Models of inflammation: Carrageenan- or complete Freund's Adjuvant (CFA)-induced edema and hypersensitivity in the rat

Neurturin GF Enhances the Acute Cytokine Response of Inflamed Skin

Epidermal keratinocytes, immune cells, and sensory nerves all contribute to immune balance and skin homeostasis. Keratinocyte's release of GFs, neuromodulators, and immune activators is particularly important because each can evoke local (skin) and systemic (ie, immune and neural) responses that can initiate and exacerbate skin pathophysiology. From studies of skin and neural GFs, we hypothesized that neurturin (Nrtn), a member of the GDNF family that is expressed in the skin, has particular importance in this process. In this study, we examine how elevation of Nrtn in skin keratinocytes impacts early cytokine expression in response to complete Freund's adjuvant-mediated inflammation. Nrtn-overexpressing mice and wild-type mice injected with Nrtn exhibit an enhanced level of TNFα and IL-1β cytokines in the skin, a response previously shown to support healing. In vitro assays suggest that one source of the Nrtn-induced TNFα increase is keratinocytes, which are shown to express Nrtn and mRNAs encoding the Nrtn receptors GFRα2, Ret, ITGB1, and NCAM. These findings support the contribution of keratinocyte-derived Nrtn as an autocrine/paracrine factor that acts as a first-line defense molecule that regulates the initial cytokine response to inflammatory challenge.

Evaluating the effect of the antiPCSK9 vaccine on systemic inflammation and oxidative stress in an experimental mouse model

BACKGROUND

To investigate whether the antiPCSK9 vaccine can affect the CRP and oxidative stress (OS) during acute systemic inflammation.

METHODS

Male albino mice were randomly divided into three groups: non-treated mice (the sham group), treated with a nonspecific stimulator of the immune response - Freund's complete adjuvant (CFA; the CFA group), and vaccinated mice treated with CFA (the vaccine group). The vaccine group was subcutaneously immunized with the antiPCSK9 formulation, 4 × in bi-weekly intervals. To induce inflammation, all mice were subjected to the CFA challenge after the vaccination plan. The hsCRP level and OS status were evaluated by a mouse CRP ELISA kit and the pro-oxidant antioxidant balance (PAB) assay, respectively.

RESULTS

The vaccine induced a high-titter IgG antiPCSK9 antibody, which was accompanied with a significant PCSK9 reduction (-24.7% and -28.5% compared with the sham and CFA group, respectively), and the inhibition of PCSK9/LDLR interaction (-27.8% and -29.4%, respectively). hsCRP was significantly increased in the vaccine and CFA groups by 225% and 274% respectively, when compared with the sham group; however, it was non-significantly decreased (-18%; p = 0.520) in the vaccine group in comparison with the CFA group. The PAB values indicated that OS was significantly increased in the CFA group (by 72.7%) and the vaccine group (by 76%) when compared to the sham group; however, there was no significant difference in the PAB values between the vaccine and CFA groups.

CONCLUSION

The antiPCSK9 vaccine failed to significantly reduce the serum hs-CRP and OS induced in the CFA-challenged albino mice.

Peripheral CaV2.2 Channels in the Skin Regulate Prolonged Heat Hypersensitivity during Neuroinflammation

Neuroinflammation can lead to chronic maladaptive pain affecting millions of people worldwide. Neurotransmitters, cytokines, and ion channels are implicated in neuroimmune cell signaling, but their roles in specific behavioral responses are not fully elucidated. Voltage-gated CaV2.2 channel activity in skin controls rapid and transient heat hypersensitivity induced by intradermal (i.d.) capsaicin via IL-1ɑ cytokine signaling. CaV2.2 channels are not, however, involved in mechanical hypersensitivity that developed in the i.d. capsaicin animal model. Here, we show that CaV2.2 channels are also critical for heat hypersensitivity induced by i.d. complete Freund adjuvant (CFA). i.d. CFA, a model of chronic neuroinflammation, involves ongoing cytokine signaling for days leading to pronounced edema and hypersensitivity to sensory stimuli. Peripheral CaV2.2 channel activity in the skin was required for the full development and week-long time course of heat hypersensitivity induced by i.d. CFA, but paw edema and mechanical hypersensitivity were independent of CaV2.2 channel activity. CFA induced increases in several cytokines in hindpaw fluid including IL-6 which was also dependent on CaV2.2 channel activity. Using IL-6-specific neutralizing antibodies in vivo, we show that IL-6 contributes to heat hypersensitivity and that neutralizing both IL-1ɑ and IL-6 was even more effective at reducing the magnitude and duration of CFA-induced heat hypersensitivity. Our findings demonstrate a functional link between CaV2.2 channel activity and the release of IL-6 in the skin and show that CaV2.2 channels have a privileged role in the induction and maintenance of heat hypersensitivity during chronic forms of neuroinflammation in the skin.

Bioisosteric Replacement in the Search for Biologically Active Compounds: Design, Synthesis and Anti-Inflammatory Activity of Novel [1,2,4]triazino[2,3-c]quinazolines

Background: Designing novel biologically active compounds with anti-inflammatory properties based on condensed quinazolines is a significant area of interest in modern medicinal chemistry. In the present study, we describe the development of promising new bioactive molecules through the bioisosteric replacement of a carbon atom with a sulfur atom in anti-inflammatory agents, specifically 3-methyl-2-oxo-2H-[1,2,4]triazino[2,3-c]quinazolin-6-yl)butanoate. Methods: Design and synthetic studies have led to the series of previously unknown substituted 2-[((3-R-2-oxo-2H-[1,2,4]triazino[2,3-c]quinazolin-6-yl)methyl)thio]carboxylic acids and their esters. These compounds were synthesized by reacting 6-chloroalkyl-3-R-2H-[1,2,4]triazino[2,3-c]quinazolin-2-ones with sulfanylalkyl carboxylic acids and their functional derivatives. The purity and structure of the obtained compounds were confirmed using a set of physicochemical methods, including elemental analysis, HPLC-MS, and 1H NMR spectroscopy. Molecular modeling, predicted toxicity, drug-likeness, and pharmacokinetics data were used to select compounds for evaluation of their effects on acute aseptic inflammation (carrageenan-induced paw edema test) and on markers of the inflammatory process. Results: The compound 2-((1-(3-methyl-2-oxo-2H-[1,2,4]triazino[2,3-c]quinazolin-6-yl)ethyl)thio)acetic acid (compound 2e) was identified as the most active anti-inflammatory agent (AA = 53.41%), demonstrating significant inhibition of both paw edema development and the generation of pro-inflammatory cytokines and mediators. Conclusions: Results from docking studies and analysis of "structure-affinity" correlations revealed that these compounds are promising candidates for further modification and detailed investigation of their anti-inflammatory activity.

The Analgesic Effect of Morphine on Peripheral Opioid Receptors: An Experimental Research

Opioids represent one of the key pillars in postoperative pain management, but their use has been associated with a variety of serious side effects. Thus, it is crucial to investigate the timing and course of opioid administration in order to ensure a best efficacy to side-effect profile. The aim of our article was to investigate the analgesic effects of locally administered morphine sulfate (intraplantar) in a carrageenan-induced inflammation model in rats. After carrageenan administration, the rats were divided into 10 equal groups and were injected with either morphine 5 mg/kg or 0.9% saline solution at different time intervals, depending on the assigned group. The analgesic effect was assessed through thermal stimulation. Our results showed that paw withdrawal time was significantly higher in rats treated with morphine compared to those in the control group 9.18 ± 3.38 compared to 5.14 ± 2.21 seconds, p=0.012). However, differences were more pronounced at certain time intervals post-carrageenan administration (at 180 minutes compared to 360 minutes, p=0.003 and at 180 minutes compare to 1440 minutes p<0.001), indicating that efficacy varies depending on the timing of treatment. In conclusion, our findings support the hypothesis that locally administered morphine may alleviate pain under inflammatory conditions and underscores the importance of considering treatment timing when evaluating the analgesic effect.

Inflammatory pain in mice induces light cycle-dependent effects on sleep architecture

As a syndrome, chronic pain comprises physical, emotional, and cognitive symptoms such as disability, negative affect, feelings of stress, and fatigue. A rodent model of long-term inflammatory pain, induced by complete Freund's adjuvant (CFA) injection, has previously been shown to cause anhedonia and dysregulated naturalistic behaviors, in a manner similar to animal models of stress. We examined whether this extended to alterations in circadian rhythms and sleep, such as those induced by chronic social defeat stress, using actigraphy and wireless EEG. CFA-induced inflammatory pain profoundly altered sleep architecture in male and female mice. Injection of the hind paw, whether with CFA or saline, reduced some measures of circadian rhythmicity such as variance, period, and amplitude. CFA increased sleep duration primarily in the dark phase, while sleep bout length was decreased in the light and increased in the dark phase. Additionally, CFA reduced wake bout length, especially during the dark phase. Increases in REM and SWS duration and bouts were most significant in the dark phase, regardless of whether CFA had been injected at its onset or 12 hours prior. Taken together, these results indicate that inflammatory pain acutely promotes but also fragments sleep.

