Modeling human arthritic diseases in nonhuman primates

MHC-DRB alleles with amino acids Val11, Phe13, and the shared epitopes promote collagen-induced arthritis and a rapid IgG1 response in Filipino cynomolgus macaques

Macaques are useful animal models for studying the pathogenesis of rheumatoid arthritis (RA) and the development of anti-rheumatic drugs. The purpose of this study was to identify the major histocompatibility complex (MHC) polymorphisms associated with the pathology of collagen-induced arthritis (CIA) and anti-collagen IgG induction in a cynomolgus macaque model, as MHC polymorphisms affect the onset of CIA in other animal models. Nine female Filipino cynomolgus macaques were immunized with bovine type II collagen (b-CII) to induce CIA, which was diagnosed clinically by scoring the symptoms of joint swelling over 9 weeks. MHC polymorphisms and anti-b-CII antibody titers were compared between symptomatic and asymptomatic macaques. Four of 9 (44%) macaques were defined as the CIA-affected group. Anti-b-CII IgG in the affected group increased in titer approximately 3 weeks earlier compared with the asymptomatic group. The mean plasma IgG1 titer in the CIA-affected group was significantly higher (p < 0.05) than that of the asymptomatic group. Furthermore, the cynomolgus macaque MHC (Mafa)-DRB1*10:05 or Mafa-DRB1*10:07 alleles, which contain the well-documented RA-susceptibility five amino acid sequence known as the shared epitope (SE) in positions 70 to 74, with valine at position 11 (Val11, V11) and phenylalanine at position 13 (Phe13, F13), were detected in the affected group. In contrast, no MHC polymorphisms specific to the asymptomatic group were identified. In conclusion, the presence of V11 and F13 along with SE in the MHC-DRB1 alleles seems essential for the production of IgG1 and the rapid induction of severe CIA in female Filipino cynomolgus macaques.

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.

How to Model Rheumatoid Arthritis in Animals: From Rodents to Non-Human Primates

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease influenced by both genetic and environmental factors. At present, rodent models are primarily used to study the pathogenesis and treatment of RA. However, the genetic divergences between rodents and humans determine differences in the development of RA, which makes it necessary to explore the establishment of new models. Compared to rodents, non-human primates (NHPs) are much more closely related to humans in terms of the immune system, metabolic conditions, and genetic make-up. NHPs model provides a powerful tool to study the development of RA and potential complications, as well as preclinical studies in drug development. This review provides a brief overview of the RA animal models, emphasizes the replication methods, pros and cons, as well as evaluates the validity of the rodent and NHPs models.

Selected Resources for Pathology Evaluation of Nonhuman Primates in Nonclinical Safety Assessment

Humans and nonhuman primates (NHPs) share numerous anatomical and physiological characteristics, thereby explaining the importance of NHPs as essential animal models for translational medicine and nonclinical toxicity testing. Researchers, toxicologic pathologists, toxicologists, and regulatory reviewers must be familiar with normal and abnormal NHP biological traits when designing, performing, and interpreting data sets from NHP studies. The current compilation presents a list of essential books, journal articles, and websites that provide context to safety assessment and research scientists working with NHP models. The resources used most frequently by the authors have been briefly annotated to permit readers to rapidly ascertain their applicability to particular research endeavors. The references are aimed primarily for toxicologic pathologists working with cynomolgus and rhesus macaques and common marmosets in efficacy and safety assessment studies.

Pain-like behavior in the collagen antibody-induced arthritis model is regulated by lysophosphatidic acid and activation of satellite glia cells

Inflammatory and neuropathic-like components underlie rheumatoid arthritis (RA)-associated pain, and lysophosphatidic acid (LPA) is linked to both joint inflammation in RA patients and to neuropathic pain. Thus, we investigated a role for LPA signalling using the collagen antibody-induced arthritis (CAIA) model. Pain-like behavior during the inflammatory phase and the late, neuropathic-like phase of CAIA was reversed by a neutralizing antibody generated against LPA and by an LPA_1/3 receptor inhibitor, but joint inflammation was not affected. Autotaxin, an LPA synthesizing enzyme was upregulated in dorsal root ganglia (DRG) neurons during both CAIA phases, but not in joints or spinal cord. Late-phase pronociceptive neurochemical changes in the DRG were blocked in Lpar1 receptor deficient mice and reversed by LPA neutralization. In vitro and in vivo studies indicated that LPA regulates pain-like behavior via the LPA₁ receptor on satellite glia cells (SGCs), which is expressed by both human and mouse SGCs in the DRG. Furthermore, CAIA-induced SGC activity is reversed by phospholipid neutralization and blocked in Lpar1 deficient mice. Our findings suggest that the regulation of CAIA-induced pain-like behavior by LPA signalling is a peripheral event, associated with the DRGs and involving increased pronociceptive activity of SGCs, which in turn act on sensory neurons.

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

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

The establishment of a rheumatoid arthritis primate model in Macaca fascicularis

Background

Rheumatoid arthritis (RA) is a long-term autoimmune disorder that mostly affects the joints and leads to the destruction of cartilage. An RA model in non-human primates is especially useful because of their close phylogenetic relationship to humans in terms of cross-reactivity to compounds developed using modern drug technologies.

Methods

We used a collagen-induced arthritis (CIA) model in Macaca fascicularis. CIA was induced by the immunization of chicken type II collagen. Swelling was measured as the longitudinal and transverse axes of 16 proximal interphalangeal joints.

Results

A new system for visual evaluation was created, with a perfect score of 16. Individual behavioral analysis was also conducted. Serum was collected once a week after the first immunization. Blood chemistry and inflammatory cytokine parameters were higher in the CIA group than in the wild type group.

Conclusion

In conclusion, we established CIA in M. fascicularis, and the results can be used for drug evaluation models.

Comparative genetics of the major histocompatibility complex in humans and nonhuman primates

The major histocompatibility complex (MHC) is one of the most gene-dense regions of the mammalian genome. Multiple genes within the human MHC (HLA) show extensive polymorphism, and currently, more than 26,000 alleles divided over 39 different genes are known. Nonhuman primate (NHP) species are grouped into great and lesser apes and Old and New World monkeys, and their MHC is studied mostly because of their important role as animal models in preclinical research or in connection with conservation biology purposes. The evolutionary equivalents of many of the HLA genes are present in NHP species, and these genes may also show abundant levels of polymorphism. This review is intended to provide a comprehensive comparison relating to the organization and polymorphism of human and NHP MHC regions.

