after the third exposure. Our model is significantly better than previous ones due to cell type and the repeated exposure protocol.

Humane Society International's global campaign to end animal testing

The Research & Toxicology Department of Humane Society International (HSI) operates a multifaceted and science-driven global programme aimed at ending the use of animals in toxicity testing and research. The key strategic objectives include: a) ending cosmetics animal testing worldwide, via the multinational Be Cruelty-Free campaign; b) achieving near-term reductions in animal testing requirements through revision of product sector regulations; and c) advancing humane science by exposing failing animal models of human disease and shifting science funding toward human biology-based research and testing tools fit for the 21st century. HSI was instrumental in ensuring the implementation of the March 2013 European sales ban for newly animal-tested cosmetics, in achieving the June 2013 cosmetics animal testing ban in India as well as major cosmetics regulatory policy shifts in China and South Korea, and in securing precedent-setting reductions in in vivo data requirements for pesticides in the EU through the revision of biocides and plant protection product regulations, among others. HSI is currently working to export these life-saving measures to more than a dozen industrial and emerging economies.

A vision becoming reality

Non-animal science in toxicology and health research has been progressing for decades, but only now is it being seen widely as advanced science. The emergence of novel human biology-based tools and models, combined with legislative and regulatory change, a 21st century concept for toxicology, continuing failures in the drug pipeline, and systematic critiques of animal models, have created a pivotal moment of change. The leading edge is starting to become the norm. Humans and other animals are likely to benefit as a result.

Animal models of asthma: reprise or reboot?

Animal models of disease represent the pinnacle of hierarchical research efforts to validate targets and compounds for therapeutic intervention. Yet models of asthma, particularly in the mouse, which, for practical reasons, has become the sine qua non of asthma research, have been a bone of contention for decades. With barely a nod to their limitations and an extensive history of translational failures, they continue to be used for target identification and to justify the clinical evaluation of new compounds. Recent improvements - including sensitization directly to the airways; use of more relevant allergens; development of a chronic rather than short-term condition; utilization of techniques to measure lung function beyond uninterpretable measures of airway hyperresponsiveness - are laudable but cannot bridge the chasm between the models and the myriad complexities of the human disorder and multiple asthma endophenotypes. While further model developments are necessary, including recognition of key environmental factors beyond allergens, the judicious integration with newer ex vivo and in vitro techniques, including human precision-cut lung slices, reprograming of patient-derived induced pluripotent stem cells and fibroblasts to epithelial and smooth muscle cells, and use of other clinical samples to create a more holistic depiction of activities, might improve their translational success.