Inflammation induces α1-adrenoceptor expression in peripheral blood mononuclear cells of patients with complex regional pain syndrome.

Persistent regional and systemic inflammation may promote pain and hyperalgesia in complex regional pain syndrome (CRPS). In this study, we investigated whether stimulation of α1-adrenoceptors (α1-AR) on peripheral blood mononuclear cells (PBMC) might contribute to this inflammatory state. PBMC were isolated from venous blood collected from 21 CRPS patients and 21 sex and age-matched controls. Lipopolysaccharide (LPS), a bacterial toxin, was administered to cultured PBMC for 24 h to trigger inflammation. Exposure to LPS resulted in heightened gene expression of α1-AR subtype B (α1B-AR) in PBMC of CRPS patients relative to controls. Interleukin (IL)-1ß and IL-6 levels did not change when the α1-AR agonist phenylephrine was administered to naïve PBMC. However, α1-AR stimulation following LPS treatment increased IL-6 mRNA and protein levels in PBMC of patients and controls. To investigate the possible consequence of heightened IL-6 levels on immunoglobulin G antibody production, PBMC were stimulated with CD40 ligand and IL-21 to generate plasmablasts (B cells that secrete antibodies). This response was similar in patients and controls. Adding IL-6 to the cell culture medium increased plasmablast differentiation in controls and antibody production both in patients and controls. These findings suggest that the inflammatory cascade associated with elevated levels of IL-6 may generate α1B-AR expression in CRPS PBMC. A reciprocal interaction between heightened α1-AR expression in PBMC and IL-6 secretion may contribute to systemic inflammation and antibody production in CRPS.

A positive feedback loop between alpha1-adrenoceptors and inflammatory cytokines in keratinocytes.

A positive feedback loop between inflammatory cytokines and alpha1-adrenoceptors (α1-AR) (a target of the sympathetic nervous system neurotransmitter norepinephrine) influences inflammatory responses in immune cells. This cross-talk between the sympathetic nervous system and immune system may play a role in promoting chronic inflammation. Emerging evidence shows that α1-AR interact with inflammatory cytokines in keratinocytes, and this epidermal adrenergic signalling may contribute to skin inflammatory responses following injury, disease or stress. In this study, utilizing an in vitro approach, we hypothesized that α1-AR interact in a positive feedback loop with inflammatory mediators in keratinocytes. The pro-inflammatory cytokine tumor necrosis factor α (TNFα) was used to induce an inflammatory state in cultured keratinocytes. TNFα increased interleukin (IL)-1ß, IL-6, IL-8 and nerve growth factor (NGF) production and gene expression levels of α1-AR subtype B (α1B-AR). Additional stimulation of α1-AR further increased IL-6 levels, while maintaining high levels of IL-8 and decreasing levels of IL-1ß and NGF. Our results suggest that reciprocal influences between α1-ARs and inflammatory cytokines may play a role in normal inflammatory responses. However, if unchecked, this cycle could contribute to pathology (e.g. chronic inflammatory diseases, chronic pain conditions, and stress-induced cancer progression).

Tumor necrosis factor α induces α1B-adrenergic receptor expression in keratinocytes.

Keratinocytes produce cytokines and nerve growth factor (NGF) as part of a repair response to injury, disease or stress, and express alpha1-adrenoceptors (α1-AR). The expression of these receptors is elevated in some inflammatory diseases and chronic pain conditions. In this study, we investigated whether inflammatory signalling affects α1-AR expression in keratinocytes in vitro. Tumor necrosis factor α (TNFα) was administered to human keratinocytes, after which the levels of other key pro-inflammatory cytokines and NGF were measured. The production of these cytokines and NGF increased in cells treated with TNFα compared to untreated cells. Furthermore, exposure to TNFα increased gene expression of the α1-AR subtype B in keratinocytes. Our results suggest that inflammatory cytokines released during injury stimulate α1-AR expression in keratinocytes. The up-regulation of α1-AR may amplify the adrenergic sensitivity of these cells to catecholamines released during sympathetic nervous system activation after injury which, in turn, could heighten the inflammatory response.

An Intense, But Ecologically Valid, Resistance Exercise Session Does Not Alter Growth Factors Associated With Cognitive Health.

