Background and Aims High intensity interval training (HIIT) has been shown to improve traditional and non-traditional cardiovascular risk factors in the general population and in chronic diseases. However, intense exercise has the potential to suppress immune function and promote systemic inflammation. Renal transplant recipients (RTRs) are immunologically vulnerable and therefore thorough understanding of the effects of different exercise regimes is required to inform exercise advice and guidelines. The aim of this study was to explore the immune and inflammatory effects of HIIT in comparison to moderate intensity continuous training (MICT) in RTRs. Method Renal transplant recipients (n = 24, age (years) = 48 ± 13, BMI = 27.2 ± 5.6 kg.m2, eGFR (mL·min· 1.73 m2) = 58 ± 19) were randomised into one of three thrice-weekly 8 week exercise programmes: HIIT A (16 min interval training with 4, 2 and 1 min intervals at 80%–90% of peak oxygen uptake (V̇O2 peak), HIIT B (4 × 4 min interval training at 80%–90% V̇O2peak) or MICT (∼40 min cycling at 50%–60% V̇O2peak). Peripheral blood mononuclear cells were isolated at baseline, mid-training, post-training and three months post-training and stained for lymphocyte and monocyte phenotypic and activation markers. Plasma cytokines (IL-6, IL-10 and TNF-α) were measured by affinity ELISA kits. Results Friedman’s ANOVA was used to assess within-group differences and a Kruskal-Wallis H test was used to assess between-group differences; any significant findings were followed up using a post-hoc test. There were no differences in circulating lymphocyte or monocyte lineage markers within or between groups over time (P > 0.05). Cytokines did not change in relation to exercise within or between groups over time (P > 0.05). Conclusion This is the first study to investigate the effects of HIIT on immune parameters and inflammation markers longitudinally in RTRs or other immunosuppressed populations. Our data do not indicate any evidence for adverse effects of HIIT on circulating lymphocytes, monocytes or cytokines and suggest that such exercise regimes may be immunologically safe for immunosuppressed patients. We recommend further investigations involving larger sample size to confirm our results.

Introduction: Orthotopic tumour mouse models are often preferred to subcutaneous models due to their increased clinical relevance and pathophysiological features, as the tumour microenvironment can influence stromal interaction, immune response, angiogenesis, tumour growth and progression as well as response to treatment. Orthotopic implantation of liver cancer cell lines can be time consuming and inefficient due to the surgical procedures involved to establish the tumour. This study assesses the benefits of replacing traditional invasive surgical orthotopic implantation of two hepatic tumour cell lines with a minimally invasive ultrasound guided approach. Tumour growth of both implantation methods were assessed using ultrasound and bioluminescence, as well as duration of surgery and animal recovery time. In addition, the immune landscape of both implantation methods was assessed using flow cytometry. Methods: Hep3B and Hepa 1-6 cells were transfected with luciferase for bioluminescence imaging. Hep3B-luc or Hepa 1-6-luc cells were orthotopically injected into the left liver lobe of C57BL/6 mice via either conventional surgery or ultrasound guided injection. Tumour growth was measured using both Ultrasound (Fujifilm Vevo 3100 imaging system, Visualsonics) and bioluminescence (IVIS® Spectrum in vivo imaging system, Perkin Elmer). Surgery times were recorded as the duration each animal was under anaesthesia. Recovery times were reported as the time animals were held in recovery before returning to their cage. An in house validated flow cytometry T cell panel was used to assess T cell infiltration in the Hepa1-6 syngeneic model. Results: A comparison of tumour volume versus tumour associated bioluminescence demonstrated good correlation between both methods for each cell line. The duration of surgery and post implantation recovery times were significantly reduced for mice that underwent ultrasound-guided implantation compared to surgery, as well as fewer post-operative clinical observations. No significant difference in body weight was observed throughout the study. T cell infiltration by flow cytometry assessment enabled further evaluation of potential differences in the immune landscape of Hepa 1-6 tumours. Conclusion: Ultrasound guided implantation of orthotopic hepatic tumours is a minimally invasive technique that leads to improved recovery times for animals, which adheres to the principles of the 3R’s. The time taken for ultrasound guided implantation compared to traditional surgical methods was also significantly reduced, enabling a higher throughput of animals on study. Tumour growth kinetics in both Hep3B and Hepa 1-6 models were comparable between the 2 methods. Citation Format: Chris Payne, Yasmin Amer, Ruth Storer, Ganisha Hutchinson, Lucy Harris, Amanda Miles, Yinfei Yin. Comparison between surgical and ultrasound-guided orthotopic implantation of hepatocellular carcinoma models in mice using ultrasound and bioluminescence imaging [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1660.

