Preventive Supplementation of Omega-3 Reduces Pain and Pro-inflammatory Cytokines in a Mouse Model of Complex Regional Pain Syndrome Type I

Complex regional pain syndrome type I (CRPS-I) is a condition that responds poorly to treatments. The role of omega-3 fatty acids in the treatment of inflammatory disorders is well described in the literature; however, few studies have evaluated its therapeutic benefits in different types of pain. We evaluated the potential antihyperalgesic and anti-inflammatory effects of preventive omega-3 supplementation in an animal model of CRPS-I. In experiment 1, Swiss female mice were supplemented for 30 days with omega-3 before the induction of the CRPS-I model and 14 days after. Mechanical hyperalgesia was evaluated at baseline and from the 4th to the 14th day after CPRS-I induction along with open field locomotor activity after 30 days of supplementation. In experiment 2, Swiss female mice were supplemented for 30 days with omega-3 and then subjected to the CRPS-I model. Twenty-four hours later the animals were euthanized, and tissue samples of the spinal cord and right posterior paw muscle were taken to measure pro-inflammatory cytokine TNF and IL-1β concentrations. Omega-3 supplementation produced antihyperalgesic and anti-inflammatory effects, as well as reducing pro-inflammatory cytokine concentrations, without altering the animals’ locomotion. No open field locomotor changes were found. The 30-day supplementation at the tested dose was effective in the CRPS-I model.

Immunoregulatory Effect of Preventive Supplementation of Omega-3 Fatty Acid in a Complex Regional Pain Syndrome Type I Model in Mice

Objective

Complex regional pain syndrome (CRPS) is usually triggered by trauma or a surgical procedure, and it typically becomes an established one after an intense inflammatory process with chronic pain and edema as the main symptoms. Available treatments for CRPS have low efficacy. This study aimed to evaluate the clinical and immunoregulatory effects of omega-3 polyunsaturated fatty acid (PUFA) supplementation on paw edema and anti- and pro-inflammatory cytokines and macrophage phenotypes in the chronic post-ischemia pain (CPIP) preclinical model of CRPS-Type I.

Methods

Female Swiss mice were supplemented with omega-3, corn oil, or saline and then submitted to the CPIP model of ischemia/reperfusion (I/R) injury. Supplementation was carried out for 30 days prior to and up to 2 or 15 days after the induction of CPIP, according to experimental protocols. The supplementation protocol included 1,500 mg/kg of omega-3 or corn oil through an intragastric route (gavage). Paw edema, interleukin- (IL-) 4, IL-10, transforming growth factor-β1 (TGF-β1), monocyte chemotactic protein-1 (MCP-1), and tumor necrosis factor (TNF) were then measured in the paw skin and muscle by enzyme-linked immunosorbent assay (ELISA), and macrophage phenotypes (M1 and M2) assessed in the paw muscle by Western blotting.

Results

The CPIP model induced an increase in paw thickness up to 72 h post-I/R. Mice supplemented with omega-3 compared to the saline group displayed reduced edema but neither altered skin IL-4 or skin and muscle TGF-β1, TNF, and MCP-1 concentrations, nor did they exhibit significantly altered muscle macrophage phenotype on the 2nd-day post-CPIP. However, omega-3 supplementation reversed the I/R-related reduction in IL-4 in the paw muscle compared to groups supplemented with saline and corn oil. Furthermore, omega-3 promoted the reduction of IL-10 levels in the paw skin, compared to animals with lesions supplemented with saline, until the 2nd-day post-CPIP. On the 15th day post-CPIP, IL-10 was significantly increased in the muscle of animals supplemented with omega-3 compared to the saline group.

Conclusion

The results suggest that omega-3 PUFA supplementation has anti-inflammatory effects in the CPIP model of CRPS-Type I, significantly reducing paw edema and regulating concentrations of anti-inflammatory cytokines, including IL-4 and IL-10.

Decrease of IL-1β and TNF in the Spinal Cord Mediates Analgesia Produced by Ankle Joint Mobilization in Complete Freund Adjuvant-Induced Inflammation Mice Model

Objective

This study aims to investigate the effects of ankle joint mobilization (AJM) on mechanical hyperalgesia and peripheral and central inflammatory biomarkers after intraplantar (i.pl.) Complete Freund’s Adjuvant (CFA)-induced inflammation.

Methods

Male Swiss mice were randomly assigned to 3 groups (n = 7): Saline/Sham, CFA/Sham, and CFA/AJM. Five AJM sessions were carried out at 6, 24, 48, 72, and 96 h after CFA injection. von Frey test was used to assess mechanical hyperalgesia. Tissues from paw skin, paw muscle and spinal cord were collected to measure pro-inflammatory (TNF, IL-1β) and anti-inflammatory cytokines (IL-4, IL-10, and TGF-β1) by ELISA. The macrophage phenotype at the inflammation site was evaluated by Western blotting assay using the Nitric Oxide Synthase 2 (NOS 2) and Arginase-1 immunocontent to identify M1 and M2 macrophages, respectively.

Results

Our results confirm a consistent analgesic effect of AJM following the second treatment session. AJM did not change cytokines levels at the inflammatory site, although it promoted a reduction in M2 macrophages. Also, there was a reduction in the levels of pro-inflammatory cytokines IL-1β and TNF in the spinal cord.

