Evaluating the validity of animal models for research into therapies for immune-based disorders

Resistin's, obesity and insulin resistance: the continuing disconnect between rodents and humans

PURPOSE

This review aimed to discuss the conflicting findings from resistin research in rodents and humans as well as recent advances in our understanding of resistin's role in obesity and insulin resistance.

METHODS

A comprehensive review and synthesis of resistin's role in obesity and insulin resistance as well as conflicting findings from resistin research in rodents and humans.

RESULTS

In rodents, resistin is increased in high-fat/high-carbohydrate-fed, obese states characterized by impaired glucose uptake and insulin sensitivity. Resistin plays a causative role in the development of insulin resistance in rodents via 5' AMP-activated protein kinase (AMPK)-dependent and AMPK-independent suppressor of cytokine signaling-3 (SOCS-3) signaling. In contrast to rodents, human resistin is primarily secreted by peripheral-blood mononuclear cells (PBMCs) as opposed to white adipocytes. Circulating resistin levels have been positively associated with central/visceral obesity (but not BMI) as well as insulin resistance, while other studies show no such association. Human resistin has a role in pro-inflammatory processes that have been conclusively associated with obesity and insulin resistance. PBMCs, as well as vascular cells, have been identified as the primary targets of resistin's pro-inflammatory activity via nuclear factor-κB (NF-κB, p50/p65) and other signaling pathways.

CONCLUSION

Mounting evidence reveals a continuing disconnect between resistin's role in rodents and humans due to significant differences between these two species with respect to resistin's gene and protein structure, differential gene regulation, tissue-specific distribution, and insulin resistance induction as well as a paucity of evidence regarding the resistin receptor and downstream signaling mechanisms of action.

Primate models in organ transplantation

Large animal models have long served as the proving grounds for advances in transplantation, bridging the gap between inbred mouse experimentation and human clinical trials. Although a variety of species have been and continue to be used, the emergence of highly targeted biologic- and antibody-based therapies has required models to have a high degree of homology with humans. Thus, the nonhuman primate has become the model of choice in many settings. This article will provide an overview of nonhuman primate models of transplantation. Issues of primate genetics and care will be introduced, and a brief overview of technical aspects for various transplant models will be discussed. Finally, several prominent immunosuppressive and tolerance strategies used in primates will be reviewed.

Induction of experimental autoimmune encephalomyelitis with recombinant human myelin oligodendrocyte glycoprotein in incomplete Freund's adjuvant in three non-human primate species

The experimental autoimmune encephalitis (EAE) model is used for preclinical research into the pathogenesis of multiple sclerosis (MS), mostly in inbred, specific pathogen free (SPF)-raised laboratory mice. However, the naive state of the laboratory mouse immune system is considered a major hurdle in the translation of principles from the EAE model to the MS patient. Non-human primates (NHP) have an immune system harboring T- and B-cell memory against environmental antigens, similar as in humans. We sought to further refine existing NHP EAE models, which may help to bridge the gab between mouse EAE models and MS. We report here on new EAE models in three NHP species: rhesus monkeys (Macaca mulatta), cynomolgus monkeys (Macaca fascicularis) and common marmosets (Callithrix jacchus). EAE was induced with recombinant human myelin oligodendrocyte glycoprotein extracellular domain (1–125) (rhMOG) formulated in incomplete Freund’s adjuvant (IFA). IFA lacks the bacterial antigens that are present in complete Freund’s adjuvant (CFA), which are notorious for the induction of discomforting side effects. Clinically evident EAE could be induced in two out of five rhesus monkeys, six out of six cynomolgus monkeys and six out of six common marmosets. In each of these species, the presence of an early, high anti-rhMOG IgM response is correlated with EAE with an earlier onset and more severe disease course. Animals without an early high IgM response either did not develop disease (rhesus monkeys) or developed only mild signs of neurological deficit (marmoset and cynomolgus monkeys).

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.

Discrepant effects of human interferon-gamma on clinical and immunological disease parameters in a novel marmoset model for multiple sclerosis

The core pathogenic process in the common marmoset model of multiple sclerosis (MS) is the activation of memory-like T cells specific for peptide 34 to 56 derived from the extracellular domain of myelin/oligodendrocyte glycoprotein (MOG_34-56). Immunization with MOG_34-56 in incomplete Freund’s adjuvant is a sufficient stimulus for in vivo activation of these T cells, together with the induction of MS-like disease and CNS pathology. Ex vivo functional characteristics of MOG_34-56 specific T cells are specific cytolysis of peptide pulsed target cells and high IL-17A production. To indentify possible functions in this new model of T helper 1 cells, which play a central pathogenic role in MS models induced with complete Freund’s adjuvant, we tested the effect of human interferon-γ (IFNγ) administration during disease initiation of the disease (day 0–25) and around the time of disease expression (psd 56–81). The results show a clear modulatory effect of early IFNγ treatment on humoral and cellular autoimmune parameters, but no generalized mitigating effect on the disease course. These results argue against a prominent pathogenic role of T helper 1 cells in this new marmoset EAE model.

