Molecular Signatures of Endocannabinoid Induced Pain Relief in Humans: Lifestyle Interventions, Systemic and Localised Changes
Phase: NA
Conditions: Osteoarthritis, Knee
Sponsor: University of Nottingham

 
 
 
  
Official Title: Molecular Signatures of Endocannabinoid Induced 
Pain Relief in Humans: Lifestyle Interventions, Systemic and 
Localised Changes 
  
Brief Title:  lIfestyle iNterventionS for PaIn ReliEf (INSPIRE) 
  
FMHS REC reference: 473-0322 
Date and version number: Version 1.3; 23.06.2023 
Date approved by FMHS REC: 19.07.2023 
Document Type: Study Protocol 
Sponsor: University of Nottingham 
Trial Registration:        www.clinicaltrials.gov 
ClinicalTrials.gov Identifier: NCT05670314 
 

 
 
SCIENTIFIC BACKGROUND 
Knee osteoarthritis (OA) is a prevalent source of impairment worldwide and is often addressed in 
primary care settings (Cui, A. et al. 2020 PMID: 34505846). In the UK, approximately one in 
twenty-five individuals seek medical consultation for knee osteoarthritis each year (Yu, D. et al. 
2015 PMID: 26163287). 
Regular exercise is recommended by all major clinical guidelines for managing knee OA pain and 
is typically the first-line treatment offered in primary care (Moseng, T. et al. 2024 PMID: 
38212040). Should an exercise intervention prove ineffective in enhancing pain perception, 
patients are directed for physiotherapy. Following a thorough evaluation by physiotherapists, a 
range of exercise therapies has been recommended, differing in modality, intensity, and duration, 
yet yielding inconsistent outcomes.  
The intervention used in this trial is part of a web-based version of the Supported Osteoarthritis 
Self-Management Programme (SOASP), developed in Sweden. From 2008 to 2017, over 75,000 
patients participated, with 2,339 physiotherapists and occupational therapists trained to deliver it. 
SOASP is currently offered in 700 clinics across Sweden and has been rated good to very good 
by 94% of participants for its effectiveness, safety, and acceptability (Jönsson, T., et al 2019 
PMID: 31536554). Given the high prevalence of knee OA, there is a clear need for therapies that 
are both effective and cost-efficient. However, barriers such as adherence, limited mobility, and 
healthcare costs challenge implementation. Digital delivery of SOASP via Joint Academy has 
proven equally effective and widely accepted in Sweden, and our previous UK-based work has 
also shown strong effectiveness for this approach (Gohir et al 2021 PMID: 33620447).  
Chronic knee OA pain is influenced by systemic inflammation and metabolic factors such as poor 
diet, excess weight, and metabolic syndrome, which contribute to “meta-inflammation” through 
dysregulation of adipokines, cytokines, and lipids (Zhang et al. 2024 PMID: 38243159). A 
systematic review and meta-analysis of 73 studies show significant reductions in self-reported 
pain severity following nutrition interventions (Brain, K. et al. 2019 PMID: 30294938) and 
prebiotics may hold promise for the management of knee OA in adults with obesity (Fortuna, R. 
et al. 2024 PMID: 38713231). In addition, the endocannabinoid (EC) system plays a central role 
in pain regulation and emotional response to chronic pain (Woodhams, S. G., et al. 2015). PMID: 
25846617). Prebiotic fibre supplementation may support gut health, reduce systemic 
inflammation, and improve biomarkers linked to OA and chronic pain, complementing the effects 
of exercise. 
Emerging evidence links gut microbiome composition to OA-related knee pain, with studies 
indicating its role in pain intensity, progression, and sensitivity- including neuropathic pain - largely 
through inflammation modulation (Ding, W. et al. 2021 PMID: 32889847). Short chain fatty acids 
(SCFAs), produced by bacterial fermentation of dietary fibre, mediate many of the microbiome’s 
anti-inflammatory effects. However, the interactions between physiotherapy exercise, prebiotic 

 
inulin supplementation, pain modulation, inflammatory biomarkers, and the gut microbiome 
remain poorly understood. Specifically, the effects of inulin and exercise on pain, microbiome 
composition, inflammatory markers, and circulating SCFA levels in individuals with knee OA have 
yet to be explored.  
Rationale: This trial will adopt a 2x2 factorial design to assess the individual and combined effects 
of exercise and prebiotic inulin supplementation over six weeks. The study will evaluate their 
effect on knee osteoarthritis (OA) pain, as well as molecular and gut microbiome parameters. 
STUDY OBJECTIVES 
PRIMARY OBJECTIVE 
1-To assess the magnitude of the effect of prebiotic supplementation (inulin) side by side with 
physiotherapy exercise versus placebo (maltodextrin) on knee pain 
  