Background and Aims Cardiovascular disease (CVD) is a major cause of morbidity and mortality in renal transplant recipients (RTRs). General CVD risk scores underestimate the risk in RTRs who also exhibit elevated inflammation and impaired immune function. Exercise has a positive impact on these unique factors and there is growing consensus on the need for formal and specific exercise guidelines in RTRs. Despite this, there is limited rigorous research in this population, particularly surrounding novel high intensity interval training (HIIT) versus moderate intensity continuous training (MICT). Method 24 RTRs (male 17; eGFR 55 ml/min/1.73 m2 [26-90]; age 48 years [27-76]) were randomised to: HIITA (n=8; 4, 2 and 1 min intervals; 80-90% of watts at peak oxygen uptake (V̇O2 peak)), HIITB (n=8, 4 × 4 min intervals; 80-90% V̇O2 peak) or MICT (n=8, ∼35.5 min; 50-60% V̇O2 peak) for 24 supervised sessions on a stationary bike (approx. 3x/week over 8 weeks). Assessments of cardiorespiratory fitness, body composition (weight and body fat %), and physical function (sit-to-stand 60 (STS60), gait speed, and calf strength) were conducted pre and post-intervention. Data were analysed using ANCOVA and paired samples t-tests. Results Twenty participants completed the intervention, 8 of whom reached the required intensity (HIITA 0/6 [0%], HIITB 3/8 [38%], MICT 5/6 [83%]). Although participants completed 92% (average) of the 24 sessions, there were 105 cancelled/rearranged sessions (illness 68, other commitments 33, investigator illness 4) and an average duration of 10 weeks to complete the intervention. There were significant post-training improvements in V̇O2 peak (ml/kg/min)(See Table 1: HIITA, p=0.007; HIITB, p=0.025; MICT, p=0.012) and in peak power output (wattpeak)(HIITA, p=0.001; HIITB, p=0.005; MICT, p=0.002) for all groups. There was a significant post-training reduction in systolic and diastolic blood pressure (SBP and DBP, respectively) in MICT (p<0.001) and a significant reduction in DBP in HIITB (p<0.001). There were no significant changes in body composition. Gait speed improved in MICT (p=0043) and STS60 performance improved in HIITA (p=0.012). After controlling for baseline values, there were no significant between group differences for any post-training variables. Conclusion Enhanced cardiorespiratory fitness has been widely reported to correlate with a reduced risk of CVD and mortality. These early feasibility results, whilst acknowledging some baseline variations, show promising effects of both HIIT and MICT on the cardiorespiratory fitness of RTRs. Results also show promising reductions in blood pressure, a leading risk factor for CVD. Although fewer RTRs met the required intensity for the HIIT protocols than MICT, there were no serious adverse events or detrimental results reported. There were a large number of sessions cancelled due to illness; potentially attributable to immunosuppressive agents. We would recommend further large-scale trials of different HIIT protocols potentially with shorter intervals and less intense recovery periods in order to facilitate the achievement of the required intensity. Overall, these results further support the call for specific exercise guidance in this population in order to supplement current post-transplantation clinical advice.

Background Kidney transplant recipients (KTRs) exhibit unique elevated inflammation, impaired immune function, and increased cardiovascular risk. Although exercise reduces cardiovascular risk, there is limited research on this population, particularly surrounding novel high-intensity interval training (HIIT). The purpose of this pilot study was to determine the feasibility and acceptability of HIIT in KTRs. Methods Twenty KTRs (male 14; eGFR 58±19 mL/min/1.73 m2; age 49±11 years) were randomised and completed one of three trials: HIIT A (4-, 2-, and 1-min intervals; 80–90% watts at V̇O2peak), HIITB (4×4 min intervals; 80–90% V̇O2peak) or MICT (~40 min; 50–60% V̇O2peak) for 24 supervised sessions on a stationary bike (approx. 3x/week over 8 weeks) and followed up for 3 months. Feasibility was assessed by recruitment, retention, and intervention acceptability and adherence. Results Twenty participants completed the intervention, and 8 of whom achieved the required intensity based on power output (HIIT A, 0/6 [0%]; HIITB, 3/8 [38%]; MICT, 5/6 [83%]). Participants completed 92% of the 24 sessions with 105 cancelled and rescheduled sessions and an average of 10 weeks to complete the intervention. Pre-intervention versus post-intervention V̇O2peak (mL/kg-1/min-1) was 24.28±4.91 versus 27.06±4.82 in HIITA, 24.65±7.67 versus 27.48±8.23 in HIIT B, and 29.33±9.04 versus 33.05±9.90 in MICT. No adverse events were reported. Conclusions This is the first study to report the feasibility of HIIT in KTRs. Although participants struggled to achieve the required intensity (power), this study highlights the potential that exercise has to reduce cardiovascular risk in KTRs. HIIT and MICT performed on a cycle, with some modification, could be considered safe and feasible in KTRs. Larger scale trials are required to assess the efficacy of HIIT in KTRs and in particular identify the most appropriate intensities, recovery periods, and session duration. Some flexibility in delivery, such as incorporating home-based sessions, may need to be considered to improve recruitment and retention. Trial registration ISRCTN, ISRCTN17122775. Registered on 30 January 2017.