ATROSAB, a humanized antagonistic anti-tumor necrosis factor receptor one-specific antibody

Tumor necrosis factor (TNF) signals through two membrane receptors, TNFR1 and TNFR2, and TNFR1 is known to be the major pathogenic mediator of chronic and acute inflammatory diseases. Present clinical intervention is based on neutralization of the ligand TNF. Selective inhibition of TNF receptor 1 (TNFR1) provides an alternative opportunity to neutralize the pro-inflammatory activity of TNF while maintaining the advantageous immunological responses mediated by TNFR2, including immune regulation, tissue homeostasis and neuroprotection. We recently humanized a mouse anti-human TNFR1 monoclonal antibody exhibiting TNFR1-neutralizing activity. This humanized antibody has been converted into an IgG1 molecule (ATROSAB) containing a modified Fc region previously demonstrated to have greatly reduced effector functions. Purified ATROSAB, produced in CHO cells, showed strong binding to human and rhesus TNFR1-Fc fusion protein and mouse embryonic fibroblasts transfected with a recombinant TNFR1 fusion protein with an affinity identical to the parental mouse antibody H398. Using chimeric human/mouse TNFR1 molecules, the epitope of ATROSAB was mapped to the N-terminal region (amino acid residues 1-70) comprising the first cysteine-rich domain (CRD1) and the A1 sub-domain of CRD2. In vitro, ATROSAB inhibited typical TNF-mediated responses like apoptosis induction and activation of NFκB-dependent gene expression such as IL-6 and IL-8 production. These findings open the way to further analyze the therapeutic activity of ATROSAB in relevant disease models in non-human primates.

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.

Evoked potential and behavioral outcomes for experimental autoimmune encephalomyelitis in Lewis rats

A reliable outcome measurement is needed to assess the effects of experimental lesions in the rat spinal cord as well as to assess the benefits of therapies designed to modulate them. The Basso, Beattie, and Bresnahan (BBB) behavioral scores can be indicative of the functionality in motor pathways. However, since lesions are often induced in the more accessible dorsal parts associated with the sensory pathways, the BBB scores may not be ideal measure of the disability. We propose somatosensory evoked potential (SEP) as a complementary measure to assess the integrity of sensory pathways. We used the focal experimental autoimmune encephalomyelitis (EAE) model, in which focal demyelinating lesions were induced by injecting cytokine-ethidium bromide into dorsal white matter after MOG-IFA immunization. Both the SEP and BBB measures reflected injury; however, the SEP was uniformly and consistently altered after the injury whereas the BBB varied widely. The results suggest that the SEP measures are more sensitive and reliable markers of focal spinal cord demyelination compared to the behavioral measures like the BBB score.

Rhesus monkey immature monocyte-derived dendritic cells generate alloantigen-specific regulatory T cells from circulating CD4+CD127-/lo T cells

BACKGROUND

Generation of non-human primate regulatory T cells (Treg) with alloantigen (alloAg) specificity would allow their testing in preclinical transplant models. Low recovery of Treg from peripheral blood limits their potential utility. In small animals and humans, conventional myeloid dendritic cells (DC) have been shown to select or induce alloAg-specific Treg.

METHODS

We combined enrichment of rhesus macaque blood CD4 Treg based on IL-7Ralpha (CD127) expression with their stimulation in mixed leukocyte cultures with immature, allogeneic control or vitamin (Vit) D3/IL-10-conditioned monocyte-derived DC. After co-culture in IL-2 and IL-15 for up to 14 days, the ability of the resulting T cells to suppress alloreactive effector T-cell proliferation was assessed.

RESULTS

CD4CD127 T cells represented approximately 7% of normal rhesus circulating CD4 T cells and were enriched for forkhead box P3 (Foxp3) cells. When stimulated with control allogeneic DC, they exhibited much inferior proliferative responses compared with bulk CD4 or CD4CD127 cells. This anergic state was reversed by exogenous IL-2 and IL-15. After 10 to 14 days culture of CD4CD127 T cells with immature allogeneic DC, particularly maturation-resistant VitD3/IL-10 DC, the frequency of Foxp3 T cells was increased. The cultured cells markedly inhibited CD4 effector T-cell proliferation in a dose-related and donor alloAg-specific manner.

