Chicken type II collagen induced immune tolerance of mesenteric lymph node lymphocytes by enhancing beta2-adrenergic receptor desensitization in rats with collagen-induced arthritis

High gastrointestinal digestive stability endows chondroitin sulfate-soluble undenatured type II collagen complex with high activity: Improvement of osteoarthritis in rats

Previously, we prepared a chondroitin sulfate-soluble undenatured type II collagen complex (CS-SC II) with low salt content. This paper further explored the differences between CS-SC II and SC II in terms of gastrointestinal digestive characteristics and osteoarthritis (OA) improvement. In vitro and in vivo experiments showed that the gastric digestive stability of CS-SC II was high under both pH 2.0 and pH 3.0, the α1 chain and triple helix structure of type II collagen retained >60 %. However, SC II had high gastric digestive stability only under pH 3.0. Furthermore, intestinal digestion had little effect on α1 chains of CS-SC II and SC II, and distribution experiments showed that they might exert their biological activities in the intestine. CS-SC II had obvious improvement in OA rats at 1.0 mg/kg/d, that is, the joint swelling was significantly reduced and the weight-bearing ratio of the right hind limb was increased to 49 %, which was close to that of 4.0 mg/kg/d SC II. The wear of articular cartilage, Mankin and OARSI scores of rats in CS-SC II group were significantly reduced. The effects of low-dose CS-SC II on the proportion of regulatory T cells (Treg), mRNA expression of OA key biomarkers (Il6, Ccl7, MMP-3 and MMP13) and signaling pathway genes (NF-κB, AKT or AMPKα) were comparable to those of high-dose SC II. These results showed that CS-SC II might have greater potential to improve OA at a lower dose than SC II due to its high gastrointestinal digestive stability at a wide range of pH conditions.

Differences between soluble and insoluble undenatured type II collagen in improving osteoarthritis in rats and their potential mechanisms

Our previous research showed that soluble (SC II) and insoluble (IC II) undenatured type II collagen had significant differences during gastrointestinal digestion in vitro, and SC II exposed more type II collagen with triple helix structure. However, the differences in their in vivo digestive characteristics, improvement on osteoarthritis (OA), and possible mechanisms have not been elucidated. The aim of this study was to explore these issues. After oral administration of SC II and IC II, the joint swelling of OA rats significantly reduced, and the weight bearing ratio of right hind limb significantly increased, especially in SC II group (raised to 48%). The Mankin and OARSI scores decreased by 35% and 48% in SC II group, respectively. SC II and IC II increased the mRNA expression of anti-inflammatory factors and the proportion of regulatory T cells (Treg). Importantly, type II collagen released by IC II during in vivo gastrointestinal digestion was far less than SC II, which explained the higher ability of SC II to induce immune tolerance in small intestine than IC II. Bioinformatics analysis showed that the differential genes between model and control were significantly enriched in PI3K/AKT, PPAR and AMPK signalling pathways, and 24 hub genes were analyzed. SC II significantly down-regulated the mRNA expression of Il6, Ccl7, NF-κB, AKT and up-regulated the mRNA expression of Scd1. These results showed that SC II was superior to IC II in improving OA by inducing immune tolerance and could regulate key biomarkers and signalling pathways in OA rats.

Undenatured type II collagen and its role in improving osteoarthritis

Osteoarthritis (OA) is a degenerative joint disease, affecting 32.5 million US adults or 242 million people worldwide. There is no cure for OA. Many animal and clinical trials showed that oral administration of undenatured type II collagen could significantly reduce the incidence of OA or alleviate the symptoms of articular cartilage. Type II collagen is an important component of cartilage matrix. This article reviewed research progress of undenatured type II collagen including its methods of extraction and preparation, structure and characterization, solubility, thermal stability, gastrointestinal digestive stability, its role in improving OA, and the mechanism of its action in improving OA. Type II collagen has been extensively explored for its potential in improving arthritis. Methods of extraction of type II collagen are inefficient and tedious. The method of limited enzymatic hydrolysis is mainly used to prepare soluble undenatured type II collagen (SC II). The solubility, thermal and gastrointestinal digestive stability of SC II are affected by the sources of raw material, pH, salt ions, and temperature. Oral administration of undenatured type II collagen improves OA, whereas its activity is affected by the sources, degree of denaturalization, intervention methods and doses. However, the influence of the structure of undenatured type II collagen on its activity and the mechanism are unclear. The findings in this review support that undenatured type II collagen can be used in the intervention or auxiliary intervention of patients with OA.

