Fibroblast-derived PI16 sustains inflammatory pain via regulation of CD206+ myeloid cells

Originally identified in fibroblasts, Protease Inhibitor (PI)16 was recently shown to be crucial for the development of neuropathic pain via effects on blood-nerve barrier permeability and leukocyte infiltration, though its impact on inflammatory pain has not been established. Using the complete Freund's Adjuvant inflammatory pain model, we show that Pi16-/- mice are protected against sustained inflammatory pain. Accordingly, intrathecal delivery of a PI16 neutralizing antibody in wild-type mice prevented sustained CFA pain. In contrast to neuropathic pain models, we did not observe any changes in blood-nerve barrier permeability due to PI16 deletion. Instead, Pi16-/- mice display reduced macrophage density in the CFA-injected hindpaw. Furthermore, there was a significant bias toward CD206hi (anti-inflammatory) macrophages in the hindpaw and associated dorsal root ganglia. Following CFA, intrathecal depletion of CD206+ macrophages using mannosylated clodronate liposomes promoted sustained pain in Pi16-/- mice. Similarly, an IL-10 neutralizing antibody also promoted sustained CFA pain in the Pi16-/ when administered intrathecally. Collectively, our results point to fibroblast-derived PI16 mediating substantial differences in macrophage phenotype in the pain neuroaxis under conditions of inflammation. The co-expression of PI16 alongside fibroblast markers in human DRG raise the likelihood that a similar mechanism operates in human inflammatory pain states. Collectively, our findings may have implications for targeting fibroblast-immune cell crosstalk for the treatment of chronic pain.

Orofacial anti-hypernociceptive effect of citral in acute and persistent inflammatory models in rats

Orofacial pain has significant psychological and physiological effects. Citral (3,7-dimethyl-2,6-octadienal) is the main component of Cymbopogon citratus (DC) Stapf, an herb with analgesic properties. Although citral has been considered a potent analgesic, its putative effects on orofacial pain are still unknown.

OBJECTIVE

The objective of this study is to test the hypothesis that citral modulates orofacial pain using two experimental models: formalin-induced hyperalgesia in the vibrissae area and during persistent temporomandibular hypernociception using Complete Freund's Adjuvant - CFA test.

METHODS

For the formalin test, citral (100 and 300 mg/kg, oral gavage) or its vehicle (Tween 80, 1 %) were given 1 h before the formalin injection subcutaneously (sc) into the vibrissae area. For the CFA model, we analyzed the prophylactic (100 mg/kg of citral by oral gavage, 1 h before CFA injection) and the chronic therapeutic (citral treatment 1-hour post-CFA injection and daily post-CFA injection) effect of citral or its vehicle in animals treated with CFA for 8 days.

RESULTS

Citral caused a decrease in formalin-induced local inflammation and the time spent performing nociceptive behavior in a dose-dependent fashion. Similarly, prophylactic and therapeutic citral treatment decreased the CFA-induced persistent mechanical hypernociception in the temporomandibular area.

CONCLUSION

Our data strengthen the notion that citral plays a powerful antinociceptive role by decreasing orofacial hypernociception in formalin and CFA models.

The Combined Effect of Curcumin and Crocin on the Reduction of Inflammatory Responses in Arthritic Rats

The present study evaluated the anti-arthritic impact of combined crocin and curcumin on Adjuvant Induced Arthritis (AIA) in rats. Arthritis model was induced in rats by injecting Complete Freund's adjuvant (CFA) into the right hind paw and was subsequently treated with crocin and curcumin. Evaluation of anti-arthritic activity was carried out using paw swelling, hematological parameters, biochemical parameters, inflammatory cytokines, and histopathology of rats. The results showed increased paw swelling, increased serum markers levels, including CRP, RF, ALP, ALT, and AST, and inflammatory cytokines (ILlβ and TNFα) along with histology changes (cartilage and bone degradation) in arthritic rats when compared to the normal group. Crocin, curcumin and crocin + curcumin administration at different doses (especially combination at 40 mg/kg and 30 mg/kg respectively), as well as MTX revealed suitable therapeutic effect on AIA rats. Moreover, both phytochemicals and their combination at different doses showed effective anti-arthritic effects owing to their anti-inflammatory effects. Therefore, crocin and curcumin, either alone or in combination, can be a suitable treatment modality for rheumatoid arthritis .