The purpose of this investigation was to assess the acute changes in growth factors associated with cognitive health following two ecologically valid, intense resistance exercise sessions. Twenty-nine late-middle-aged adults performed one session of either (a) moderate-load resistance exercise or (b) high-load resistance exercise. Venous blood was collected prior to warm-up, immediately following exercise and 30 min following exercise. Serum was analyzed for brain-derived neurotrophic factor, insulin-like growth factor 1, and vascular endothelial growth factor. Session intensity was determined by blood lactate concentration and session rating of perceived exertion. Postexercise blood lactate was greater following moderate-load when compared with high-load resistance exercise. Subjective session intensity was rated higher by the session rating of perceived exertion following moderate-load when compared with high-load resistance exercise. No differences were observed in serum growth factor levels between groups. Ecologically valid and intense moderate-load or high-load exercise methods do not alter serum growth factor levels in late-middle-aged adults.

Twelve weeks of resistance training does not influence peripheral levels of neurotrophic growth factors or homocysteine in healthy adults: a randomized-controlled trial.

INTRODUCTION: There is growing evidence for a preventative effect of resistance training on cognitive decline through physiological mechanisms; yet, the effect of resistance training on resting growth factors and homocysteine levels is incompletely understood. This study aimed to investigate the effect of intense resistance training, for 12 weeks, on changes in peripheral growth factors and homocysteine in late middle-aged adults. METHODS: 45 healthy adults were enrolled into the single-site parallel groups' randomized-controlled trial conducted at the Department of Exercise Science, Strength and Conditioning Laboratory, Murdoch University. Participants were allocated to the following conditions: (1) high-load resistance training (n = 14), or (2) moderate-load resistance training (n = 15) twice per week for 12 weeks; or (3) non-exercising control group (n = 16). Data were collected from September 2016 to December 2017. Fasted blood samples were collected at baseline and within 7 days of trial completion for the analysis of resting serum brain-derived neurotrophic factor (BDNF), insulin-like growth factor 1, vascular endothelial growth factor, and plasma homocysteine levels. RESULTS: No differences in baseline to post-intervention change in serum growth factors or plasma homocysteine levels were observed between groups. A medium effect was calculated for BDNF change within the high-load condition alone (+ 12.9%, g = 0.54). CONCLUSIONS: High-load or moderate-load resistance training twice per week for 12 weeks has no effect on peripheral growth factors or homocysteine in healthy late middle-aged adults. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry: ACTRN12616000690459.

Validation and Characterization of a Novel Peptide That Binds Monomeric and Aggregated ß-Amyloid and Inhibits the Formation of Neurotoxic Oligomers.

Although the formation of ß-amyloid (Aß) deposits in the brain is a hallmark of Alzheimer disease (AD), the soluble oligomers rather than the mature amyloid fibrils most likely contribute to Aß toxicity and neurodegeneration. Thus, the discovery of agents targeting soluble Aß oligomers is highly desirable for early diagnosis prior to the manifestation of a clinical AD phenotype and also more effective therapies. We have previously reported that a novel 15-amino acid peptide (15-mer), isolated via phage display screening, targeted Aß and attenuated its neurotoxicity (Taddei, K., Laws, S. M., Verdile, G., Munns, S., D'Costa, K., Harvey, A. R., Martins, I. J., Hill, F., Levy, E., Shaw, J. E., and Martins, R. N. (2010) Neurobiol. Aging 31, 203-214). The aim of the current study was to generate and biochemically characterize analogues of this peptide with improved stability and therapeutic potential. We demonstrated that a stable analogue of the 15-amino acid peptide (15M S.A.) retained the activity and potency of the parent peptide and demonstrated improved proteolytic resistance in vitro (stable to t = 300 min, c.f. t = 30 min for the parent peptide). This candidate reduced the formation of soluble Aß42 oligomers, with the concurrent generation of non-toxic, insoluble aggregates measuring up to 25-30 nm diameter as determined by atomic force microscopy. The 15M S.A. candidate directly interacted with oligomeric Aß42, as shown by coimmunoprecipitation and surface plasmon resonance/Biacore analysis, with an affinity in the low micromolar range. Furthermore, this peptide bound fibrillar Aß42 and also stained plaques ex vivo in brain tissue from AD model mice. Given its multifaceted ability to target monomeric and aggregated Aß42 species, this candidate holds promise for novel preclinical AD imaging and therapeutic strategies.

Stimulation of alpha-1 adrenoceptors may intensify cutaneous inflammation in complex regional pain syndrome.