SECONDARY OBJECTIVES 
1-To assess the combined effects of exercise and prebiotic inulin supplementation (synergistic 
effect) over six weeks 
2-To elucidate the molecular pathways involved in pain relief induced by exercise and gut 
microbiome modulation in individuals with painful knee osteoarthritis 
STUDY DESIGN 
The INSPIRE study is a 2x2 factorial randomised controlled trial in the community setting at 
Nottingham with participants identified as having knee arthritis, 1:1:1:1 randomised to web-based 
exercises, inulin, exercise and inulin or placebo and usual care. 
SETTING 

 
 
Home based - Community Setting 
  
The study design came as a result of analysis of 18 long qualitative interviews with participants 
of the iBEAT-OA trial who had completed the physiotherapy intervention. Analysis of these 
interviews showed a significant interest and desire on the part of individuals affected with knee 
OA to use nutritional strategies to improve their pain outcomes. Thus the idea of improving gut 
microbiome health to improve pain relief was incorporated into the digital physiotherapy protocol. 
This project was discussed with two patient collaborators whose input was used for drafting the 
first protocol. The final versions of the participant facing documentation (PIS, consent form, 
invitation letter and flyer) were reviewed by two patient representatives (TM and LW) who have 
revised them and commented on them, all their feedback was incorporated.   
RECRUITMENT 
Participants with knee pain who had consented to be contacted for future research will be invited 
from existing Academic Rheumatology, City Hospital Nottingham's databases (Millar, B. et al. 
2020 PMID: 32199451) to participate in the study. Nottingham Post adverts will be used to make 
up for any recruitment shortfalls. All eligible individuals will be sent the participant information 
sheet and if they are interested they will contact the research centre to be recruited.  
INCLUSION AND EXCLUSION 
CRITERIA 
 Inclusion criteria: 
  
·    Participants with any pain in or around a knee on most days for more than 3 months 
·    Participant is willing and able to give informed consent for participation in the study 
PATIENT AND PUBLIC INVOLVEMENT 

 
·    Participant eligibility includes those aged >18 years who have a body mass index (BMI) 
between 18.5 and 39.9 kg/m2 
  
 Exclusion criteria: 
  
The participant may not enter the study if ANY of the following apply: 
·    Have psychosocial or gastrointestinal (e.g. malabsorptive conditions such as IBS/IBD, 
coeliac) 
·    Are taking the following medications: immunosuppressants, anticoagulants, amiodarone 
and/or perhexiline 
·    Are currently following or anticipated to commence a specialised commercially available 
weight loss diet and/or programme 
·    Pregnant or breastfeeding 
·    History or current psychiatric illness (including clinical depression) 
·    History or current neurological condition (e.g. epilepsy) 
·    Those undergoing revision, having severe hip OA, inflammatory arthropathies 
·    Diagnosed non-OA cause of knee pain (e.g. rheumatoid arthritis) 
·    Neuropathy or diabetes mellitus 
·    Having taken part in a research study in the last 3 months involving invasive procedures 
or an inconvenience allowance 
  
RANDOMISATION AND BLINDING 
 Randomisation will be done using a computer-generated randomisation and allocation 
concealment software called “sealed envelope” (https://www.sealedenvelope.com/). At least 
thirty participants will be divided equally between the treatment arms. Blinding for the exercise 
intervention is not feasible at this stage since participants will be informed if they have been 
randomly assigned to one of the exercise groups. Because this might affect the motivation of 

 
 
participants who were randomly assigned to the non-exercise arms, they will be offered access 
to the web-based exercise programme after completing the trial. Although it is challenging to blind 
exercise intervention studies, both the research examiner and the participants will be blind to the 
intervention and the food supplementation.  
MATERIALS 
 Inulin fibre (20g) in powder form, maltodextrin (10g) in powder form, Joint Academy app, faecal 
sample kit, blood sample collection materials.  
PHYSIOTHERAPY INTERVENTION 
  INSPIRE will use a web-based exercises platform known as Joint Academy (JA) as a previous 
RCT from our group demonstrated promising results for this platform (Gohir et al 2021 PMID: 
33620447). The Swedish face-to-face self-management programme "Artrosskolan" (The 
Osteoarthritis School), which offered structured information and exercises for knee arthritis to a 
relevant population with the condition, served as the model for this programme. The JA company 
has granted permission for this study to be carried out  using their digital platform. 
The exercise intervention has been described in detail previously (Gohir et al 2021 PMID: 
33620447). It is focused on a mixture of concentric and eccentric exercises with open and closed-
chain movements, for strengthening the legs including the muscles around the hips and knee 
joints as well as exercises to improve balance. An open kinetic chain is defined as “a combination 
of successively arranged joints in which the terminal segments can move freely” (Karandikar et al 
2011 PMID: 21871418), while closed chain exercises are those in which the proximal joints move 
while the distal portion of the extremities is in a stationary position (Karandikar et al 2011 PMID: 
21871418). The programme also includes educational sessions covering the fundamentals of OA, 
its treatment, self-managing symptoms of OA and the benefits of maintaining a healthy lifestyle. 
  