Effects of the Cathepsin K Inhibitor ONO-5334 and Concomitant Use of ONO-5334 with Methotrexate on Collagen-Induced Arthritis in Cynomolgus Monkeys

We examined whether the cathepsin K inhibitor, ONO-5334, administered alone or in combination with methotrexate (MTX), could ameliorate joint destruction evoked by collagen-induced arthritis (CIA) in female cynomolgus monkeys. CIA was induced by immunizing with bovine type II collagen. ONO-5334 (30 mg/kg/day) was orally administered once daily and MTX (10 mg/body/day) twice weekly for 9 weeks. X-ray (evaluation of joint destruction) and swelling (inflammatory) scores of proximal interphalangeal (PIP), distal interphalangeal (DIP), and metacarpophalangeal (MP) joints were evaluated. Urinary concentrations of C-terminal telopeptide of type I collagen (CTX-I) and type II collagen (CTX-II) were measured. Arthritis, accompanied by bone and cartilage destruction, was successfully induced in this collagen-induced arthritis monkey model. ONO-5334 showed no suppressive effect on joint swelling, while the joint swelling scores in the MTX and combination (ONO-5334 + MTX) groups were less than 50% compared with the control group. ONO-5334 decreased X-ray score by a mean of 64% (p<0.05 vs the control group), and MTX also decreased in X-ray score by a mean of 46% but with no statistical significance. Combination of ONO-5334 and MTX further decreased the X-ray score by 28% over MTX group (74% reduction vs the control group, p<0.01). Maximum increase in CTX-I (10-fold) and CTX-II (7-fold) compared to baseline was observed at 7 and 3 weeks after the first sensitization, respectively. After treatment with ONO-5334 alone or in combination with MTX, concentrations were maintained near baseline for both markers. In conclusion, ONO-5334 prevented joint destruction but not joint inflammation in this monkey CIA model. Concomitant use of ONO-5334 with MTX reduced architectural joint destruction compared to MTX alone; therefore, ONO-5334 may help to prevent joint destruction in combination with MTX for the treatment of rheumatoid arthritis.

Extensive Alternative Splicing of KIR Transcripts

The killer-cell Ig-like receptors (KIR) form a multigene entity involved in modulating immune responses through interactions with MHC class I molecules. The complexity of the KIR cluster is reflected by, for instance, abundant levels of allelic polymorphism, gene copy number variation, and stochastic expression profiles. The current transcriptome study involving human and macaque families demonstrates that KIR family members are also subjected to differential levels of alternative splicing, and this seems to be gene dependent. Alternative splicing may result in the partial or complete skipping of exons, or the partial inclusion of introns, as documented at the transcription level. This post-transcriptional process can generate multiple isoforms from a single KIR gene, which diversifies the characteristics of the encoded proteins. For example, alternative splicing could modify ligand interactions, cellular localization, signaling properties, and the number of extracellular domains of the receptor. In humans, we observed abundant splicing for KIR2DL4, and to a lesser extent in the lineage III KIR genes. All experimentally documented splice events are substantiated by in silico splicing strength predictions. To a similar extent, alternative splicing is observed in rhesus macaques, a species that shares a close evolutionary relationship with humans. Splicing profiles of Mamu-KIR1D and Mamu-KIR2DL04 displayed a great diversity, whereas Mamu-KIR3DL20 (lineage V) is consistently spliced to generate a homolog of human KIR2DL5 (lineage I). The latter case represents an example of convergent evolution. Although just a single KIR splice event is shared between humans and macaques, the splicing mechanisms are similar, and the predicted consequences are comparable. In conclusion, alternative splicing adds an additional layer of complexity to the KIR gene system in primates, and results in a wide structural and functional variety of KIR receptors and its isoforms, which may play a role in health and disease.

A methodological review of induced animal models of autoimmune diseases

Autoimmune disorders are characterized by a loss of immune tolerance and consequent autoimmunity-mediated disease manifestation. Experimental models are invaluable research tools helping us to understand disease pathogenesis and to search for novel therapeutics. Animal models of autoimmune diseases consist of two groups, spontaneous and induced models. In this review article, we focus on the induced models of autoimmune diseases. Due to the complex nature of autoimmune disorders, many strategies have been applied for the induction of corresponding experimental models in animals like monkeys, rabbits, rats, and mice. Methodologically, these strategies can be categorized into three categories, namely immunization with autoantigen, transfer of autoimmunity, and induction by environmental factors. In this review article, we aim to provide a comprehensive overview of the field of induced experimental autoimmune diseases. On the one hand, we describe and summarize the different strategies used for induction of experimental autoimmune disease. On the other hand, we discuss how to select a strategy for modeling human disease, including the choice of an appropriate species and method for such an approach.

Experimental animal models for rheumatoid arthritis

Rheumatoid Arthritis (RA) is an autoimmune systemic disorder of unknown etiology and is characterized by chronic inflammation and synovial infiltration of immune cells. RA is associated with decreased life expectancy and quality of life. The research on RA is greatly simplified by animal models that help us to investigate the complex system involving inflammation, immunological tolerance and autoimmunity. The animal models of RA with a proven track record of predictability for efficacy in humans include: collagen type II induced arthritis in rats as well as mice, adjuvant induced arthritis in rats and antigen induced arthritis in several species. The development of novel treatments for RA requires the interplay between clinical observations and studies in animal models. However, each model features a different mechanism driving the disease expression; the benefits of each should be evaluated carefully in making the appropriate choice for the scientific problem to be investigated. In this review article, we focus on animal models of arthritis induced in various species along with the genetic models. The review also discussed the similarity and dissimilarities with respect to human RA.

Autoimmunity as a Driving Force of Cognitive Evolution

In the last decades, increasingly robust experimental approaches have formally demonstrated that autoimmunity is a physiological process involved in a large range of functions including cognition. On this basis, the recently enunciated “brain superautoantigens” theory proposes that autoimmunity has been a driving force of cognitive evolution. It is notably suggested that the immune and nervous systems have somehow co-evolved and exerted a mutual selection pressure benefiting to both systems. In this two-way process, the evolutionary-determined emergence of neurons expressing specific immunogenic antigens (brain superautoantigens) has exerted a selection pressure on immune genes shaping the T-cell repertoire. Such a selection pressure on immune genes has translated into the emergence of a finely tuned autoimmune T-cell repertoire that promotes cognition. In another hand, the evolutionary-determined emergence of brain-autoreactive T-cells has exerted a selection pressure on neural genes coding for brain superautoantigens. Such a selection pressure has translated into the emergence of a neural repertoire (defined here as the whole of neurons, synapses and non-neuronal cells involved in cognitive functions) expressing brain superautoantigens. Overall, the brain superautoantigens theory suggests that cognitive evolution might have been primarily driven by internal cues rather than external environmental conditions. Importantly, while providing a unique molecular connection between neural and T-cell repertoires under physiological conditions, brain superautoantigens may also constitute an Achilles heel responsible for the particular susceptibility of Homo sapiens to “neuroimmune co-pathologies” i.e., disorders affecting both neural and T-cell repertoires. These may notably include paraneoplastic syndromes, multiple sclerosis as well as autism, schizophrenia and neurodegenerative diseases. In the context of this theoretical frame, a specific emphasis is given here to the potential evolutionary role exerted by two families of genes, namely the MHC class II genes, involved in antigen presentation to T-cells, and the Foxp genes, which play crucial roles in language (Foxp2) and the regulation of autoimmunity (Foxp3).