CONCLUSION

Stimulation of rhesus CD4CD127 T cells with immature and especially maturation-resistant allogeneic DC, generated highly-suppressive, alloAg-specific Treg. Without resorting to a more purified starting population, this approach may have therapeutic utility in clinically relevant transplant models.

A monoclonal antibody selection for immunohistochemical examination of lymphoid tissues from non-human primates

Non-human primates (NHPs) offer valuable animal models for basic research into human diseases and for the preclinical validation of new therapeutics. Detailed in situ examination of the involved cell types using immunohistochemistry is often hampered by the lack of cross-reactive antibodies (Abs). In the current study, we have tested a large panel of monoclonal antibodies raised against human leukocyte differentiation and activation markers for cross-reactivity on cryosections of lymphoid tissue from six NHP species. In total, we have tested 130 Abs against 69 antigens expressed in tissues from one great ape species (chimpanzee/Pan troglodytes), two Old World species (rhesus macaque/Macaca mulatta and cynomolgus macaque/Macaca fascicularis), and three New World species (common marmoset/Callithrix jacchus, cotton-top tamarin/Saguinus oedipus, and owl monkey/Aotus triviogatus). We have found a large panel of cross-reactive Abs: 93 of 102 (91%) in chimpanzee, 97 of 125 (78%) in rhesus macaque, 70 of 109 (64%) in cynomolgus macaque, 69 of 116 (60%) in common marmoset, 40 of 81 (49%) in cotton-top tamarin, and 35 of 80 (44%) in owl monkey. The availability of a reliable panel of cross-reactive markers is important to gaining further insight into immunological processes in disease-affected tissues from NHP species.

Clinical, pathological, and immunologic aspects of the multiple sclerosis model in common marmosets (Callithrix jacchus)

The efficacy of many new immunomodulatory therapies for multiple sclerosis (MS) patients has often been disappointing, reflecting our incomplete understanding of this enigmatic disease. There is a growing awareness that, at least in part, there may be limited applicability to the human disease of results obtained in the widely studied MS model experimental autoimmune encephalomyelitis in rodents. This review describes the experimental autoimmune encephalomyelitis model developed in a small neotropical primate, the common marmoset (Callithrix jacchus). The model has features including clinicopathologic correlation patterns, lesion heterogeneity, immunologic mechanisms, and disease markers that more closely mimic the human disease. Several unique features of experimental autoimmune encephalomyelitis in marmosets, together with their outbred nature and close genetic and immunologic similarities to humans, create an attractive experimental model for translational research into MS, particularly for the preclinical evaluation of new biologic therapeutic molecules that cannot be investigated in rodents because of their species specificity. Moreover, this model provides new insights into possible pathogenetic mechanisms in MS.

Distinct spatiotemporal pattern of CNS lesions revealed by USPIO-enhanced MRI in MOG-induced EAE rats implicates the involvement of spino-olivocerebellar pathways

USPIO-enhanced MRI allows non-invasive visualization of mononuclear cell infiltration into CNS lesions in MS and EAE. Herein, we show a distinct spatiotemporal pattern of CNS lesions that reveals the involvement of spino-olivocerebellar pathways in MOG-induced EAE rats using USPIO-enhanced MRI. Specifically, lesions of the inferior olives were observed primarily in the acute phase whereas lesions of cerebellum or spinal cord/brainstem were observed during the relapse phase. Further, behavioral deficits observed from these animals are consistent with the functional role of spino-olivocerebellar pathways in coordination and movement. Collectively, our results provide new insights into the pathophysiology of this animal model of MS.

Auditing protein therapeutics management by professional APCs: toward prevention of immune responses against therapeutic proteins

Alloimmunization is a crippling concern in the management of patients undergoing administration of protein therapeutics as evidenced in replacement therapy and other treatment procedures. Several issues in the genesis and modulation of such deleterious immune responses have been studied. While authors have focused on the downstream events of the specific immune response and suggested modification of protein therapeutics to eliminate epitopes that interact with B cell receptors, T cell receptors, or MHCII molecules, the mechanisms underlying Ag interaction with APCs, a step upstream of immune effectors, have been grossly neglected. We wish to emphasize that the recent knowledge in understanding the capacities of an APC to handle an Ag and the importance of the surrounding microenvironment in this process are crucial for designing novel protein therapeutics with reduced immunogenicity.

