Serum and MRI biomarkers in mobile device texting: a pilot study

Does the Interaction between Local and Systemic Inflammation Provide a Link from Psychology and Lifestyle to Tissue Health in Musculoskeletal Conditions?

Musculoskeletal conditions are known to involve biological, psychological, social and, often, lifestyle elements. However, these domains are generally considered in isolation from each other. This siloed approach is unlikely to be adequate to understand the complexity of these conditions and likely explains a major component of the disappointing effects of treatment. This paper presents a hypothesis that aims to provide a foundation to understand the interaction and integration between these domains. We propose a hypothesis that provides a plausible link between psychology and lifestyle factors with tissue level effects (such as connective tissue dysregulation/accumulation) in musculoskeletal conditions that is founded on understanding the molecular basis for interaction between systemic and local inflammation. The hypothesis provides plausible and testable links between mind and body, for which empirical evidence can be found for many aspects. We present this hypothesis from the perspective of connective tissue biology and pathology (fibrosis), the role of inflammation locally (tissue level), and how this inflammation is shaped by systemic inflammation through bidirectional pathways, and various psychological and lifestyle factors via their influence on systemic inflammation. This hypothesis provides a foundation for new consideration of the development and refinement of personalized multidimensional treatments for individuals with musculoskeletal conditions.

Occupational Activities: Factors That Tip the Balance From Bone Accrual to Bone Loss

Bone adaptation to persistent overloading can be counteracted by superimposed inflammatory and loading-induced damage that can tip the balance from bone accrual to loss.

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It is commonly assumed that beneficial adaptations in bone occur with vigorous exercise, yet any adaptive re/modeling in bone undergoing persistent overloading can be counteracted by superimposed inflammatory, compressive, and tensile loading–induced damage responses above thresholds of tissue fatigue failure and repair. This leads to a tenuous balance between achieving bone accrual and loss.

Forced treadmill running reduces systemic inflammation yet worsens upper limb discomfort in a rat model of work-related musculoskeletal disorders

BACKGROUND

Musculoskeletal disorders can result from prolonged repetitive and/or forceful movements. Performance of an upper extremity high repetition high force task increases serum pro-inflammatory cytokines and upper extremity sensorimotor declines in a rat model of work-related musculoskeletal disorders. Since one of the most efficacious treatments for musculoskeletal pain is exercise, this study investigated the effectiveness of treadmill running in preventing these responses.

METHODS

Twenty-nine young adult female Sprague-Dawley rats were used. Nineteen were trained for 5 weeks to pull a lever bar at high force (15 min/day). Thirteen went on to perform a high repetition high force reaching and lever-pulling task for 10 weeks (10-wk HRHF; 2 h/day, 3 days/wk). From this group, five were randomly selected to undergo forced treadmill running exercise (TM) during the last 6 weeks of task performance (10-wk HRHF+TM, 1 h/day, 5 days/wk). Results were compared to 10 control rats and 6 rats that underwent 6 weeks of treadmill running following training only (TR-then-TM). Voluntary task and reflexive sensorimotor behavioral outcomes were assessed. Serum was assayed for inflammatory cytokines and corticosterone, reach limb median nerves for CD68+ macrophages and extraneural thickening, and reach limb flexor digitorum muscles and tendons for pathological changes.

RESULTS

10-wk HRHF rats had higher serum levels of IL-1α, IL-1β and TNFα, than control rats. In the 10-wk HRHF+TM group, IL-1β and TNFα were lower, whereas IL-10 and corticosterone were higher, compared to 10-wk HRHF only rats. Unexpectedly, several voluntary task performance outcomes (grasp force, reach success, and participation) worsened in rats that underwent treadmill running, compared to untreated 10-wk HRHF rats. Examination of forelimb tissues revealed lower cellularity within the flexor digitorum epitendon but higher numbers of CD68+ macrophages within and extraneural fibrosis around median nerves in 10-wk HRHF+TM than 10-wk HRHF rats.

CONCLUSIONS

Treadmill running was associated with lower systemic inflammation and moderate tendinosis, yet higher median nerve inflammation/fibrosis and worse task performance and sensorimotor behaviors. Continued loading of the injured tissues in addition to stress-related factors associated with forced running/exercise likely contributed to our findings.

Manual therapy prevents onset of nociceptor activity, sensorimotor dysfunction, and neural fibrosis induced by a volitional repetitive task