Safety, Biodistribution, and Efficacy of an AAV-5 Vector Encoding Human Interferon-Beta (ART-I02) Delivered via Intra-Articular Injection in Rhesus Monkeys with Collagen-Induced Arthritis

Preclinical studies to assess biodistribution, safety, and initial efficacy of ART-I02, an adeno-associated type 5 (rAAV5) vector expressing human interferon β (hIFN-β), were performed in a total of 24 rhesus monkeys with collagen-induced arthritis. All monkeys were naïve or showed limited neutralizing antibody (Nab) titers to AAV5 at the start of the study. Animals were injected with a single intra-articular dose of ART-I02 or placebo, consisting of 3.2×10(13) vg (Dose A=maximum feasible dose), 4.58×10(12) vg (Dose B), or placebo in the first affected finger joint, the ipsilateral knee, and ankle joint at the same time point. Animals were monitored for clinical parameters and well-being with a maximum of 4 weeks, with the option that the severity of arthritis could necessitate an earlier time point of sacrifice. No adverse events were noted after injection of ART-I02. No abnormalities were observed after histological evaluation of all organs. At both dose levels, immunohistochemical staining indicated expression of hIFN-β. In animals injected with Dose A, we observed stabilization or a reduction in swelling in the finger joint in which vector was administered. The highest copy numbers of vector DNA were detected in synovial tissue of the injected joint and the draining lymph node of the injected knee. High titers of Nab to rAAV5 were observed at the end of the study. Five monkeys developed an rAAV5-specific T-cell response. Two monkeys developed Nab to hIFN-β. In conclusion, intra-articular injection of ART-I02 was well-tolerated and did not induce adverse events. After administration of Dose A of ART-I02, we observed a beneficial effect on joint swelling, substantiated by decreased histological inflammation and bone erosion scores. A GMP vector for clinical application has been manufactured and is currently being tested in GLP rodent studies, with the aim to move forward to a clinical trial.

Clinical efficacy of a new CD28-targeting antagonist of T cell co-stimulation in a non-human primate model of collagen-induced arthritis

T cells have a central pathogenic role in the aetiopathogenesis of rheumatoid arthritis (RA), and are therefore a favoured target of immunotherapy aiming at physical or functional elimination. Here we report an efficacy test of FR104, a new co-stimulation inhibitor directly targeting CD28 on T cells, in a translationally relevant model, the rhesus monkey model of collagen-induced arthritis (CIA). As a relevant comparator we used abatacept [cytotoxic T lymphocyte antigen immunoglobulin (CTLA Ig)], an antagonist of CTLA-4 binding to CD80/86 clinically approved for treatment of RA. Treatment with either compound was started at the day of CIA induction. Although FR104 previously demonstrated a higher control of T cell responses in vitro than abatacept, both compounds were equally potent in the suppression of CIA symptoms and biomarkers, such as the production of C-reactive protein (CRP) and interleukin (IL)-6 and anti-collagen type II (CII) serum antibody (IgM/IgG). However, in contrast to abatacept, FR104 showed effective suppression of CII-induced peripheral blood mononuclear cell (PBMC) proliferation. The current study demonstrates a strong potential of the new selective CD28 antagonist FR104 for treatment of RA.

The preclinical pharmacology of the high affinity anti-IL-6R Nanobody® ALX-0061 supports its clinical development in rheumatoid arthritis

Introduction

The pleiotropic cytokine interleukin-6 (IL-6) plays an important role in the pathogenesis of different diseases, including rheumatoid arthritis (RA). ALX-0061 is a bispecific Nanobody® with a high affinity and potency for IL-6 receptor (IL-6R), combined with an extended half-life by targeting human serum albumin. We describe here the relevant aspects of its in vitro and in vivo pharmacology.

Methods

ALX-0061 is composed of an affinity-matured IL-6R-targeting domain fused to an albumin-binding domain representing a minimized two-domain structure. A panel of different in vitro assays was used to characterize the biological activities of ALX-0061. The pharmacological properties of ALX-0061 were examined in cynomolgus monkeys, using plasma levels of total soluble (s)IL-6R as pharmacodynamic marker. Therapeutic effect was evaluated in a human IL-6-induced acute phase response model in the same species, and in a collagen-induced arthritis (CIA) model in rhesus monkeys, using tocilizumab as positive control.

Results

ALX-0061 was designed to confer the desired pharmacological properties. A 200-fold increase of target affinity was obtained through affinity maturation of the parental domain. The high affinity for sIL-6R (0.19 pM) translated to a concentration-dependent and complete neutralization of sIL-6R in vitro. In cynomolgus monkeys, ALX-0061 showed a dose-dependent and complete inhibition of hIL-6-induced inflammatory parameters, including plasma levels of C-reactive protein (CRP), fibrinogen and platelets. An apparent plasma half-life of 6.6 days was observed after a single intravenous administration of 10 mg/kg ALX-0061 in cynomolgus monkeys, similar to the estimated expected half-life of serum albumin. ALX-0061 and tocilizumab demonstrated a marked decrease in serum CRP levels in a non-human primate CIA model. Clinical effect was confirmed in animals with active drug exposure throughout the study duration.

Conclusions

ALX-0061 represents a minimized bispecific biotherapeutic of 26 kDa, nearly six times smaller than monoclonal antibodies. High in vitro affinity and potency was demonstrated. Albumin binding as a half-life extension technology resulted in describable and expected pharmacokinetics. Strong IL-6R engagement was shown to translate to in vivo effect in non-human primates, demonstrated via biomarker deregulation as well as clinical effect. Presented results on preclinical pharmacological properties of ALX-0061 are supportive of clinical development in RA.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-015-0651-0) contains supplementary material, which is available to authorized users.

The translational value of non-human primates in preclinical research on infection and immunopathology

The immune system plays a central role in the defense against environmental threats - such as infection with viruses, parasites or bacteria - but can also be a cause of disease, such as in the case of allergic or autoimmune disorders. In the past decades the impressive development of biotechnology has provided scientists with biological tools for the development of highly selective treatments for the different types of disorders. However, despite some clear successes the translation of scientific discoveries into effective treatments has remained challenging. The often-disappointing predictive validity of the preclinical animal models that are used in the selection of the most promising vaccine or drug candidates is the Achilles heel in the therapy development process. This publication summarizes the relevance and usage of non-human primates as pre-clinical model in infectious and autoimmune diseases, in particular for biologicals, which due to their high species-specificity are inactive in lower species.