The Anti-Inflammatory, Analgesic, and Antioxidant Effects of Polyphenols from Brassica oleracea var. capitata Extract on Induced Inflammation in Rodents

This study investigates the anti-inflammatory, analgesic, and antioxidant properties of polyphenols extracted from Brassica oleracea var. capitata (cabbage) ethanolic extract (BOE). Given the historical use of cabbage in traditional medicine for treating various ailments, this research aims to validate these effects scientifically. The study involved the characterization of BOE's bioactive compounds using Fourier Transform Infrared Spectroscopy (FTIR) and Liquid Chromatography-Diode Array Detection-Electro-Spray Ionization Mass Spectrometry (HPLC-DAD-ESI MS) analysis. We assessed the anti-inflammatory and analgesic effects of topical and oral BOE administration on rodent models with acute and subacute inflammation. Additionally, the antioxidant capacity of orally administered BOE was evaluated. The results showed that BOE possesses significant levels of phenolic compounds with a potent antioxidant activity. The topical administration of BOE demonstrated notable anti-inflammatory effects in the tested rodent models, which were comparable with nonsteroidal anti-inflammatory drugs. These findings suggest that BOE could be a valuable natural remedy for inflammation-related conditions, supporting its traditional uses and highlighting its potential for further pharmacological development.

Peripheral CaV2.2 channels in skin regulate prolonged heat hypersensitivity during neuroinflammation

Neuroinflammation can lead to chronic maladaptive pain affecting millions of people worldwide. Neurotransmitters, cytokines, and ion channels are implicated in neuro-immune cell signaling but their roles in specific behavioral responses are not fully elucidated. Voltage-gated CaV2.2 channel activity in skin controls rapid and transient heat hypersensitivity induced by intradermal capsaicin via IL-1α cytokine signaling. CaV2.2 channels are not, however, involved in mechanical hypersensitivity that developed in the same animal model. Here, we show that CaV2.2 channels are also critical for heat hypersensitivity induced by the intradermal (id) Complete Freund's Adjuvant (CFA) model of chronic neuroinflammation that involves ongoing cytokine signaling for days. Ongoing CFA-induced cytokine signaling cascades in skin lead to pronounced edema, and hypersensitivity to sensory stimuli. Peripheral CaV2.2 channel activity in skin is required for the full development and week-long time course of heat hypersensitivity induced by id CFA. CaV2.2 channels, by contrast, are not involved in paw edema and mechanical hypersensitivity. CFA induced increases in cytokines in hind paws including IL-6 which was dependent on CaV2.2 channel activity. Using IL-6 specific neutralizing antibodies, we show that IL-6 contributes to heat hypersensitivity and, neutralizing both IL-1α and IL-6 was even more effective at reducing the magnitude and duration of CFA-induced heat hypersensitivity. Our findings demonstrate a functional link between CaV2.2 channel activity and the release of IL-6 in skin and show that CaV2.2 channels have a privileged role in the induction and maintenance of heat hypersensitivity during chronic forms of neuroinflammation in skin.

Models in vivo and in vitro for the study of acute and chronic inflammatory activity: A comprehensive review

Inflammatory conditions are among the principal causes of morbidity worldwide, and their treatment continues to be a challenge, given the restricted availability of effective and safe drugs. Thus, the identification of new compounds with biological activity that can be used for the treatment of inflammatory disorders is an essential field in medical and health research, in order to improve the health and quality of life of patients suffering from these diseases. Evaluation of the anti-inflammatory activity of drugs requires the implementation of models that accurately depict the biochemical and/or physiological responses that characterize human inflammation; for this reason, several in vitro and in vivo models have been developed, providing a platform for discovering novel or repurposed compounds. For this reason, in the present review we have selected twelve commonly used models for the evaluation of the anti-inflammatory effect, and extensively describes the difference between in vivo and in vitro models of inflammation, highlighting their advantages and limitations. On the other hand, the inflammatory mechanisms involved in them, the methods employed for their establishment, and the different parameters assessed to determine the anti-inflammatory activity of a given compound are extensively discussed. We expect to provide a comprehensive guide for the improved selection of a suitable model for the preclinical evaluation of plausible anti-inflammatory agents.

Transdermal Delivery of Cannabidiol for the Management of Acute Inflammatory Pain: A Comprehensive Review of the Literature

The emerging field of nanotechnology has paved the way for revolutionary advancements in drug delivery systems, with nanosystems emerging as a promising avenue for enhancing the therapeutic potential and the stability of various bioactive compounds. Among these, cannabidiol (CBD), the non-psychotropic compound of the Cannabis sativa plant, has gained attention for its therapeutic properties. Consequently, researchers have devoted significant efforts to unlock the full potential of CBD's clinical benefits, where various nanosystems and excipients have emerged to overcome challenges associated with its bioavailability, stability, and controlled release for its transdermal application. Therefore, this comprehensive review aims to explain CBD's role in managing acute inflammatory pain and offers an overview of the state of the art of existing delivery systems and excipients for CBD. To summarize this review, a summary of the cannabinoids and therapeutical targets of CBD will be discussed, followed by its conventional modes of administration. The transdermal route of administration and the current topical and transdermal delivery systems will also be reviewed. This review will conclude with an overview of in vivo techniques that allow the evaluation of the anti-inflammatory and analgesic potentials of these systems.

Central and peripheral mechanism of MOTS-c attenuates pain hypersensitivity in a mice model of inflammatory pain

BACKGROUND

Inflammatory pain is caused by damaged tissue or noxious stimuli, accompanied by the release of inflammatory mediators that often leads to severe hyperalgesia and allodynia with limited therapy options. Recently, a novel mitochondrial-derived peptide (named MOTS-c) was reported to regulate obesity, metabolic homeostasis and inflammatory response. The aim of this study was to investigate the effects of MOTS-c and its related regulatory mechanisms involved in inflammatory pain.

METHODS

Male Kunming mice (8-10 weeks-old) were intraplantar injected with formalin, capsaicin, λ-Carrageenan and complete Freund adjuvant (CFA) to establish acute and chronic inflammatory pain. The effects of MOTS-c on the above inflammatory pain mice and its underlying mechanisms were examined by behavioral tests, quantitative polymerase chain reaction (qPCR), western blotting, enzyme linked immunosorbent assay (ELISA), immunohistochemistry (IHC) and immunofluorescence (IF).

RESULTS

Behavioral experiments investigated the potential beneficial effects of MOTS-c on multiple acute and chronic inflammatory pain in mice. The results showed that MOTS-c treatment produced potent anti-allodynic effects in formalin-induced acute inflammatory pain, capsaicin-induced nocifensive behaviors and λ-Carrageenan/CFA-induced chronic inflammatory pain model. Further mechanistic studies revealed that central MOTS-c treatment significantly ameliorated CFA-evoked the release of inflammatory factors and activation of glial cells and neurons in the spinal dorsal horn. Moreover, peripheral MOTS-c treatment reduced CFA-evoked inflammatory responses in the surface structure of hindpaw skin, accompanied by inhibiting excitation of peripheral calcitonin gene-related peptide (CGRP) and P2X3 nociceptive neurons.

CONCLUSIONS

The present study indicates that MOTS-c may serve as a promising therapeutic target for inflammatory pain.

ROS scavenging activity of polydopamine nanoparticle-loaded supramolecular gelatin-based hydrogel promoted cardiomyocyte proliferation

Reactive oxygen species (ROS) play essential roles in cellular functions, but maintaining ROS balance is crucial for effective therapeutic interventions, especially during cell therapy. In this study, we synthesized an injectable gelatin-based hydrogel, in which polydopamine nanoparticles were entrapped using supramolecular interactions. The surfaces of the nanoparticles were modified using adamantane, enabling their interactions with β-cyclodextrin-conjugated with gelatin. We evaluated the cytotoxicity and antioxidant properties of the hydrogel on neonatal rat cardiomyocytes (NRCM), where it demonstrated the ability to increase the metabolic activity of NRCMs exposed to hydrogen peroxide (H2O2) after 5 days. Hydrogel-entrapped nanoparticle exhibited a high scavenging capability against hydroxyl radical, 1'-diphenyl-2-picrylhydrazyl radicals, and H2O2, surpassing the effectiveness of ascorbic acid solution. Notably, the presence of polydopamine nanoparticles within the hydrogel promoted the proliferation activity of NRCMs, even in the absence of excessive ROS due to H2O2 treatment. Additionally, when the hydrogel with nanoparticles was injected into an air pouch model, it reduced inflammation and infiltration of immune cells. Notably, the levels of anti-inflammatory factors, IL-10 and IL-4, were significantly increased, while the pro-inflammatory factor TNF-α was suppressed. Therefore, this novel ROS-scavenging hydrogel holds promise for both efficient cell delivery into inflamed tissue and promoting tissue repair.