Chemical characterization and anti-arthritic appraisal of Monotheca buxifolia methanolic extract in Complete Freund's Adjuvant-induced arthritis in Wistar rats

The current study was designed to evaluate the anti-oxidant and anti-arthritic potential of a traditionally used herb, Monotheca buxifolia. The M. buxifolia methanolic extract (MBME) was prepared from the aerial parts of the plant followed by chemical characterization with GC-MS. The anti-oxidant potential of the MBME was demonstrated by DPPH scavenging activity. The effects of MBME on protein denaturation and membrane stabilization were determined by inhibition of egg albumin denaturation and RBC membrane stabilization assays, respectively. The in vivo anti-arthritic potential of the MBME at 50, 100, and 150 mg/kg/day was evaluated in Complete Freund's Adjuvant-induced polyarthritis in Wistar rats treated for 21 days. Phytochemicals, such as linolenic acid methyl ester, n-hexadecanoic acid, vitamin E, α-amyrin, and β-amyrin were detected in the GC-MS analysis. The plant extract exhibited a 55.20 ± 0.69% scavenging of free radicals at 100 µg/ml concentration. It significantly (p < 0.05) stabilized human RBC membrane (65.06 ± 0.22%) and inhibited protein denaturation (70.53 ± 0.34%) at 100 mg/ml concentration. The diclofenac sodium (DS) and MBME at 150,100, and 50 mg/kg reduced the paw edema, restored the body weight, and altered blood parameters including CRP. The MBME significantly reduced the MDA and increased the SOD, CAT, and GSH levels in liver tissue homogenate in treated rats. The serum concentration of TNF-α and PGE2 was remarkably (p < 0.01-< 0.0001) restored by the DS and MBME dose dependently. The histopathological study showed that MBME 150 mg/kg commendably restored the ankle joint inflammation, bone erosion, and cartilage damage in polyarthritic rats. It was concluded that the anti-oxidant, anti-inflammatory and anti-arthritic effects of MBME might be attributed to phenols, flavonoids, triterpenoids, vitamin E, phytol, and other fatty acids. This study showed the anti-arthritic potential of Monotheca buxifolia and thus validates its traditional claim.

Interferon-β suppresses inflammatory pain through activating µ-opioid receptor

Interferons (IFNs) are cytokines secreted by infected cells that can interfere with viral replication. Besides activating antiviral defenses, type I IFNs also exhibit diverse biological functions. IFN-β has been shown to have a protective effect against neurotoxic and inflammatory insults on neurons. Therefore, we aimed to investigate the possible role of IFN-β in reducing mechanical allodynia caused by Complete Freund's Adjuvant (CFA) injection in rats. We assessed the antinociceptive effect of intrathecal IFN-β in naïve rats and the rats with CFA-induced inflammatory pain. After the behavioral test, the spinal cords of the rats were harvested for western blot and immunohistochemical double staining. We found that intrathecal administration of IFN-β in naïve rats can significantly increase the paw withdrawal threshold and paw withdrawal latency. Further, the intrathecal injection of a neutralizing IFN-β antibody can reduce the paw withdrawal threshold and paw withdrawal latency, suggesting that IFN-β is produced in the spinal cord in normal conditions and serves as a tonic inhibitor of pain. In addition, intrathecal injection of IFN-β at dosages from 1000 U to 10000 U demonstrates a significant transient dose-dependent inhibition of CFA-induced inflammatory pain. This analgesic effect is reversed by intrathecal naloxone, suggesting that IFN-β produces an analgesic effect through central opioid receptor-mediated signaling. Increased expression of phospho-µ-opioid receptors after IFN-β injection was observed on western blot, and immunohistochemical staining showed that µ-opioids co-localized with IFN-α/βR in the dorsal horn of the spinal cord. The findings of this study demonstrate that the analgesic effect of IFN-β is through µ-opioid receptors activation in spial cord.

The Impact of Synovial NF-κB Activation on Apoptosis Pattern Change During Adjuvant-induced Inflammation

Introduction:

Apoptosis dysregulation plays a substantial role in the pathophysiology of chronic inflammation and its related symptoms such as edema. Regulation of NF-κB activation is involved in apoptosis pattern change. The current study aimed at verifying the effects of local inflammation on edema and changes in apoptotic markers, and investigating the possible role of NF-κB in apoptosis pattern change during different stages of complete Freund’s adjuvant (CFA)-induced knee arthritis in rats.

Methods:

A total of 96 male Wistar rats were divided into different experimental groups. Arthritis was evoked into the right knee articular joint. Changes made in knee edema were assessed by caliper on the days 0, 7, 14, and 21 of the study. Synovial NF-κB and levels of apoptotic markers were evaluated during different stages of the study using Western blot technique.

Results:

CFA injection caused intense edema during the whole study period. Synovial NF-κB level increased during the whole study period. The level of apoptotic markers increased during the acute phase of study. But during chronic phase, the apoptosis level decreased. Inh-NF-κB administration increased synovial apoptosis during the whole study period.