Dynamic Frequency of Blood CD4+CD25+ Regulatory T Cells in Rats with Collagen-induced Arthritis

CD4+CD25+ regulatory T cells (CD4+CD25+ Tregs) have been shown to play a regulatory or suppressive role in the immune response and are possibly relevant to the pathogenesis of autoimmune diseases. In the present study, we attempted to investigate the frequency of CD4+CD25+ Tregs in peripheral blood (PB) of collagen-induced arthritis (CIA) rats during the development of arthritis, to determine whether their frequency is involved in the immunoregulation of this disease. The results showed that normal rats had similar frequencies of CD4+CD25+ Tregs in PB during the experiment time, expressed as a percentage of CD4+CD25+Foxp3+ T cells among the CD4+ T lymphocyte population. In contrast, the frequency of CD4+CD25+Foxp3+ T cells in CIA rats was found to change during the development of arthritis. In CIA rats, there is a significant negative correlation between the frequency of CD4+CD25+Foxp3+ T cells and paw swelling (r=-0.786, p< 0.01). The relationship between the frequency of CD4+CD25+Foxp3+ T and immune activation was not found in normal rats. During the time course, the frequency of CD4+CD25+Foxp3+ T was lower in CIA rats than in normal ones. The data suggest that the frequency of PB CD4+CD25+ Tregs may be a promising marker for arthritis activity.

PDL241, a novel humanized monoclonal antibody, reveals CD319 as a therapeutic target for rheumatoid arthritis

Introduction

Targeting the CD20 antigen has been a successful therapeutic intervention in the treatment of rheumatoid arthritis (RA). However, in some patients with an inadequate response to anti-CD20 therapy, a persistence of CD20^- plasmablasts is noted. The strong expression of CD319 on CD20^- plasmablast and plasma cell populations in RA synovium led to the investigation of the potential of CD319 as a therapeutic target.

Methods

PDL241, a novel humanized IgG₁ monoclonal antibody (mAb) to CD319, was generated and examined for its ability to inhibit immunoglobulin production from plasmablasts and plasma cells generated from peripheral blood mononuclear cells (PBMC) in the presence and absence of RA synovial fibroblasts (RA-SF). The in vivo activity of PDL241 was determined in a human PBMC transfer into NOD scid IL-2 gamma chain knockout (NSG) mouse model. Finally, the ability of PDL241 to ameliorate experimental arthritis was evaluated in a collagen-induced arthritis (CIA) model in rhesus monkeys.

Results

PDL241 bound to plasmablasts and plasma cells but not naïve B cells. Consistent with the binding profile, PDL241 inhibited the production of IgM from in vitro PBMC cultures by the depletion of CD319⁺ plasmablasts and plasma cells but not B cells. The activity of PDL241 was dependent on an intact Fc portion of the IgG₁ and mediated predominantly by natural killer cells. Inhibition of IgM production was also observed in the human PBMC transfer to NSG mouse model. Treatment of rhesus monkeys in a CIA model with PDL241 led to a significant inhibition of anti-collagen IgG and IgM antibodies. A beneficial effect on joint related parameters, including bone remodeling, histopathology, and joint swelling was also observed.

Conclusions

The activity of PDL241 in both in vitro and in vivo models highlights the potential of CD319 as a therapeutic target in RA.

The value of extended pedigrees for next-generation analysis of complex disease in the rhesus macaque

Complex diseases (e.g., cardiovascular disease and type 2 diabetes, among many others) pose the biggest threat to human health worldwide and are among the most challenging to investigate. Susceptibility to complex disease may be caused by multiple genetic variants (GVs) and their interaction, by environmental factors, and by interaction between GVs and environment, and large study cohorts with substantial analytical power are typically required to elucidate these individual contributions. Here, we discuss the advantages of both power and feasibility afforded by the use of extended pedigrees of rhesus macaques (Macaca mulatta) for genetic studies of complex human disease based on next-generation sequence data. We present these advantages in the context of previous research conducted in rhesus macaques for several representative complex diseases. We also describe a single, multigeneration pedigree of Indian-origin rhesus macaques and a sample biobank we have developed for genetic analysis of complex disease, including power of this pedigree to detect causal GVs using either genetic linkage or association methods in a variance decomposition approach. Finally, we summarize findings of significant heritability for a number of quantitative traits that demonstrate that genetic contributions to risk factors for complex disease can be detected and measured in this pedigree. We conclude that the development and application of an extended pedigree to analysis of complex disease traits in the rhesus macaque have shown promising early success and that genome-wide genetic and higher order -omics studies in this pedigree are likely to yield useful insights into the architecture of complex human disease.

Evaluation of the anti-arthritic activity of the hydroethanolic leaf extract of Alchornea cordifolia in rats

BACKGROUND

Different decoctions of Alchornea cordifolia leaves are used by Yoruba herbalists (Southwest Nigeria) for the local treatment of ulcers, rheumatic pains, febrile convulsions, and for enhancing physical performance.

MATERIALS AND METHODS

In this study, the anti-arthritic effect of 100 - 400 mg/kg/day of the hydroethanolic leaf extract of Alchornea cordifolia (HEAC) was investigated in Complete Freund's Adjuvant (CFA)-induced arthritic rats as a way of evaluating its efficacy in the local management of arthritis. In addition, the effects of HEAC on liver and renal function parameters as well as its effect on the antioxidant enzyme system were investigated. Arthritis was induced using 0.1 ml of 10 mg/ml of Complete Freund's Adjuvant (CFA) following 1 h oral pretreatment and 8(th) day post-arthritic induction with 100, 200 and 400 mg/kg/day of HEAC and 3 mg/kg/day of celecoxib as the reference drug. The anti-arthritic activity of HEAC was assessed based on the ability of HEAC to alter the paw edema diameter, body weight, full blood count, renal and liver function markers, glycoprotein, lysosomal enzymes and possible antioxidant potential in the arthritic rats.

RESULTS

Oral pretreatment with 100, 200, and 400 mg/kg/day of HEAC produced significant (p<0.001, p<0.05 and p<0.01) reductions in the paw edema diameter in a non-dose dependent fashion in ACF-induced arthritic rats with the 100 mg/kg/day of HEAC producing the most significant anti-arthritic effect. Similarly, HEAC increased hepatic GSH levels, CAT and SOD activities suggesting possible antioxidant mechanism for its anti-arthritic effect.