Anti-hyperalgesic and anti-inflammatory effects of 4R-tobacco cembranoid in a mouse model of inflammatory pain

4R is a tobacco cembranoid that binds to and modulates cholinergic receptors and exhibits neuroprotective and anti-inflammatory activity. Given the established function of the cholinergic system in pain and inflammation, we propose that 4R is also analgesic. Here, we tested the hypothesis that systemic 4R treatment decreases pain-related behaviors and peripheral inflammation via modulation of the alpha 7 nicotinic acetylcholine receptors (α7 nAChRs) in a mouse model of inflammatory pain. We elicited inflammation by injecting Complete Freund's Adjuvant (CFA) into the hind paw of male and female mice. We then assessed inflammation-induced hypersensitivity to cold, heat, and tactile stimulation using the Acetone, Hargreaves, and von Frey tests, respectively, before and at different time points (2.5 h - 8d) after a single systemic 4R (or vehicle) administration. We evaluated the contribution of α7 nAChRs 4R-mediated analgesia by pre-treating mice with a selective antagonist of α7 nAChRs followed by 4R (or vehicle) administration prior to behavioral tests. We assessed CFA-induced paw edema and inflammation by measuring paw thickness and quantifying immune cell infiltration in the injected hind paw using hematoxylin and eosin staining. Lastly, we performed immunohistochemical and flow cytometric analyses of paw skin in α7 nAChR-cre::Ai9 mice to measure the expression of α7 nAChRs on immune subsets. Our experiments show that systemic administration of 4R decreases inflammation-induced peripheral hypersensitivity in male and female mice and inflammation-induced paw edema in male but not female mice. Notably, 4R-mediated analgesia and anti-inflammatory effects lasted up to 8d after a single systemic administration on day 1. Pretreatment with an α7 nAChR-selective antagonist prevented 4R-mediated analgesia and anti-inflammatory effects, demonstrating that 4R effects are via modulation of α7 nAChRs. We further show that a subset of immune cells in the hind paw expresses α7 nAChRs. However, the number of α7 nAChR-expressing immune cells is unaltered by CFA or 4R treatment, suggesting that 4R effects are independent of α7 nAChR-expressing immune cells. Together, our findings identify a novel function of the 4R tobacco cembranoid as an analgesic agent in both male and female mice that reduces peripheral inflammation in a sex-dependent manner, further supporting the pharmacological targeting of the cholinergic system for pain treatment.

Combination Drug Therapy for the Management of Chronic Neuropathic Pain

Chronic neuropathic pain (NP) is an increasingly prevalent disease and leading cause of disability which is challenging to treat. Several distinct classes of drugs are currently used for the treatment of chronic NP, but each drug targets only narrow components of the underlying pathophysiological mechanisms, bears limited efficacy, and comes with dose-limiting side effects. Multimodal therapies have been increasingly proposed as potential therapeutic approaches to target the multiple mechanisms underlying nociceptive transmission and modulation. However, while preclinical studies with combination therapies showed promise to improve efficacy over monotherapy, clinical trial data on their efficacy in specific populations are lacking and increased risk for adverse effects should be carefully considered. Drug-drug co-crystallization has emerged as an innovative pharmacological approach which can combine two or more different active pharmaceutical ingredients in a single crystal, optimizing pharmacokinetic and physicochemical characteristics of the native molecules, thus potentially capitalizing on the synergistic efficacy between classes of drugs while simplifying adherence and minimizing the risk of side effects by reducing the doses. In this work, we review the current pharmacological options for the treatment of chronic NP, focusing on combination therapies and their ongoing developing programs and highlighting the potential of co-crystals as novel approaches to chronic NP management.

Appraisal of anti-inflammatory and immunomodulatory potential of ramipril against Freund's adjuvant-provoked arthritic rat model

Because of evident role of renin-angiotensin system in the etiology of rheumatoid arthritis, the current study's objective was to assess the anti-arthritic efficacy of ramipril through CFA-instigated arthritic model. The drug has been shown to have anti-inflammatory potential. CFA-instigated arthritic model assessed the anti-arthritic efficacy of ramipril by estimating different parameters, including paw volume, arthritic index scoring, haematological and biochemical attributes, histological and radiographic analyses, and various cytokines level. Ramipril significantly (p < 0.001) reduced paw volume and the arthritic index especially at the dose of 4mg/kg. The biochemical and haematological changes were likewise restored to normal by ramipril administration with an increase in anti-inflammatory cytokines while reducing pro-inflammatory cytokines level. Ramipril's ability to prevent arthritis by preserving the normal architecture of arthritis-induced joints is further supported by radiographic and histological investigation. The study's findings demonstrated ramipril's considerable anti-arthritic activity. To identify the precise mechanism of action, however, thorough mechanistic studies are still needed.

Tonantzitlolone B Modulates the Endogenous Opioid System to Promote Antinociception in Mice

Tonantzitlolone B (TZL-B) is a diterpene isolated from the roots of Stillingia loranthacea. Its antinociceptive effects were investigated in male Swiss mice using the following models of pain: formalin test, inflammation induced by Complete Freund's Adjuvant (CFA), tail flick test, and cold plate test. The influence of TZL-B on the opioid system was assessed in vivo, using opioid antagonists; in silico, investigating the chemical similarity among TZL-B and opioid agonists; and ex vivo, measuring preproenkephalin (PENK) gene expression in the spinal cord by RT-qPCR. TZL-B (10-1000 μg/kg) promoted antinociception in the four experimental models without impairing mice's motor function. TZL-B did not alter paw edema during CFA-induced inflammation. The antinociceptive effects of TZL-B in the tail flick and cold plate tests were diminished by the opioid antagonists naloxone (5 mg/kg), NOR-BNI (0.5 mg/kg), naltrindole (3 mg/kg), and CTOP (1 mg/kg), indicating the involvement of κ-, δ-, and μ-opioid receptors. TZL-B showed no significant chemical similarity to opioid agonists, but the treatment with TZL-B (1000 μg/kg) increased PENK gene expression in the spinal cord of mice. These data suggest that TZL-B promotes antinociception by enhancing the transcription of PENK, hence modulating the endogenous opioid system.

Myeloid Vamp3 deletion attenuates CFA-induced inflammation and pain in mice via ameliorating macrophage infiltration and inflammatory cytokine production

Persistent inflammation and associated pain significantly impact individuals' quality of life, posing substantial healthcare challenges. Proinflammatory cytokines, released by activated macrophages, play crucial roles in the development of chronic inflammatory conditions such as rheumatoid arthritis. To identify and evaluate potential therapeutic interventions targeting this process for mitigating inflammation and pain, we created myeloid cell-specific knockout of Vamp3 (vesicle-associated membrane protein 3) mice (Vamp3 Δmyel) by crossing LysM-Cre mice with newly engineered Vamp3flox/flox mice. Bone marrow-derived macrophages and peritoneal resident macrophages from Vamp3 Δmyel mice exhibited a significant reduction in TNF-α and IL-6 release compared to control mice. Moreover, Vamp3 deficiency led to decreased paw edema and ankle joint swelling induced by intraplantar injection of complete Freund's adjuvant (CFA). Furthermore, Vamp3 depletion also mitigated CFA-induced mechanical allodynia and thermal hyperalgesia. Mechanistically, Vamp3 loss ameliorated the infiltration of macrophages in peripheral sites of the hind paw and resulted in reduced levels of TNF-α and IL-6 in the CFA-injected paw and serum. RT-qPCR analysis demonstrated downregulation of various inflammation-associated genes, including TNF-α, IL-6, IL-1β, CXCL11, TIMP-1, COX-2, CD68, and CD54 in the injected paw at the test day 14 following CFA administration. These findings highlight the novel role of Vamp3 in regulating inflammatory responses and suggest it as a potential therapeutic target for the development of novel Vamp-inactivating therapeutics, with potential applications in the management of inflammatory diseases.

Geraniol Suppresses Oxidative Stress, Inflammation, and Interstitial Collagenase to Protect against Inflammatory Arthritis

Geraniol (GER) is a plant-derived acyclic isoprenoid monoterpene that has displayed anti-inflammatory effects in numerous in vivo and in vitro models. This study was therefore designed to evaluate the antiarthritic potential of GER in complete Freund's adjuvant (CFA)-induced inflammatory arthritis (IA) model in rats. IA was induced by intraplantar injection of CFA (0.1 mL), and a week after CFA administration, rats were treated with various doses of methotrexate (MTX; 1 mg/kg) or GER (25, 50, and 100 mg/kg). Treatments were given on every alternate day, and animals were sacrificed on the 35th day. Paw volume, histopathological, hematological, radiographic, and qPCR analyses were performed to analyze the severity of the disease. GER significantly reduced paw edema after 35 days of treatment, and these results were comparable to the MTX-treated group. GER-treated animals displayed a perfect joint structure with minimal inflammation and no signs of cartilage or bone damage. Moreover, GER restored red blood cell and hemoglobin levels, normalized erythrocyte sedimentation rate, platelet, and c-reactive protein values, and also attenuated the levels of rheumatoid factor. RT-qPCR analysis demonstrated that GER decreased mRNA expression of pro-inflammatory cytokines like tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta. GER also down-regulated the transcript levels of cyclooxygenase-2 (COX-2), microsomal prostaglandin E synthase-1, prostaglandin D2 synthase, and interstitial collagenase (MMP-1). Molecular docking of GER with COX-2, TNF-α, and MMP-1 also revealed that the antiarthritic effects of GER could be due to its direct interactions with these mediators. Based on our findings, it is conceivable that the antiarthritic effects of GER could be attributed to downregulation of pro-inflammatory mediators and protease like MMP-1.

Evaluation of the antiedematogenic and anti-inflammatory properties of Ximenia americana L. (Olacaceae) bark extract in experimental models of inflammation

Edema is one of the obvious indicators of inflammation and a crucial factor to take into account when assessing a substance's capacity to reduce inflammation. We aimed to evaluate the antiedematogenic and anti-inflammatory profile of the hydroethanolic barks extract of Ximenia americana (HEXA). The possible antiedematogenic and anti-inflammatory effect of EHXA (50, 100 mg/kg and 250 mg/kg v.o) was evaluated using the paw edema induced by carrageenan, zymosan, dextran, CFA and by different agents inflammatory (serotonin, histamine, arachidonic acid and PGE2), and pleurisy model induced by carrageenan and its action on IL-1β and TNF-α levels was also evaluated. HEXA demonstrated a significant antiedematogenic effect at concentrations of 50, 100 and 250 mg/kg on paw edema induced by carrageenan, zymosan and dextran. However, the concentration of 50 mg/kg as standard, demonstrating the effect in the subchronic model, induced CFA with inhibition of 59.06 %. In models of histamine-induced paw edema, HEXA showed inhibition of - 30 min: 40.49 %, 60 min: 44.70 % and 90 min: 48.98 %; serotonin inhibition - 30 min: 57.09 %, 60 min: 66.04 % and 90 min: 61.79 %; arachidonic acid inhibition - 15 min: 36.54 %, 30 min: 51.10 %, 45 min: 50.32 % and 60 min: 76.17 %; and PGE2 inhibition - 15 min: 67.78 %, 30 min: 62.30 %, 45 min: 54.25 % and 60 min: 47.92 %. HEXA significantly reduced (p < 0.01) leukocyte migration in the pleurisy model and reduced TNF-α and IL-1β levels in pleural lavage (p < 0.0001). The results showed that HEXA has the potential to have an antiedematogenic impact in both acute and chronic inflammation processes, with a putative mode of action including the suppression or regulation of inflammatory mediators.

