Complete Freund's Adjuvant Research Articles

Deciphering farnesol's anti-arthritic and immunomodulatory potential by targeting multiple pathways: a combination of network pharmacology guided exploration and experimental verification.

Farnesol (FAR), a sesquiterpene alcohol, has documented FAR's anti-inflammatory and antioxidant activities. Current study was undertaken to assess the efficacy and mechanism of FAR in arthritis by employing network pharmacology and experimental models. Two experimental models comprising formaldehyde- and complete Freund's adjuvant (CFA)-induced arthritis evaluated the efficacy of FAR in treating arthritis. Various parameters were assessed. Then, a network pharmacology approach was applied to gain further insight into the potential mechanism and signaling pathways. FAR significantly reduced paw volume and the arthritic score and improved the hematological and biochemical changes. Radiographic and histological examination showed the anti-arthritic efficacy of FAR, which was associated with down-regulation of pro-inflammatory mediators and upregulation of anti-inflammatory mediators. Network pharmacology analysis revealed that FAR may exert its anti-arthritic effects by targeting specific genes associated with arthritis. Pathway analysis revealed the involvement of three key signaling pathways (IL-17 signaling, TNF signaling, and toll-like receptor signaling) in the development and progression of arthritis. The results pointed out the protective attributes of farnesol against formaldehyde and CFA-induced arthritis via modulation of multiple targets. This study provides a valuable reference for the development of a new treatment or complementary therapy for arthritis.

Chronic inflammatory pain reduces fentanyl intake during early acquisition of fentanyl self-administration, but does not change motivation to take fentanyl in male and female rats

The co-occurrence of chronic pain and opioid misuse has led to numerous preclinical investigations of pain-opioid interactions to examine how pain manipulations alter the reinforcing properties of opioids. However, preclinical investigations of chronic pain effects on opioid drug self-administration have produced inconsistent results. Our previous work demonstrated that established fentanyl self-administration is resistant to change by induction of chronic inflammatory pain (Complete Freund's Adjuvant; CFA) in male and female rats, while other laboratories have shown that CFA increased fentanyl self-administration in male but not female rats when pain induction precedes self-administration, which may be a critical factor in determining the effects of chronic pain on self-administration. The present study was designed similarly to Higginbotham et al. (2022) to test the effects of CFA on fentanyl self-administration in rats that underwent pain prior to acquisition of fentanyl self-administration. Male and female rats treated with hindpaw CFA or saline were trained to intravenously self-administer (IVSA) fentanyl for 3 weeks under limited access to fentanyl (2 h per day) conditions. After 3 weeks of fentanyl IVSA acquisition, we tested motivation to take fentanyl using progressive ratio testing and dose-response testing. CFA male and female rats self-administered less fentanyl than saline-treated controls during week 1 of acquisition, but not during weeks 2–3 of acquisition. Intra-session analysis of week 1 data demonstrated that chronic inflammatory pain suppressed fentanyl intake towards the end of week 1 and at the end of each operant session. We also report no effects of chronic inflammatory pain on motivation to take fentanyl. We discuss potential methodological explanations for differences between these results and prior reports. Our findings demonstrate that CFA temporarily suppresses fentanyl IVSA in animals without changing motivation to take fentanyl or promoting escalation of opioid use, suggesting that chronic inflammatory pain is unlikely to promote long-term risk of opioid misuse.

Anti-arthritic potential and antioxidant properties of infusion, fractions and flavonoid glycosides from Dipteryx alata (baru) leaves

