Rabbit models of human diseases for diagnostics and therapeutics development

Animal models of neuropsychiatric systemic lupus erythematosus: deciphering the complexity and guiding therapeutic development

Systemic lupus erythematosus (SLE) poses formidable challenges due to its multifaceted etiology while impacting multiple tissues and organs and displaying diverse clinical manifestations. Genetic and environmental factors contribute to SLE complexity, with relatively limited approved therapeutic options. Murine models offer insights into SLE pathogenesis but do not always replicate the nuances of human disease. This review critically evaluates spontaneous and induced animal models, emphasizing their validity and relevance to neuropsychiatric SLE (NPSLE). While these models undoubtedly contribute to understanding disease pathophysiology, discrepancies persist in mimicking some NPSLE intricacies. The lack of literature addressing this issue impedes therapeutic progress. We underscore the urgent need for refining models that truly reflect NPSLE complexities to enhance translational fidelity. We encourage a comprehensive, creative translational approach for targeted SLE interventions, balancing scientific progress with ethical considerations to eventually improve the management of NPSLE patients. A thorough grasp of these issues informs researchers in designing experiments, interpreting results, and exploring alternatives to advance NPSLE research.

Ocular tear fluid biomarkers collected by contact lenses

PURPOSE

To collect tear fluid biomarkers from contact lenses (CLs) and determine the impact of CL wear duration.

METHODS

Rabbits were fitted with commercial etafilcon A CLs, which were collected after 1 min, 4 and 8 h (n = 4/time point). Tear fluid proteins and cytokines were extracted from the CLs and quantified. An exploratory comparison was performed between CLs and Schirmer Strips (SS) for a 1 min duration.

RESULTS

The concentration of MUC5AC was significantly higher after 4 h of CL wear. The expression of all investigated cytokines (IL-1α, IL-1β, IL-8, IL-17A, IL-21, Leptin, MIP-1β, MMP-9, NCAM-1, and TNF-α) was detectable after 1 min of CL wear, and over time, all showed significant variations throughout the 8-h CL wear period. Notably, IL-1α significantly increased by 8 h of CL wear, while MMP-9 decreased. Albumin and lysozyme did not show significant variations with CL wear. Differences between CLs and SS after 1 min were statistically significant for albumin, Leptin, TNF-α, IL-1α, IL-1β, and IL-8.

CONCLUSIONS

The duration of CL wear significantly affects the collection of some tear fluid biomarkers. Albumin, MUC5AC, and cytokines may have individual and synergistic diagnostic or prognostic potential. CLs and SS were similar for lysozyme and MUC5AC but differed in the collection of albumin and some cytokines. CLs are a viable tear fluid collection method for biomarker analyses and can be immediately added as a routine clinical test by being FDA-approved medical devices.

Physiologically based pharmacokinetic models for systemic disposition of protein therapeutics in rabbits

Physiologically based pharmacokinetic (PBPK) modelling is an important tool to predict drug disposition in the body. Rabbits play a pivotal role as a highly valued small animal model, particularly in the field of ocular therapeutics, where they serve as a crucial link between preclinical research and clinical applications. In this context, we have developed PBPK models designed specifically for rabbits, with a focus on accurately predicting the pharmacokinetic profiles of protein therapeutics following intravenous administration. Our goal was to comprehend the influence of key physiological factors on systemic disposition of antibodies and their functional derivatives. For the development of the systemic PBPK models, rabbit physiological factors such as gene expression, body weight, neonatal fragment crystallizable receptor (FcRn) binding, target binding, target concentrations, and target turnover rate were meticulously considered. Additionally, key protein parameters, encompassing hydrodynamic radius, binding kinetic constants (KD, koff), internal degradation of the protein-target complex, and renal clearance, were represented in the models. Our final rabbit models demonstrated a robust correlation between predicted and observed serum concentration-time profiles after single intravenous administration in rabbits, covering IgG, Fab, F(ab)2, Fc, and Fc fusion proteins from various publications. These pharmacokinetic simulations offer a promising platform for translating preclinical findings to clinical settings. The presented rabbit intravenous PBPK models lay an important foundation for more specific applications of protein therapeutics in ocular drug development.