NS5806 reduces carrageenan-evoked inflammation by suppressing extracellular signal-regulated kinase activation in primary sensory neurons and immune cells

BACKGROUND

The compound NS5806 attenuates neuropathic pain via inhibiting extracellular signal-regulated kinase (ERK) activation in neuronal somata located at the dorsal root ganglion (DRG) and superficial spinal dorsal horn. NS5806 also reduces the expansion of DRG macrophages and spinal microglia several days after peripheral nerve injury, implying an anti-inflammatory effect.

METHODS

To test whether NS5806 inhibits inflammation, as a model we intraplantarly injected carrageenan into a hind paw of the rat. To examine whether NS5806 reduces carrageenan-evoked mechanical allodynia, thermal hyperalgesia, and edema, as well as ERK activation in the nerve fibres, mast cells, and macrophages in the hind paw skin, we used behavioural, immunohistochemical, and cytological methods.

RESULTS

NS5806 did not impair motor function, affect basal nociception, or cause edema in naive rats. Six hours after carrageenan injection, mechanical allodynia, thermal hyperalgesia, and edema appeared in the rat's ipsilateral hind paw, and all were reduced by intraplantar co-injection of NS5806. NS5806 suppressed carrageenan-evoked ERK activation in the peripheral axons and somata of L4 DRG neurons, as well as mast cells and macrophages in the paw skin. NS5806 also reduced carrageenan-evoked mast cell degranulation and macrophage proliferation. NS5806 and the ERK pathway inhibitor PD98059 had a similar effect in inhibiting the proliferation of cultured RAW264.7 macrophages. Furthermore, all the in vivo anti-inflammatory effects of NS5806 were similar to those of PD98059.

CONCLUSIONS

Acting like an ERK pathway inhibitor, NS5806 reduces inflammation-evoked mechanical allodynia, thermal hyperalgesia, and edema by suppressing ERK activation in primary sensory neurons, mast cells, and macrophages.

SIGNIFICANCE

Previous studies show that NS5806 only acts on neurons. This report unveils that NS5806 also acts on immune cells in the skin to exert its anti-inflammatory effects. Since NS5806 is lipid soluble for skin penetration, it suggests that NS5806 could also be developed into an anti-inflammatory drug for external use.

Anti-inflammatory, anti-nociceptive and anti-pyretic activities of Cenchrus ciliaris L

ETHNOPHARMACOLOGICAL RELEVANCE

Cenchrus ciliaris L. belongs to the family Poaceae and is found all over the world. It is native to the Cholistan desert of Pakistan where it is locally known as 'Dhaman'. Owing to high nutritional value, C. ciliaris is used as fodder while seeds are used for bread making which are consumed by locals. It also possesses medicinal value and is extensively employed to treat pain, inflammation, urinary tract infection, and tumors.

AIM OF STUDY

Studies on the pharmacological activities of C. ciliaris are scarce in spite of its several traditional uses. To the best of our knowledge, no comprehensive study has been conducted on anti-inflammatory, analgesic and anti-pyretic activity of C. ciliaris until now. Here we employed an integrative phytochemical and in - vivo framework to evaluate the potential biological activities of C. ciliaris against inflammation, nociception and pyrexia experimentally induced in rodents.

MATERIAL AND METHODS

C. ciliaris was collected from the desert of Cholistan, Bahawalpur, Pakistan. Phytochemical profiling of C. ciliaris was done by employing GC-MS analysis. Anti-inflammatory activity of plant extract was initially determined by various in - vitro assays including albumin denaturation assay and RBC membrane stabilization assays. Finally, rodents were utilized to evaluate in - vivo anti-inflammatory, antipyretic and anti-nociceptive activities.

RESULTS

Our data revealed the presence of 67 phytochemicals in methanolic extract of C. ciliaris. The methanolic extract of C. ciliaris provided RBC membrane stabilization by 65.89 ± 0.32% and protection against albumin denaturation by 71.91 ± 3.42% at 1 mg/ml concentration. In in - vivo acute inflammatory models, C. ciliaris exhibited 70.33 ± 1.03, 62.09 ± 8.98, 70.24 ± 0.95% anti-inflammatory activity at concentration of 300 mg/ml against carrageenan, histamine and serotonin induced inflammation. In CFA induced arthritis, inhibition of inflammation was found to be 48.85 ± 5.11% at 300 mg/ml dose after 28 days of treatment. In anti-nociceptive assays C. ciliaris exhibited significant analgesic activity in both peripheral and centrally mediated pain. The C. ciliaris also reduced the temperature by 75.26 ± 1.41% in yeast induced pyrexia.

CONCLUSION

C. ciliaris exhibited anti-inflammatory effect against acute and chronic inflammation. It also showed significant anti-nociceptive and anti-pyretic activity which endorses its traditional use in the management of pain and inflammatory disorders.

Primary somatosensory cortex bidirectionally modulates sensory gain and nociceptive behavior in a layer-specific manner

The primary somatosensory cortex (S1) is a hub for body sensation of both innocuous and noxious signals, yet its role in somatosensation versus pain is debated. Despite known contributions of S1 to sensory gain modulation, its causal involvement in subjective sensory experiences remains elusive. Here, in mouse S1, we reveal the involvement of cortical output neurons in layers 5 (L5) and 6 (L6) in the perception of innocuous and noxious somatosensory signals. We find that L6 activation can drive aversive hypersensitivity and spontaneous nocifensive behavior. Linking behavior to neuronal mechanisms, we find that L6 enhances thalamic somatosensory responses, and in parallel, strongly suppresses L5 neurons. Directly suppressing L5 reproduced the pronociceptive phenotype induced by L6 activation, suggesting an anti-nociceptive function for L5 output. Indeed, L5 activation reduced sensory sensitivity and reversed inflammatory allodynia. Together, these findings reveal a layer-specific and bidirectional role for S1 in modulating subjective sensory experiences.

REV-ERB activation as a novel pharmacological approach for treating inflammatory pain

Pain is a complex problem affecting millions of people worldwide. The current therapies to reduce pain are limited as many treatment options inadequately address the causes of pain, lead to tolerance of the drug, or have adverse effects including abuse potential. While there are many causes of pain, one underlying mechanism to the pathogenesis and maintenance of pain conditions is chronic inflammation driven by the NLRP3 inflammasome. Several inflammasome inhibitors are currently under investigation however have the potential to suppress the functioning of the innate immune system, which may cause unwanted affects in patients. Here, we show that the nuclear receptor REV-ERB can suppress the activation of the inflammasome when pharmacologically activated with small molecule agonists. Additionally, REV-ERB activation appears to have analgesic potential in a model of acute inflammatory pain, likely as a result of inflammasome suppression.

Novel mannich-based derivative of 2-mercaptobenzimidazole (AK7): a new candidate for the treatment of inflammatory arthritis owing to its NF-κB1 inhibitory potential

This study investigated the anti-arthritic potential of novel mannich-based derivatives of 2-mercaptobenzimidazole (AK7 and AK9) in rats. The compounds were characterized by NMR and FTIR spectroscopies and their acute anti-inflammatory effects were measured by carrageenan (CRG)-induced paw edema model. The most potent doses of AK7 and AK9 were subsequently evaluated in the complete Freund's adjuvant (CFA)-induced inflammatory arthritis model. AK7 and AK9 inhibited CRG-induced inflammation in a dose-dependent fashion and a similar reduction in CFA-induced paw inflammation was observed. Moreover, X-ray and histopathological analyses of AK7-treated animals displayed normal joint structure whereas AK9, despite of its anti-inflammatory effects, failed to protect against cartilage destruction. Interestingly, biochemical analysis revealed a better safety profile for AK7 than for AK9 and methotrexate. Both compounds suppressed mRNA levels of pro-inflammatory mediators (IRAK1, NF-κB1, TNF-α, IL1B) while only AK7 reduced the transcript levels of interstitial collagenase (MMP1). Molecular docking analysis of AK7 and AK9 with TNF-α and MMP1 also supported the experimental data. These findings clearly highlight the beneficial effects of AK7 in the prevention and/or treatment of inflammatory arthritis.