CONCLUSION

Overall, results of this study lend credence to the folkloric use of water decoction of Alchornea cordifolia leaves against rheumatoid arthritis. However, further pharmacological investigations would be required at isolating and determining the active anti-arthritic molecule(s) in HEAC in the nearest future.

Identification of MHC class I sequences in four species of Macaca of China

Tibetan macaques (Macaca thibetana), stump-tailed macaques (M. arctoides), Assamese macaques (M. assamensis), and northern pig-tailed macaques (M. leonina) are four major species of Macaca in China. In order to effectively use these species in biomedical research, thorough investigations of their MHC immunogenetics are required. In this study, we identified MHC class I sequences using cDNA cloning and sequencing on a cohort of six M. thibetana, three M. arctoides, three M. assamensis, and three M. leonina derived from Sichuan and Yunnan provinces of China. Eighty new alleles were identified, including 26 MHC-A alleles, 46 MHC-B alleles, and 8 MHC-I alleles. Among them, Math-A1*126:01, Math-B*190:01, Math-B*191:01, Math-B*192:01, Maar-A1*127:01, Maar-A1*129:01, and Maas-A1*128:01 represent lineages that had not been reported earlier in Macaca. Phylogenetic analyses show that no obvious separation of lineages among these species of Macaca. This study provides important information about the MHC immunogenetics for the four major species of Chinese macaques and adds value to these species as model organisms in biomedical research.

A case report of spontaneous polyarthritis in cynomolgus monkeys

Veterinary x-ray photography and examinations of synovial fluid, blood and urine were conducted on a Cynomolgus Monkey from China (5 years old) which exhibited macroscopically visible systemic joint swelling after the quarantine period. The presence of inflammatory cells in the synovial fluid obtained by arthrocentesis, high counts of neutrophils, monocytes and large unstained cells and the elevated serum CRP level suggested that the lesions in this animal were due to polyarthritis.

The significance of non-human primates as preclinical models of human arthritic disease

BACKGROUND

The broad immunological gap between inbred SPF-raised strains of mice and rats and the diverse rheumatoid arthritis (RA) patient population limits the predictive value of the existing disease models for clinical success of new therapies, in particular for those using highly specific biologicals.

OBJECTIVE

This review argues that because of their closer immunological and physiological proximity to patients, disease models in non-human primates (NHPs) may bridge this gap and help reduce the failure of many (± 80%) new therapies in clinical trials. In various research areas, NHPs are an accepted intermediate between disease models in rodents and the ultimate introduction for clinical use in patients. However, with the exception of transplantation, this is not the case for immune-mediated inflammatory disorders, such as RA, although useful preclinical models are being developed.

METHOD

The validity and use of the rhesus monkey model of collagen-induced arthritis as a preclinical RA model is reviewed. The discussion comprises present genetic and immunological aspects, biomarkers, and an overview of published preclinical therapy evaluations.

CONCLUSION

It is time to consider the use of NHPs with a greater evolutionary proximity to humans as models for preclinical evaluation of new human-specific drugs for arthritic disease.

Excision of femoral head and neck for treatment of coxofemoral degenerative joint disease in a rhesus macaque (Macaca mulatta)

Nonhuman primates are a valuable model for osteoarthritis. Osteoarthritis has been extensively studied in nonhuman primates in both naturally occurring and induced disease states. However, little published information describes naturally occurring osteoarthritis of the coxofemoral joints of nonhuman primates. We report a case of naturally occurring coxofemoral joint osteoarthritis in a rhesus macaque. This case radiographically resembled hip dysplasia reported in other species and demonstrated a rapid progression in severity of lameness, with accompanying loss of muscle mass in the affected limb. We excised the femoral head and neck to alleviate the pain that accompanied the osteoarthritis. Physical therapy was initiated, and dual-energy X-ray absorptiometry and video recordings were performed to evaluate the macaque's response to surgical intervention. By 3 mo postoperatively, the macaque had regained full use of the affected limb.

Comparative analysis of inflammatory infiltrates in collagen-induced arthritis, kidney graft rejection and delayed-type hypersensitivity in non-human primates

OBJECTIVES

Non-human primates are immunologically closely related to humans providing relevant models of inflammatory disorders often used to evaluate new immunomodulating therapies. The aim of the study was to compare inflammatory infiltrates of acute graft rejection (AR) and collagen-induced arthritis (CIA) to delayed-type hypersensitivity (DTH) reactions as the latter model may serve as a less invasive animal model.

MATERIALS AND METHODS

Tissue samples of AR, CIA and DTH were obtained from rhesus monkeys used in several pre-clinical studies. The infiltrate composition was determined by immunohistochemical analysis.

RESULTS

The infiltrates in AR consisted of T cells, macrophages and B cells. The presence of lymphoid structures in AR suggested ongoing intragraft immune activation. The synovia of CIA contained predominantly macrophages and few T cells. The DTH infiltrates were dominated by T cells when the challenged was ovalbumin (OVA) and by macrophages when the challenge was tetanus toxoid (TT).

CONCLUSIONS

The histology of AR resembles aspects of DTH to OVA while that of CIA showed similarities of the DTH to TT. The DTH reaction could serve as a model to study immunomodulating drugs for acute rejection and the acute inflammatory phase of autoimmunity.

Development of macromolecular prodrug for rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease that is considered to be one of the major public health problems worldwide. The development of therapies that target tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and co-stimulatory pathways that regulate the immune system have revolutionized the care of patients with RA. Despite these advances, many patients continue to experience symptomatic and functional impairment. To address this issue, more recent therapies that have been developed are designed to target intracellular signaling pathways involved in immunoregulation. Though this approach has been encouraging, there have been major challenges with respect to off-target organ side effects and systemic toxicities related to the widespread distribution of these signaling pathways in multiple cell types and tissues. These limitations have led to an increasing interest in the development of strategies for the macromolecularization of anti-rheumatic drugs, which could target them to the inflamed joints. This approach enhances the efficacy of the therapeutic agent with respect to synovial inflammation, while markedly reducing non-target organ adverse side effects. In this manuscript, we provide a comprehensive overview of the rational design and optimization of macromolecular prodrugs for treatment of RA. The superior and the sustained efficacy of the prodrug may be partially attributed to their Extravasation through Leaky Vasculature and subsequent Inflammatory cell-mediated Sequestration (ELVIS) in the arthritic joints. This biologic process provides a plausible mechanism, by which macromolecular prodrugs preferentially target arthritic joints and illustrates the potential benefits of applying this therapeutic strategy to the treatment of other inflammatory diseases.