Physicochemical Characterization of Yogurt Fortified with Microencapsulated Cinnamon (Cinnamomum zeylanicum) and Its Effects on Metabolic Syndrome Induced in Rabbits (Oryctolagus cuniculus)

Chronic noncommunicable diseases are a global health problem causing increased rates of mortality and sick leaves, which can be reduced by controlling dyslipidemia and hyperglycemia. Experimental and clinical studies have demonstrated the antidiabetic, lipid-lowering, antiobesogenic, anti-inflammatory, and antihypertensive properties of cinnamon; therefore, its use in yogurt can help reverse the effects of these diseases. Our study aims to evaluate the effect of a microencapsulated aqueous extract of cinnamon (Cinnamomum zeylanicum) (MCE Cz) incorporated in a yogurt drink on metabolic syndrome (MS) in a rabbit (Oryctolagus cuniculus). Physicochemical, microbiological, and proximal chemical characterization; total phenol, flavonoid, and 2,2-diphenyl-1-picrylhydrazil activity quantification; intestinal bioaccessibility; sensory analysis; MS induction through diet; and treatment with 5, 10, and 20 mg/kg of flavonoids contained in the MCE Cz were performed to help evaluate morphological, biochemical, and lipid peroxidation measurements in the liver and heart. The results show that the addition of MCE Cz in the yogurt modified the yogurt texture, increased its adhesiveness and firmness, and imparted a characteristic cinnamon color and biological value by providing intestinally bioaccessible antioxidants with antioxidant potential by reducing lipoperoxidation in the liver and heart after treatment. MCE Cz reduced the weight of the animals by up to 38.5% and the abdominal circumference by 29%. Biochemically, it decreased glucose levels by 24.38%, total cholesterol levels by 69.2%, triglyceride levels by 72.69%, and low-density lipoprotein levels by 89.25%; it increased high-density lipoprotein levels by 67.08%. Therefore, adding MCE Cz in doses of 5 and 10 mg of flavonoids in drinkable yogurt can be an alternative to preparing functional foods with physicochemical attributes and biological properties that can be consumed at all stages of life without undesirable effects. Moreover, it can act as a potential adjuvant in the treatment of comorbidities related to MS.

Contact lenses as novel tear fluid sampling vehicles for total RNA isolation, precipitation, and amplification

The tear fluid is a readily accessible, potential source for biomarkers of disease and could be used to monitor the ocular response to contact lens (CL) wear or ophthalmic pathologies treated by therapeutic CLs. However, the tear fluid remains largely unexplored as a biomarker source for RNA-based molecular analyses. Using a rabbit model, this study sought to determine whether RNA could be collected from commercial CLs and whether the duration of CL wear would impact RNA recovery. The results were referenced to standardized strips of filtered paper (e.g., Shirmer Strips) placed in the inferior fornix. By performing total RNA isolation, precipitation, and amplification with commercial kits and RT-PCR methods, CLs were found to have no significant differences in RNA concentration and purity compared to Schirmer Strips. The study also identified genes that could be used to normalize RNA levels between tear samples. Of the potential control genes or housekeeping genes, GAPDH was the most stable. This study, which to our knowledge has never been done before, provides a methodology for the detection of RNA and gene expression changes from tear fluid that could be used to monitor or study eye diseases.