Dipteryx alata Vogel., popularly known as "baru", is a native species of Brazilian cerrado used by "Ribeirinhos" in the North Araguaia microregion. In the traditional medicine, maceration of barks or leaves infusion are used to treat back and muscle pain, osteoporosis and rheumatism. However, few studies have demonstrated the pharmacological effects of this species. The goal of this study was to perform phytochemicals studies of lyophilized infusion of D. alata leaves (LI-DA), as well as obtaining ethyl acetate fraction (EAF-DA) and hydromethanolic fraction (HMF-DA), and isolated flavonoids. The antioxidant of LI-DA, EAF-DA and HMF-DA, anti-inflammatory effects of LI-DA and quercetin-3-O-β-glucoside-7-O-α-rhamnoside (DA-1) and quercetin-7-O-α-rhamnoside (DA-2) were performed while in silico tests were used for absorption, distribution, metabolism, excretion and toxicity predictions of DA-1 and DA-2. LI-DA, EAF-DA and HMF-DA were evaluated in antioxidant assays (2, 2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid - ABTS; 2,2-diphenyl-1-picrylhydrazyl - DPPH; hydrogen peroxide - H2O2; reducing power and oxidation of β-carotene). The DA-1 and DA-2 were isolated from EAF-DA using chromatographic methods and characterized by Nuclear Magnetic Resonance (NMR) spectrometer. The Programs ProTox 3.0 and ADMETlab 2.0 were used for the prediction studies of DA-1 and DA-2. Mice received a single dose of LI-DA (3, 30, and 100 mg/kg), DA-1 (3 mg/kg) and DA-2 (3 mg/kg) and were subjected to inflammation induced by Complete Freund's Adjuvant (CFA) and in the zymosan-induced articular inflammation model. DA-1 and DA-2 have been identified for the first time in the leaves of D. alata. LI-DA, EAF-DA and HMF-DA demonstrated a high level of antioxidant activity as measured by ABTS (IC50 ≤ 5.62 μg/mL) and DPPH (IC50 ≤ 11.45 μg/mL). Oral administration of LI-DA (3, 30 and 100 mg/kg), DA-1 (3 mg/kg) and DA-2 (3 mg/kg) showed significantly reduced edema, cold and mechanical allodynia in the CFA-induced inflammation model (24 hours). LI-DA (3, 30, and 100 mg/kg) and DA-1 (3 mg/kg) reduced leukocytes migration into the joint cavity, mechanical allodynia, edema and NO production in mice (24 hours) in the zymosan-induced articular inflammation model. Additionally, DA-2 (3 mg/kg) reduced leukocyte migration and LI-DA (30 mg/kg) reduced protein exudation (24 hours) in zymosan model. DA-1 and DA-2 showed good oral bioavailability and low toxicity predicted by the ProTox model. This is the first chemical and biological study performed of D. alata infusion and two quercetin glycoside derivatives. The results indicated promising potential for the treatment of inflammation, pain, and rheumatism, supporting the traditional use of the infusion obtained from the leaves of D. alata.

The analgesic effect and mechanism of the active components screening from Corydalis yanhusuo by P2X3 receptors

Ethnopharmacological relevanceCavidine (CAV) is the main bioactive ingredient of Corydalis ternata f. yanhusuo (Y.H.Chou & Chun C.Hsu) Y.C.Zhu, which is a traditional Chinese herbal containing a variety of uses such as analgesic, anticancer, and anti-inflammatory properties. Aim of the studyThe goal is to screen Corydalis yanhusuo for anti-central sensitization active components and investigate and clarify the pharmacological mechanism and therapeutic efficacy of the active ingredient CAV in the treatment of chronic pain. Material and MethodsFirst, cell membrane immobilized chromatography was used to screen the bioactive ingredients in Corydalis yanhusuo. Spare nerve injury (SNI) model and complete Freund's adjuvant (CFA) mice model were constructed to identify the analgesic effect of CAV. RNA-seq and bioinformatics analyses were used to explore the potential targets of CAV in CFA mice and SNI mice. HE staining was used to observe the infiltration of inflammatory cells in the dorsal root ganglion (DRG) and spinal cord(SC) of CFA mice and SNI mice. WB and qPCR were used to detect the level of inflammatory factors TNF-α, IL-1β, and IL-6 in DRG and SC of mice. SNI and CFA mice were used to study the effect and mechanism of CAV on microglial activation. Results9 potential active ingredients were screened out from Corydalis yanhusuo that can regulate P2X3 receptors. CAV showed good analgesic effects, increased the mechanical pain and thermal pain thresholds of CFA mice and SNI mice, inhibited the expression of DRG and SC inflammatory factors, downregulated IBA-1, and inhibited microglial activation. Further in vivo and in vitro experiments showed that CAV significantly inhibited the expression of P2X3 receptors and the activation of its downstream MAPK pathway in DRG neurons and SC. ConclusionThis study is the first to indicate that CAV exerts an analgesic effect by inhibiting microglia activation via the P2X3 signaling pathway axis, providing the clinical utility of CAV in chronic pain therapy.