Structure of type II collagen from sturgeon cartilage and its effect on adjuvant-induced rheumatoid arthritis in rats

The purpose of this paper was to extract and characterize type II collagen of sturgeon cartilage (SC-CII), and to explore the effects of taking SC-CII orally on rheumatoid arthritis (RA) in rats. SC-CII showed a triple-helix structure (RPN = 0.12), with d1 of 11.82 Å and d2 of 4.08 Å, which was analyzed by FT-IR, CD, XRD, and MS. It was constructed of the repeating tripeptide unit Gly-X-Y, where X and Y are generally Pro or Hyp, proved by amino acid composition and peptide mass fingerprinting. Furthermore, the effects of SC-CII on RA were evaluated. Ankle thickness was significantly decreased in SC-CII groups, with changes in lymphocyte proliferation also observed. Compared with the model control group, there was an evident decrease in TNF-α, IL-1β, COX-2, MCP-1, and TLR-4 mRNA levels, but no remarkable differences in APF, MMP-3, and MyD88 mRNA levels in the SC-CII groups. In addition, TNF-α, IL-1β, RF, Anti-CII Ab were significantly reduced in the SC-CII groups, proved by ELISA. Therefore, SC-CII showed alleviating effects on RA through the TLR4/MyD88-NFκB pathway.

Therapeutic Effect of Nile Tilapia Type II Collagen on Rigidity in CD8+ Cells by Alleviating Inflammation and Rheumatoid Arthritis in Rats by Oral Tolerance

Fibrillins are microfibril-associated macro glycoproteins found in connective tissues and structurally related to latent TGF-β-binding proteins (LTBPs). The special cellular immunity and blocking glycoprotein receptors IIb and IIIa of fibrillins are emerging topics in recent years. In this study, Nile Tilapia type IIcollagen (NTCII) was extracted and purified from the skull cartilages by a pepsin-soluble method. Amino acid analysis indicated that NTCII consisted of 315/1000 glycine residues, 72/1000 hydroxyproline residues and 108/1000 proline residues. SDS-PAGE analysis showed that NTCII was composed of three identical 130 kDa α-chains. The results of glycoprotein/carbohydrate assay indicated that the total polysaccharide content of NTCII was 5.6–19.0%. The IR spectrum of NTCII displayed five characteristic peaks of amide I, II, III, A, B. NTCII at 10–100 μg/mL concentration downregulated the content of cytokines in the presence or absence of LPS, especially the secretion of cytokines IL-6, IL-1β and TNF-α. Interestingly, NTCII promoted the secretion of Fas/Apo-1 compared to the control group and 25 μg/mL of NTCII resulted in a higher Fas/Apo-1 secretion level in CD8⁺ T cells. FITC-TCII fluorescence images confirmed that NTCII could bind to the membrane surface of CD8⁺ T cells, leading to the induction of rigidity. NTCII could bind to the membrane surface of CD8⁺ T cells that leads to the induction of rigidity, as evidenced by the FITC-NTCII fluorescence images. The qRT-PCR gene expression analysis of caspase-8 collected with Fas/Apo-1 was upregulated significantly in the 1 and 50 μg/mL NTCII-treated groups compared with the control group. Overall, the results conclude that the rigidity did not lead to an increase in inflammatory factors in CD8⁺ T cells treated with NTCII. The oral administration of NTCII 3 mg/kg dosage caused more prominent repair of damaged ankle cartilage than the 1 mg/kg dosage in Freund’s adjuvant-induced model of arthritis in rats. Therefore, this study disclosed the immunological and anti-arthritic effect of fibrillar collagen, which could be a potential biomaterial for practical applications with lower toxicity.