New drug discovery strategies for rheumatoid arthritis: a niche for nonhuman primate models to address systemic complications in inflammatory arthritis

INTRODUCTION

Despite the tremendous advances made in the treatment of rheumatoid arthritis (RA), there is still excess mortality observed in RA patients, which is mainly caused by cardiovascular disease (CVD). Altered lipid metabolism plays a major role in the etiology of CVD. A second common complication observed in RA patients is anemia. Both conditions are serious, reduce quality of life and are undertreated.

AREAS COVERED

The authors postulate that there is a specific niche for nonhuman primate models of inflammatory arthritis to address these systemic complications that occur in RA. Furthermore, the authors postulate that these nonhuman primate models are a useful platform to unveil the mechanisms underlying dyslipidemia and anemia, which are responsible for the manifestation of these complications.

EXPERT OPINION

The presence of currently untreated systemic complications of RA, such as dyslipidemia and anemia, provides interesting opportunities to include these in the preclinical evaluation of new therapies. In the selection of relevant models for the evaluation of new treatments for RA or the identification of new targets for therapy, we postulate that nonhuman primates should be considered as a valid preclinical model. Because of their closer immunological and physiological proximity to humans, these models in nonhuman primates can be valuable for studying disease-related aspects that cannot be addressed in rodent models.

Rodent preclinical models for developing novel antiarthritic molecules: comparative biology and preferred methods for evaluating efficacy

Rodent models of immune-mediated arthritis (RMIA) are the conventional approach to evaluating mechanisms of inflammatory joint disease and the comparative efficacy of antiarthritic agents. Rat adjuvant-induced (AIA), collagen-induced (CIA), and streptococcal cell wall-induced (SCW) arthritides are preferred models of the joint pathology that occurs in human rheumatoid arthritis (RA). Lesions of AIA are most severe and consistent; structural and immunological changes of CIA best resemble RA. Lesion extent and severity in RMIA depends on experimental methodology (inciting agent, adjuvant, etc.) and individual physiologic parameters (age, genetics, hormonal status, etc.). The effectiveness of antiarthritic molecules varies with the agent, therapeutic regimen, and choice of RMIA. All RMIA are driven by overactivity of proinflammatory pathways, but the dominant molecules differ among the models. Hence, as with the human clinical experience, the efficacy of various antiarthritic molecules differs among RMIA, especially when the agent is a specific cytokine inhibitor.

Collagen-induced arthritis in common marmosets: a new nonhuman primate model for chronic arthritis

INTRODUCTION

There is an ever-increasing need for animal models to evaluate efficacy and safety of new therapeutics in the field of rheumatoid arthritis (RA). Particularly for the early preclinical evaluation of human-specific biologicals targeting the progressive phase of the disease, there is a need for relevant animal models. In response to this requirement we set out to develop a model of collagen-induced arthritis (CIA) in a small-sized nonhuman primate species (300 to 400 g at adult age); that is, the common marmoset (Callithrix jacchus).

METHODS

Twenty-two animals divided into three experiments were immunized with collagen type II (CII) of either bovine or chicken origin with different immunization strategies. The animals were analyzed for clinical manifestation of arthritis, hematology and clinical chemistry, immunological responses against CII and histopathological features of the arthritis.

RESULTS

Clinically manifest arthritis was observed in almost 100% (21 out of 22) of the animals. Fifty percent of the animals developed semi-acute CIA while the other 50% displayed a more chronic disease. Both cellular (CD3/CD4 and CD3/CD8) and humoral responses (IgM and IgG) against CII were involved in the development of the disease. Besides mild histopathological changes in bone and cartilage, severe inflammation in extraarticular tissues like periosteum and subcutaneous tissues was observed.

CONCLUSIONS

This new model in marmosets more closely resembles chronic RA with respect to the chronic disease course and pathomorphological presentation than the more acute monophasic and destructive CIA model in macaques. This model can therefore fill a niche in preclinical testing of new human specific therapeutics.

Genomic plasticity of the MHC class I A region in rhesus macaques: extensive haplotype diversity at the population level as revealed by microsatellites

The Mamu-A genes of the rhesus macaque show different degrees of polymorphism, transcription level variation, and differential haplotype distribution. Per haplotype, usually one “major” transcribed gene is present, A1 (A7), in various combinations with “minor” genes, A2 to A6. In silico analysis of the physical map of a heterozygous animal revealed the presence of similar Mamu-A regions consisting of four duplication units, but with dissimilar positions of the A1 genes on both haplotypes, and in combination with different minor genes. Two microsatellites, D6S2854 and D6S2859, have been selected as potential tools to characterize this complex region. Subsequent analysis of a large breeding colony resulted in the description of highly discriminative patterns, displaying copy number variation in concert with microsatellite repeat length differences. Sequencing and segregation analyses revealed that these patterns are unique for each Mamu-A haplotype. In animals of Indian, Burmese, and Chinese origin, 19, 15, or 9 haplotypes, respectively, could be defined, illustrating the occurrence of differential block duplications and subsequent rearrangements by recombination. The haplotypes can be assigned to 12 unique combinations of genes (region configurations). Although most configurations harbor two transcribed A genes, one or three genes per haplotype are also present. Additionally, haplotypes lacking an A1 gene or with an A1 duplication appear to exist. The presence of different transcribed A genes/alleles in monkeys from various origins may have an impact on differential disease susceptibilities. The high-throughput microsatellite technique will be a valuable tool in animal selection for diverse biomedical research projects.

Preclinical models of multiple sclerosis in nonhuman primates

Biotechnology has enabled the development of specifically acting therapies for immune-mediated inflammatory disorders (IMIDs) based on biological molecules. The high species specificity precludes safety and effectivity testing in lower species (mice and rats), thus creating a need for valid experimental models in nonhuman primates (NHPs). Here, we review the creation of relevant NHP model(s) for multiple sclerosis (MS), an IMID of the human CNS. We will also discuss how the model(s) can help in the translation of a scientific principle developed in lower species into a therapy for MS.

Erratum to: rhesus macaque MHC class I molecules show differential subcellular localizations

The MHC class I gene family of rhesus macaques is characterised by considerable gene duplications. While a HLA-C-orthologous gene is absent, the Mamu-A and in particular the Mamu-B genes have expanded, giving rise to plastic haplotypes with differential gene content. Although some of the rhesus macaque MHC class I genes are known to be associated with susceptibility/resistance to infectious diseases, the functional significance of duplicated Mamu-A and Mamu-B genes and the expression pattern of their encoded proteins are largely unknown. Here, we present data of the subcellular localization of AcGFP-tagged Mamu-A and Mamu-B molecules. We found strong cell surface and low intracellular expression for Mamu-A1, Mamu-A2 and Mamu-A3-encoded molecules as well as for Mamu-B*01704, Mamu-B*02101, Mamu-B*04801, Mamu-B*06002 and Mamu-B*13401. In contrast, weak cell surface and strong intracellular expression was seen for Mamu-A4*1403, Mamu-B*01202, Mamu-B*02804, Mamu-B*03002, Mamu-B*05704, Mamu-I*010201 and Mamu-I*0121. The different expression patterns were assigned to the antigen-binding alpha1 and alpha2 domains, suggesting failure of peptide binding is responsible for retaining 'intracellular' Mamu class I molecules in the endoplasmic reticulum. These findings indicate a diverse functional role of the duplicated rhesus macaque MHC class I genes.