Conclusion:

It seems that apoptosis pattern change plays an important role in the progression and modulation of CFA-induced inflammation and its related symptoms. Also, it can be concluded that synovial NF-κB had a crucial role in synovial apoptosis change during the study period.

Effect of new polyherbal formulations DF1911, DF2112 and DF2813 on CFA induced inflammation in rat model

BACKGROUND

Aim of the present study was to evaluate anti-inflammatory activity of newly developed polyherbal formulations DF1911, DF2112 and DF2813. These newly developed formulations are modifications of Dashamoola, a well known Ayurvedic formulation, along with addition of new plants.

METHODS

Complete Freund's adjuvant (CFA) induced inflammation in rat was used as an experimental model. Effects of the treatment in rats were monitored by physiological and biochemical parameters, histopathology and through gene expression studies.

RESULTS

Diclofenac sodium showed maximum percentage inhibition (56.8 ± 3.5%) of paw edema followed by Dashamoola Kwatha (19.9 ± 1.8%). Among test formulations treated groups, DF1911 at 250 mg/kg bw (48.2 ± 5.4%, p < 0.001) and DF2112 at 250 mg/kg bw (49.9 ± 3.5%, p < 0.001) showed significant and maximum increase in percentage inhibition of paw edema as compared to Dashamoola Kwatha. Hematological alterations in CFA rats were normalized after treatment with test formulations. Results of serum markers and histopathological observations also supported the activity of formulations. Increased MDA levels in liver tissue of CFA injected animals significantly (p < 0.05) decreased by Diclofenac sodium and test formulation treated groups. DF1911, DF2112 and DF2813 showed down-regulation of IL1-β (~6.4-fold, ~5.2-fold and ~7.6-fold), IL-6 (~1.1-fold, ~1.6-fold and ~1.9-fold), TNF-α (~2.0-fold, ~4.6-fold and ~3.5-fold), and iNOS (~1.2-fold, ~1.8-fold and ~1.1-fold) in inflamed paw tissue compared to negative control group, respectively.

CONCLUSIONS

The anti-inflammatory effects of DF1911 and DF2112 in rats were significantly higher than the Dashamoola Kwatha and are comparable to Diclofenac sodium.

Melastoma malabathricum Linn attenuates complete freund's adjuvant-induced chronic inflammation in Wistar rats via inflammation response

BACKGROUND

Natural products use for arthritis treatment is gaining importance in the medical worldt. Various studies reports medical importance of Melastoma malabathricum Linn. (MM) (Melastomataceae), also known as "putki," has a broad range of health benefits, for its free radical scavenging constituents. The current investigation scrutinizes the antioxidant and anti-inflammatory effect of MM against adjuvant-induced arthritis in experimental rats.

METHODS

High-performance thin layer chromatography (HPTLC) was used for estimation of phytochemical-constituents present in the MM extract. Protective effect of MM extract in Wistar rats was estimated using CFA-induced model. The rats were divided into different groups with six rats in each group. All animals received oral administration of MM and indomethacin for 28 days. The body weight and arthritic score were scrutinized at regular intervals. At the end of experimental protocol, the rats were sacrificed, and blood samples were used for antioxidant, hematological parameters, pro-inflammatory and inflammatory mediator, respectively. Histopathological observation was used to evaluate the protective effect of MM extract.

RESULT & DISCUSSION

Current study confirmed the preventive effect of MM against adjuvant-induced paw edema, paw redness and arthritic progression. MM significantly (P < 0.001) modulated the oxidative stress parameters as well as hematological parameter induced by CFA. The result also altered the distorted level of proinflammatory mediators and inflammatory mediator, which further reinforce the implication of MM in CFA induced arthritis. Histological analyses of joints of rats showed a reduction in the synovial hyperplasia and mononuclear infiltration in the MM treated group which provides evidence for the antiarthritic effect of MM.

CONCLUSION

From above parameters our study states that the MM is capable of restraining the alteration produced via adjuvant-induced arthritis in aminals. The repressing effect of MM could be attributed, at least in part, to antioxidant, hematological and anti-inflammatory effect. Figure Caption: Melastoma Malabathricum Linn Attenuates Complete Freund's Adjuvant-Induced Chronic Inflammation in Wistar rats by Inflammation Response.

KYNA analogue SZR72 modifies CFA-induced dural inflammation- regarding expression of pERK1/2 and IL-1β in the rat trigeminal ganglion

Background

Neurogenic inflammation has for decades been considered an important part of migraine pathophysiology. In the present study, we asked the question if administration of a novel kynurenic acid analogue (SZR72), precursor of an excitotoxin antagonist and anti-inflammatory substance, can modify the neurogenic inflammatory response in the trigeminal ganglion.