Characterization of naturally occurring CD4+CD25+ regulatory T cells in rhesus monkeys

BACKGROUND

Translational research in a relevant preclinical model is recommended before Treg-inducing protocols can be implemented in humans. We have characterized rhesus monkey CD25 cells phenotypically and functionally.

METHODS

The phenotype of CD4(+)CD25(high) cells was determined by FACS, focusing on established markers of mouse and human Treg cells. Percentages of cells positive for CD45RA, CD62L, and intracellular CTLA-4 and FOXP3 were compared between CD4(+)CD25(high) and CD4(+)CD25(-) cells. CD25 cells stimulated with anti-CD3, ConA, and/or allogeneic peripheral blood mononuclear cells were mixed with freshly isolated CD25 cells. The suppressive activity of the CD25 cells in vitro was assessed using several experimental conditions.

RESULTS

Rhesus monkey CD4(+)CD25(high) cells expressed high intracellular levels of CTLA-4 and FOXP3, whereas expression was negligible in CD4(+)CD25(-) cells. The CD25(high) population was mostly CD45RA(-), indicative of a memory phenotype. The CD25(+) cells were anergic, because they showed low proliferative responses, no interleukin-2 production, and some interferon-gamma and interleukin-10 production. Proliferation of CD4(+)CD25(-) cells stimulated by anti-CD3 or allogeneic cells was decreased when CD4(+)CD25(-) cells were added at a 1:1 ratio. In addition, we found that CD25 cells inhibited the interleukin-2 and interferon-gamma production by anti-CD3-stimulated CD25 cells in a dose-dependent fashion, through a cell-cell contact-dependent mechanism.

CONCLUSIONS

Rhesus monkey CD4(+)CD25(+) cells have similar phenotypic and functional characteristics as natural Tregs in humans. These findings allow testing of Treg expansion and induction protocols in a relevant preclinical model, the rhesus monkey.

Preclinical assessment of therapeutic antibodies against human CD40 and human interleukin-12/23p40 in a nonhuman primate model of multiple sclerosis

BACKGROUND

Proinflammatory cytokines, such as interleukin (IL)-12 and IL-23, and costimulatory molecules on antigen-presenting cells (APC), such as CD40, are critical to autoreactive T cell activation by APC, and hence, are considered relevant targets of therapy for immune-mediated inflammatory diseases (IMID).

OBJECTIVE

The current review discusses the preclinical evaluation of two novel immunotherapeutic monoclonal antibodies (mAbs), one directed against human IL-12/23p40 and the other against CD40. As the antibodies only recognize their target molecule in primates, the efficacy could not be tested in rodent models.

RESULTS

As a preclinical IMID model for the in vivo evaluation of both mAbs, we have used the experimental autoimmune/allergic encephalomyelitis (EAE) model in common marmoset monkeys (Callithrix jacchus). Both mAbs show beneficial activities in the EAE model when administered early in disease development as well as after the onset of brain inflammation. The treatment effects were evaluated using a combination of quantitative magnetic resonance imaging and a series of ex vivo and immunopathological evaluations.

CONCLUSION

The promising effects during ongoing disease in a relevant preclinical IMID model illustrate the potential of these two antibodies as treatment of IMID, in particular for multiple sclerosis on which disease EAE has been modeled.

Quantitative MRI-pathology correlations of brain white matter lesions developing in a non-human primate model of multiple sclerosis

Experimental autoimmune encephalomyelitis (EAE) induced with recombinant human myelin/oligodendrocyte glycoprotein in the common marmoset is a useful preclinical model of multiple sclerosis in which white matter lesions can be well visualized with MRI. In this study we characterized lesion progression with quantitative in vivo MRI (4.7 T; T(1) relaxation time +/- Gd-DTPA; T(2) relaxation time; magnetization transfer ratio, MTR, imaging) and correlated end stage MRI presentation with quantitative ex vivo MRI (formaldehyde fixed brains; T(1) and T(2) relaxation times; MTR) and histology. The histopathological characterization included axonal density measurements and the numeric quantification of infiltrated macrophages expressing markers for early active [luxol fast blue (LFB) or migration inhibition factor-related protein-14 positive] or late active/inactive [periodic acid Schiff (PAS) positive] demyelinating lesion. MRI experiments were done every two weeks until the monkeys were sacrificed with severe EAE-related motor deficits. Compared with the normal appearing white matter, lesions showed an initial increase in T(1) relaxation times, leakage of Gd-DTPA and decrease in MTR values. The progressive enlargement of lesions was associated with stabilized T(1) values, while T(2) initially increased and stabilized thereafter and MTR remained decreased. Gd-DTPA leakage was highly variable throughout the experiment. MRI characteristics of the cortex and (normal appearing) white matter did not change during the experiment. We observed that in vivo MTR values correlated positively with the number of early active (LFB+) and negatively with late active (PAS+) macrophages. Ex vivo MTR and relaxation times correlated positively with the number of PAS-positive macrophages. None of the investigated MRI parameters correlated with axonal density.