Endogenous Derivatives of Linoleic Acid and their Stable Analogs Are Potential Pain Mediators

Psoriasis is characterized by intense pruritus, with a subset of individuals with psoriasis experiencing thermal hypersensitivity. However, the pathophysiology of thermal hypersensitivity in psoriasis and other skin conditions remains enigmatic. Linoleic acid is an omega-6 fatty acid that is concentrated in the skin, and oxidation of linoleic acid into metabolites with multiple hydroxyl and epoxide functional groups has been shown to play a role in skin barrier function. Previously, we identified several linoleic acid‒derived mediators that were more concentrated in psoriatic lesions, but the role of these lipids in psoriasis remains unknown. In this study, we report that two such compounds-9,10-epoxy-13-hydroxy-octadecenoate and 9,10,13-trihydroxy-octadecenoate-are present as free fatty acids and induce nociceptive behavior in mice but not in rats. By chemically stabilizing 9,10-epoxy-13-hydroxy-octadecenoate and 9,10,13-trihydroxy-octadecenoate through the addition of methyl groups, we observed pain and hypersensitization in mice. The nociceptive responses suggest an involvement of the TRPA1 channel, whereas hypersensitive responses induced by these mediators may require both TRPA1 and TRPV1 channels. Furthermore, we showed that 9,10,13-trihydroxy-octadecenoate‒induced calcium transients in sensory neurons are mediated through the Gβγ subunit of an unidentified G-protein coupled receptor (GPCR). Overall, mechanistic insights from this study will guide the development of potential therapeutic targets for the treatment of pain and hypersensitivity.

Validation of traditional claims of anti-arthritic efficacy of trans-Himalayan snow mountain garlic (Allium ampeloprasum L.) extract using adjuvant-induced arthritis rat model: A comparative evaluation with normal garlic (Allium sativum L.) and dexamethasone

ETHNOPHARMACOLOGICAL RELEVANCE

Snow Mountain Garlic (SMG) (Allium ampeloprasum L.) is a wild trans-Himalayan member of the genus Allium, valued for its anti-inflammatory and anti-arthritic properties in the mountain folk medicinal system (Sowa-Rigpa). Despite its age-old medicinal usage by traditional therapists and the native population for various ailments including rheumatism, there is no scientific validation of its phyto-pharmaceutical merits.

AIM OF THE STUDY

The present pre-clinical study compared the in-vivo anti-arthritic effects of SMG with reported efficacy doses of normal garlic (Allium sativum L.) extract and dexamethasone in a complete Freund's adjuvant (CFA)-induced arthritis rat model.

MATERIALS AND METHODS

The female Wistar rats were immunized by the subplannter injection of CFA into the right hind footpad. Aqueous extracts of SMG and normal garlic were administered orally at a dose of 250 mg/kg and 500 mg/kg for 28 days. Dexamethasone was used as positive control drug. Behavioral parameters including paw markers, arthritis index, joint stiffness, body weight change, etc. were measured. Also, the changes in histopathological indices, hematological profile, inflammatory mediators, and serum cytokines level was determined.

RESULTS

Treatment of rats with SMG extracts significantly (p < 0.001) prevented the reduction in body weight and hematological changes as well as ameliorated clinical symptoms such as arthritic index, joint stiffness, arthritis score, edema, hyperalgesia, and histopathological indices. This was associated with a significant reduction in the serum levels of RF, CRP, anti-CCP, and proinflammatory cytokines exhibiting strong anti-arthritic potential. SMG extracts could also significantly down regulate the NF-κB, COX-2, and iNOS expression in the ankle joint tissues.

CONCLUSIONS

The present study is the first attempt to validate the phyto-pharmaceutical efficacy of this folk garlic variety from the trans-Himalayan region. Overall, SMG extract showed remarkable preventive anti-inflammatory and anti-arthritic activities which were closely comparable to therapeutic effects of dexamethasone and at par or even better than normal garlic w.r.t. several study parameters.

Discovery of , a Selective CNS Penetrant Chemical Probe as Transient Receptor Potential Ankyrin 1 (TRPA1) Antagonist

Transient receptor potential ankyrin 1 (TRPA1) is a voltage-dependent, ligand-gated ion channel, and activation thereof is linked to a variety of painful conditions. Preclinical studies have demonstrated the role of TRPA1 receptors in a broad range of animal models of acute, inflammatory, and neuropathic pain. In addition, a clinical study using the TRPA1 antagonist GRC-17536 (Glenmark Pharmaceuticals) demonstrated efficacy in a subgroup of patients with painful diabetic neuropathy. Consequently, there is an increasing interest in TRPA1 inhibitors as potential analgesics. Herein, we report the identification of a fragment-like hit from a high-throughput screening (HTS) campaign and subsequent optimization to provide a novel and brain-penetrant TRPA1 inhibitor (compound 18, BAY-390), which is now being made available to the research community as an open-source in vivo probe.

The Double Insult of Neonatal Cystitis Plus Adult Somatic Inflammation Results in Corticotropin Releasing Factor Type II Receptor-Dependent Bladder Hypersensitivity in Female Rats

The spinal mechanisms of visceral hypersensitivity are poorly understood, particularly when there is an interaction with somatic systems. Recently we demonstrated that rats which were pretreated with neonatal bladder inflammation (NBI) and subsequently pretreated as adults with bladder re-inflammation had augmented reflex and neuronal responses to urinary bladder distension via a corticotropin-releasing factor receptor type II (CRFR2) mechanism. Another insult producing similar augmented responses is somatic inflammation induced by Complete Freund's Adjuvant (CFA) in the hindlimb. Using neurochemical measures and both reflex and neuronal responses to urinary bladder distension as endpoints, the present study probed the role of CRFR2-related mechanisms in bladder hyperalgesia secondary to NBI and CFA-induced hindlimb inflammation. ELISA measures of the lumbosacral spinal cord demonstrated increased CRFR2 protein following pretreatment with NBI+CFA. Intrathecal CRFR2 antagonists blocked the augmentation of visceromotor responses to distension following pretreatment with both NBI+CFA. Lumbosacral dorsal horn neuronal responses to bladder distension in rats pretreated with NBI+CFA were attenuated by the spinal topical administration of a CRFR2 antagonist. These findings are the first demonstration of a somatovisceral interaction working via CRFR2 receptors and support the therapeutic value of these agents in the treatment of painful bladder disorders, particularly when triggered by somatic events. (Word Count 199). PERSPECTIVE: Bladder hypersensitivity occurs following neonatal cystitis and an adult insult such as somatic inflammation. This paper demonstrates that CRFR2-related mechanisms are associated with this hypersensitivity. This supports the therapeutic value of these agents in the treatment of painful bladder disorders, particularly when triggered by somatic events.

An In Vivo Mouse Model for Chronic Inflammation-Induced Immune Suppression: A "Factory" for Myeloid-Derived Suppressor Cells (MDSCs)

Myeloid-derived suppressor cells (MDSCs) represent a heterogeneous population of immature myeloid cells known to play a role in perpetuating a wide range of pathologies, such as chronic infections, autoimmune diseases, and cancer. MDSCs were first identified in mice by the markers CD11b+ Gr1+ , and later, based on their morphology, they were classified into two subsets: polymorphonuclear MDSCs, identified by the markers CD11b+ Ly6G+ Ly6CLow , and monocytic MDSCs, detected as being CD11b+ Ly6G- Ly6CHi . MDSCs are studied as immunosuppressive cells in various diseases characterized by chronic inflammation and are associated with disease causes/triggers such as pathogens, autoantigens, and cancer. Therefore, different diseases may diversely affect MDSC metabolism, migration, and differentiation, thus influencing the generated MDSC functional features and ensuing suppressive environment. In order to study MDSCs in a pathology-free environment, we established and calibrated a highly reproducible mouse model that results in the development of chronic inflammation, which is the major cause of MDSC accumulation and immune suppression. The model presented can be used to study MDSC phenotypes, functional diversity, and plasticity. It also permits study of MDSC migration from the bone marrow to peripheral lymphatic and non-lymphatic organs and MDSC crosstalk with extrinsic factors, both in vivo and ex vivo. Furthermore, this model can serve as a platform to assess the effects of anti-MDSC modalities. © 2022 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol: Repetitive M.tb immunizations for the induction of chronic inflammation Alternate Protocol 1: Creating a lower grade of inflammation by changing the site of immunization Alternate Protocol 2: In vivo evaluation of immune status Support Protocol 1: Preparation of reconstituted M.tb aliquots and M.tb-IFA emulsions for each of the three injections Support Protocol 2: Preparation of an ovalbumin lentiviral expression vector Support Protocol 3: Fluorescence titering assay for the lentiviral expression vector Support Protocol 4: Spleen excision, tissue dissociation, and preparation of a single-cell suspension Support Protocol 5: Labeling of splenocytes with CFSE proliferation dye.

"Shikonin inhibits microglia activation and reduces CFA-induced mechanical hyperalgesia in an animal model of pain"

Shikonin is an ointment produced from Lithospermun erythrorhizon which has been used in traditional medicine both in Europe and Asia for wound healing and is associated with anti-inflammatory properties. The goal of this work is to assess the analgesic properties of Shikonin in the CFA-induced inflammation model of pain. Rats were subjected to inflammation of the hind paw by CFA injection with a preventive injection of Shikonin and compared to either a control group or to a CFA-inflamed group with the vehicle drug solution. Inflammation of the hind paw by CFA was assessed by measurement of the dorsal to plantar diameter. Mechanical thresholds were established by means of the Von Frey filaments which are calibrated filaments that exert a defined force. Finally, the spinal cord of the studied animals was extracted to analyse the microglia population through immunohistochemistry using the specific marker Iba-1. Our results show that Shikonin reduces the paw oedema caused by CFA inflammation. Subsequently, there is a concomitant restoration of the mechanical thresholds reduced by CFA hind paw injection. Additionally, spinal microglia is activated after CFA-induced inflammation. Our results show that microglia is inhibited by Shikonin and has concomitant restoration of the mechanical thresholds. Our findings demonstrate for the first time that Shikonin inhibits microglia morphological changes and thereby ameliorates pain-like behaviour elicited by mechanical stimulation.