Structure- and machine learning-guided engineering demonstrate that a non-canonical disulfide in an anti-PD-1 rabbit antibody does not impede antibody developability

Rabbits produce robust antibody responses and have unique features in their antibody repertoire that make them an attractive alternative to rodents for in vivo discovery. However, the frequent occurrence of a non-canonical disulfide bond between complementarity-determining region (CDR) H1 (C35a) and CDRH2 (C50) is often seen as a liability for therapeutic antibody development, despite limited reports of its effect on antibody binding, function, and stability. Here, we describe the discovery and humanization of a human-mouse cross-reactive anti-programmed cell death 1 (PD-1) monoclonal rabbit antibody, termed h1340.CC, which possesses this non-canonical disulfide bond. Initial removal of the non-canonical disulfide resulted in a loss of PD-1 affinity and cross-reactivity, which led us to explore protein engineering approaches to recover these. First, guided by the sequence of a related clone and the crystal structure of h1340.CC in complex with PD-1, we generated variant h1340.SA.LV with a potency and cross-reactivity similar to h1340.CC, but only partially recovered affinity. Side-by-side developability assessment of both h1340.CC and h1340.SA.LV indicate that they possess similar, favorable properties. Next, and prompted by recent developments in machine learning (ML)-guided protein engineering, we used an unbiased ML- and structure-guided approach to rapidly and efficiently generate a different variant with recovered affinity. Our case study thus indicates that, while the non-canonical inter-CDR disulfide bond found in rabbit antibodies does not necessarily constitute an obstacle to therapeutic antibody development, combining structure- and ML-guided approaches can provide a fast and efficient way to improve antibody properties and remove potential liabilities.

The rabbit as an animal model to study innate immunity genes: Is it better than mice?

The European rabbit (Oryctolagus cuniculus) was the first animal model used to understand human diseases like rabies and syphilis. Nowadays, the rabbit is still used to study several human infectious diseases like syphilis, HIV and papillomavirus. However, due to several mainly practical reasons, it has been replaced as an animal model by mice (Mus musculus). The rabbit and mouse share a recent common ancestor and are classified in the superorder Glires which arose at approximately 82 million years ago (mya). These species diverged from the Primates’ ancestor at around 92 million years ago and, as such, one expects the rabbit-human and mouse-human genetic distances to be very similar. To evaluate this hypothesis, we developed a set of tools for automatic data extraction, sequence alignment and similarity study, and a web application for visualization of the resulting data. We aligned and calculated the genetic distances for 2793 innate immune system genes from human, rabbit and mouse using sequences available in the NCBI database. The obtained results show that the rabbit-human genetic distance is lower than the mouse-human genetic distance for 88% of these genes. Furthermore, when we considered only genes with a difference in genetic distance higher than 0.05, this figure increase to 93%. These results can be explained by the increase of the mutation rates in the mouse lineage suggested by some authors and clearly show that, at least looking to the genetic distance to human genes, the European rabbit is a better model to study innate immune system genes than the mouse.

Evaluation of chimeric antigen receptor of humanized rabbit-derived T cell receptor-like antibody

T-cell receptor (TCR)-like antibodies that specifically recognize antigenic peptides presented on major histocompatibility complex (MHC) molecules have been developed for next-generation cancer immunotherapy. Recently, we reported a rapid and efficient method to generate TCR-like antibodies using a rabbit system. We humanized previously generated rabbit-derived TCR-like antibodies reacting Epstein-Barr virus peptide (BRLF1p, TYPVLEEMF) in the context of HLA-A24 molecules, produced CAR-T cells, and evaluated their anti-tumor effects using in vitro and in vivo tumor models. Humanization of the rabbit-derived TCR-like antibodies using the complementarity-determining region grafting technology maintained their specificity and affinity. We prepared a second-generation chimeric antigen receptor (CAR) using scFv of the humanized TCR-like antibodies and then transduced them into human T-cells. The CAR-T cells specifically recognized BRLF1p/MHC molecules and lysed the target cells in an antigen-specific manner in vitro. They also demonstrated anti-tumor activity in a mouse xenograft model. We report the generation of CAR-T cells using humanized rabbit-derived TCR-like antibodies. Together with our established and efficient generation procedure for TCR-like antibodies using rabbits, our platform for the clinical application of humanized rabbit-derived TCR-like antibodies to CAR-T cells will help improve next-generation cancer immunotherapy.