Benzylpiperidine derivatives as new dual μ-opioid and σ1 receptor ligands with potent antinociceptive effects

Dual-acting μ-opioid receptor (MOR)/sigma-1 receptor (σ1R) ligands have displayed promise in exerting robust antinociceptive effects while reducing opioid-related side effects. To discover safer and more effective analgesics, we designed, prepared, and evaluated 30 benzylpiperidine derivatives as dual MOR and σ1R ligands. The obtained benzylpiperidine analogs were tested for MOR and σ1R binding affinity in vitro. The best compound 52 showed high affinity for both MOR [Ki (MOR) = 56.4 nM] and σ1R [Ki (σ1R) = 11.0 nM] and produced potent antinociceptive effects in the abdominal contraction test (ED50 = 4.04 mg/kg in mice), carrageenan-induced inflammatory pain model (ED50 = 6.88 mg/kg in mice), formalin test (ED50 = 13.98 mg/kg in rats) and complete Freund’s adjuvant (CFA)-induced chronic pain model (ED50 = 7.62 mg/kg in mice). Moreover, 52 had less MOR-related adverse effects than oxycodone, including constipation, acute hyperlocomotion and physical dependence. The above results suggested that 52 may be a promising candidate for the development of safer analgesics.

Neurotensin-expressing lateral hypothalamic neurons alleviate neuropathic and inflammatory pain via neurotensin receptor signaling

Persistent, severe pain negatively impacts health and wellbeing, but half of patients do not receive adequate relief from current treatments. Understanding signals that modulate central pain processing could point to new strategies to manage severe pain. Administering Neurotensin (Nts) or Nts receptor (NtsR) agonists into the brain provides analgesia comparable to pharmacologic opioids. However, the endogenous sources of Nts that modify pain processing and might be leveraged for pain relief remained unknown. We previously characterized a large population of Nts-expressing neurons in the lateral hypothalamic area (LHANts neurons) that project to brain regions that participate in descending control of pain processing. We hypothesized that LHANts neurons are an endogenous source of Nts and activating them would alleviate pain dependent on Nts signaling via NtsRs. To test this, we injected NtsCre mice in the LHA with AAVs to cre-dependently express either mCherry (Control) or the excitatory hM3Dq in LHANts neurons, permitting their stimulation after treatment with the hM3Dq ligand clozapine N-oxide (CNO). Activating LHANts neurons had no effect on thermal pain and mechanical responses in naïve mice. By contrast, both spared nerve injury- (SNI) and complete Freund’s adjuvant (CFA)-induced mechanical hypersensitivity was completely reversed by CNO-stimulation of LHANts neurons. Pretreatment with the Nts receptor antagonist SR142948 reduced CNO-mediated analgesia, indicating that LHANts neurons alleviate chronic pain in an Nts receptor-dependent manner. Taken together these data identify LHANts neurons as an endogenous source of Nts that modulates central pain processing and may inform future development of Nts-based targets to treat severe pain.

Elucidation of neuronal activity in mouse models of temporomandibular joint injury and inflammation by in vivo GCaMP Ca2+ imaging of intact trigeminal ganglion neurons.

Patients with temporomandibular disorders (TMDs) typically experience facial pain and discomfort or tenderness in the temporomandibular joint (TMJ), causing disability in daily life. Unfortunately, existing treatments for TMD are not always effective, creating a need for more advanced, mechanism-based therapies. In this study, we used in vivo GCaMP3 Ca2+ imaging of intact trigeminal ganglia (TG) to characterize functional activity of the TG neurons in vivo, specifically in mouse models of TMJ injury and inflammation. This system allows us to observe neuronal activity in intact anatomical, physiological, and clinical conditions and to assess neuronal function and response to various stimuli. We observed a significant increase in spontaneously and transiently activated neurons responding to mechanical, thermal, and chemical stimuli in the TG of mice with TMJ injection of complete Freund adjuvant or with forced mouth opening (FMO). An inhibitor of the calcitonin gene-related peptide receptor significantly attenuated FMO-induced facial hypersensitivity. In addition, we confirmed the attenuating effect of calcitonin gene-related peptide antagonist on FMO-induced sensitization by in vivo GCaMP3 Ca2+ imaging of intact TG. Our results contribute to unraveling the role and activity of TG neurons in the TMJ pain, bringing us closer to understanding the pathophysiological processes underlying TMJ pain after TMJ injury. Our study also illustrates the utility of in vivo GCaMP3 Ca2+ imaging of intact TG for studies aimed at developing more targeted and effective treatments for TMJ pain.