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.

Monotherapy with the vitamin D3 analogue MC1288 does not result in prolonged kidney allograft survival in rhesus monkeys

The active form of vitamin D3, 1,25(OH)2D3, has pronounced immunoregulatory properties and is a potential treatment of immune-based disorders. However, the central role of this hormone in calcium and bone metabolism complicates its long-term use as an immunomodulator. Some newly developed vitamin D3-derived analogues, such as MC1288, have an improved immunoregulatory potential and prolong allograft survival in rodent models. Such compounds might be a valuable component of immunosuppressive treatment regimen in transplantation and autoimmunity. The rhesus monkey provides a useful model for the preclinical validation of new therapeutic strategies for transplantation. The present study shows that MC1288 inhibits both proliferation and interferon-gamma production by rhesus peripheral blood mononuclear cells in a mixed lymphocyte reaction. We have tested the maximum tolerated dose of MC1288 in a rhesus monkey model of kidney transplantation. The observed effects on serum calcium and parathyroid hormone confirm the in vivo activity of MC1288. However, as a monotherapy, MC1288 did not cause prolongation of the kidney allograft survival in rhesus monkeys.

MRI-guided immunotherapy development for multiple sclerosis in a primate

Multiple sclerosis is a serious neurological disease that affects 1 in 1000 young adults in Europe and the USA. The development of an effective therapy for this enigmatic disease is plagued by the failure of many treatments to reproduce in patients the promising effects observed in animal models. This review describes a new preclinical model in a non-human primate that might help to bridge the gap between currently used animal models and the patients.

Suppression of Ongoing Disease in a Nonhuman Primate Model of Multiple Sclerosis by a Human-Anti-Human IL-12p40 Antibody

IL-12p40 is a shared subunit of two cytokines with overlapping activities in the induction of autoreactive Th1 cells and therefore a potential target of therapy in Th1-mediated diseases. We have examined whether ongoing disease in a nonhuman primate model of multiple sclerosis (MS) can be suppressed with a new human IgG1kappa Ab against human IL-12p40. Lesions developing in the brain white matter were visualized and characterized with standard magnetic resonance imaging techniques. To reflect the treatment of MS patients, treatment with the Ab was initiated after active brain white matter lesions were detected in T2-weighted images. In placebo-treated control monkeys we observed the expected progressive increase in the total T2 lesion volume and markedly increased T2 relaxation times, a magnetic resonance imaging marker of inflammation. In contrast, in monkeys treated with anti-IL-12p40 Ab, changes in the total T2 lesion volume and T2 relaxation times were significantly suppressed. Moreover, the time interval to serious neurological deficit was delayed from 31 +/- 10 to 64 +/- 20 days (odds ratio, 0.312). These results, in a disease model with high similarity to MS, are important for ongoing and planned trials of therapies that target IL-12 and/or IL-23.

Biological activity of an intravenous preparation of human vaccinia immune globulin in mouse models of vaccinia virus infection

The biological activity of a new intravenous (i.v.) preparation of human vaccinia immune globulin (VIGIV) was evaluated in two mouse models of vaccinia virus (VV) infection. In a mouse tail lesion model, female CD-1 mice were inoculated i.v. with 7 x 10(4) PFU of VV to produce >10 lesions per tail 8 days later. In a mouse lethality model, female severe combined immunodeficient (SCID) mice were inoculated i.v. with 3 x 10(4) PFU of VV to produce 100% mortality within 45 days. The ability of VIGIV to reduce tail lesion formation in CD-1 mice and mortality in SCID mice was determined by (i) pretreatment of a lethal VV dose with VIGIV prior to i.v. inoculation into SCID mice and (ii) i.v. administration of VIGIV to CD-1 and SCID mice the day before and up to 8 days after VV infection. VIGIV reduced the proportion of CD-1 mice with >10 tail lesions in a dose-related manner when VIGIV was given 1 day before and up to 1 day after VV inoculation. The pretreatment of VV with VIGIV prolonged survival and decreased mortality. VIGIV (100 and 400 mg/kg) prolonged survival when given up to 4 days after VV inoculation, and the 400-mg/kg dose reduced the mortality rate by 80% when given the day before or immediately after VV inoculation. The biological activity of VIGIV was demonstrated in both the immunocompetent and immunocompromised murine models. The timing of treatment relative to VV inoculation appeared to be important for the demonstration of VIGIV's biological activity.