Current Progress and Prospects in Rabbit Cloning

Somatic cell nuclear transfer (SCNT) shows great value in the generation of transgenic animals, protection of endangered animals, and stem cell therapy. The combination of SCNT and gene editing has produced a variety of genetically modified animals for life science and medical research. Rabbits have unique advantages as transgenic bioreactors and human disease models; however, the low SCNT efficiency severely impedes the application of this technology. The difficulty in SCNT may be attributable to the abnormal reprogramming of somatic cells in rabbits. This review focuses on the abnormal reprogramming of cloned mammalian embryos and evaluates the progress and prospects of rabbit somatic cell cloning.

Reactivity of selected markers of innate and adaptive immunity in rabbits experimentally infected with antigenic variants of RHD (Lagovirus europaeus/GI.1a)

Lagovirus europaeus/GI.1 causes a fatal viral condition in rabbits characterized by acute viral hepatitis and disseminated intravascular coagulation. Due to rapid viral and environmental changes variants (Lagovirus europaeus/GI.1a and GI.2) have appeared and few immunological studies were performed. The aim of the study was to determine innate and adaptive immunity parameters in rabbits infected with six Lagovirus europeus/GI.1a viruses. To achieve the goal several methods were used, i.e. cytometry, microscopy, biochemical and cytochemical tests, spectrophotometry. The results show that three immunotypes exists among the studied strains and they differ in innate (mainly) and adaptive immunity, partly depending on hemagglutination. The peak of changes is 24 h post infection in phagocytosis markers of polymorphonuclear cells and CD8⁺ T cells. Lagovirus europaeus/GI.1a strains differ from Lagovirus europaeus/GI.1 in terms of immunological response based on our previous work concerning the same parameters in immunological response against this disease.

Modulation of Cathepsin S (CTSS) Regulates the Secretion of Progesterone and Estradiol, Proliferation, and Apoptosis of Ovarian Granulosa Cells in Rabbits

Simple Summary

In goat and sheep, CTSS is reported to be important for the development and maturation of oocytes by regulating cell proliferation and apoptosis. The purpose of this study was to investigate the role of CTSS in regulating cell apoptosis and hormone secretion in rabbit granulosa cells. Our results suggested that the CTSS gene can promote the proliferation of granulosa cells and reduce its apoptosis in vitro, while overexpression of CTSS promoted the secretion of progesterone and estrogen in rabbit granulosa cells. Therefore, manipulation of CTSS may improve development of oocytes, and thus provide an approach for better manipulation of rabbit reproductive performance.

Abstract

Cathepsin S (CTSS) is a member of cysteine protease family. Although many studies have demonstrated the vital role of CTSS in many physiological and pathological processes including tumor growth, angiogenesis and metastasis, the function of CTSS in the development of rabbit granulosa cells (GCS) remains unknown. To address this question, we isolated rabbit GCS and explored the regulatory function of the CTSS gene in cell proliferation and apoptosis. CTSS overexpression significantly promoted the secretion of progesterone (P4) and estrogen (E2) by increasing the expression of STAR and CYP19A1 (p < 0.05). We also found that overexpression of CTSS increased GCS proliferation by up-regulating the expression of proliferation related gene (PCNA) and anti-apoptotic gene (BCL2). Cell apoptosis was markedly decreased by CTSS activation (p < 0.05). In contrast, CTSS knockdown significantly decreased the secretion of P4 and E2 and the proliferation of rabbit GCS, while increasing the apoptosis of rabbit GCS. Taken together, our results highlight the important role of CTSS in regulating hormone secretion, cell proliferation, and apoptosis in rabbit GCS. These results might provide a basis for better understanding the molecular mechanism of rabbit reproduction.

