Subcutaneous inflammation (panniculitis) in tibio-tarsal joint of rats inoculated with complete Freund's adjuvant

Anti-inflammatory effects of hunger are transmitted to the periphery via projection-specific AgRP circuits

Caloric restriction has anti-inflammatory effects. However, the coordinated physiological actions that lead to reduced inflammation in a state of caloric deficit (hunger) are largely unknown. Using a mouse model of injury-induced peripheral inflammation, we find that food deprivation reduces edema, temperature, and cytokine responses that occur after injury. The magnitude of the anti-inflammatory effect that occurs during hunger is more robust than that of non-steroidal anti-inflammatory drugs. The effects of hunger are recapitulated centrally by activity in nutrient-sensing hypothalamic agouti-related protein (AgRP)-expressing neurons. We find that AgRP neurons projecting to the paraventricular nucleus of the hypothalamus rapidly and robustly reduce inflammation and mediate the majority of hunger's anti-inflammatory effects. Intact vagal efferent signaling is required for the anti-inflammatory action of hunger, revealing a brain-to-periphery pathway for this reduction in inflammation. Taken together, these data begin to unravel a potent anti-inflammatory pathway engaged by hypothalamic AgRP neurons to reduce inflammation.

Potential Value of FAPI PET/CT in the Detection and Treatment of Fibrosing Mediastinitis: Preclinical and Pilot Clinical Investigation

Fibrosing mediastinitis (FM) is a rare proliferative disease within the mediastinum that leads to pulmonary hypertension, which has been regarded as a major cause of death. This study aims to evaluate the potential value of fibroblast activation protein inhibitor (FAPI)-PET/CT in the integration of diagnosis and treatment of FM through targeting FAPI in fibrosis rats and provide a theoretical basis for clinical management of FM patients. By performing a 18F-FAPI PET/CT scan, the presence of FAPI-avid in the fibrotic lesion was determined. Through a fibrosis rat model, 18F-FAPI-74 was used for lesion imaging and 177Lu-FAPI-46 was utilized to investigate the potential therapeutic effect on FM in vivo. In addition, biodistribution analysis and radiation dosimetry were carried out. With the 177Lu-FAPI-46 pharmacokinetic data of rats as the input, the estimated dose for female adults was computed, which can provide some useful information for the safe application of radiolabeled FAPI in the detection and treatment of FM in patients. Then, major findings on the use of FAPI PET/CT and SPECT/CT in FM were presented. 18F-FAPI-74 showed a high-level uptake in FM lesions of patients (SUVmax 7.94 ± 0.26), which was also observed in fibrosis rats (SUVmax 2.11 ± 0.23). Consistently, SPECT/CT imaging of fibrosis rats also revealed that 177Lu-FAPI-46-avid was active for up to 60 h in fibrotic lesions. In addition to this robust diagnostic performance, a possible therapeutic impact was evaluated as well. It turned out that no spontaneous healing of lesions was observed in the control group, whereas there was complete healing on day 9, day 11, and day 14 in the 30, 100, and 300 MBq groups, respectively. With a significant difference in the free of event rate in the Kaplan-Meier curve among four groups (P < 0.001), a dose of 300 MBq displayed the best therapeutic effect, and no obvious damage was observed in the kidney. Furthermore, organ-absorbed doses and an effective dose (0.4320 mSv/MBq) of 177Lu-FAPI-46 presumed for patients were assumed to give a preliminary indication of its safe use in clinical practice. In conclusion, 18F-FAPI-46 PET/CT can be a potentially valuable tool for the diagnosis of FM. Of note, 177Lu-FAPI-46 may be a novel and safe radiolabeled reagent for the integration of diagnosis and treatment of FM.

Antioxidant, hepatoprotective, genoprotective, and cytoprotective effects of quercetin in a murine model of arthritis

Rheumatoid arthritis is a highly debilitating inflammatory autoimmune disease which is characterized by joint destruction. The present study sought to investigate the effect of quercetin in rats with complete Freund's adjuvant-induced arthritis. Animals were divided into control/saline, control/quercetin (5 mg/kg, 25 mg/kg, and 50 mg/kg) arthritis/saline, and arthritis/quercetin (5 mg/kg, 25 mg/kg, and 50 mg/kg); the treatments were administered for 45 days. Biochemical, oxidative stress, genotoxicity, and cytotoxicity parameters were evaluated. All doses of quercetin reduced the levels of aspartate aminotransferase, thiobarbituric acid-reactive substances, and reactive oxygen species; however, only treatment with 25 or 50 mg/kg increased catalase activity. Total thiol and reduced glutathione levels were not significantly affected by the induction nor by the treatments. Genotoxicity assessed by DNA damage, and cytotoxicity through picogreen assay, decreased after treatments with quercetin. Our results present evidence of the antioxidant, cytoprotective, genoprotective and hepatoprotective, and effects of quercetin, demonstrating its potential as a candidate for coadjuvant therapy.