Structural characterization and in vitro immunogenicity evaluation of amphibian-derived collagen type II from the cartilage of Chinese Giant Salamander (Andrias davidianus)

Collagen type II (CT-II) has unique biological activities and functions, yet the knowledge on amphibian-derived CT-II is rare. Herein, acid-soluble collagen (ASC) and pepsin-soluble collagen (PSC) were successfully isolated and characterized from the cartilage of Chinese Giant Salamander (CGS). The in vitro immunogenicity of collagen was then evaluated and compared with that of the standard bovine CT-II (SCT-II) by T-lymphocyte cell proliferation activity. Results demonstrated that ASC and PSC were predominantly CT-II along with minor collagen type I and maintained intact triple-helical structure of nature collagen. Compared with SCT-II, higher glycine content (337.80 and 339.93 residues/1000 residues) and lower degree of proline hydroxylation (51.81% and 52.52%) were observed in ASC and PSC. Additionally, PSC showed comparable T _d (63 °C) and higher T _m (109 °C) than SCT-II (64 °C and 103 °C, respectively), indicating its high thermal and structural stability. SEM revealed that the lyophilized ASC and PSC had interconnected porous network structures of collagen-based materials. Moreover, different from SCT-II, both ASC and PSC presented no immunogenicity because they did not cause obvious proliferation of murine T-lymphocyte regardless of the induced concentration of collagen increased from 8 to 417 μg/mL. These data suggested that the amphibian-derived CGS cartilage collagens avoid the immunogenic risk of terrestrial animal collagen, and show high thermal stability and potential advantage in biomedical application.

Bidirectional Role of β2-Adrenergic Receptor in Autoimmune Diseases

Disorder of the sympathetic nervous system (SNS) is closely related to the pathogenesis of various autoimmune diseases (ADs). Catecholamine triggered beta2-adrenergic receptor (β2-AR) signaling is important in creating a bidirectional response in the progression of ADs due to factors including diverse expression patterns, single nucleotide polymorphisms (SNPs), biased signals, and desensitization of β2-AR, as well as different subtypes of Gα binding to β2-AR. In this review, we summarize the actions of β2-AR signaling in regulating the functions of immunocytes and in the pathogenesis of ADs, and the application of β2-AR agonists or antagonists in treating major types of ADs is also discussed. We suggest that restoring the immune balance via a soft regulation of the expression or activation of β2-AR is one of the promising therapeutic strategies for systematic ADs.

Effects of cichoric acid extract from Echinacea purpurea on collagen-induced arthritis in rats

Cichoric acid extract (CAE) from Echinacea purpurea L. was used to investigate the anti-arthritic effect by using collagen-induced arthritis (CIA) rat model. The hind paw swelling volume and the body weight were measured and recorded. All the drug solutions were administered orally to rats for a total of 28 days. On day 28, the rats were anaesthetized and decapitated. The thymus and spleen were weighed for the determination of the organ index. The concentration of tumor necrosis factor alpha (TNFα), interleukin-1 beta (IL-1β) and prostaglandin E2 (PGE-2) in the serum was measured using commercially available ELISA kits. Total and phosphor-NF-κB and Cox-2 protein expression in synovial tissues were determined by histological slides quantification and western blot analysis. Our data showed that administration of all doses of CAE (8, 16, and 32 mg/kg) significantly decreased the paw swelling, restored body weight gain and decreased the organ index of the thymus and spleen compared with that of the CIA group. CAE (8, 16, and 32 mg/kg) treatment significantly reduced the levels of TNFα, IL-1β and PGE-2 in serum compared with the CIA group. Histopathological analysis demonstrated that CAE has obvious anti-arthritic activity. In addition, CAE (32 mg/kg) significantly decreased the levels of nuclear factor-κB (NF-κB), TNFα and cyclooxygenase 2 (Cox-2) in synovium tissues of the ankle joint compared with the CIA group. Furthermore, CAE administration significantly decreased the protein expression of phosphor-NF-κB and Cox-2 in synovium tissues of the knee joint compared with the CIA group. The results suggest that the anti-inflammatory activity of CAE may account for its anti-arthritic effect, and CAE could be a potential therapeutic drug for the treatment of rheumatoid arthritis (RA).