The crucial role of NR2A mediating the activation of satellite glial cells in the trigeminal ganglion contributes to orofacial inflammatory pain during TMJ inflammation

Temporomandibular joint inflammatory diseases are a significant subtype of temporomandibular disorders (TMD) characterized by inflammatory pain in the orofacial area. The N-methyl-D-aspartate receptor (NMDAR), specifically the NR2A subtype, was crucial in neuropathic pain. However, the exact role of NR2A in inflammatory pain in the TMJ and the molecular and cellular mechanisms mediating peripheral sensitization in the trigeminal ganglion (TG) remain unclear. This study utilized male and female mice to induce the TMJOA model by injecting Complete Freund's adjuvant (CFA) into the TMJ and achieve conditional knockout (CKO) of NR2A in the TG using Cre/Loxp technology. The Von-Frey filament test results showed that CFA-induced orofacial pain with reduced mechanical withdrawal threshold (MWT), which was not developed in NR2A CKO mice. Additionally, the up-regulation of interleukin (IL)-1β, IL-6, and nerve growth factor (NGF) in the TG induced by CFA did not occur by NR2A deficiency. In vitro, NMDA activated satellite glial cells (SGCs) with high expression of glial fibrillary acidic protein (GFAP), and both NMDA and LPS led to increased IL-1β, IL-6, and NGF in SGCs. NR2A deficiency reduced these stimulating effects of NMDA and LPS. The regulation of IL-1β involved the p38, Protein Kinase A (PKA), and Protein Kinase C (PKC) pathways, while IL-6 signaling relied on PKA and PKC pathways. NGF regulation was primarily through the p38 pathway. This study highlighted NR2A's crucial role in the TG peripheral sensitization during TMJ inflammation by mediating ILs and NGF, suggesting potential targets for orofacial inflammatory pain management.

Artemisia pallens W. Attenuates Inflammation and Oxidative Stress in Freund's Complete Adjuvant-Induced Rheumatoid Arthritis in Wistar Rats.

Rheumatoid arthritis (RA) is an autoimmune disease that causes distinctive inflammatory symptoms and affects over 21 million people worldwide. RA is characterized by severe discomfort, swelling, and degradation of the bone and cartilage, further impairing joint function. The current study investigates the antiarthritic effect of a methanolic extract of Artemisia pallens (methanolic extract of A. pallens, MEAP), an aromatic herb. Artemisinin content (% per dry weight of the plant) was estimated using a UV Vis spectrophotometer. In the present study, animals were divided into six groups (n = 6). The control group (group I) was injected with 0.25% of carboxymethyl cellulose. The arthritic control group (group II) was treated with Freund's complete adjuvant (by injecting 0.1 mL). Prednisolone (10 mg/kg), a lower dose of MEAP (100 mg/kg), a medium dose of MEAP (200 mg/kg), and a higher dose of MEAP (400 mg/kg) were orally delivered to groups III, IV, V, and VI, respectively. Freund's complete adjuvant was administered into the sub-plantar portion of the left-hind paw in all the groups except vehicle control to induce rheumatoid arthritis. Weight variation; joint diameter; paw volume; thermal and mechanical hyperalgesia; hematological, biochemical, and oxidative stress parameters; radiology; and a histopathological assessment of the synovial joint were observed in order to evaluate the antiarthritic effect of the methanolic extract of A. pallens. In this study, the estimated content of artemisinin was found to be 0.28% (per dry weight of the plant), which was in good agreement with the reported value. MEAP (200 and 400 mg/kg) caused a significant reduction in increased paw volume and joint diameter in arthritic rats while significantly increasing body weight and the mechanical threshold of thermal algesia. Moreover, complete blood counts and serum enzyme levels improved significantly. Radiological analysis showed a reduction in soft tissue swelling and small erosions. A histopathological examination of the cells revealed reduced cell infiltration and the erosion of joint cartilage in MEAP-administered arthritic rats. The present research suggests that the antiarthritic activity of the methanolic extract of A. pallens wall is promising, as evidenced by the findings explored in our rat model.

Inflammatory pain resolution by mouse serum-derived small extracellular vesicles

Current treatments for chronic pain have limited efficacy and significant side effects, warranting research on alternative strategies for pain management. One approach involves using small extracellular vesicles (sEVs), or exosomes, to transport beneficial biomolecular cargo to aid pain resolution. Exosomes are 30–150 nm sEVs that can be beneficial or harmful depending on their source and cargo composition. We report a comprehensive multi-modal analysis of different aspects of sEV characterization, miRNAs, and protein markers across sEV sources. To investigate the short- and long-term effects of mouse serum-derived sEVs in pain modulation, sEVs from naïve control or spared nerve injury (SNI) model male donor mice were injected intrathecally into naïve male recipient mice. These sEVs transiently increased basal mechanical thresholds, an effect mediated by opioid signaling as this outcome was blocked by naltrexone. Mass spectrometry of sEVs detected endogenous opioid peptide leu-enkephalin. sEVs from naïve female mice have higher levels of leu-enkephalin compared to male, matching the analgesic onset of leu-enkephalin in male recipient mice. In investigating the long-term effect of sEVs, we observed that a single prophylactic intrathecal injection of sEVs two weeks prior to induction of the pain model in recipient mice accelerated recovery from inflammatory pain after complete Freund’s adjuvant (CFA) injection. Our exploratory studies examining immune cell populations in spinal cord and dorsal root ganglion using ChipCytometry suggested alterations in immune cell populations 14 days post-CFA. Flow cytometry confirmed increases in CD206+ macrophages in the spinal cord in sEV-treated mice. Collectively, these studies demonstrate multiple mechanisms by which sEVs can attenuate pain.