ABSTRACT: Alpha-1 adrenoceptors are overexpressed in the epidermis of a subgroup of patients with complex regional pain syndrome (CRPS). Activating α 1 -adrenoceptors in epidermal cells increases production of the proinflammatory cytokine interleukin-6 (IL-6), a mediator of inflammation. To investigate whether this might exacerbate inflammation in CRPS, primary keratinocytes or dermal fibroblasts were cultured from skin biopsies obtained from the affected limb of 25 patients and a similar site in 28 controls. The fundamental proinflammatory cytokine, tumor necrosis factor alpha, was administered for 24 hours to initiate inflammation. After this, cells were incubated for 6 hours with the α 1 -adrenoceptor agonist phenylephrine. Exposure to tumor necrosis factor alpha induced proinflammatory cytokine mRNA production and protein secretion in keratinocytes and fibroblasts and enhanced α 1B -adrenoceptor mRNA expression in keratinocytes. Additional stimulation of α 1 adrenoceptors with phenylephrine increased the production of IL-6 mRNA and protein secretion in both cell types. Under all conditions, gene and protein α 1 -adrenoceptor levels and cytokine gene expression and protein secretion were similar, overall, in patients and controls, except for abnormally high α 1 -adrenoceptor protein levels in the keratinocytes of 3 of 17 patients. These findings suggest that persistent inflammation in CRPS is not due to dysfunction of skin cells but is a normal response to extrinsic signals. After α 1 -adrenoceptor stimulation of keratinocytes, increases in IL-6 mRNA but not protein were proportional to basal α 1 -adrenoceptor protein levels. Skin cells play an important role in persistent inflammation in CRPS. Potentially, a positive feedback loop between α 1 -adrenoceptors and IL-6 production in skin cells contributes to this inflammatory state.

Direct exposure of guinea pig CNS to human luteinizing hormone increases cerebrospinal fluid and cerebral beta amyloid levels.

BACKGROUND/AIMS: Luteinizing hormone (LH) has been shown to alter the metabolism of beta amyloid (Aß), a key protein in Alzheimer's disease (AD) pathogenesis. While LH and components required for LH receptor signalling are present in the brain, their role in the CNS remains unclear. In vitro, LH has been shown to facilitate neurosteroid production and alter Aß metabolism. However, whether LH can directly modulate cerebral Aß levels in vivo has not previously been studied. In this study, we investigated the effect of chronic administration of LH to the guinea pig CNS on cerebral Aß levels. METHODS: Gonadectomised male animals were administered, via cortical placement, either placebo or LH slow-release pellets. At 14 and 28 days after treatment, animals were sacrificed. Brain, plasma and CSF were collected and Aß levels measured via ELISA. Levels of the Aß precursor protein (APP) and the neurosteroidogenic enzyme cytochrome P450 side-chain cleavage enzyme (P450scc) were also assayed. RESULTS: An increase in CSF Aß40 levels was observed 28 days following treatment. These CSF data also reflected changes in Aß40 levels observed in brain homogenates. No change was observed in plasma Aß40 levels but APP and its C-terminal fragments (APP-CTF) were significantly increased in response to LH exposure. Protein expression of P450scc was increased after 28 days of LH exposure, suggesting activation of the LH receptor. CONCLUSION: These data indicate that direct exposure of guinea pig CNS to LH results in altered brain Aß levels, perhaps due to altered APP expression/metabolism.

2018 update of the APLAR recommendations for treatment of rheumatoid arthritis.

AIM: To update recommendations based on current best evidence concerning the treatment of rheumatoid arthritis (RA), focusing particularly on the role of targeted therapies, to inform clinicians on new developments that will impact their current practice. MATERIALS AND METHODS: A search of relevant literature from 2014 to 2016 concerning targeted therapies in RA was conducted. The RA Update Working Group evaluated the evidence and proposed updated recommendations using the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach, to describe the quality of evidence and strength of recommendations. Recommendations were finalized through consensus using the Delphi technique. RESULTS: This update provides 16 RA treatment recommendations based on current best evidence and expert clinical opinion. Recommendations 1-3 deal with the use of conventional synthetic disease-modifying antirheumatic drugs. The next three recommendations (4-6) cover the need for screening and management of infections and comorbid conditions prior to starting targeted therapy, while the following seven recommendations focus on use of these agents. We address choice of targeted therapy, switch, tapering and discontinuation. The last three recommendations elaborate on targeted therapy for RA in special situations such as pregnancy, cancer, and major surgery. CONCLUSION: Rheumatoid arthritis remains a significant health problem in the Asia-Pacific region. Patients with RA can benefit from the availability of effective targeted therapies, and these updated recommendations provide clinicians with guidance on their use.

Distinct effects of testosterone on plasma and cerebrospinal fluid amyloid-beta levels.