Biozzi mice: Of mice and human neurological diseases

In 1972 Guido Biozzi selectively bred mice to study the immunopathological mechanisms underlying polygenic diseases. One line, the Biozzi antibody high (AB/H) mouse (now designated the ABH strain) was later found to be highly susceptible to many experimentally induced diseases such as autoimmune encephalomyelitis, autoimmune neuritis, autoimmune uveitis, as well as virus-induced demyelination and has thus been a key mouse strain to study human inflammatory neurological diseases. In this paper we discuss the background of the Biozzi ABH mouse and review how studies with these mice have shed light on the pathogenic mechanisms operating in chronic neurological disease.

Non-human primate models of experimental autoimmune encephalomyelitis: Variations on a theme

Despite years of intensive research into multiple sclerosis (MS) scientists have not yet succeeded in developing an absolute therapy for the treatment of this disabling disease of the human central nervous system. The wide immunological gap between inbred rodent strains and the heterogeneous human population is probably the single most important factor that hampers the translation of scientific principles developed in rodents into effective therapies for MS. Because of the closer immunological proximity to humans, non-human primates provide useful experimental models that may help to bridge this gap. Here we review the models of experimental autoimmune encephalomyelitis in rhesus macaques and common marmosets. We will discuss the salient points of the models and suggest how these may represent the spectrum of inflammatory demyelinating diseases of the central nervous system in humans.

Modeling human arthritic diseases in nonhuman primates

Models of rheumatoid arthritis (RA) in laboratory animals are important tools for research into pathogenic mechanisms and the development of effective, safe therapies. Rodent models (rats and mice) have provided important information about the pathogenic mechanisms. However, the evolutionary distance between rodents and humans hampers the translation of scientific principles into effective therapies. The impact of the genetic distance between the species is especially seen with treatments based on biological molecules, which are usually species-specific. The outbred nature and the closer anatomical, genetic, microbiological, physiological, and immunological similarity of nonhuman primates to humans may help to bridge the wide gap between inbred rodent strain models and the heterogeneous RA patient population. Here we review clinical, immunological and pathological aspects of the rhesus monkey model of collagen-induced arthritis, which has emerged as a reproducible model of human RA in nonhuman primates.

Treatment with chimeric anti-human CD40 antibody suppresses MRI-detectable inflammation and enlargement of pre-existing brain lesions in common marmosets affected by MOG-induced EAE

Common marmosets, a Neotropical monkey species, are protected against clinical and neuropathological consequences of experimentally induced autoimmune encephalomyelitis (EAE) by prophylactic treatment with ch5D12, a humanized antagonist antibody against human CD40. In the current study we have tested whether ch5D12 acts therapeutically against the enlargement and inflammatory activity of existing (brain) white matter lesions using serial magnetic resonance imaging (MRI). The results show in all PBS treated monkeys (n=4) a rapid enlargement of T2 lesions together with an increment of the T2 signal intensity due to inflammatory edema. Treatment with ch5D12 delayed the enlargement of T2 lesions in 2 out of 3 tested monkeys while in 3 out of 3 monkeys the T2 signal increment of lesions was suppressed. In conjunction with previously published data on the clinical benefit of anti-CD40 treatment in the marmoset EAE model, the current findings support antibody-mediated blockade of CD40 interaction with its ligand CD154 as a potential treatment of MS.

Modelling of multiple sclerosis: lessons learned in a non-human primate

The many, highly specific, biological therapies for immune-based diseases create a need for valid preclinical animal models. The wide immunological gap between human beings and laboratory mouse or rat models makes many disease models in these species invalid. In this review, we report a non-human-primate model of chronic multiple sclerosis (MS)-experimental autoimmune encephalitis (EAE) in the common marmoset (Callithrix jacchus)-that can help bridge this wide gap. The genetic and immunological similarity of marmosets and human beings and the clinical and neuropathological similarity of the EAE model to MS provide a unique experimental platform for research into basic immunopathogenetic mechanisms and for the development of more effective treatments for MS.