Effect of Diclofenac and Andrographolide Combination on Carrageenan-Induced Paw Edema and Hyperalgesia in Rats

Studies into drug combination at low doses are a promising approach to the management of pain and inflammation. The aim of this study was to evaluate the anti-edema and anti-hyperalgesic effects of a combination of diclofenac and andrographolide. Male Sprague-Dawley rats were first treated with diclofenac or andrographolide alone (3–100 mg/kg), as well as a combination of the 2 drugs. Carrageenan was then injected into the right hind paw of rats, and changes in paw volume and sensitivity to mechanical (von Frey) and thermal (Hargreaves test) stimuli measured. Results showed drug combination produced synergistic effects at reducing paw edema especially at lower doses, with a Loewe synergy score of 13.02 ± 8.75 in SynergyFinder and a combination index of .41 ± .18 after isobolographic analysis. Again synergy scores for decreasing response to 1.0 and 3.6 g force application of von Frey filaments after drug combination were 10.127 ± 5.68 and 8.554 ± 6.53, respectively, in SynergyFinder. Synergistic effects were also seen after drug combination in the Hargreaves test with a synergy score of 5.136 ± 16.38. In conclusion, combination of diclofenac with andrographolide showed better pharmacologic effects after carrageenan injection and was more synergistic at low-dose combinations.

Role of cathepsin K in the expression of mechanical hypersensitivity following intra-plantar inflammation

Persistent/chronic inflammatory pain involves multiple pathophysiological mechanisms and is far more complex than acute/momentary pain. Current therapeutics for chronic inflammatory pain are often not effective because the etiology responsible for the pain is not addressed by traditional pharmacological treatments. Cathepsin K is a cysteine protease that has mostly been studied in the context of bone and joint disorders. Previous work by others has shown that inhibition of cathepsin K activity reduces osteoarthritis-associated nociception in joints. However, the role of cathepsin K in cutaneous inflammation is understudied. We assessed the effectiveness of genetic deletion or pharmacological inhibition of cathepsin K in male mice on the expression of nocifensive behaviors after formalin injection or mechanical and thermal hypersensitivity after injection of complete Freund’s adjuvant (CFA) into the mouse hind paw. Our data demonstrate that cathepsin K knockout mice (Ctsk^−/−) have a reduction in nocifensive behaviors in the formalin test. In addition, Ctsk^−/− do not develop mechanical hypersensitivity after CFA injection for up to 7 days. Moreover, we found that inhibition of cathepsin K reduced mechanical hypersensitivity after CFA injection and mRNA levels, protein levels, and cathepsin K activity levels were elevated after CFA injection. Based upon our data, cathepsin K is indicated to play a role in the expression of chemically-induced cutaneous hypersensitivity, as Ctsk^−/− mice do not develop mechanical hypersensitivity and show a reduction in nocifensive behaviors. Further research is needed to determine whether attenuating cathepsin K activity may generate a clinically relevant therapeutic.

Structural analysis of TrkA mutations in patients with congenital insensitivity to pain reveals PLCγ as an analgesic drug target

Chronic pain is a major health issue, and the search for new analgesics has become increasingly important because of the addictive properties and unwanted side effects of opioids. To explore potentially new drug targets, we investigated mutations in the NTRK1 gene found in individuals with congenital insensitivity to pain with anhidrosis (CIPA). NTRK1 encodes tropomyosin receptor kinase A (TrkA), the receptor for nerve growth factor (NGF) and that contributes to nociception. Molecular modeling and biochemical analysis identified mutations that decreased the interaction between TrkA and one of its substrates and signaling effectors, phospholipase Cγ (PLCγ). We developed a cell-permeable phosphopeptide derived from TrkA (TAT-pQYP) that bound the Src homology domain 2 (SH2) of PLCγ. In HEK-293T cells, TAT-pQYP inhibited the binding of heterologously expressed TrkA to PLCγ and decreased NGF-induced, TrkA-mediated PLCγ activation and signaling. In mice, intraplantar administration of TAT-pQYP decreased mechanical sensitivity in an inflammatory pain model, suggesting that targeting this interaction may be analgesic. The findings demonstrate a strategy to identify new targets for pain relief by analyzing the signaling pathways that are perturbed in CIPA.

Amphiphilic Poly-N-vinylpyrrolidone Nanoparticles as Carriers for Nonsteroidal, Anti-Inflammatory Drugs: Pharmacokinetic, Anti-Inflammatory, and Ulcerogenic Activity Study

Nanoparticles are increasingly utilized as drug delivery agents. Previously, we have developed a drug delivery system based on amphiphilic derivatives of poly-N-vinylpyrrolidone (PVP-OD4000) with excellent biocompatibility. In the current study, we assessed the pharmacokinetics, anti-inflammatory profile, and ulcerogenic potential of indomethacin (IMC)-loaded PVP-OD4000 nanoparticles compared to the free drug. Wistar male rats were utilized for a pharmacokinetics study and an anti-inflammatory study. Loaded IMC exhibited a slower elimination rate (p < 0.05) and a higher blood plasma concentration at 8 and 24 h after intraperitoneal injection compared with free IMC. In addition, decreased uptake of loaded IMC in the liver and kidney compared to free IMC (p < 0.05) was detected. Furthermore, PVP-OD4000 nanoparticles loaded with IMC showed an enhanced anti-inflammatory effect compared to free IMC (p < 0.05) in carrageenan-induced and complete Freund’s adjuvant-induced−(CFA) sub-chronic and chronic paw edema treatment (p < 0.01; p < 0.01). Notably, upon oral administration of loaded IMC, animals had a significantly lower ulcer score and Paul’s Index (3.9) compared to the free drug (p < 0.05). The obtained results suggest that IMC loaded to PVP nanoparticles exhibit superior anti-inflammatory activity in vivo and a safe gastrointestinal profile and pose a therapeutic alternative for the currently available NSAIDs’ administration.

Sida tuberculata: In vitro cytotoxicity and in vivo anti-inflammatory effect

ETHNOPHARMACOLOGICAL RELEVANCE

Sida tuberculata R. E. Fries (Malvaceae) is a pioneer species considered a weed in farm fields in Southern Brazil. Widely distributed in South Brazil, S. tuberculata is popularly used to treat inflammatory conditions.

AIMS OF THE STUDY

The current study aimed to assess the in vitro cytotoxic and in vivo anti-inflammatory properties of S. tuberculata.

MATERIALS AND METHODS

Initially, extracts obtained from leaves (STLE) and roots (STRE) were submitted to cytotoxicity tests using human leukocytes (non-malignant cell line) and HepG2 and MCF-7 (tumor cell lines). In sequence, anti-inflammatory properties were investigated against carrageenan-induced peritonitis model.

RESULTS

In vitro analyses displayed a significant decrease in human leukocytes viability without genotoxic damage. IC₅₀ results from tumor cells presented significant decrease in cell viability, slightly more pronounced for STRE. In addition, STLE significantly inhibited the inflammatory and oxidative parameters (TBARS, NPSH, SOD, MPO activity, cell influx, and cytokines release).

CONCLUSION

Our findings indicate S. tuberculata extracts have cytotoxic potential more pronounced on tumor cell lines, as well as leaves extract shows a significant reduction in acute inflammation process, as already reported for Sida genus and specifically for this species.

Advances and Barriers in Understanding Presynaptic N-Methyl-D-Aspartate Receptors in Spinal Pain Processing

For decades, N-methyl-D-aspartate (NMDA) receptors have been known to play a critical role in the modulation of both acute and chronic pain. Of particular interest are NMDA receptors expressed in the superficial dorsal horn (SDH) of the spinal cord, which houses the nociceptive processing circuits of the spinal cord. In the SDH, NMDA receptors undergo potentiation and increases in the trafficking of receptors to the synapse, both of which contribute to increases in excitability and plastic increases in nociceptive output from the SDH to the brain. Research efforts have primarily focused on postsynaptic NMDA receptors, despite findings that presynaptic NMDA receptors can undergo similar plastic changes to their postsynaptic counterparts. Recent technological advances have been pivotal in the discovery of mechanisms of plastic changes in presynaptic NMDA receptors within the SDH. Here, we highlight these recent advances in the understanding of presynaptic NMDA receptor physiology and their modulation in models of chronic pain. We discuss the role of specific NMDA receptor subunits in presynaptic membranes of nociceptive afferents and local SDH interneurons, including their modulation across pain modalities. Furthermore, we discuss how barriers such as lack of sex-inclusive research and differences in neurodevelopmental timepoints have complicated investigations into the roles of NMDA receptors in pathological pain states. A more complete understanding of presynaptic NMDA receptor function and modulation across pain states is needed to shed light on potential new therapeutic treatments for chronic pain.