Anti-inflammatory and anti-arthritic activities of ethanolic extract of Myxopyrum serratulum A.W. Hill

BackgroundRheumatoid arthritis (RA) is a debilitating inflammatory disorder characterized by an overactive immune system targeting joints, leading to inflammation and intense pain. While current RA therapies effectively alleviate symptoms, they are often associated with significant side effects. This study aimed to assess the anti-inflammatory and anti-arthritic properties of an Ethanolic Extract of Myxopyrum serratulum A.W. Hill (EEMS) using animal models.ResultsThe acute toxicity study with EEMS (2000 mg/kg, p.o.) on rats showed no toxicity or mortality up to the highest dose. Inflammation was induced using carrageenan, and rats were treated with varying doses of EEMS (100, 200, and 400 mg/kg, p.o.) and diclofenac to assess anti-inflammatory effects. Anti-arthritic efficacy was evaluated using Complete Freund’s adjuvant (CFA)-induced inflammation, comparing EEMS to methotrexate. The results revealed dose-dependent anti-inflammatory effects of EEMS and a reversal of arthritic-induced weight loss in treated groups. Paw volume reduction was significant in both EEMS and methotrexate groups. Biochemical analyses showed elevated markers in the arthritic control group, which were normalized by EEMS and methotrexate. Notably, EEMS (400 mg/kg) significantly reduced cathepsin-D levels compared to the positive control. EEMS administration also lowered hepatic lipid peroxidation and increased endogenous antioxidants (SOD, GSH, and GPX). The 200 and 400 mg/kg doses reduced the iNOS/GADPH ratio, while the 400 mg/kg dose restored cellular and joint structure and significantly decreased IL1 levels.ConclusionsIn conclusion, EEMS demonstrated substantial protective effects, mitigating health risks associated with chronic inflammation such as arthritis. These findings underscore the ethnomedical potential of Myxopyrum serratulum as a promising anti-inflammatory and anti-arthritis agent. The study suggests that EEMS could be a viable alternative or complementary therapy for RA, offering therapeutic benefits with potentially fewer side effects than current treatments.

Spinal PTP1B Regulated NMDA Receptor-mediated Nociceptive Transmission and Peripheral Inflammation-induced Pain Sensitization.

Protein tyrosine phosphatases (PTPs) catalyze the dephosphorylation of several pain-related substrates in spinal cord dorsal horn and are critically involved in the modification of pain transmission. The current study demonstrated that protein tyrosine phosphatase 1B (PTP1B), a unique endoplasmic reticulum-resident member of PTP family, displayed an activity-dependent increase in its protein expression and synaptic localization in spinal dorsal horn of adult male rats. PTP1B interacted with the Src Homology 3 (SH3) domain of Synapse-Associated Protein 102 (SAP102), one of the postsynaptic scaffolding proteins that anchored PTP1B at postsynaptic sites. The SAP102-tethered PTP1B augmented the synaptic transmission mediated specifically by GluN2B subunit-containing N-methyl-D-aspartate subtype glutamate receptors. Interference with PTP1B activity or disruption of its interaction with SAP102 attenuated GluN2B-mediated nociceptive transmission and ameliorated pain sensitization induced by intraplantar injection of Complete Freund's Adjuvant. These data suggested that the activity-dependent synaptic redistribution of PTP1B served as an important mechanism regulating GluN2B receptor activity and that manipulation of PTP1B synaptic targeting might represent an effective approach for the treatment of chronic inflammatory pain.

