Immunity against a Chlamydia infection and disease may be determined by a balance of IL-17 signaling

Most vaccines developed against Chlamydia using animal models provide partial protection against a genital tract infection. However, protection against the oviduct pathology associated with infertility is highly variable and often has no defining immunological correlate. When comparing two adjuvants (CTA1-DD and a combination of Cholera toxin plus CpG- oligodeoxynucleotide–CT/CpG) combined with the chlamydial major outer membrane protein (MOMP) antigen and delivered via the intranasal (IN), sublingual (SL) or transcutaneous (TC) routes, we identified two vaccine groups with contrasting outcomes following infection. SL immunization with MOMP/CTA1-DD induced a 70% reduction in the incidence of oviduct pathology, without significantly altering the course of infection. Conversely, IN immunization with MOMP/CT/CpG prevented an ascending infection, but not the oviduct pathology. This anomaly presented a unique opportunity to study the mechanisms by which vaccines can prevent oviduct pathology, other than by controlling the infection. The IL-17 signaling in the oviducts was found to associate with both the enhancement of immunity to infection and the development of oviduct pathology. This conflicting role of IL-17 may provide some explanation for the discordance in protection between infection and disease and suggests that controlling immunopathology, as opposed to the rapid eradication of the infection, may be essential for an effective human chlamydial vaccine that prevents infertility.

The mouse model of Chlamydia genital tract infection: a review of infection, disease, immunity and vaccine development

Chlamydia trachomatis is the most common sexually transmitted bacterial infection worldwide. The impact of this pathogen on human reproduction has intensified research efforts to better understand chlamydial infection and pathogenesis. Whilst there are animal models available that mimic the many aspects of human chlamydial infection, the mouse is regarded as the most practical and widely used of the models. Studies in mice have greatly contributed to our understanding of the host-pathogen interaction and provided an excellent medium for evaluating vaccines. Here we explore the advantages and disadvantages of all animal models of chlamydial genital tract infection, with a focus on the murine model and what we have learnt from it so far.

Corticosterone accelerates atherosclerosis in the apolipoprotein E-deficient mouse

Chronic stress is an important risk factor for atherosclerosis, which is a chief process in the development of cardiovascular disease. Increased circulating levels of corticosterone have been documented in several animal models of chronic stress. However, it remains to be established whether corticosterone is sufficient to exacerbate atherosclerosis. To test this hypothesis, apolipoprotein E (ApoE)-deficient mice were fed a high-fat diet for 13 weeks with exposure to either corticosterone or vehicle in the drinking water (CORT and Con). Corticosterone treatment significantly increased atherosclerotic plaque area at the aortic root. Such exacerbation of atherosclerosis was accompanied by significantly lower levels of circulating white blood cells and serum interleukin-1β (IL-1β), and significantly elevated serum concentrations of total cholesterol, low-density lipoprotein (LDL), very-low-density lipoprotein (VLDL) and small dense low-density lipoprotein (sd-LDL) in CORT mice when compared to Con mice. These findings demonstrate that corticosterone is sufficient to exacerbate atherosclerosis in vivo despite its anti-inflammatory properties and that this marked pro-atherogenic phenotype is primarily associated with increased dyslipidaemia.

Species-specific homing mechanisms of human prostate cancer metastasis in tissue engineered bone

The development of effective therapeutic strategies against prostate cancer bone metastases has been impeded by the lack of adequate animal models that are able to recapitulate the biology of the disease in humans. Bioengineered approaches allow researchers to create sophisticated experimentally and physiologically relevant in vivo models to study interactions between cancer cells and their microenvironment under reproducible conditions. The aim of this study was to engineer a morphologically and functionally intact humanized organ bone which can serve as a homing site for human prostate cancer cells. Transplantation of biodegradable tubular composite scaffolds seeded with human mesenchymal progenitor cells and loaded with rhBMP-7 resulted in the development of a chimeric bone construct including a large number of human mesenchymal cells which were shown to be metabolically active and capable of producing extracellular matrix components. Micro-CT analysis demonstrated that the newly formed ossicle recapitulated the morphological features of a physiological organ bone with a trabecular network surrounded by a cortex-like outer structure. This microenvironment was supportive of the lodgement and maintenance of murine haematopoietic cell clusters, thus mimicking a functional organ bone. Bioluminescence imaging demonstrated that luciferase-transduced human PC3 cells reproducibly homed to the humanized tissue engineered bone constructs, proliferated, and developed macro-metastases. This model allows the analysis of interactions between human prostate cancer cells and a functional humanized bone organ within an immuno-incompetent murine host. The system can serve as a reproducible platform to study effects of therapeutics against prostate cancer bone metastases within a humanized microenvironment.