The mosaic of KIR haplotypes in rhesus macaques

To further refine and improve biomedical research in rhesus macaques, it is necessary to increase our knowledge concerning both the degree of allelic variation (polymorphism) and diversity (gene copy number variation) in the killer cell immunoglobulin-like receptor (KIR) gene cluster. Pedigreed animals in particular should be studied, as segregation data will provide clues to the linkage of particular KIR genes/alleles segregating on a haplotype and to its gene content as well. A dual strategy allowed us to screen the presence and absence of genes and the corresponding transcripts, as well as to track differences in transcription levels. On the basis of this approach, 14 diverse KIR haplotypes have been described. These haplotypes consist of multiple inhibitory and activating Mamu-KIR genes, and any gene present on one haplotype may be absent on another. This suggests that the cost of accelerated evolution by recombination may be the loss of certain framework genes on a haplotype.

Rhesus macaque MHC class I molecules show differential subcellular localizations

The MHC class I gene family of rhesus macaques is characterised by considerable gene duplications. While a HLA-C-orthologous gene is absent, the Mamu-A and in particular the Mamu-B genes have expanded, giving rise to plastic haplotypes with differential gene content. Although some of the rhesus macaque MHC class I genes are known to be associated with susceptibility/resistance to infectious diseases, the functional significance of duplicated Mamu-A and Mamu-B genes and the expression pattern of their encoded proteins are largely unknown. Here, we present data of the subcellular localization of AcGFP-tagged Mamu-A and Mamu-B molecules. We found strong cell surface and low intracellular expression for Mamu-A1, Mamu-A2 and Mamu-A3-encoded molecules as well as for Mamu-B*01704, Mamu-B*02101, Mamu-B*04801, Mamu-B*06002 and Mamu-B*13401. In contrast, weak cell surface and strong intracellular expression was seen for Mamu-A4*1403, Mamu-B*01202, Mamu-B*02804, Mamu-B*03002, Mamu-B*05704, Mamu-I*010201 and Mamu-I*0121. The different expression patterns were assigned to the antigen-binding α1 and α2 domains, suggesting failure of peptide binding is responsible for retaining ‘intracellular’ Mamu class I molecules in the endoplasmic reticulum. These findings indicate a diverse functional role of the duplicated rhesus macaque MHC class I genes.

Leflunomide induces immunosuppression in collagen-induced arthritis rats by upregulating CD4+CD25+ regulatory T cells

This study was to investigate the effect of leflunomide on the immunosuppressive CD4+CD25+ regulatory T cells (CD4+CD25+ Tregs) in collagen-induced arthritis (CIA) rats. CIA was induced by collagen type II in Wistar rats. Immunofluorescence flow cytometry and RT-PCR were used to determine the proportion of CD4+CD25+ Tregs and the expression of Foxp3 mRNA, respectively. Proliferation of T lymphocytes was assayed with MTT reagent, and the level of transforming growth factor β1 (TGF-β1) in the supernatant of concanavalin A (Con A)-induced T lymphocytes was determined by ELISA kit. Our investigations demonstrated that inhibition of arthritis by leflunomide was related to changes in CD4+CD25+ Tregs. In addition, A771726, which is the active metabolite of leflunomide, promoted the differentiation of spleen lymphocytes into CD4+CD25+ Tregs, increased antiinflammatory cytokine TGF-β1 secretion, and adjusted the activity of Con A-induced lymphocytes in vitro.

Compound evolutionary history of the rhesus macaque MHC class I B region revealed by microsatellite analysis and localization of retroviral sequences

In humans, the single polymorphic B locus of the major histocompatibility complex is linked to the microsatellite MIB. In rhesus macaques, however, haplotypes are characterized by the presence of unique combinations of multiple B genes, which may display different levels of polymorphism. The aim of the study was to shed light on the evolutionary history of this highly complex region. First, the robustness of the microsatellite MIB-linked to almost half of the B genes in rhesus macaques (Mamu-B)–for accurate B haplotyping was studied. Based on the physical map of an established haplotype comprising 7 MIB loci, each located next to a certain Mamu-B gene, two MIB loci, MIB1 and MIB6, were investigated in a panel of MHC homozygous monkeys. MIB1 revealed a complex genotyping pattern, whereas MIB6 analysis resulted in the detection of one or no amplicon. Both patterns are specific for a given B haplotype, show Mendelian segregation, and even allow a more precise haplotype definition than do traditional typing methods. Second, a search was performed for retroelements that may have played a role in duplication processes as observed in the macaque B region. This resulted in the description of two types of duplicons. One basic unit comprises an expressed Mamu-B gene, adjacent to an HERV16 copy closely linked to MIB. The second type of duplicon comprises a Mamu-B (pseudo)gene, linked to a truncated HERV16 structure lacking its MIB segment. Such truncation seems to coincide with the loss of B gene transcription. Subsequent to the duplication processes, recombination between MIB and Mamu-B loci appears to have occurred, resulting in a hyperplastic B region. Thus, analysis of MIB in addition to B loci allows deciphering of the compound evolutionary history of the class I B region in Old World monkeys.

A splice site mutation converts an inhibitory killer cell Ig-like receptor into an activating one

The killer cell Ig-like receptor (KIR) 3DH protein in rhesus macaques (Macaca mulatta) is thought to be an activating one because it contains a charged arginine in its transmembrane domain and has a truncated cytoplasmic domain. MmKIR3DH has thus far been characterized by an analysis of cDNA. Its presence and polymorphism has been further investigated by examining mRNA transcripts and genomic sequences in families. Multiple copies of MmKIR3DH are present per animal, suggesting that the gene has been duplicated on some haplotypes. All transcripts are truncated and lack exon 8. Investigation of the gene itself shows that exon 8 is present, intact, and homologous to MmKIR2DL4. However, there is a mutation in the donor splice site of intron 8, which is absent in MmKIR2DL4 genomic sequences. This mutation introduces a frameshift, subsequently resulting in a premature stopcodon. To further verify this mutation, a cohort of unrelated animals from different geographical locations was examined, and both exon 8 and the splice site mutation were seen to be present in their MmKIR3DH genes. The data suggest that the splice site mutation causes the truncation of the MmKIR3DH transcript and the subsequent loss of its inhibitory motifs further downstream. Loss of inhibitory potential through different mutations is observed in other primate species as well, suggesting convergent evolution; however, this is the first report to document that a mutation in an intron produces a similar effect.