Type II collagen and gelatin from silvertip shark (Carcharhinus albimarginatus) cartilage: isolation, purification, physicochemical and antioxidant properties

Type II acid soluble collagen (CIIA), pepsin soluble collagen (CIIP) and type II gelatin (GII) were isolated from silvertip shark (Carcharhinus albimarginatus) cartilage and examined for their physicochemical and antioxidant properties. GII had a higher hydroxyproline content (173 mg/g) than the collagens and cartilage. CIIA, CIIP and GII were composed of two identical α1 and β chains and were characterized as type II. Amino acid analysis of CIIA, CIIP and GII indicated imino acid contents of 150, 156 and 153 amino acid residues per 1000 residues, respectively. Differing Fourier transform infrared (FTIR) spectra of CIIA, CIIP and GII were observed, which suggested that the isolation process affected the secondary structure and molecular order of collagen, particularly the triple-helical structure. The denaturation temperature of GII (32.5 °C) was higher than that of CIIA and CIIP. The antioxidant activity against 1,1-diphenyl-2-picrylhydrazyl radicals and the reducing power of CIIP was greater than that of CIIA and GII. SEM microstructure of the collagens depicted a porous, fibrillary and multi-layered structure. Accordingly, the physicochemical and antioxidant properties of type II collagens (CIIA, CIIP) and GII isolated from shark cartilage were found to be suitable for biomedical applications.

Pro-apoptotic effect of epigallo-catechin-3-gallate on B lymphocytes through regulating BAFF/PI3K/Akt/mTOR signaling in rats with collagen-induced arthritis

To investigate the role of PI3K/Akt/mTOR signaling mediated by B cell-activating factor belonging to the TNF family (BAFF) involved in anti-apoptosis of B lymphocytes in rats with collagen-induced arthritis (CIA) and the regulation of epigallo-catechin-3-gallate (EGCG). Sprague-Dawley rats were immunized to induce CIA. CIA rats were randomly separated into different groups and treated with EGCG (40, 80 mg/kg), Paeoniflorin (100mg/kg) from day 18 to day 38 after immunization. The effects of EGCG on B lymphocytes were evaluated by the levels of BAFF, anti-CII antibody, IgA, IgG and IgM, and the expressions of BAFF receptor, P110δ, p-Akt, mTORC1, Bcl-xL and Bim. B lymphocyte proliferations were analyzed by MTT assay. Apoptosis of B lymphocyte were assayed by flow cytometry. Results showed that, in CIA rats, the levels of BAFF, anti-CII antibody, IgA, IgG and IgM enhanced. BAFF receptor, P110δ, p-AKT, mTORC1 and Bcl-xL were expressed highly, while Bim expression decreased. EGCG (40, 80 mg/kg) and Paeoniflorin decreased the levels of BAFF, anti-CII antibody, IgA, IgG, IgM and the expressions of BAFF receptor, P110δ, p-AKT, mTORC1, Bcl-xL in CIA rats, and increased Bim expression. Further studies showed that EGCG could reduce the expression of P110δ and mTORC1 in vitro. EGCG inhibited B lymphocyte proliferation and induced B lymphocyte apoptosis. In conclusion, BAFF/BAFF receptor might regulate B cell anti-apoptosis through PI3K/Akt/mTOR pathway. EGCG had therapeutic effects on CIA rats, which might be relative to the inhibition effects of EGCG on BAFF and PI3K/Akt/mTOR signaling, and then the apoptosis of B lymphocytes was promoted further.

BAFF/BAFF-R involved in antibodies production of rats with collagen-induced arthritis via PI3K-Akt-mTOR signaling and the regulation of paeoniflorin

ETHNOPHARMACOLOGICAL RELEVANCE

Paeoniflorin (Pae) is extracted from the root of paeonia lactiflora which have attracted attention for anti-rheumatic and immune modulating properties.

AIM OF THE STUDY

To investigate the role of PI3K/Akt/mTOR signaling mediated by BAFF/BAFF-R in antibodies production and the regulation of Pae on the signaling pathway in rats with collagen-induced arthritis (CIA).

MATERIALS AND METHODS

CIA rats were randomly separated into different groups and treated with Pae (25, 100mg/kg) from day 18 to day 38 after immunization. The effects of Pae on B lymphocytes of CIA rats were evaluated by the levels of BAFF, anti-CII antibody, IgA, IgG and IgM, and the expressions of BAFF-R, PI3K, p-Akt and mTOR.

RESULTS

In CIA rats, the levels of anti-CII antibody, IgA, IgG and IgM in serum enhanced, BAFF, BAFF-R, PI3K, p-Akt and mTOR were highly expressed. Pae (100mg/kg) obviously decreased arthritis score, relieved ankle and paw swelling, improved spleen histopathology in CIA rats, decreased the levels of IgA, IgM, IgG and anti-CII antibody, and significantly decreased the expressions of BAFF, BAFF-R, PI3K, p-Akt and mTOR.