Comparison of the adjuvant activity of emulsions with different physicochemical properties on the antibody response towards the venom of West African carpet viper (Echis ocellatus)

Adjuvant emulsions are widely used to enhance the antibody response of the animals used as immunoglobulin source for producing antivenoms. Usually, the adjuvant activity of emulsions is attributed both to their ability to trigger "danger" signals from cells in which they induce death, and to form depots from which immunogens are slowly released. However, there is contradictory evidence suggesting that adjuvant activity of emulsions is independent of the dispersion type and the rate of immunogen release. In order to test how physical properties of emulsions, composed of mineral oil and water, affect their ability to enhance the antibody response towards snake venoms, we compared water-in-oil (W/O) emulsions prepared at volume ratios of 70/30, 50/50 or 30/70, a 50/50 oil-in-water (O/W) emulsion, and a water-in-oil-in-water (W/O/W) multiple emulsion. Comparison included their droplet-size, viscosity, rate of immunogen release and ability to enhance the antibody response of mice immunized with the venom of the African viperid snake Echis ocellatus. It was found that all emulsions released a low amount of venom, and that the 50/50 (W/O) and the multiple emulsion (W/O/W) were those that induced the higher anti-venom antibody response. Our results suggest that the ability of emulsions to enhance the anti-venom response is not associated to their ability to form depots from which the venom is slowly released.

Free and nanoencapsulated vitamin D3 : effects on E-NTPDase and E-ADA activities in an animal model with induced arthritis

The effect of vitamin D3 in oral solution (VD3 ) and vitamin D3 -loaded nanocapsules (NC-VD3 ) was analysed in animals with complete Freund's adjuvant (CFA) induced arthritis (AR). For this purpose, we evaluated scores for arthritis, thermal hyperalgesia and paw oedema, as well as histological analyses and measurements of the activity of the ectonucleoside triphosphate diphosphohydrolase (E-NTPDase) and ecto-adenosine deaminase (E-ADA) enzymes in rat lymphocytes. Haematological and biochemical parameters were also determined. The doses administered were 120 UI/day of VD3 and 15.84 UI/day of NC-VD3 . Fifteen days after the induction of AR, the groups were treated for 15 days with vitamin D3 . The results demonstrated that VD3 was able to reduce arthritis scores, thermal hyperalgesia and paw oedema in rats with CFA-induced arthritis. However, treatment with NC-VD3 did not reduce arthritis scores. The histological analyses showed that both formulations were able to reduce the inflammatory changes induced by CFA. The activity of E-NTPDase in rat lymphocytes was higher in the AR compared with the control group, while the activity of E-ADA was lower. This effect was reversed after the 15-day treatment. Data from this study indicates that both forms of vitamin D3 seem to contribute to decreasing the inflammatory process induced by CFA, possibly altering the activities of ectoenzymes. Copyright © 2016 John Wiley & Sons, Ltd.

SIGNIFICANCE OF THE STUDY

The effects promoted by both formulations of vitamin D3 , either in oral solution or nanoencapsulated form, strongly suggests the softening of the inflammatory process induced by complete Freund's adjuvant (CFA), possibly altering the E-NTPDase and E-ADA activities. However, it is known that vitamin D has a beneficial effect on the modulation of the immune system components responsible for the inflammatory process. Moreover, the establishment of responses to treatment with vitamin D3 may provide an alternative for inhibiting the proinflammatory response, assisting in our understanding of the immunopathology of this disease and possibly improving the signs and symptoms that hinder the quality of life of patients with rheumatoid arthritis.

HIGHLIGHTS

Evaluation of the effects on the E-NTPDase and E-ADA activities in an animal model of induced arthritis. Two formulations of vitamin D3 were used: form oral solution and nanoencapsulated. Vitamin D3 seems to contribute to the inflammatory process induced by CFA. Vitamin D3 possibly alters the E-NTPDase and E-ADA activities. Vitamin D3 may be an alternative supplementary treatment for chronic arthritis.