Sanguinarine-Chelerythrine Fraction of Coptis chinensis Exerts Anti-inflammatory Activity in Carrageenan Paw Oedema Test in Rats and Reveals Reduced Gastrotoxicity

Inflammatory diseases are a common therapeutic problem and nonsteroidal anti-inflammatory drugs are not deprived of side effects, of which ulcerogenic activity is one of the most frequent. The aim of the study was to evaluate the anti-inflammatory activity of the sanguinarine-chelerythrine (SC) fraction of Coptis chinensis and its influence on the integrity of gastric mucosa. The study was conducted on sixty male rats randomly divided into six experimental groups: two control groups (a negative control group CON and a positive control group CAR); three groups receiving an investigational fraction of C. chinensis (1, 5, 10 mg/kg i.g.) named SC1, SC5, and SC10, respectively; and a group receiving indomethacin (IND) (10 mg/kg i.g.) as a reference drug. In all animals, the carrageenan-induced paw oedema was measured; PGE2 release, TNFα production, and MMP-9 concentration in inflamed tissue were determined. Additionally, the macroscopic and microscopic damage of gastric mucosa was evaluated. Administration of SC dose-dependently inhibited the second phase of carrageenan rat paw oedema and PGE2 release, decreased the production of TNFα, and reduced the concentration of MMP-9, and the efficacy of the highest dose was comparable to the effect of IND. Contrary to IND, no gastrotoxic activity of SC was detected. The investigated sanguinarine-chelerythrine fraction of C. chinensis seems to be a promising candidate for further research on new anti-inflammatory and analgesic drugs characterized with a safer gastric profile compared to existing NSAIDs.

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.

The Use of κ-Carrageenan in Egg Yolk Free Extender Improves the Efficiency of Canine Semen Cryopreservation

κ-Carrageenan is a plant polysaccharide derived from red seaweeds reported to possess potential medicinal and antioxidants activities. The present study aimed to identify the cryoprotective effects of κ-carrageenan on the quality of frozen-thawed canine semen. Twenty-eight ejaculates were collected and diluted in a Tris egg-yolk-free extender supplemented with various concentrations of κ-carrageenan (0.0%, 0.1%, 0.2%, 0.3%, and 0.5%). The addition of κ-carrageenan to the extender at a 0.2% concentration induced a significant increase in the total motility (TM) and the rapid progressive motility (RPM) of canine sperm. Among the experimental groups, the highest percentage of sperms with intact acrosomes was found in the 0.5% κ-carrageenan group (p < 0.05). Apoptosis levels were significantly lower in the 0.1% and 0.2% κ-carrageenan treatment. Moreover, sperm in the κ-carrageenan supplemented group showed a significantly higher expression of antiapoptotic (Bcl-2) and lower expression of NADPH oxidase (NOX5), spermine synthase (SMS), and spermine oxidase (SMOX) genes than those in the control group. In conclusion, the addition of κ-carrageenan to the freezing extender improved the overall efficiency of frozen-thawed dog spermatozoa.

Selected Thiadiazine-Thione Derivatives Attenuate Neuroinflammation in Chronic Constriction Injury Induced Neuropathy

Neuropathic pain refers to a lesion or disease of peripheral and/or central somatosensory neurons and is an important body response to actual or potential nerve damage. We investigated the therapeutic potential of two thiadiazine-thione [TDT] derivatives, 2-(5-propyl-6-thioxo-1, 3, 5-thiadiazinan-3-yl) acetic acid [TDT1] and 2-(5-propyl-2-thioxo-1, 3, 5-thiadiazinan-3-yl) acetic acid [TDT2] against CCI (chronic constriction injury)-induced neuroinflammation and neuropathic pain. Mice were used for assessment of acute toxicity of TDT derivatives and no major toxic/bizarre responses were observed. Anti-inflammatory activity was assessed using the carrageenan test, and both TDT1 and TDT2 significantly reduced carrageenan-induced inflammation. We also used rats for the induction of CCI and performed allodynia and hyperalgesia-related behavioral tests followed by biochemical and morphological analysis using RT-qPCR, immunoblotting, immunohistochemistry and immunofluorescence. Our findings revealed that CCI induced clear-cut allodynia and hyperalgesia which was reversed by TDT1 and TDT2. To determine the function of TDT1 and TDT2 in glia-mediated neuroinflammation, Iba1 mRNA and protein levels were measured in spinal cord tissue sections from various experimental groups. Interestingly, TDT1 and TDT2 substantially reduced the mRNA expression and protein level of Iba1, implying that TDT1 and TDT2 may mitigate CCI-induced astrogliosis. In silico molecular docking studies predicted that both compounds had an effective binding affinity for TNF-α and COX-2. The compounds interactions with the proteins were dominated by both hydrogen bonding and van der Waals interactions. Overall, these results suggest that TDT1 and TDT2 exert their neuroprotective and analgesic potentials by ameliorating CCI-induced allodynia, hyperalgesia, neuroinflammation and neuronal degeneration in a dose-dependent manner.

Novel 1,3,4-Oxadiazole Derivatives of Pyrrolo[3,4-d]Pyridazinone Exert Anti-Inflammatory Activity without Acute Gastrotoxicity in the Carrageenan-Induced Rat Paw Edema Test

Background and Purpose

Due to the risk of gastrointestinal damage and various tissue toxicity associated with non-steroidal anti-inflammatory drugs (NSAIDs) use, investigating new anti-inflammatory agents with efficacy comparable to that of NSAIDs but reduced toxicity is still a major challenge and a clinical need. Based on our previous study, new 1,3,4-oxadiazole derivatives of pyrrolo[3,4-d]pyridazinone, especially 6-butyl-3,5,7-trimethyl-1-[[4-[[4-(4-nitrophenyl)piperazin-1-yl]methyl]-5-thioxo-1,3,4-oxadiazol-2-yl]methoxy]pyrrolo[3,4-d]pyridazin-4-one and 6-butyl-1-[[4-[[4-(4-chlorophenyl)-4-hydroxy-1-piperidyl]methyl]-2-thioxo-1,3,4-oxadiazol-5-yl]methoxy]-3,5,7-trimethyl-pyrrolo[3,4-d]pyridazin-4-one (hereafter referred to as the compounds 10b and 13b, respectively) seem to be promising anti-inflammatory agents. This study aimed to elucidate the effects of these two new derivatives on the course of experimental rat inflammation, liver and kidney function, and gastric mucosa.

Methods

The anti-inflammatory effect of compounds 10b and 13b was evaluated using the carrageenan-induced paw edema test in rats. The increase in paw volume (paw edema), prostaglandin E₂ (PGE₂), tumor necrosis factor-α (TNF-α) and myeloperoxidase (MPO) levels, histological alterations, and inflammatory cell infiltration in paw tissue were determined. Serum alanine transaminase (ALT) and aspartate transaminase (AST) activities, serum urea and creatinine levels, as well as changes in gastric mucosa, were measured as indicators of hepatic, renal, and gastric toxicity.

Results

Pretreatment with both novel derivatives at 10 mg/kg and 20 mg/kg doses reduced paw edema, counteracted the increased PGE₂ and TNF-α levels, reduced the influx of inflammatory cells, and decreased histopathological alterations in paw tissue. Compound 13b at a dose of 20 mg/kg was more effective than indomethacin in reversing the increased TNF-α levels and reducing the influx of inflammatory cells. Only compound 13b at all studied doses (5, 10, or 20 mg/kg) counteracted the increased MPO level in paw tissue. Both compounds neither caused alterations in ALT, AST, urea, creatinine parameters nor gastric mucosal lesions.

Conclusion

New compounds exert an anti-inflammatory effect, presumably via inhibiting inflammatory mediators release and inflammatory cell infiltration. Moreover, both possess a more favorable benefit–risk profile than indomethacin, especially compound 13b.

[68Ga]Ga-4HMSA a promising new PET tracer for imaging inflammation

BACKGROUND

Imaging diagnosis of inflammation has been challenging for many years. Inflammation imaging agents commonly used in nuclear medicine, such as [⁶⁷Ga]Ga-citrate and 2-deoxy-2-[¹⁸F]fluoro-D-glucose ([¹⁸F]FDG) showed some limitations. The identification of a radiotracer with high specificity and low radiation dose is clinically important. With the commercialization of ⁶⁸Ge/⁶⁸Ga generators and the high ⁶⁸Ga cyclotron production capacity, the study of ⁶⁸Ga-based tracer for inflammation has increased and shown good potential. In the present work, we report the synthesis of 4HMSA, a new acyclic chelator, and its first investigation for ⁶⁸Ga complexation and as a new positron emission tomography (PET) imaging agent of inflammation in comparison to [⁶⁸Ga]Ga-citrate.

RESULTS

The present experimental studies have shown that the novel [⁶⁸Ga]Ga-4HMSA is stable allowing imaging of inflammation in a preclinical model of adjuvant- and pathogen-based inflammation involving intraplantar injection of complete Freund's adjuvant (CFA). We also found that [⁶⁸Ga]Ga-4HMSA displayed similar uptakes in the inflamed paw than [⁶⁸Ga]Ga-citrate, which are superior compared to those of contralateral (non-injected) paws at days 1-3 from PET imaging. [⁶⁸Ga]Ga-citrate accumulated in the upper body of the animal such as the liver, lungs and the heart, whereas the [⁶⁸Ga]Ga-4HMSA revealed low uptakes in the majority of the organs and was cleared relatively rapidly from blood circulation through the kidneys and bladder.

CONCLUSION

The results highlight the potential of [⁶⁸Ga]Ga-4HMSA as an interesting alternative to [⁶⁸Ga]Ga-citrate for inflammation imaging by PET. The new PET tracer also offers additional advantages than [⁶⁸Ga]Ga-citrate in term of dosimetry and lower overall background activity.