Increased levels of Escherichia-Shigella and Klebsiella in the gut contribute to the responsivity of placebo analgesia

Placebo analgesia is observed in both humans and animals. Given the complexity of placebo analgesia involving a variety of neurobiological, psychological, and psychosocial processes, further investigation into its underlying mechanisms is essential. Gut microbiota has been implicated in the responsivity of placebo analgesia, but its precise role remains unknown and warrants further investigations. Here, we conducted a conditioning training model with chronic inflammatory pain induced by complete Freund's adjuvant (CFA) in mice, associating parecoxib with different cues. Hierarchical clustering analysis of placebo analgesia behaviors was employed to classify mice into responders and non-responders phenotypes. Approximately 40% of CFA mice undergoing conditioning training exhibited placebo analgesia. Notably, placebo analgesia responders displayed reduced anxiety-like behaviors. 16S rRNA results revealed a distinct composition of gut microbiota composition among the control, placebo analgesia non-responders and responders groups. Notably, levels of Escherichia Shigella and Klebsiella in the gut were increased considerably in the placebo analgesia responders as compared to both control and non-responders groups. In conclusion, placebo analgesia responders demonstrated marked analgesia, reduced anxiety-like behaviors, and increased levels of Escherichia-Shigella and Klebsiella, implying a potential linkage between gut microbiota and placebo analgesia.

Evaluation of the Impact of Pistacia atlantica Desf. Oleo-gum Resin on Complete Freund’s Adjuvant-induced Arthritis in a Wistar Rat Model

Background: Pistacia atlantica Desf., also known as Atlantic pistachio or Mt. Atlas mastic tree, has been used in traditional medicine for its anti-inflammatory properties, helping to reduce inflammation in conditions like arthritis. Additionally, the tree's resin possesses antioxidant properties that can help protect against oxidative stress. The anti-arthritic efficacy of Pistacia atlantica oleo-gum resin extract (PAG) remains unvalidated, as its potential therapeutic benefits have not been substantiated. In the current investigation, we have substantiated the inhibitory properties of the PAG in mitigating the development of rheumatoid arthritis induced by Complete Freund's Adjuvant in rats. Methods: Male Wistar rats weighing 160±10 g were subjected to immunization through intradermal injection of 0.1 mL of Complete Freund's Adjuvant (CFA) into the left hind metatarsal footpad. Following the induction of adjuvant arthritis, oral administration of PAG was initiated at doses of 10, 400, and 800 mg/kg once a day. Prednisolone (10 mg/kg, daily) was employed as a positive control in this study. Various parameters, including paw swelling, arthritic index, body weight loss, spleen index, thymus index, serum cytokines, inflammatory mediators, and histological alterations, as well as nitrite glutathione and catalase level, were measured. Furthermore, the expression and activity of matrix metalloproteinase (MMP)-2 and MMP-9 were evaluated. Results: PAG exhibited noteworthy efficacy in attenuating paw swelling and reducing the arthritic index. Moreover, it resulted in enhanced body weight loss and a consequential reduction in the thymus index. PAG (400mg/kg) significantly decreased the level of serum nitrite in the intervention group, as well as the levels of serum glutathione. On the other hand, catalase activity increased, the activity of MMP-9 decreased, and the level of MMP-2 increased compared to the intervention group. The histopathological results revealed that PAG (at doses of 400 mg/kg) had the best therapeutic effects. Conclusion: In conclusion, the present study confirms the anti-arthritic activity of PAG in rats. The extract of PAG was found to prevent rheumatoid arthritis induced by Complete Freund's Adjuvant, as evidenced by the significant suppression of paw swelling and arthritic index.

Deletion of Card9 eliminates the detrimental facets of mycobacterial adjuvants

Although mycobacterial adjuvants are capable of eliciting a strong adaptive humoral and cellular immunity, they also sometimes provoke detrimental outcomes, including autoimmune/inflammatory syndromes. Here, we show that the deletion of caspase recruitment domain family member 9 (Card9), a signaling adaptor of a set of innate immune receptors, can eliminate the detrimental effects of mycobacterial adjuvants. Long-lasting tissue-destructive skin inflammation at the site of complete Freund's adjuvant (CFA) injection, lung granuloma formation induced by intratracheal Mycobacterium bovis Bacillus Calmette-Guérin infection, and the incidence and severity of experimental autoimmune encephalomyelitis and collagen-induced arthritis induced by autoantigen immunization with CFA were considerably attenuated in Card9-deficient (Card9−/−) mice compared to control wild-type mice. Card9−/− mice showed impaired development of Th17, but not Th1, in the early phase after autoimmune induction, due to the impaired development of IL-6-producing Sirpαhigh dendritic cells, which are essential for priming pathigenic Th17, in the draining lymph nodes. However, Card9 deletion did not affect overall adaptive antibody production or delayed-type hypersensitivity following immunization with CFA, indicating that humoral and type 1 immune responses remained intact. These results suggest that avoiding the activation of Card9 signaling during vaccination with mycobacteria-containing vaccines may mitigate the risk of detrimental type 3 immune responses, while preserving type 1 immune responses that are effective against intracellular pathogens and cancers.