Use of genetically modified muscle and fat grafts to repair defects in bone and cartilage

We report a novel technology for the rapid healing of large osseous and chondral defects, based upon the genetic modification of autologous skeletal muscle and fat grafts. These tissues were selected because they not only possess mesenchymal progenitor cells and scaffolding properties, but also can be biopsied, genetically modified and returned to the patient in a single operative session. First generation adenovirus vector carrying cDNA encoding human bone morphogenetic protein-2 (Ad.BMP-2) was used for gene transfer to biopsies of muscle and fat. To assess bone healing, the genetically modified (“gene activated”) tissues were implanted into 5mm-long critical size, mid-diaphyseal, stabilized defects in the femora of Fischer rats. Unlike control defects, those receiving gene-activated muscle underwent rapid healing, with evidence of radiologic bridging as early as 10 days after implantation and restoration of full mechanical strength by 8 weeks. Histologic analysis suggests that the grafts rapidly differentiated into cartilage, followed by efficient endochondral ossification. Fluorescence in situ hybridization detection of Y-chromosomes following the transfer of male donor muscle into female rats demonstrated that at least some of the osteoblasts of the healed bone were derived from donor muscle. Gene activated fat also healed critical sized defects, but less quickly than muscle and with more variability. Anti-adenovirus antibodies were not detected. Pilot studies in a rabbit osteochondral defect model demonstrated the promise of this technology for healing cartilage defects. Further development of these methods should provide ways to heal bone and cartilage more expeditiously, and at lower cost, than is presently possible.

Calcitonin receptor plays a physiological role to protect against hypercalcemia in mice

It is well established that calcitonin is a potent inhibitor of bone resorption; however, a physiological role for calcitonin acting through its cognate receptor, the calcitonin receptor (CTR), has not been identified. Data from previous genetically modified animal models have recognized a possible role for calcitonin and the CTR in controlling bone formation; however, interpretation of these data are complicated, in part because of their mixed genetic background. Therefore, to elucidate the physiological role of the CTR in calcium and bone metabolism, we generated a viable global CTR knockout (KO) mouse model using the Cre/loxP system, in which the CTR is globally deleted by >94% but <100%. Global CTRKOs displayed normal serum ultrafiltrable calcium levels and a mild increase in bone formation in males, showing that the CTR plays a modest physiological role in the regulation of bone and calcium homeostasis in the basal state in mice. Furthermore, the peak in serum total calcium after calcitriol [1,25(OH)2D3]-induced hypercalcemia was substantially greater in global CTRKOs compared with controls. These data provide strong evidence for a biological role of the CTR in regulating calcium homeostasis in states of calcium stress.

PPARγ-independent induction of growth arrest and apoptosis in prostate and bladder carcinoma

Background Although PPARγ antagonists have shown considerable pre-clinical efficacy, recent studies suggest PPARγ ligands induce PPARγ-independent effects. There is a need to better define such effects to permit rational utilization of these agents. Methods We have studied the effects of a range of endogenous and synthetic PPARγ ligands on proliferation, growth arrest (FACS analysis) and apoptosis (caspase-3/7 activation and DNA fragmentation) in multiple prostate carcinoma cell lines (DU145, PC-3 and LNCaP) and in a series of cell lines modelling metastatic transitional cell carcinoma of the bladder (TSU-Pr1, TSU-Pr1-B1 and TSU-Pr1-B2). Results 15-deoxy-prostaglandin J2 (15dPGJ2), troglitazone (TGZ) and to a lesser extent ciglitazone exhibited inhibitory effects on cell number; the selective PPARγ antagonist GW9662 did not reverse these effects. Rosiglitazone and pioglitazone had no effect on proliferation. In addition, TGZ induced G0/G1 growth arrest whilst 15dPGJ2 induced apoptosis. Conclusion Troglitazone and 15dPGJ2 inhibit growth of prostate and bladder carcinoma cell lines through different mechanisms and the effects of both agents are PPARγ-independent.