DIETARY INTERVENTION 
 Inulin fibre (20g) in powder form (commonly found in root vegetables such as chicory) will be 
randomly allocated to eligible participants in order to test specific effects on gut microbiome 

 
composition and metabolic markers. Inulin is easily dissolvable in liquid and can be incorporated 
into the usual diet - by adding water, juice, smoothies, cereal, yogurt.  
CONTROL PLACEBO GROUP 
 The control group will continue with routine self-management which is offered in the community 
setting and will be instructed to receive maltodextrin (10g) in powder form (commonly found in 
corn, potatoes, rice) which can be consumed by adding to breakfast cereal/ smoothie/ yogurt or 
drink of choice similar to inulin will serve as a control/placebo to compare the effects observed 
with inulin. 
FOLLOW UP DURATION 
  Six weeks post-intervention.  
RESEARCH ASSESSMENT 
 Following outcome measures will be assessed: 
·    Quantitative Sensory Testing – QST (Pressure pain threshold – PPT and Temporal 
summation – TS) 
·    SCFAs, EC, gut microbiome and inflammatory pain-related biomarkers 
·    Physical functioning (Time up and go test, 30-second sit to stand test) 
·    Grip strength 
·    Hospital Anxiety and Depression Scale (HADS) 
DESCRIPTION OF INTERVENTION 

 
 
  The study will be communicated verbally and in writing to participants who have knee pain from 
OA. Participants who meet the study's eligibility requirements will sign an informed consent form 
and be randomly assigned to either the interventional groups or the control/placebo group. 
All groups will have an assessment session with experienced staff with blood samples taken at 
baseline and a Numerical Rating Scale (NRS) (Hjermstad, M. J. et al. 2011 PMID: 21621130), 
physical functioning and other outcomes (grip strength (Roberts, H. C. et al. 2011  PMID: 
21624928), Time up and go test (Barry et al 2014 PMID: 24484314), 30-second sit to stand test 
(Jones, C. J., et al. 1999 PMID: 10380242), Quantitative Sensory Testing (QST) (Arant, K. R. et 
al. 2022 PMID: 34597800)). Participants will be asked to fill in questionnaires on health and 
anxiety/depression (Hospital Anxiety and Depression Scale (HADS) (Zigmond, A. S. & Snaith, R. 
P. 1983 PMID: 6880820) that they will have been sent via post before the study visit. They will 
also be sent a faecal sample kit and will be asked to provide a faecal sample to bring to their 
baseline appointment. 
The exercise interventional groups will be sent an email with a link to access the JA online 
platform. The physiotherapy intervention will begin once log-in and a kick-off call with an assigned 
personal physiotherapist is complete. The intervention will consist of a  6-week online physical 
therapy course that includes exercises, information, contact with a personal physiotherapist, and 
instruction on behavioural and lifestyle modifications, and can be accessed using a smartphone 
or tablet. Through frequent email prompts, the programme also promotes commitment to physical 
activity. Participants will first complete a physical test measuring lower limb strength and respond 
to an online questionnaire that covers topics like physical function, health-related quality of life, 
and the severity of joint discomfort. The online baseline evaluation will include this questionnaire. 
In addition to some functional exercises like sit-to-stand and stair climbing, the exercise 
intervention will include knee and hip exercises.  
 The placebo and inulin groups will receive pre-measured pots containing either the supplement 
or placebo powder for each week, along with scoops. Participants will be instructed to take either 
2 or 3 scoops daily, depending on whether they are in the inulin or placebo group. They will also 
be provided with guidance on incorporating their daily dose into their diet, such as mixing it into 
smoothies or using it as a topping on yoghurts and breakfast cereals. Participants will be asked 
to maintain a daily dietary compliance record to track their supplement intake, including any 
missed doses and the reasons for not taking the supplement. If participants experience adverse 
effects, such as severe bloating or nausea, that prevent them from continuing with the 
supplement, they will be instructed to notify a member of the study team. 
 After the six weeks of interventions, all participants will fill in the same questionnaires and perform 
the physical tests, to enable evaluation. Participants and the researcher will meet in person twice: 
once at enrolment and again six weeks later. 
OUTCOMES 

