An aerosol challenge model of tuberculosis in Mauritian cynomolgus macaques

Background

New interventions for tuberculosis are urgently needed. Non-human primate (NHP) models provide the most relevant pre-clinical models of human disease and play a critical role in vaccine development. Models utilising Asian cynomolgus macaque populations are well established but the restricted genetic diversity of the Mauritian cynomolgus macaques may be of added value.

Methods

Mauritian cynomolgus macaques were exposed to a range of doses of M. tuberculosis delivered by aerosol, and the outcome was assessed using clinical, imaging and pathology-based measures.

Results

All macaques developed characteristic clinical signs and disease features of tuberculosis (TB). Disease burden and the ability to control disease were dependent on exposure dose. Mauritian cynomolgus macaques showed less variation in pulmonary disease burden and total gross pathology scores within exposure dose groups than either Indian rhesus macaques or Chinese cynomolgus macaques

Conclusions

The genetic homogeneity of Mauritian cynomolgus macaques makes them a potentially useful model of human tuberculosis.

Comparative effectiveness of alternative clinical pathways for primary hip and knee joint replacement patients: a pragmatic randomized, controlled trial

OBJECTIVE

Total hip replacement (THR) and total knee replacement (TKR) (arthroplasty) surgery for end-stage osteoarthritis (OA) are ideal candidates for optimization through an algorithmic care pathway. Using a comparative effectiveness study design, we compared the effectiveness of a new clinical pathway (NCP) featuring central intake clinics, dedicated inpatient resources, care guidelines and efficiency benchmarks vs. the standard of care (SOC) for THR or TKR.

METHODS

We compared patients undergoing primary THR and TKR who received surgery in NCP vs. SOC in a randomised controlled trial within the trial timeframe. 1,570 patients (1,066 SOC and 504 NCP patients) that underwent surgery within the study timeframe from urban and rural practice settings were included. The primary endpoint was improvement in Western Ontario and McMaster University osteoarthritis index (WOMAC) overall score over 12 months post-surgery. Secondary endpoints were improvements in the physical function (PF) and bodily pain (BP) domains of the Short Form 36 (SF-36).

RESULTS

NCP patients had significantly greater improvements from baseline WOMAC scores compared to SOC patients after adjusting for covariates (treatment effect=2.56; 95% confidence interval (CI) [1.10-4.01]). SF-36 BP scores were significantly improved for both hip and knee patients in the NCP (treatment effect=3.01, 95% CI [0.70-5.32]), but SF-36 PF scores were not. Effects of the NCP were more pronounced in knee patients.

CONCLUSION

While effect sizes were small compared with major effects of the surgery itself, an evidence-informed clinical pathway can improve health related quality of life (HRQoL) of hip and knee arthroplasty patients with degenerative joint disorder in routine clinical practice for up to 12 months post-operatively. CLINICALTRIALS.GOV IDENTIFIER: NCT00277186.

Establishment of an aerosol challenge model of tuberculosis in rhesus macaques and an evaluation of endpoints for vaccine testing

The establishment of an aerosol challenge model in nonhuman primates (NHPs) for the testing of vaccines against Mycobacterium tuberculosis would assist the global effort to optimize novel vaccination strategies. The endpoints used in preclinical challenge studies to identify measures of disease burden need to be accurate and sensitive enough to distinguish subtle differences and benefits afforded by different tuberculosis (TB) vaccine regimens when group sizes are inevitably small. This study sought to assess clinical and nonclinical endpoints as potentially sensitive measures of disease burden in a challenge study with rhesus macaques by using a new protocol of aerosol administration of M. tuberculosis. Immunological and clinical readouts were assessed for utility in vaccine evaluation studies. This is the first example of TB vaccine evaluation with rhesus macaques where long-term survival was one of the primary endpoints. However, we found that in NHP vaccine efficacy studies with maximum group sizes of six animals, survival did not provide a valuable endpoint. Two approaches used in human clinical trials for the evaluation of the gamma interferon (IFN-gamma) response to vaccination (enzyme-linked immunospot [ELISpot] assay and enzyme-linked immunosorbent assay [ELISA]) were included in this study. The IFN-gamma profiles induced following vaccination were found not to correlate with protection, nor did the level of purified protein derivative (PPD)-specific proliferation. The only readout to reliably distinguish vaccinated and unvaccinated NHPs was the determination of lung lesion burden using magnetic resonance (MR) imaging combined with stereology at the end of the study. Therefore, the currently proposed key markers were not shown to correlate with protection, and only imaging offered a potentially reliable correlate.

Determination of lesion volume by MRI and stereology in a macaque model of tuberculosis

Sensitive and reproducible methods are needed to measure the impact on the host following experimental challenge with Mycobacterium tuberculosis, in order to determine the degree of protection conferred by new vaccines. Here we compare how well different clinical and post-mortem measures of disease burden predict the response by the host to increasing doses of M. tuberculosis in rhesus and cynomolgus macaques. The total lung and lesion volume was quantified from magnetic resonance imaging (MRI) digital stacks obtained from lungs of M. tuberculosis infected animals that were formalin fixed and scanned ex-vivo. The total lung lesion volume relative to the fixed whole lung volume was superior at indicating disease burden when compared to thoracic radiography, pathology scores, changes in body weight and temperature, as well as erythrocyte haemoglobin concentrations and sedimentation rate. The total lesion volume accurately reflected differences in challenge doses of M. tuberculosis that ranged from 30 to 500 CFU delivered by aerosol. The determination of total lesion volume from MR images demonstrated a species-dependent difference between rhesus and cynomolgus macaques in susceptibility to M. tuberculosis infection. MR stereology provides an accurate, quantifiable and relatively simple assessment, which can be easily standardized between laboratories and should form an essential component of the clinical assessment of disease progression, or vaccine efficacy.