Nervous System Sampling for General Toxicity and Neurotoxicity Studies in Rabbits

Although manuscripts for multiple species recommending nervous system sampling for histopathology evaluation in safety assessment have been published in the past 15 years, none have addressed the laboratory rabbit. Here, we describe 2 trimming schemes for evaluating the rabbit brain in nonclinical toxicity studies. In both schemes, the intact brain is cut in the coronal plane to permit bilateral assessment. The first scheme is recommended for general toxicity studies (tier 1) in screening agents where there is no anticipated neurotoxic potential; this 6-section approach is consistent with the Society of Toxicologic Pathology (STP) "best practice" recommendations for brain sampling in nonrodents (Toxicol Pathol 41: 1028-1048, 2013¹). The second trimming scheme is intended for dedicated neurotoxicity studies (tier 2) to characterize known or suspected neurotoxicants where the nervous system is a key target organ. This tier 2 strategy relies on coronal trimming of the whole brain into 3-mm-thick slices and then evaluating 12 sections. Collection of spinal cord, ganglia, and nerve specimens for rabbits during nonclinical studies should follow published STP "best practice" recommendations for sampling the central nervous system¹ and peripheral nervous system (Toxicol Pathol 46: 372-402, 2018²).

Myeloperoxidase and Lysozymes as a Pivotal Hallmark of Immunity Status in Rabbits

Simple Summary

Rabbit breeding is a very important element in the context of broadly understood industrial breeding, as rabbits are one of the main and most frequently chosen economic directions. Effective rabbit breeding, however, requires full control over the health of these animals, which is particularly related to the orientation regarding their immune status. There are many indicators that can be used to assess the immune system, but the greatest attention should be paid to those that change rapidly over time and reflect the body’s first line of defense. Peripheral blood granulocytes contain enzymes with strong antimicrobial properties, the level of which changes as a result of various external factors, e.g., viral infection, which was assessed in this study. The aim of the study was to evaluate the dynamics of myeloperoxidase (MPO) and lysozyme (LZM) in the experimental infection of rabbits with the Lagovirus europaeus/GI.1a virus, which is a pathogen causing high mortality, decimating rabbit farms all over the world in a short time. The results obtained in the dynamic system show that the levels of assessed enzymes significantly change in the blood during infection. Assessing the immune system using these indicators could therefore be a potential biomarker for the immune status of rabbits.

Abstract

Infectious diseases, due to their massive scale, are the greatest pain for all rabbit breeders. Viral infections cause enormous economic losses in farms. Treating sick rabbits is very difficult and expensive, so it is very important to prevent disease by vaccinating. In order to successfully fight viral infections, it is important to know about the immune response of an infected animal. The aim of this study was to analyze the immune response mediated by antimicrobial peptides (myeloperoxidase (MPO) and lysozyme (LZM)) in peripheral blood neutrophils and rabbit serum by non-invasive immunological methods. The study was carried out on mixed breed rabbits that were experimentally infected with two strains (Erfurt and Rossi) of the Lagovirus europaeus/GI.1a virus. It has been observed that virus infection causes changes in the form of statistically significant increases in the activity of MPO and LZM concentration, while in the case of LZM activity only statistically significant decreases were noted. Additionally, clinical symptoms typical for the course of the disease were noted, and the probability of survival of the animals at 60 h p.i. (post infection) was 30% for the Erfurt strain, and −60% for the Rossi strain. The obtained results of MPO and LZMs suggest that these enzymes, especially MPO, may serve as a prognostic marker of the state of the immune system of rabbits.

Hybridoma technology a versatile method for isolation of monoclonal antibodies, its applicability across species, limitations, advancement and future perspectives

The advancements in technology and manufacturing processes have allowed the development of new derivatives, biosimilar or advanced improved versions for approved antibodies each year for treatment regimen. There are more than 700 antibody-based molecules that are in different stages of phase I/II/ III clinical trials targeting new unique targets. To date, approximately more than 80 monoclonal antibodies (mAbs) have been approved. A total of 7 novel antibody therapeutics had been granted the first approval either in the United States or European Union in the year 2019, representing approximately 20% of the total number of approved drugs. Most of these licenced mAbs or their derivatives are either of hybridoma origin or their improvised engineered versions. Even with the recent development of high throughput mAb generation technologies, hybridoma is the most favoured method due to its indigenous nature to preserve natural cognate antibody pairing information and preserves innate functions of immune cells. The recent advent of antibody engineering technology has superseded the species level barriers and has shown success in isolation of hybridoma across phylogenetically distinct species. This has led to the isolation of monoclonal antibodies against human targets that are conserved and non-immunogenic in the rodent. In this review, we have discussed in detail about hybridoma technology, its expansion towards different animal species, the importance of antibodies isolated from different animal sources that are useful in biological applications, advantages, and limitations. This review also summarizes the challenges and recent progress associated with hybridoma development, and how it has been overcome in these years to provide new insights for the isolation of mAbs.