 
  Primary outcome: 
·    Numerical Rate Score (NRS) for pain to assess changes in response to the interventions. 
Secondary outcomes: 
·    Changes in markers of pain assessed by quantitative sensory testing, and in markers of 
inflammation 
·    Changes in gut microbiome composition and serum levels of short chain fatty acids 
(SCFAs) in response to the interventions. 
·    Changes in functional outcomes (e.g., 30 second sit to stand test, get up and go test)  
  
STATISTICAL ANALYSIS PLAN 
 The clinical trial data will be analysed using the appropriate parametric and non-parametric 
statistical tests, we will compare outcome measures (such as pain sensitivity and pain ratings) 
between the exercise and non-exercise groups while adjusting for baseline scores. 
Secondary analyses (i.e., correlations between changes in SCFAs and changes in pain 
measures) will be conducted using the appropriate type of statistical test based on data normality 
(e.g., Spearman's). 
A planned analysis of covariance (ANCOVA) will be conducted to assess differences in follow-up 
outcome measures among treatment groups while adjusting for baseline levels. The model will 
include treatment group (arm: inulin only, exercise only, inulin &exercise, control/placebo) as a 
categorical independent variable and baseline outcome scores as a covariate. Model 
assumptions will be evaluated through residual diagnostics to ensure the validity of the analysis 
To further explore differences between groups, post hoc pairwise comparisons will be conducted, 
including comparisons between groups and an evaluation of potential interactions to assess 
potential synergy between treatments. 
R studio and Graph Pad PRISM will be used for the statistical analyses.  
SAMPLE SIZE AND JUSTIFICATION 

 
 
 Primary outcome is a Numerical Rate Score (NRS) for pain as used in our previous exercise 
intervention study (Gohir et al 2021 PMID: 33620447). The 2x2 factorial design with 30 individuals 
per block (total n=120) has 80% to detect differences of 0.51 SDs. In our own study delivering the 
exercise intervention the effect size observed was a drop of 0.84 SDs in the exercise arm 
compared with only 0.2 SDs in the control arm (who only received a leaflet). In addition, the study 
has adequate power to detect moderate main effects of inulin on pain outcomes, with 30 
participants per group providing ~75–80% power to detect an effect size of Cohen’s d ~ 0.6 at α 
= 0.05. If changes in gut microbiome via dietary supplementation can achieve a difference of 0.51 
or higher in NRS, the study is powered to detect them. 
Secondary outcomes: a key goal of this study is to link changes in molecular markers in serum 
to changes in pain and other outcomes (n=120, 60 per arm for the 2x2 intervention). For instance, 
the effect sizes in changes in a circulating molecular pain modulator observed previously from 
0.32 to 0.71 nmol/L; SD=0.61 after 6 weeks of inulin supplementation hence yielding an effect 
size of 0.62 STDs. It increased from 1.61-1.82 nmol/L; SD=0.31 yielding an effect size of 0.61 
STDs with the exercise intervention.  
DATA MANAGEMENT 
  Data will be gathered during the first and last sessions of the INSPIRE trial. Trained local 
research personnel will compile all the data sources, and data entry in a RedCAP database will 
be done in a consistent manner. This will comprise data from QST, 30CST, and TUG as well as 
questionnaires. The data entry site will enter data from the clinical research forms (CRF) from the 
initial and final study visits. 
ADVERSE EVENTS 
 Since the interventions in the current study are using components sourced from common 
foods and routine exercise, we foresee no adverse reaction or side effects. Increasing 
fibre intake may result in bloating amongst those who have a low habitual intake of dietary 
fibre. However, such effects are mild and not considered as a safety concern. Participants 
will be asked to record any side effects like bloating using the dietary compliance diary 
and will be advised to stop taking the supplement if they experience severe bloating. 
Between 2008 and 2017, 75,000 participants participated in these activities' trials, and no 
significant side effects were reported (Thorstensson, C. A. 2015 PMID: 25345913). An 
increase in back, hip, or knee pain is a remote possibility (Luan, L., 2022 PMID: 
35091326). Using an online interface, we will track the patient's pain levels every week to 
see if there has been an increase in discomfort. The subject will be advised to discontinue 

 
study participation and get in touch with their GP if their pain worsens to the point that 
they begin to struggle with everyday tasks. 
 Criteria for terminating the study: It is not anticipated that circumstances will arise 
that necessitate the termination of this study because it only consists of two 
assessments, does not involve investigational medications or medical devices, and the 
same intervention has not resulted in any serious adverse events in over 70,000 
participants in Sweden. 
  
Funding source 
This study is funded by UKRI grant MR/W026813/1 and supported by infrastructure provided by 
the NIHR Nottingham Biomedical Research Centre (BRC).