CONCLUSION

PI3K/Akt/mTOR signaling mediated by BAFF/BAFF-R participates in antibodies production by B lymphocytes of CIA rats. Pae had therapeutic effects on rats with CIA. These effects might be relative to regulating PI3K/Akt/mTOR signal mediated by BAFF/BAFF-R, and down regulate the antibodies production further.

Oral Administration of Shark Type II Collagen Suppresses Complete Freund's Adjuvant-Induced Rheumatoid Arthritis in Rats

Objective: Shark type II collagen (SCII) is extracted as a glycoprotein from the cartilage of blue shark (Prionace glauca). We aim to confirm the effects of oral tolerance of SCII on inflammatory and immune responses to the ankle joint of rheumatoid-arthritis rats induced by Complete Freund’s Adjuvant (CFA). Materials and Methods: The onset of rheumatoid arthritis (RA) was observed 14 ± x days after injection of CFA. Rats in the control group were treated with acetic acid by oral administration (0.05 mmol kg⁻¹d⁻¹, days 14–28), while rats in experimental groups were treated by oral administration with SCII (1 or 3 mg kg⁻¹d⁻¹, days 14–28), Tripterygium wilfordii polyglycosidium (TWP) (10 mg kg⁻¹d⁻¹, days 14–28), and bovine type II collagen from US (US-CII) (1 mg kg⁻¹d⁻¹, days 14–28), respectively. The severity of arthritis was evaluated by the articular swelling. The immunological indexes observed included delayed type hypersensitivity (DTH) reaction, the level of interleukins 10 (IL-10) in rat blood serum and morphological characterization. Mixed lymphocyte culture (MLC) was performed to investigate the relationship between T cell apoptosis and specific immune tolerance induced by SCII. Results: Treatment with SCII for 2 weeks significantly attenuated the acute inflammation. The rats orally administrated with SCII at the level of 3 mg kg⁻¹d⁻¹ (SCII 3) and US-CII had decreased DTH reaction compared with rats in control group. Rats treated with SCII 3 had the highest level of IL-10 with 102 pg/mL. SCII with concentration of 10 μg/L could help to significantly enhance level of Fas/Apo-1 in T cell in vitro. The result of histological staining indicated that the recovery of the articular membranes of ankle joint in SCII 3 group was greatly enhanced. Conclusions: Our results suggest that appropriate dose of SCII can not only ameliorate symptoms but also modify the disease process of Complete-Freunds-Adjuvant-induced arthritis. Oral administration of SCII might be a potential candidate as a novel drug for further investigation.

Expression and function of β-arrestin 2 stimulated by IL-1β in human fibroblast-like synoviocytes and the effect of paeoniflorin

The aim of this study was to explore the expression and function of β-arrestin 2 in human fibroblast-like synoviocytes (FLS) stimulated by IL-1β and the effect of paeoniflorin (Pae). We isolated and cultured human FLS, which were stimulated by IL-1β. The FLS proliferations were detected by [3H] thymidine incorporation. The level of cAMP stimulated by IL-1β on different times was investigated by radioimmunoassay, and the activity of PKA was measured by luminescent kinase assay. The expression of β-arrestin 2 was measured by western blot. We found that the human FLS proliferation increased apparently in 24 h, and the activities of PKA and cAMP accumulation increased significantly in 6 h after stimulated by IL-1β, while cAMP accumulation and the activities of PKA decreased especially in 24 h when the expression of β-arrestin 2 increased significantly. Decreased cAMP accumulation and the increased expression of β-arrestin 2 may reveal a positive correlation with the FLS proliferation. Pae (10(-5), 10(-6), 10-7 mol•L(-1)) in vitro could suppress the FLS proliferation and the high expression of β-arrestin 2. The expression of β-arrestin 2 may have a positive correlation with the human FLS proliferation, while the activities of PKA and cAMP accumulation have a negative correlation with the proliferation. The increased β-arrestin 2 may down-regulate cAMP-PKA signaling pathway and promote FLS proliferation. Pae may suppress the expression of β-arrestin 2 and up-regulate cAMP-PKA signaling, which may be one of the mechanisms for the effects of Pae on inhibiting human FLS proliferation.