Protective potential of Bacillus subtilis (NMCC-path-14) against extraarticular manifestations during acute and sub-acute phase of arthritis using mice model

Extra-articular manifestations (EAM), which are associated with rheumatoid arthritis (RA), affect the quality of life of patients and are one of the critical causes of early mortality. This study was aimed at investigating whether Bacillus subtilis NMCC-path-14 (1 × 108 CFU/animal/day) could serve as a valuable therapeutic agent in managing EAM using complete Freund's adjuvant (CFA) induced arthritis during acute and sub-acute phases. Arthritis was induced using intra-dermal administration of CFA in the right hind paw of mice on day 1. Dexamethasone (Dexa) (5 mg/kg/day/animal) was used as a standard treatment. Animals in Dexa and Bacillus subtilis concurrent treatment (BS-CT) received treatments on day 1. The Bacillus subtilis pre-treatment (BS-PT) group received a probiotic dose 7 days before arthritis induction. Parameters like body weight, relative organ weight, colon length, hematology, serum biochemistry, antioxidant capacity, and histopathology of liver, kidney, spleen, colon, stress-related behavioral changes, and cortisol levels were evaluated on days 7 (acute) and 14 (sub-acute). Dexa failed to manage the EAM in arthritic mice and instead exacerbated them. On the other hand, B. subtilis NMCC-path-14 significantly declined EAM with no notable side effects, highlighting its safety and effectiveness. The current data show that B. subtilis NMCC-path-14 may be an alternative option for arthritis treatment that can reduce systemic symptoms associated with arthritis. More studies are required to comprehend the underlying mechanisms of mitigating the EAM by B. subtilis NMCC-path-14.

Upregulation of Phosphodiesterase 7A Contributes to Concurrent Pain and Depression via Inhibition of cAMP-PKA-CREB-BDNF Signaling and Neuroinflammation in the Hippocampus of Mice.

Phosphodiesterases (PDEs) are enzymes that catalyze the hydrolysis of cyclic adenosine monophosphate AMP (cAMP) and/or cyclic guanosine monophosphate (cGMP). PDE inhibitors can mitigate chronic pain and depression when these disorders occur individually; however, there is limited understanding of their role in concurrent chronic pain and depression. We aimed to evaluate the mechanisms of action of PDE using 2 mouse models of concurrent chronic pain and depression. C57BL/6J mice were subjected to partial sciatic nerve ligation (PSNL) to induce chronic neuropathic pain or injected with complete Freund's adjuvant (CFA) to induce inflammatory pain, and both animals showed depression-like behavior. First, we determined the change in PDE expression in both animal models. Next, we determined the effect of PDE7 inhibitor BRL50481 or hippocampal PDE7A knockdown on PSNL- or CFA-induced chronic pain and depression-like behavior. We also investigated the role of cAMP-protein kinase A (PKA)-cAMP response element binding protein (CREB)-brain-derived neurotrophic factor (BDNF) signaling and neuroinflammation in the effect of PDE7A inhibition on PSNL- or CFA-induced chronic pain and depression-like behavior. This induction of chronic pain and depression in the 2 animal models upregulated hippocampal PDE7A. Oral administration of PDE7 inhibitor, BRL50481, or hippocampal PDE7A knockdown significantly reduced mechanical hypersensitivity and depression-like behavior. Hippocampal PDE7 inhibition reversed PSNL- or CFA-induced downregulation of cAMP and BDNF and the phosphorylation of PKA, CREB, and p65. cAMP agonist forskolin reversed these changes and caused milder behavioral symptoms of pain and depression. BRL50481 reversed neuroinflammation in the hippocampus in PSNL mice. Hippocampal PDE7A mediated concurrent chronic pain and depression in both mouse models by inhibiting cAMP-PKA-CREB-BDNF signaling. Inhibiting PDE7A or activating cAMP-PKA-CREB-BDNF signaling are potential strategies to treat concurrent chronic pain and depression.

Temporomandibular Joint Pain Measurement by Bite Force and Von Frey Filament Assays in Mice.