The effect of testosterone on the levels of the Alzheimer's disease amyloid-beta peptide (Abeta) was investigated in guinea pigs. Castrated guinea pigs (GPX) were administered testosterone at two different dosages, following which plasma and cerebrospinal fluid (CSF) Abeta_{40} levels were measured. Plasma Abeta_{40} levels were reduced in GPX in the early stages of low-dose testosterone treatment, whereas CSF Abeta_{40} levels were only reduced by the time circulating testosterone had returned to untreated GPX levels. The supraphysiological testosterone dose did not reduce CSF Abeta_{40} levels significantly until circulating testosterone was back to uncastrated levels, whereas plasma Abeta_{40} levels significantly increased over time in these animals. These results indicate that the extent of testosterone-induced changes to Abeta_{40} levels and their response rates depend on both the tissue examined and testosterone dosage.

Efficient production of a mature and functional gamma secretase protease.

Baculoviral protein expression in insect cells has been previously used to generate large quantities of a protein of interest for subsequent use in biochemical and structural analyses. The MultiBac baculovirus protein expression system has enabled, the use of a single baculovirus to reconstitute a protein complex of interest, resulting in a larger protein yield. Using this system, we aimed to reconstruct the gamma (γ)-secretase complex, a multiprotein enzyme complex essential for the production of amyloid-ß (Aß) protein. A MultiBac vector containing all components of the γ-secretase complex was generated and expression was observed for all components. The complex was active in processing APP and Notch derived γ-secretase substrates and proteolysis could be inhibited with γ-secretase inhibitors, confirming specificity of the recombinant γ-secretase enzyme. Finally, affinity purification was used to purify an active recombinant γ-secretase complex. In this study we demonstrated that the MultiBac protein expression system can be used to generate an active γ-secretase complex and provides a new tool to study γ-secretase enzyme and its variants.

Cerebral thrombosis in systemic lupus erythematosus with the antibody antiphospholipid syndrome.

Systemic lupus erythematosus (SLE) has numerous manifestations. Haematology is the common system influenced by the disease. The antibody antiphospholipid syndrome, secondary hematology disorder in SLE, is related to high incidence of thrombosis. The thrombosis events like myocardial infarction and stroke are high in mortality. We reported a-36-year old woman treated for lung tuberculosis (TB) with secondary infection, nephritis lupus, and pancytopenia. The general condition has improved and the patient was planned to discharge while she suddenly fell down, unconscious and had seizure. The CT-scan showed an area of hypodensity on the left thalamus. Haematology results showed high level of fibrinogen and D-dimer as the signs of thrombosis. The anticardiolipin antibody was intermediately positive for IgG and IgM, but lupus anticoagulan was weakly positive. The serial test within 2 months still showed positive IgG. The patient received supportive treatment, heparinization, neurotropic drugs and anticonvulsant. She was discharged in good condition while continuing oral anticoagulant to prevent recurrent seizure.

Is there a relationship between serum C-reactive protein level and dyslipidaemia in systemic lupus erythematosus?

AIM: to look for the association between CRP and dyslipidaemia in SLE. METHODS: seventy six patients fulfilled the American College of Rheumatology criteria for classification of Systemic Lupus Erythematosus (SLE) (revised in 1997) were enrolled in our study. Clinical and laboratory measures included complete history and physical examination, determination of serum CRP level by latex agglutination test and lipid profile. Statistical significance of association was analysed by X2 test. T-test were used to compare values of each lipid component between positive and negative CRP group. All analyses were performed using the SPSS 10.0 computer software. RESULTS: the study was done in 76 (73 female and 3 male) SLE patients. Dyslipidaemia was found in 57 patients (75.0%). Hypercholesterolemia was found in 31 patients (40.8%), hypertriglyceridemia in 33 patients (43.4%), low HDL cholesterol in 19 patients (25%) and high LDL cholesterol in 28 patients (36.8%). Patients with positive CRP (66 patients) demonstrated dyslipidaemia in 49 patients (74.2%) and patients with negative CRP (10 patients) showed dyslipidaemia in 8 patients (80.0%)(P 1.0). There was no association between CRP and abnormal values of each lipid component (cholesterol, triglyceride, HDL and LDL cholesterol)(P value 0.30, 0.74, 0.43, 0.15 respectively). There was also no association between CRP and dyslipidaemia as a whole (P 1.00). The difference between serum level of each lipid component between positive and negative CRP group was also non significant (P value 0.68, 0.90, 0.96, 0.59 respectively). CONCLUSION: there was no association between CRP and dyslipidaemia in SLE patients. In the development of dyslipidaemia in SLE, factors other than inflammation should be put into consideration.