Methods

Inflammation in the trigeminal ganglion was induced by local dural application of Complete Freunds Adjuvant (CFA). Levels of phosphorylated MAP kinase pERK1/2 and IL-1β expression in V1 region of the trigeminal ganglion were investigated using immunohistochemistry and Western blot.

Findings

Pretreatment with one dose of SZR72 abolished the CFA-induced pERK1/2 and IL-1β activation in the trigeminal ganglion. No significant change was noted in case of repeated treatment with SZR72 as compared to a single dose.

Conclusions

This is the first study that demonstrates that one dose of KYNA analog before application of CFA can give anti-inflammatory response in a model of trigeminal activation, opening a new line for further investigations regarding possible effects of KYNA derivates.

A cell-permeant peptide corresponding to the cUBP domain of USP5 reverses inflammatory and neuropathic pain

Background

Cav3.2 T-type calcium currents in primary afferents are enhanced in various painful pathological conditions, whereas inhibiting Cav3.2 activity or expression offers a strategy for combating the development of pain hypersensitivity. We have shown that Cav3.2 channel surface density is strongly regulated by the ubiquitination machinery and we identified the deubiquitinase USP5 as a Cav3.2 channel interacting protein and regulator of its cell surface expression. We also reported that USP5 is upregulated in chronic pain conditions. Conversely, preventing its binding to the channel in vivo mediates analgesia in inflammatory and neuropathic pain models.

Results

To identify which USP5 domain is responsible for the interaction, we used a series of USP5-derived peptides corresponding to different regions in nUBP, cUBP, UBA1, and UBA2 domains to outcompete full length USP5. We identified a stretch of amino acid residues within the cUBP domain of USP5 as responsible for binding to Cav3.2 calcium channels. Based on this information, we generated a TAT-cUBP1-USP5 peptide that could disrupt the Cav3.2/USP5 interaction in vitro and tested its physiological effect in well-established models of persistent inflammatory pain (CFA test) and chronic mononeuropathy and polyneuropathy in mice (partial sciatic nerve injury and the (ob/ob) diabetic spontaneous neuropathic mice). Our results reveal that the TAT-cUBP1-USP5 peptide attenuated mechanical hyperalgesia induced by both Complete Freund’s Adjuvant and partial sciatic nerve injury, and thermal hyperalgesia in diabetic neuropathic animals. In contrast, Cav3.2 null mice were not affected by the peptide in the partial sciatic nerve injury model. Cav3.2 calcium channel levels in diabetic mice were reduced following the administration of the TAT-cUBP1-USP5 peptide.

Conclusions

Our findings reveal a crucial region in the cUBP domain of USP5 that is important for substrate recognition and binding to the III-IV linker of Cav3.2 channels. Targeting the interaction of this region with the Cav3.2 channel can be exploited as the basis for therapeutic intervention into inflammatory and neuropathic pain.

Experimental inflammation following dural application of complete Freund's adjuvant or inflammatory soup does not alter brain and trigeminal microvascular passage

Background

Migraine is a paroxysmal, disabling primary headache that affects 16 % of the adult population. In spite of decades of intense research, the origin and the pathophysiology mechanisms involved are still not fully known. Although triptans and gepants provide effective relief from acute migraine for many patients, their site of action remains unidentified. It has been suggested that during migraine attacks the leakiness of the blood-brain barrier (BBB) is altered, increasing the passage of anti-migraine drugs. This study aimed to investigate the effect of experimental inflammation, following dural application of complete Freund’s adjuvant (CFA) or inflammatory soup (IS) on brain and trigeminal microvascular passage.

Methods

In order to address this issue, we induced local inflammation in male Sprague-Dawley-rats dura mater by the addition of CFA or IS directly on the dural surface. Following 2, 24 or 48 h of inflammation we calculated permeability-surface area product (PS) for [⁵¹Cr]-EDTA in the trigeminal ganglion (TG), spinal trigeminal nucleus, cortex, periaqueductal grey and cerebellum.

Results

We observed that [⁵¹Cr]-EDTA did not pass into the central nervous system (CNS) in a major way. However, [⁵¹Cr]-EDTA readily passed the TG by >30 times compared to the CNS. Application of CFA or IS did not show altered transfer constants.

Conclusions

With these experiments we show that dural IS/CFA triggered TG inflammation, did not increase the BBB passage, and that the TG is readily exposed to circulating molecules. The TG could provide a site of anti-migraine drug interaction with effect on the trigeminal system.

Electronic supplementary material

The online version of this article (doi:10.1186/s10194-015-0575-8) contains supplementary material, which is available to authorized users.