Temporomandibular joint (TMJ) pain and osteoarthritis (OA) are common and debilitating disorders that impair patients' quality of life. The mechanisms driving diseases-related pain are poorly understood, and current treatments fail to provide effective and long-term therapeutic effects. Additionally, pain assessment in research, particularly orofacial pain, poses several challenges that complicate studies in both clinical and basic science settings. Therefore, we have established an inflammatory TMJ pain mouse model via intra-articular injection of CFA (Complete Freund's Adjuvant) and evaluated pain behaviors by bite force measurement and the von Frey filament test. Mice with CFA injection exhibited orofacial pain behaviors compared to PBS injection, including reduced bite force and head withdrawal threshold in the von Frey filament test. These methods are relatively easy to execute to have reproducible results and can be potentially extended to pain studies for other disease models related to TMJ disorders. Together, bite force, and the von Frey filament tests are reliable in measuring orofacial pain, as demonstrated in CFA injection-induced painful TMJOA mouse models.

Crystallin β-b2 promotes retinal ganglion cell protection in experimental autoimmune uveoretinitis.

Crystallin βb2 (crybb2) is upregulated in regenerating retinas and in various pathological conditions of the retina, including uveoretinitis. However, the role of crybb2 in this disease is largely unknown. Therefore, we used recombinant crybb2 (rcrybb2) as intravitreal treatment of B10.RIII mice prior to immunization with human interphotoreceptor retinoid-binding protein peptide 161-180 (hIRBPp161-180) in complete Freund's adjuvant (CFA) and concomitant injection of pertussis toxin (PTX) to induce experimental autoimmune uveoretinitis (EAU). In naïve mice, more beta III-tubulin (TUBB3) + and RNA-binding protein with multiple splicing (RBPMS) + cells were found in the ganglion cell layer of the retina than in EAU eyes, suggesting a loss of retinal ganglion cells (RGC) during the development of EAU. At the same time, the number of glial fibrillary acidic protein (GFAP) + cells increased in EAU eyes. RGCs were better protected in EAU eyes treated with rcrybb2, while the number of GFAP+ cells decreased. However, in retinal flatmounts, both retinal ganglion cells and retinal endothelial cells stained positive for TUBB3, indicating that TUBB3 is present in naïve B10.RIII mouse eyes not exclusive to RGCs. A significant decline in the number of RBPMS-positive retinal ganglion cells was observed in retinal flatmounts from EAU retinas in comparison to naïve retinas or EAU retinas with intravitreal rcrybb2 treatment. Whereas no significant decrease in TUBB3 levels was detected using Western blot and RT-qPCR, GFAP level, as a marker for astrocytes, increased in EAU mice compared to naïve mice. Level of Bax and Bcl2 in the retina was altered by treatment, suggesting better cell survival and inhibition of apoptosis. Furthermore, our histologic observations of the eyes showed no change in the incidence and severity of EAU, nor was the immune response affected by intravitreal rcrybb2 treatment. Taken together, these results suggest that intravitreal injection of rcrybb2 reduces retinal RGC death during the course of EAU, independent of local or systemic autoimmune responses. In the future, treating posterior uveitis with rcrybb2 to protect RGCs may offer a promising novel therapeutic strategy.

Peripheral Inflammation is accompanied by Cerebral Hypoperfusion in Mice.

Chronic pain is a disabling condition that is accompanied by neuropsychiatric comorbidities such as anxiety, depression, and cognitive decline. While the peripheral alterations are well-studied, we lack an understanding of how these peripheral changes can result in long-lasting brain alterations and the ensuing behavioral phenotypes. This study aims to quantify changes in cerebral blood perfusion using laser speckle contrast imaging (LSCI) in the murine Complete Freund's adjuvant (CFA) model of unilateral peripheral inflammation. Twenty female and 24 male adult C57BL/6 mice were randomly assigned to control (0.05ml saline) or 1 of 3 experimental groups receiving CFA (0.01ml, 0.05ml, and 0.1ml) on the right hindpaw. Three days after the intraplantar injections, animals were assessed for signs of pain (von Frey), working memory (y-maze), and anxiety (zero maze and open field), and subjected to craniotomy and in vivo LSCI of the parietal-temporal lobes. Unilateral administration of CFA resulted in signs of local inflammation, decreased mechanical thresholds on the affected hindpaw, signs of anxiety in the zero maze, as well as cerebral hypoperfusion in dose-dependent manner. To our knowledge, this is the first study using laser speckle contrast imaging to examine the effects of CFA-induced peripheral inflammation on cerebral blood perfusion. It serves as a first step in delineating the path by which insult to peripheral tissues can cause long-lasting brain plasticity via vascular mechanisms.