Drug provocation test in patient with antituberculosis drug allergy.

Hypersensitivity reaction is an unexpected drug adverse effect which sometimes can lead to fatal condition. Confirmation of the suspected drugs that cause hypersensitivity reaction is sometimes difficult. Drug provocation test is still a gold standard to establish the diagnosis of hypersensitivity to certain drugs or agents. Drug provocation test is a controlled drug treatment which aims at making diagnosis of hypersensitivity reaction to drugs. We reported a demonstration case of a 47 year-old female patient with hypersensitivity to anti tuberculosis drugs (isoniazid, rifampicin, pyrazinamid and ethambutol). Drug provocation test is important in this case to confirm which drug had caused hypersensitivity reaction because anti tuberculosis drugs were the treatment of choice for her illness.

The proportion of dyslipidemia in systemic lupus erythematosus patient and distribution of correlated factors.

AIM: To understand the proportion of dyslipidemia in systemic lupus erythematosus (SLE) patients and the influencing factors of dyslipidemia. METHODS: AN observational, cross-sectional study was conducted on new and longstanding SLE patients who had been diagnosed based on ARA criteria 1982 with 1997 revision. They had been hospitalized and treated at Department of Internal Medicine, Cipto Mangunkusumo National Central General Hospital and the other private Hospitals in Jakarta, i.e. Kramat Hospital in July - November 2003. The sample was selected by non probability sampling method with consecutive sampling technique. Every participant underwent history taking, physical and laboratory examination. RESULTS: There were 77 patients satisfying the inclusion criteria. The proportion of dyslipidemia in this study was 75.3%. By confidence interval of 95%, the dyslipidemia in SLE patient was 65.3% - 84.6%. The distribution of lipid profile in sample population were 43% with total cholesterol > or = 200 mg/dL, 26% with HDL cholesterol level < 40 mg/dL, 26.4% with LDL cholesterol level > or = 130 mg/dl and 44.2% with triglycerides serum level > or = 150 mg/dL. The characteristics of influencing factors in dyslipidemia prevalence for sample population consisted of 24.7% with renal involvement, 53.2% with > or = 3 years illness periods, 26% had received > or = 30 mg/day prednisone, 94.8% had not received chloroquines, and 58.4% had illness activity of Mex-SLEDAI > or = 2. By bivariate analysis, we found that illness period < 3 years tends to affect dyslipidemia with OR value of 12.04 (CI 95%, 2.54-57.05, p = 0.001). After conducting multivariate analysis by backward methods, it appears that only one significant influencing factor of dyslipidemia prevalence in SLE patient i.e. Illness period od < 3 years with OR value 12.04 (CI 95% 2.54 - 57.05, p = 0.001). CONCLUSION: Illness period of 3 years is represent a significant correlative factor for dyslipedemia prevalence. Prednisone > or = 30 mg/dL is the correlative factor for total cholesterol > or = 200 mg.dL and triglycerides > or = 150 mg/dL. Mex-SLEDAI > or = 2 is the corrective factor for HDL cholesterol < 40 mg/dL.

Testosterone replacement therapy in older male subjective memory complainers: double-blind randomized crossover placebo-controlled clinical trial of physiological assessment and safety.

Testosterone replacement therapy (TRT) has been investigated in older men as a preventative treatment against Alzheimer's disease and dementia. However, previous studies have been contradictory. We assessed TRT physiological effects in 44 older men (aged 61 ± 7.7 years) with subjective memory complaints using a double blind, randomized, crossover, placebo-controlled study. Participants were randomized into 2 groups, one group received transdermal testosterone (50 mg) daily for 24 weeks, followed by a 4 week wash-out period, then 24 weeks of placebo; the other group received the reverse treatment. Blood evaluation revealed significant increases in total testosterone, free (calculated) testosterone, dihydrotestosterone, and a decrease in luteinizing hormone levels (p<0.001) following TRT. Although there were significant increases in red blood cell counts, hemoglobin and prostate specific antigen levels following TRT, they remained within normal ranges. No significant differences in plasma amyloid beta, estradiol, sex hormone binding globulin, insulin levels, body fat percentage, or body mass index were detected. This is the first carefully controlled study that has investigated the influence of TRT in Indonesian men on blood biomarkers linked to dementia risk. Our study suggests TRT is safe and well-tolerated in this Indonesian cohort, yet longitudinal studies with larger cohorts are needed to assess TRT further, and to establish whether TRT reduces dementia risk.