Contribution of transient receptor potential ankyrin 1 to chronic pain in aged mice with complete Freund's adjuvant-induced arthritis

OBJECTIVE

To investigate age-related differences in mechanical sensitivity to inflammatory pain and determine the contribution of transient receptor potential ankyrin 1 (TRPA1) to mechanical hypersensitivity during chronic inflammation in young and aged mice with complete Freund's adjuvant (CFA)-induced arthritis.

METHODS

Mechanical sensitivity in young (3-month-old) and aged (24-month-old) wild-type (TRPA1(+/+) ) mice and TRPA1-deficient (TRPA1(-/-) ) mice was measured behaviorally for 8 weeks following injection of CFA into the plantar hind paw. The severity of inflammation was evaluated by histologic analyses and hind-paw measurements. Ex vivo preparations of the skin saphenous nerve from mice were assessed for C-fiber sensitivity.

RESULTS

Among naive (uninjured) wild-type mice, aged animals were less sensitive than young animals to mechanical stimuli. Afferent recordings of C-fibers from TRPA1(-/-) mice indicated that TRPA1 contributes to the normal mechanical sensitivity in both age groups. Following injection of CFA, both young and aged TRPA1(+/+) mice exhibited mechanical hypersensitivity. In young TRPA1(-/-) mice injected with CFA, peak development of mechanical hypersensitivity was delayed until week 4, when they exhibited a sharp decrease (9-fold) in the mechanical paw withdrawal threshold, whereas aged TRPA1(-/-) mice did not exhibit mechanical hypersensitivity at any time during the 8 weeks after CFA injection. Recordings of C-fibers from the saphenous nerve supported these findings, with results indicating that both young and aged TRPA1(+/+) mice exhibited increased action potential firing at 8 weeks after CFA injection (increases of 25% and 60%, respectively). Interestingly, among TRPA1(-/-) mice injected with CFA, mechanical firing was increased markedly in the C-fibers of young mice (increase of 80%) but not in the C-fibers of aged mice.

CONCLUSION

These findings reveal marked differences in the long-term mechanical behavioral sensitivity of aged and young mice, and suggest that TRPA1 may be a key contributor to the transition from acute to chronic inflammatory pain in response to mechanical stimuli as well as to the development of nociceptor sensitization selectively in aged mice.

An alternative technique for the induction of autoimmune valvulitis in a rat model of rheumatic heart disease

We currently use a rat model in our investigations into human rheumatic heart disease (RHD). This model traditionally involves footpad immunization with antigen emulsified in complete Freund's adjuvant (CFA). Trials to find an alternative adjuvant to CFA which produced a Th1 type response in the rats resulting in carditis were unsuccessful. However, hock immunization was found to produce the desired valvular pathology without the adverse inflammatory side-effects associated with CFA. We therefore consider the hock an ideal site for immunization, particularly when using CFA.

Effects of an antagonist of the bombesin/gastrin-releasing peptide receptor on complete Freund's adjuvant-induced arthritis in rats

OBJECTIVE

To determine the effects of RC-3095 in clinical and histopathologic parameters and inflammatory mediators on complete Freund's adjuvant-induced arthritis (CFA).

METHODS

The arthritis was induced by injection of CFA into the left hind footpad. The animals were divided into control, vehicle injected control, placebo group (saline subcutaneously 50ml/kg, once daily for 8 days after modeling), treatment group (0.3mg/kg of RC-3095 subcutaneously, once daily for 8 days after induction). Clinical evaluation was accomplished daily, through scoring of the paw edema. The animals were sacrificed 15 days after induction for collection of hind foot joints for histology. We used a histological scoring system which was previously described, and interferon (INF)-gamma, interleukin (IL)-1beta, tumor necrosis factor (TNF), interleukin (IL)-6 and interleukin (IL)-10 were measured by ELISA.

RESULTS

There was a significant inhibition of joint histological findings in the RC-3095 treated group, including synovial inflammatory infiltration and hyperplasia, cartilage and bone erosion. IFN-gamma, IL-1beta, TNF, IL-6 and IL-10 serum levels were significantly lower in the treated group. Paw swelling and subcutaneous inflammation, evaluated clinically, were not different between CFA-induced groups.

CONCLUSIONS

RC-3095 was able to improve experimental arthritis, attenuate joint damage and decrease serum levels of IFN-gamma, IL-1beta, TNF, IL-6 and IL-10. These data indicate that interference with GRP pathway is a potential new strategy for the treatment of RA that needs further investigational studies.