Human lens lipids differ markedly from those of commonly used experimental animals

Electrospray ionisation tandem mass spectrometry has allowed the unambiguous identification and quantification of individual lens phospholipids in human and six animal models. Using this approach ca. 100 unique phospholipids have been characterised. Parallel analysis of the same lens extracts by a novel direct-insertion electron-ionization technique found the cholesterol content of human lenses to be significantly higher (ca. 6 times) than lenses from the other animals. The most abundant phospholipids in all the lenses examined were choline-containing phospholipids. In rat, mouse, sheep, cow, pig and chicken, these were present largely as phosphatidylcholines, in contrast 66% of the total phospholipid in Homo sapiens was sphingomyelin, with the most abundant being dihydrosphingomyelins, in particular SM(d18:0/16:0) and SM(d18:0/24:1). The abundant glycerophospholipids within human lenses were found to be predominantly phosphatidylethanolamines and phosphatidylserines with surprisingly high concentrations of ether-linked alkyl chains identified in both classes. This study is the first to identify the phospholipid class (head-group) and assign the constituent fatty acid(s) for each lipid molecule and to quantify individual lens phospholipids using internal standards. These data clearly indicate marked differences in the membrane lipid composition of the human lens compared to commonly used animal models and thus predict a significant variation in the membrane properties of human lens fibre cells compared to those of other animals. © 2008 Elsevier B.V. All rights reserved.

Epithelial-to-mesenchymal transitions and circulating tumor cells

Epithelial-to-mesenchymal transition (EMT) phenomena endow epithelial cells with enhanced migratory and invasive potential, and as such, have been implicated in many physiological and pathological processes requiring cell migration/invasion. Although their involvement in the metastatic cascade is still a subject of debate, data are accumulating to demonstrate the existence of EMT phenotypes in primary human tumors, describe enhanced metastatic potential of EMT derivatives in animal models, and report EMT attributes in circulating tumor cells (CTCs). The relationships between EMT and CTCs remain largely unexplored, and we review here in vitro and in vivo data supporting a putative role of EMT processes in CTC generation and survival.

A comparative study of Sr-incorporated mesoporous bioactive glass scaffolds for regeneration of osteopenic bone defects

SUMMARY: Recently, the use of the pharmacological agent strontium ranelate has come to prominence for the treatment of osteoporosis. While much investigation is focused on preventing disease progression, here we fabricate strontium-containing scaffolds and show that they enhance bone defect healing in the femurs of rats induced by ovariectomy. INTRODUCTION: Recently, the use of the pharmacological agent strontium ranelate has come to prominence for the treatment of osteoporosis due to its ability to prevent bone loss in osteoporotic patients. Although much emphasis has been placed on using pharmacological agents for the prevention of disease, much less attention has been placed on the construction of biomaterials following osteoporotic-related fracture. The aim of the present study was to incorporate bioactive strontium (Sr) trace element into mesoporous bioactive glass (MBG) scaffolds and to investigate their in vivo efficacy for bone defect healing in the femurs of rats induced by ovariectomy. METHODS: In total, 30 animals were divided into five groups as follows: (1) empty defect (control), (2) empty defects with estrogen replacement therapy, (3) defects filled with MBG scaffolds alone, (4) defects filled with MBG + estrogen replacement therapy, and (5) defects filled with strontium-incorporated mesopore-bioglass (Sr-MBG) scaffolds. RESULTS: The two groups demonstrating the highest levels of new bone formation were the defects treated with MBG + estrogen replacement therapy and the defects receiving Sr-MBG scaffolds as assessed by μ-CT and histological analysis. Furthermore, Sr scaffolds had a reduced number of tartrate-resistant acid phosphatase-positive cells when compared to other modalities. CONCLUSION: The results from the present study demonstrate that the local release of Sr from bone scaffolds may improve fracture repair. Future large animal models are necessary to investigate the future relationship of Sr incorporation into biomaterials.

Melanopsin expressing intrinsically photosensitive Retinal Ganglion cells in retinal disease

Melanopsin containing intrinsically photosensitive Retinal Ganglion Cells (ipRGCs) are a class of photoreceptors with established roles in non-image forming processes. Their contributions to image forming vision may include the estimation of brightness. Animal models have been central for understanding the physiological mechanisms of ipRGC function and there is evidence of conservation of function across species. ipRGCs can be divided into 5 ganglion cell subtypes that show morphological and functional diversity. Research in humans has established that ipRGCs signal environmental irradiance to entrain the central body clock to the solar day for regulating circadian processes and sleep. In addition, ipRGCs mediate the pupil light reflex (PLR), making the PLR a readily accessible behavioural marker of ipRGC activity. Less is known about ipRGC function in retinal and optic nerve disease, with emerging research providing insight into their function in diabetes, retinitis pigmentosa, glaucoma and hereditary optic neuropathy. We briefly review the anatomical distributions, projections and basic physiological mechanisms of ipRGCs, their proposed and known functions in animals and humans with and without eye disease. We introduce a paradigm for differentiating inner and outer retinal inputs to the pupillary control pathway in retinal disease and apply this paradigm to patients with age-related macular degeneration (AMD). In these cases of patients with AMD, we provide the initial evidence that ipRGC function is altered, and that the dysfunction is more pronounced in advanced disease. Our perspective is that with refined pupillometry paradigms, the pupil light reflex can be extended to AMD assessment as a tool for the measurement of inner and outer retinal dysfunction.