The Persistent Pain Transcriptome: Identification of Cells and Molecules Activated by Hyperalgesia

During persistent pain, the dorsal spinal cord responds to painful inputs from the site of injury, but the molecular modulatory processes have not been comprehensively examined. Using transcriptomics and multiplex in situ hybridization, we identified the most highly regulated receptors and signaling molecules in rat dorsal spinal cord in peripheral inflammatory and post-surgical incisional pain models. We examined a time course of the response including acute (2 hours) and longer term (2 day) time points after peripheral injury representing the early onset and instantiation of hyperalgesic processes. From this analysis, we identify a key population of superficial dorsal spinal cord neurons marked by somatotopic upregulation of the opioid neuropeptide precursor prodynorphin, and 2 receptors: the neurokinin 1 receptor, and anaplastic lymphoma kinase. These alterations occur specifically in the glutamatergic subpopulation of superficial dynorphinergic neurons. In addition to specific neuronal gene regulation, both models showed induction of broad transcriptional signatures for tissue remodeling, synaptic rearrangement, and immune signaling defined by complement and interferon induction. These signatures were predominantly induced ipsilateral to tissue injury, implying linkage to primary afferent drive. We present a comprehensive set of gene regulatory events across 2 models that can be targeted for the development of non-opioid analgesics. PERSPECTIVE: The deadly impact of the opioid crisis and the need to replace morphine and other opioids in clinical practice is well recognized. Embedded within this research is an overarching goal of obtaining foundational knowledge from transcriptomics to search for non-opioid analgesic targets. Developing such analgesics would address unmet clinical needs.

Analgesic and Anti-Inflammatory Effects of the Synthetic Neurosteroid Analogue BNN27 during CFA-Induced Hyperalgesia

Dehydroepiandrosterone (DHEA), an adrenal and neurosteroid hormone with strong neuroprotective and immunomodulatory properties, and ligand for all high-affinity neurotrophin tyrosine kinase receptors (Trk), also exerts important effects on hyperalgesia. Its synthetic, 17-spiro-epoxy analogue, BNN27, cannot be converted to estrogen or androgen as DHEA; it is a specific agonist of TrkA, the receptor of pain regulator Nerve Growth Factor (NGF), and it conserves the immunomodulatory properties of DHEA. Our study aimed to evaluate the anti-nociceptive and anti-inflammatory properties of BNN27 during Complete Freund’s Adjuvant (CFA)-induced inflammatory hyperalgesia in mice. Hyperalgesia was evaluated using the Hargreaves test. Inflammatory markers such as cytokines, NGF and opioids were measured, additionally to corticosterone and the protein kinase B (AKT) signaling pathway. We showed for the first time that treatment with BNN27 reversed hyperalgesia produced by CFA. The effect of BNN27 involved the inhibition of NGF in the dorsal root ganglia (DRG) and the increased synthesis of opioid peptides and their receptors in the inflamed paw. We also found alterations in the cytokine levels as well as in the phosphorylation of AKT2. Our findings strongly support that BNN27 represents a lead molecule for the development of analgesic and anti-inflammatory compounds with potential therapeutic applications in inflammatory hyperalgesia.

Pituitary hormones are specifically expressed in trigeminal sensory neurons and contribute to pain responses in the trigeminal system

Trigeminal (TG), dorsal root (DRG), and nodose/jugular (NG/JG) ganglia each possess specialized and distinct functions. We used RNA sequencing of two-cycle sorted Pirt-positive neurons to identify genes exclusively expressing in L3-L5 DRG, T10-L1 DRG, NG/JG, and TG mouse ganglion neurons. Transcription factor Phox2b and Efcab6 are specifically expressed in NG/JG while Hoxa7 is exclusively present in both T10-L1 and L3-L5 DRG neurons. Cyp2f2, Krt18, and Ptgds, along with pituitary hormone prolactin (Prl), growth hormone (Gh), and proopiomelanocortin (Pomc) encoding genes are almost exclusively in TG neurons. Immunohistochemistry confirmed selective expression of these hormones in TG neurons and dural nerves; and showed GH expression in subsets of TRPV1+ and CGRP+ TG neurons. We next examined GH roles in hypersensitivity in the spinal versus trigeminal systems. Exogenous GH produced mechanical hypersensitivity when injected intrathecally, but not intraplantarly. GH-induced thermal hypersensitivity was not detected in the spinal system. GH dose-dependently generated orofacial and headache-like periorbital mechanical hypersensitivity after administration into masseter muscle and dura, respectively. Periorbital mechanical hypersensitivity was reversed by a GH receptor antagonist, pegvisomant. Overall, pituitary hormone genes are selective for TG versus other ganglia somatotypes; and GH has distinctive functional significance in the trigeminal versus spinal systems.

Effects of Resveratrol on Receptor Expression and Serum Levels of Estrogen and Progesterone in the Rat Endometritis Model

Endometritis is characterized by inflammation of the endometrial lining that leads to reduced reproductive potential. Restoring the impaired hormonal balance is an important component of endometritis treatment. The purpose of the current study was to evaluate the effects of resveratrol on estrogen and progesterone hormone status in endometritis. Mature female Sprague Dawley rats were used, and endometritis was induced by intrauterine infusion of Escherichia coli. Animals were treated with resveratrol alone or combined with marbofloxacin. Compared to the non-treated endometritis group, resveratrol treatment reduced serum oestradiol levels, increased serum progesterone levels, enhanced estrogen receptor (ER) expression in the uterine stroma, decreased ESR1 gene expression, and raised ESR2 gene expression. Resveratrol administration combined with marbofloxacin also increased ER expression in the uterine gland and progesterone receptor expression in the uterine epithelium. The findings of this study suggest that the actions of resveratrol on progesterone levels and estrogen receptor expression might be responsible for its beneficial effect in rats with endometritis.

Anti-Inflammatory and Antinociceptive Properties of Kielmeyerone A, a Chromenone Isolated from the Roots of Kielmeyera reticulata

Four new chromenones, kielmeyerones A-D (1-4), were obtained from the roots of Kielmeyera reticulata. Their structures were elucidated based on spectroscopic data (NMR and HRESIMS) interpretation. The pharmacological activity of kielmeyerone A (1), the major compound, was evaluated using in vitro and in vivo inflammation and pain models. During in vitro screening, 1, at noncytotoxic concentrations (0.097-1.56 μM), inhibited NO production by J774 macrophages stimulated with LPS and IFN-γ. In the complete Freund's adjuvant-induced inflammation model in mice, 1 (12.5-50 mg/kg) inhibited paw edema, demonstrating an anti-inflammatory effect. Additionally, 1 (12.5-50 mg/kg) induced a dose-dependent antinociceptive effect in the late phase of the formalin test, a profile similar to those of nonsteroidal anti-inflammatory drugs. Mice treated with 1 (100 mg/kg) did not show motor performance alterations using a rota-rod test. Thus, the present study has characterized new chromenones from Kielmeyera reticulata and has provided evidence of the anti-inflammatory and antinociceptive properties of one of these, kielmeyerone A (1).

Vildagliptin plasticized hydrogel film in the control of ocular inflammation after topical application: study of hydration and erosion behaviour

Vildagliptin (VID) is a dipeptidyl peptidase-4 (DPP-4) inhibitor used in controlling blood glucose level in type 2 diabetes. Vildagliptin improves beta cells function and is also suggested to effectively control the inflammation. The possible ocular anti-inflammatory property of vildagliptin has been explored using topically applied plasticized ocular film formulation. Film formulation was prepared by solvent cast and evaporation method using triethanolamine (TEA), dimethyl sulphoxide (DMSO), and polyethylene glycol 400 (PEG 400) as the plasticizer in HPMC hydrogel matrix base. Anti-inflammatory study was carried out in the carrageenan induced ocular rabbit model. Analytical methods confirmed that the drug was present almost in completely amorphized form in the film formulation. Level of hydration, swelling and erosion rate of the film played the controlling factor in the process of drug release, ocular residence and permeation. Maximum swelling rate of 363 h−1 has been shown by VHT compared to other formulation of VHD and VHP (174 and 242 h−1 respectively). Film containing DMSO exhibited highest in vitro release as well as ex vivo ocular permeation. Film formulation has shown a fast recovery of ocular inflammation in contrast to the untreated eye after inducing inflammation. Plasticized vildagliptin hydrogel film formulation could be utilized in the management and control of ocular inflammation particularly with diabetic retinopathy after proper clinical studies in higher animal and human individuals.

The role of medial prefrontal cortex projections to locus ceruleus in mediating the sex differences in behavior in mice with inflammatory pain

We tested the hypothesis that the cognitive impairment associated with inflammatory pain may result from dysregulation of the top-down control of locus ceruleus's (LC) activity by the medial prefrontal cortex (mPFC). Injection of complete Freund's adjuvant (CFA) served as a model for inflammatory pain. The CFA injection decreased the thermal thresholds in both sexes but only the male mice showed increased anxiety-like behavior and diminished cognition, while the females were not affected. Increased calcium fluorescence, a marker for neuronal activity, was detected by photometry in the mPFC of males but not in females with CFA. Next, while chemogenetic inhibition of the projections from the mPFC to the LC improved the object recognition memory of males with pain, the inhibition of the mPFC to LC pathway in female mice produced anxiolysis and spatial memory deficits. The behavior results prompted us to compare the reciprocal innervation of mPFC and LC between the sexes. We used an anterograde transsynaptic tagging technique, which relies on postsynaptic cre transfer, to assess the innervation of LC by mPFC efferents. The males showed a higher rate of postsynaptic cre transfer into LC neurons from mPFC efferents than the females. And vice versa, a retrograde tracing experiment demonstrated that LC to mPFC projection neurons were more numerous in females when compared to males. In conclusion, we provide evidence that subtle differences in the reciprocal neuronal circuit between the LC and mPFC may contribute to sex differences associated with the adverse cognitive effects of inflammatory pain.