Effect of total flavonoids of Chrysanthemum indicum on the apoptosis of synoviocytes in joint of adjuvant arthritis rats

Chrysanthemum is a traditional Chinese medicine used in China to treat inflammatory diseases. The total flavonoids Chrysanthemum indicum (TFC) were extracted from the dried bud of Chrysanthemum indicum. Our previous study had demonstrated that TFC was a new class of effective anti-inflammation, analgesia and immunoloregulation agents. In this study, we established an adjuvant arthritis (AA) model by injection of Freund's Complete Adjuvant (FCA) to investigate the effect of TFC on the apoptosis of synoviocytes in AA Rats. Synoviocytes isolated from knee joint of rats were treated with different doses of TFC in vitro. Synoviocytes proliferation was measured by MTT assay, and DNA fragmentations were evaluated on agarose gel electrophoresis. The levels of caspase-3 cleaved fragments were analyzed by Western blot. The annexin V stain assay was used to explore the inhibition of caspase-3 on the amelioration of synoviocytes apoptosis. The results showed that TFC inhibited the proliferation of synoviocytes. Electrophoresis showed higher ladders of DNA bands in the TFC group. Cleaved fragments of caspase-3 were increased significantly. Furthermore, the apoptotic synoviocytes were markedly decreased by the caspase-3 specific inhibitor. These results suggest that TFC could induce synoviocytes apoptosis and suppress proliferation of synoviocytes in adjuvant-induced arthritis rats.

A snapshot of the Mamu-B genes and their allelic repertoire in rhesus macaques of Chinese origin

The major histocompatibility complex class I gene repertoire was investigated in a large panel of rhesus macaques of Chinese origin. As observed in Indian animals, subjects of Chinese derivation display Mamu-B gene copy number variation, and the sum of expressed genes varies among haplotypes. In addition, these genes display differential transcription levels. The majority of the Mamu-B alleles discovered during this investigation appear to be unique for the population studied. Only one particular Mamu-B haplotype is shared between Indian and Chinese animals, and it must have been present in the progenitor stock. Hence, the data highlight the fact that most allelic polymorphism, and most of the Mamu-B haplotypes themselves, are of relatively recent origin and were most likely generated after the separation of the Indian and Chinese rhesus macaque populations.

Early effects of tocilizumab on bone and bone marrow lesions in a collagen-induced arthritis monkey model

To understand the contribution of IL-6/IL-6R to subchondral bone and bone marrow abnormality in RA patients and the effects of tocilizumab on those abnormalities, we evaluated early change in a collagen-induced arthritis (CIA) monkey model with or without a single administration of tocilizumab. Six CIA cynomolgus monkeys received tocilizumab and 3 CIA monkeys received vehicle only. Their interphalangeal joints were analyzed using HE, silver impregnation (SI), or immunohistochemistry (RANKL) staining. The number of osteoclasts increased in the arthritis control but was suppressed in the tocilizumab-treated animals. Osteoblast/stromal cells of the arthritis control monkeys were of monolayer, while in the tocilizumab-treated monkeys, the cells were multi-layer or differentiated osteoblasts, and the meshwork of the reticulum fibers showed recovery in the SI. Hematopoietic marrow was replaced by interstitial fluid and reticulum fibers were eliminated in the arthritic model but showed recovery in the tocilizumab-treated animals. RANKL showed overproduction with arthritis and suppressed with tocilizumab treatment. The evidence indicates that IL-6/IL-6R is involved in subchondral bone and bone marrow change in RA patients. Tocilizumab treatment recovered changes in the CIA monkeys as a result of the co-differentiation between the osteoclasts and the osteoblast/stramal cells, at least partially through the suppression of RANKL overproduction.

Preclinical models of arthritic disease in non-human primates

The costs for the development of new drugs have increased dramatically over the past 30 years. One of the main reasons for this increase is the low success rate of new drugs being approved for patient use, which is, in part, a consequence of the common use of rodent models for preclinical validation of efficacy. Especially in the development of biologicals, which are now successfully used in the treatment of rheumatoid arthritis, the selection of the right animal model is pivotal. Non-human primates could help to bridge the evolutionary gap between rodent models and human patients.

Designing new microsatellite markers for linkage and population genetic analyses in rhesus macaques and other nonhuman primates

Identification of polymorphic microsatellite loci in nonhuman primates is useful for various biomedical and evolutionary studies of these species. Prior methods for identifying microsatellites in nonhuman primates are inefficient. We describe a new strategy for marker development that uses the available whole genome sequence for rhesus macaques. Fifty-four novel rhesus-derived microsatellites were genotyped in large pedigrees of rhesus monkeys. Linkage analysis was used to place 51 of these loci into the existing rhesus linkage map. In addition, we find that microsatellites identified this way are polymorphic in other Old World monkeys such as baboons. This approach to marker development is more efficient than previous methods and produces polymorphisms with known locations in the rhesus genome assembly. Finally, we propose a nomenclature system that can be used for rhesus-derived microsatellites genotyped in any species or for novel loci derived from the genome sequence of any nonhuman primate.

Early elevation in circulating levels of C-telopeptides of type II collagen predicts structural damage in articular cartilage in the rodent model of collagen-induced arthritis

OBJECTIVE

To investigate changes in the circulating levels of the C-telopeptide of type II collagen (CTX-II) with relation to disease onset and structural damage of cartilage in a rodent model of collagen-induced arthritis (CIA), and to investigate immunolocalization of the CTX-II epitope in the articular cartilage of affected joints.

METHODS

Seven-week-old female Lewis rats were immunized with type II collagen and monitored using blood sampling at weekly intervals. At study termination (day 23), the animals were killed, synovial fluid was collected, and the affected joints were scored macroscopically for disease severity and underwent immunohistochemical evaluation.

RESULTS

At the time of disease onset (day 15), which was characterized by redness and swelling of the affected joints (mean +/- SD macroscopic severity score 9.1 +/- 1.6), there was a 355% increase in serum CTX-II levels. The early change in serum CTX-II from day 0 to day 15 showed a significant association with the severity of cartilage damage (r = 0.61, P < 0.01). Immunostaining revealed extensive presence of the CTX-II epitope in the damaged, uncalcified cartilage tissue.

CONCLUSION

The elevation in serum CTX-II concomitant with the onset of disease and proportional to cartilage damage demonstrates that CTX-II is a sensitive diagnostic tool for monitoring joint disease in the rodent model of CIA. Furthermore, the immunohistochemical findings are consistent with the concept that the major source of serum CTX-II is the damaged articular cartilage.