Epigenetic mechanisms mediating vulnerability and resilience to psychiatric disorders

The impact that stressful encounters have upon long-lasting behavioural phenotypes is varied. Whereas a significant proportion of the population will develop "stress-related" conditions such as post-traumatic stress disorder or depression in later life, the majority are considered "resilient" and are able to cope with stress and avoid such psychopathologies. The reason for this heterogeneity is undoubtedly multi-factorial, involving a complex interplay between genetic and environmental factors. Both genes and environment are of critical importance when it comes to developmental processes, and it appears that subtle differences in either of these may be responsible for altering developmental trajectories that confer vulnerability or resilience. At the molecular level, developmental processes are regulated by epigenetic mechanisms, with recent clinical and pre-clinical data obtained by ourselves and others suggesting that epigenetic differences in various regions of the brain are associated with a range of psychiatric disorders, including many that are stress-related. Here we provide an overview of how these epigenetic differences, and hence susceptibility to psychiatric disorders, might arise through exposure to stress-related factors during critical periods of development.

Slaving and release in co-infection control

Background Animal and human infection with multiple parasite species is the norm rather than the exception, and empirical studies and animal models have provided evidence for a diverse range of interactions among parasites. We demonstrate how an optimal control strategy should be tailored to the pathogen community and tempered by species-level knowledge of drug sensitivity with use of a simple epidemiological model of gastro-intestinal nematodes. Methods We construct a fully mechanistic model of macroparasite co-infection and use it to explore a range of control scenarios involving chemotherapy as well as improvements to sanitation. Results Scenarios are presented whereby control not only releases a more resistant parasite from antagonistic interactions, but risks increasing co-infection rates, exacerbating the burden of disease. In contrast, synergisms between species result in their becoming epidemiologically slaved within hosts, presenting a novel opportunity for controlling drug resistant parasites by targeting co-circulating species. Conclusions Understanding the effects on control of multi-parasite species interactions, and vice versa, is of increasing urgency in the advent of integrated mass intervention programmes.

Using DNA as a drug : challenges and opportunities for process engineers

The maturing of the biotechnology industry and a focus on productivity has seen a shift from discovery science to small-scale bench-top research to higher productivity, large scale production. Health companies are aggressively expanding their biopharmaceutical interests, an expansion which is facilitated by biochemical and bioprocess engineering. An area of continuous growth is vaccines. Vaccination will be a key intervention in the case of an influenza pandemic. The global manufacturing capacity for fast turn around vaccines is currently woefully inadequate at around 300 million shots. As the prevention of epidemics requires > 80 % vaccination, in theory the world should currently be aiming for the ability to produce around 5.3 billion vaccines. Presented is a production method for the creation of a fast turn around DNA vaccine. A DNA vaccine could have a production time scale of as little as two weeks. This process has been harnessed into a pilot scale production system for the creation of a pre-clinical grade malaria vaccine in a collaborative project with the Coppel Lab, Department of Microbiology, Monash University. In particular, improvements to the fermentation, chromatography and delivery stages will be discussed. Consideration will then be given as to how the fermentation stage affects the mid and downstream processing stages.

Mimicking the tumour microenvironment (TME): Angiogenesis in tumour progression

Two-dimensional (2D) substrates cannot accurately mimic the complex matrix of native TME, whereas 3D models can recapitulate the natural tumour progression in vitro. As part of the tumour stroma, fibroblasts and endothelial cells (ECs) are well-known to not only support tumour growth but also to reduce the efficacy of anti-cancer drugs. Particularly, ECs are involved in the process of tumour vascularisation which represents a crucial step in the progression of cancer. Most of the previous studies are carried out in animal models or 2D cultures; hence, a detailed evaluation of experimental data is poor. To address this issue, we aim to develop a novel 3D in vitro approach, to mimic native tumour angiogenesis in 3D and to quantify the developed vascular network.