APLAR rheumatoid arthritis treatment recommendations.

AIMS: Rheumatoid arthritis is a chronic inflammatory condition that affects approximately 1% of the world's population. There are a wide number of guidelines and recommendations available to support the treatment of rheumatoid arthritis; however, the evidence used for these guidelines is predominantly based on studies in Caucasian subjects and may not be relevant for rheumatoid arthritis patients in the Asia-Pacific region. Therefore, the Asia Pacific League of Associations for Rheumatology established a Steering Committee in 2013 to address this issue. MATERIALS AND METHODS: The AGREE II instrument and the ADAPTE Collaboration framework were applied to systematically identify, appraise, synthesize, and adapt international rheumatoid arthritis guidelines for use in the Asia-Pacific region. RESULTS: Forty rheumatoid arthritis treatment recommendations, based on evidence and expert opinion, were drafted and are presented in this report. CONCLUSION: The Asia Pacific of Associations for Rheumatology rheumatoid arthritis treatment recommendations are intended to serve as a reference for best practice management of rheumatoid arthritis in Asia-Pacific, focusing on local issues to ensure the delivery of basic care for these patients, and to improve their outcomes. In addition, the document will serve as a reference for national rheumatology associations in Asia-Pacific for developing guidelines in their respective countries.

Pathology associated with AAV mediated expression of beta amyloid or C100 in adult mouse hippocampus and cerebellum.

Accumulation of beta amyloid (Aß) in the brain is a primary feature of Alzheimer's disease (AD) but the exact molecular mechanisms by which Aß exerts its toxic actions are not yet entirely clear. We documented pathological changes 3 and 6 months after localised injection of recombinant, bi-cistronic adeno-associated viral vectors (rAAV2) expressing human Aß40-GFP, Aß42-GFP, C100-GFP or C100(V717F)-GFP into the hippocampus and cerebellum of 8 week old male mice. Injection of all rAAV2 vectors resulted in wide-spread transduction within the hippocampus and cerebellum, as shown by expression of transgene mRNA and GFP protein. Despite the lack of accumulation of Aß protein after injection with AAV vectors, injection of rAAV2-Aß42-GFP and rAAV2- C100(V717F)-GFP into the hippocampus resulted in significantly increased microgliosis and altered permeability of the blood brain barrier, the latter revealed by high levels of immunoglobulin G (IgG) around the injection site and the presence of IgG positive cells. In comparison, injection of rAAV2-Aß40-GFP and rAAV2-C100-GFP into the hippocampus resulted in substantially less neuropathology. Injection of rAAV2 vectors into the cerebellum resulted in similar types of pathological changes, but to a lesser degree. The use of viral vectors to express different types of Aß and C100 is a powerful technique with which to examine the direct in vivo consequences of Aß expression in different regions of the mature nervous system and will allow experimentation and analysis of pathological AD-like changes in a broader range of species other than mouse.

The Guinea Pig as a Model for Sporadic Alzheimer's Disease (AD): The Impact of Cholesterol Intake on Expression of AD-Related Genes.

We investigated the guinea pig, Cavia porcellus, as a model for Alzheimer's disease (AD), both in terms of the conservation of genes involved in AD and the regulatory responses of these to a known AD risk factor - high cholesterol intake. Unlike rats and mice, guinea pigs possess an Aß peptide sequence identical to human Aß. Consistent with the commonality between cardiovascular and AD risk factors in humans, we saw that a high cholesterol diet leads to up-regulation of BACE1 (ß-secretase) transcription and down-regulation of ADAM10 (α-secretase) transcription which should increase release of Aß from APP. Significantly, guinea pigs possess isoforms of AD-related genes found in humans but not present in mice or rats. For example, we discovered that the truncated PS2V isoform of human PSEN2, that is found at raised levels in AD brains and that increases γ-secretase activity and Aß synthesis, is not uniquely human or aberrant as previously believed. We show that PS2V formation is up-regulated by hypoxia and a high-cholesterol diet while, consistent with observations in humans, Aß concentrations are raised in some brain regions but not others. Also like humans, but unlike mice, the guinea pig gene encoding tau, MAPT, encodes isoforms with both three and four microtubule binding domains, and cholesterol alters the ratio of these isoforms. We conclude that AD-related genes are highly conserved and more similar to human than the rat or mouse. Guinea pigs represent a superior rodent model for analysis of the impact of dietary factors such as cholesterol on the regulation of AD-related genes.