Painful and disabling musculoskeletal disorders remain prevalent. In rats trained to perform repetitive tasks leading to signs and dysfunction similar to those in humans, we tested whether manual therapy would prevent the development of the pathologies and symptoms. We collected behavioral, electrophysiological, and histological data from control rats, rats that trained for 5 weeks before performing a high-repetition high-force (HRHF) task for 3 weeks untreated, and trained rats that performed the task for 3 weeks while being treated 3x/week using modeled manual therapy (MMT) to the forearm (HRHF + MMT). The MMT included bilateral mobilization, skin rolling, and long axis stretching of the entire upper limb. High-repetition high-force rats showed decreased performance of the operant HRHF task and increased discomfort-related behaviors, starting after training. HRHF + MMT rats showed improved task performance and decreased discomfort-related behaviors compared with untreated HRHF rats. Subsets of rats were assayed for presence or absence of ongoing activity in C neurons and slow Aδ neurons in their median nerves. Neurons from HRHF rats had a heightened proportion of ongoing activity and altered conduction velocities compared with control and MMT-treated rats. Median nerve branches in HRHF rats contained increased numbers of CD68 macrophages and degraded myelin basic protein, and showed increased extraneural collagen deposition, compared with the other groups. We conclude that the performance of the task for 3 weeks leads to increased ongoing activity in nociceptors, in parallel with behavioral and histological signs of neuritis and nerve injury, and that these pathophysiologies are largely prevented by MMT.

Effectiveness of conservative interventions for sickness and pain behaviors induced by a high repetition high force upper extremity task

Background

Systemic inflammation is known to induce sickness behaviors, including decreased social interaction and pain. We have reported increased serum inflammatory cytokines in a rat model of repetitive strain injury (rats perform an upper extremity reaching task for prolonged periods). Here, we sought to determine if sickness behaviors are induced in this model and the effectiveness of conservative treatments.

Methods

Experimental rats underwent initial training to learn a high force reaching task (10 min/day, 5 days/week for 6 weeks), with or without ibuprofen treatment (TRHF vs. TRHF + IBU rats). Subsets of trained animals went on to perform a high repetition high force (HRHF) task for 6 or 12 weeks (2 h/day, 3 days/week) without treatment, or received two secondary interventions: ibuprofen (HRHF + IBU) or a move to a lower demand low repetition low force task (HRHF-to-LRLF), beginning in task week 5. Mixed-effects models with repeated measures assays were used to assay duration of social interaction, aggression, forepaw withdrawal thresholds and reach performance abilities. One-way and two-way ANOVAs were used to assay tissue responses. Corrections for multiple comparisons were made.

Results

TRHF + IBU rats did not develop behavioral declines or systemic increases in IL-1beta and IL-6, observed in untreated TRHF rats. Untreated HRHF rats showed social interaction declines, difficulties performing the operant task and forepaw mechanical allodynia. Untreated HRHF rats also had increased serum levels of several inflammatory cytokines and chemokines, neuroinflammatory responses (e.g., increased TNFalpha) in the brain, median nerve and spinal cord, and Substance P and neurokinin 1 immunoexpression in the spinal cord. HRHF + IBU and HRHF-to-LRLF rats showed improved social interaction and reduced inflammatory serum, nerve and brain changes. However, neither secondary treatment rescued HRHF-task induced forepaw allodynia, or completely attenuated task performance declines or spinal cord responses.

Conclusions

These results suggest that inflammatory mechanisms induced by prolonged performance of high physical demand tasks mediate the development of social interaction declines and aggression. However, persistent spinal cord sensitization was associated with persistent behavioral indices of discomfort, despite use of conservative secondary interventions indicating the need for prevention or more effective interventions.

Electronic supplementary material

The online version of this article (doi:10.1186/s12868-017-0354-3) contains supplementary material, which is available to authorized users.

A pilot study on biomarkers for tendinopathy: lower levels of serum TNF-α and other cytokines in females but not males with Achilles tendinopathy

Background

Achilles tendinopathy is a painful musculoskeletal condition that is common among athletes, and which limits training capacity and competitive performance. The lack of biomarkers for tendinopathy limits research into risk factors and also the evaluation of new treatments. Cytokines and growth factors involved in regulating the response of tendon cells to mechanical load have potential as biomarkers for tendinopathy.

Methods

This case–control study compared serum concentration of cytokines and growth factors (TNF-α, IL-1β, bFGF, PDFG-BB, IFN-γ, VEGF) between individuals with chronic Achilles tendinopathy and controls. These were measured in fasting serum from 22 individuals with chronic Achilles tendinopathy and 10 healthy controls. Results were analysed in relation to gender and physical activity pattern.

Results

TNF-α concentration was lower in the entire tendinopathy group compared with the entire control group; none of the other cytokines were significantly different. TNF-α levels were nevertheless highly correlated with the other cytokines measured, in most of the subgroups. Analysed by gender, TNF-α and PDGF-BB concentrations were lower in the female tendinopathy group but not the male tendinopathy group. A trend was seen for lower IL-1β in the female tendinopathy group. Physical activity was correlated with TNF-α, PDGF-BB and IL-1β to varying extents for control subgroups, but not for the female tendinopathy group. No correlations were seen with BMI or duration of symptoms.

Conclusions

This pilot study indicates a lower level of TNF-α and PDGF-BB, and to some extent IL-1β among females, but not males, in the chronic phase of Achilles tendinopathy. It is suggested that future studies on tendinopathy biomarkers analyse male and female data separately. The lack of correlation between cytokine level and physical activity in the female tendinopathy group warrants further study.