Affinity maturation, humanization, and co-crystallization of a rabbit anti-human ROR2 monoclonal antibody for therapeutic applications

Antibodies are widely used as cancer therapeutics, but their current use is limited by the low number of antigens restricted to cancer cells. A receptor tyrosine kinase, receptor tyrosine kinase-like orphan receptor 2 (ROR2), is normally expressed only during embryogenesis and is tightly down-regulated in postnatal healthy tissues. However, it is up-regulated in a diverse set of hematologic and solid malignancies, thus ROR2 represents a candidate antigen for antibody-based cancer therapy. Here we describe the affinity maturation and humanization of a rabbit mAb that binds human and mouse ROR2 but not human ROR1 or other human cell-surface antigens. Co-crystallization of the parental rabbit mAb in complex with the human ROR2 kringle domain (hROR2-Kr) guided affinity maturation by heavy-chain complementarity-determining region 3 (HCDR3)-focused mutagenesis and selection. The affinity-matured rabbit mAb was then humanized by complementarity-determining region (CDR) grafting and framework fine tuning and again co-crystallized with hROR2-Kr. We show that the affinity-matured and humanized mAb retains strong affinity and specificity to ROR2 and, following conversion to a T cell-engaging bispecific antibody, has potent cytotoxicity toward ROR2-expressing cells. We anticipate that this humanized affinity-matured mAb will find application for antibody-based cancer therapy of ROR2-expressing neoplasms.

In Vivo and In Vitro Models of Diabetes: A Focus on Pregnancy

Diabetes in pregnancy is associated with an increased risk of poor outcomes, both for the mother and her offspring. Although clinical and epidemiological studies are invaluable to assess these outcomes and the effectiveness of potential treatments, there are certain ethical and practical limitations to what can be assessed in human studies.Thus, both in vivo and in vitro models can aid us in the understanding of the mechanisms behind these complications and, in the long run, towards their prevention and treatment. This review summarizes the existing animal and cell models used to mimic diabetes, with a specific focus on the intrauterine environment. Summary of this review.

Equine or porcine synovial fluid as a novel ex vivo model for the study of bacterial free-floating biofilms that form in human joint infections

Bacterial invasion of synovial joints, as in infectious or septic arthritis, can be difficult to treat in both veterinary and human clinical practice. Biofilms, in the form of free-floating clumps or aggregates, are involved with the pathogenesis of infectious arthritis and periprosthetic joint infection (PJI). Infection of a joint containing an orthopedic implant can additionally complicate these infections due to the presence of adherent biofilms. Because of these biofilm phenotypes, bacteria within these infected joints show increased antimicrobial tolerance even at high antibiotic concentrations. To date, animal models of PJI or infectious arthritis have been limited to small animals such as rodents or rabbits. Small animal models, however, yield limited quantities of synovial fluid making them impractical for in vitro research. Herein, we describe the use of ex vivo equine and porcine models for the study of synovial fluid induced biofilm aggregate formation and antimicrobial tolerance. We observed Staphylococcus aureus and other bacterial pathogens adapt the same biofilm aggregate phenotype with significant antimicrobial tolerance in both equine and porcine synovial fluid, analogous to human synovial fluid. We also demonstrate that enzymatic dispersal of synovial fluid aggregates restores the activity of antimicrobials. Future studies investigating the interaction of bacterial cell surface proteins with host synovial fluid proteins can be readily carried out in equine or porcine ex vivo models to identify novel drug targets for treatment of prevention of these difficult to treat infectious diseases.