Conclusion

Taken together, the results confirm the anti-hyperalgesic effect of AJM and suggest a central neuroimmunomodulatory effect in a model of persistent inflammation targeting the pro-inflammatory cytokines IL-1β and TNF.

Photobiomodulation and Sida tuberculata combination declines the inflammation's markers in knee-induced osteoarthritis

The aim of this study was to assess potential combination effects of photobiomodulation therapy (PBMT) with Sida tuberculata extracts on the oxidative stress and antioxidant activity, as well as on the inflammatory process. Rats with knee osteoarthritis (OA) were treated with S. tuberculata extracts and PBMT (904 nm, 18 J/cm²). The animals were evaluated for nociception and edema. The blood, knee lavage and structures, spinal cord, and brainstem were collected for biochemical analyses (lipid peroxidation, protein carbonyl content, superoxide dismutase activity, non-protein thiol levels, and measurement of nitrite/nitrate). The knee structures were also used to measure cytokine levels. PBMT lowered the damage due to oxidative stress in the knee and at distant sites from the lesion. PBMT also reduced the levels of nitric oxide and cytokines, which could explain the nociception reduction mechanism. Similarly, S. tuberculata decreased the damage by oxidative stress, levels of nitrite/nitrate, and cytokines. The therapy combination reduced levels of cytokines and nitrite/nitrate. PBMT and S. tuberculata extracts reduced the oxidative stress and inflammation. It is noteworthy that PBMT increased the antioxidant activity in the knee and at sites distant from the lesion, contributing to a more significant decrease in nociception. The combination of therapies did not present significant effects on the analyzed parameters. Therefore, it is suggested that PBM is sufficient to minimize the signs and symptoms of the knee OA in our rat model.

Balneotherapy decreases mechanical hyperalgesia by reversing BDNF and NOS2 immunocontent in spinal cord of mice with neuropathic pain

In the last decades, balneotherapy or thermalism has been used for health promotion and in the treatment of inflammatory and chronic processes. We found that balneotherapy reduced mechanical hyperalgesia, as well the increase of BDNF and NOS2 levels in the spinal cord, while increased BDNF and NOS1 in the paw. The data presented herein demonstrated for the first time in a murine model of neuropathic pain, the analgesic effect of balneotherapy with the water from the natural springs of Santo Amaro da Imperatriz-Brazil. Nevertheless, future clinical trials should be conducted to test the effectiveness of balneotherapy in neuropathic pain patients.

Acceptance for chronic dialysis treatment: insufficient and unequal

BACKGROUND

Evidence suggests that a number of end-stage renal disease (ESRD) patients die without receiving dialysis. We investigated and compared ESRD patients who died without receiving treatment and those who were accepted for dialysis.

METHODS

All patients starting chronic dialysis in 1991 in the city of Sao Paulo and prospectively registered in the Health Secretariat files were studied. From death certificates we obtained data from all patients dying with an underlying cause associated with chronic renal failure. Medical records from a sample of patients who died without receiving dialysis were reviewed.

RESULTS

Of 2127 patients, 1582 (74.7%) received dialysis and 545 (25.6%) did not. The best chance of being dialysed occurred in the 20-29 age group. The age groups with the least chance of receiving dialysis were 0-9 years and over 79 years old. The odds ratio (95% Cl) of not receiving dialysis was 12.42 (6.63-23.82) times greater for patients over 60 years old compared to those aged 10-19 years. Patients with renal failure due to congenital diseases, chronic pyelonephritis, unknown cause, and hypertension were less likely to receive dialysis than those with glomerulonephritis or diabetes.

CONCLUSIONS

Our results suggest that many ESRD patients die without receiving dialysis. Age and cause of renal disease influence the chance of being accepted for treatment. Restrictions of treatment need to be corrected to guarantee that maintenance dialysis will be accessible to ESRD patients.

[Access to chronic dialysis treatment: deficient and unequal]

OBJECTIVE

To determine the fraction of patients with end-stage renal disease (ESRD) who received dialysis treatment in the city of São Paulo in 1991 and to investigate the influence of age in the access to dialysis.

MATERIAL AND METHODS

All patients who received dialysis for ESRD in the city of São Paulo during 1991, and were registered in the Secretary of Health of São Paulo files were included in the study. In the same year, information was also collected on individuals who died having as basic cause of death a disease related to chronic renal failure. These data were obtained from death certificates files. Using simultaneously information from both data bases it was possible to ascertain the patients who died without receiving dialysis and to calculate the treated fraction in several age groups.

RESULTS

Overall 25.6% of ESRD patients did not receive treatment. There was a progressive reduction in the fraction of patients treated for those older than 40 years. In children less or equal to 9 years of age the percentage of treatment was also reduced (29%). Individuals in the age groups 60-69 and 70-79 years had a chance about 5 and 11 times greater, respectively, of dying without receiving dialysis than those in the 20-29 years group.

CONCLUSIONS

We estimate that at least one fourth of the ESRD patients died in São Paulo in 1991 without receiving dialysis treatment. Age is a major factor of discrimination for acceptance in chronic dialysis programs.