Effects of polysaccharides from rhizomes of Curcuma zedoaria on macrophage functions

The dual-targeting mechanism of an anti-inflammatory diarylheptanoid from Curcuma zedoaria (Christm.) Roscoe with the capacity for β2-adrenoreceptor agonism and NLRP3 inhibition

Chronic obstructive pulmonary disease (COPD) is a common respiratory disease characterized by symptoms of shortness of breath and chronic inflammation. Curcuma zedoaria (Christm.) Roscoe is a well-documented traditional medical herb that is frequently used in the treatment of COPD. Previously, we identified a diarylheptanoid compound (1-(4-hydroxy-5-methoxyphenyl)-7-(4,5-dihydroxyphenyl)-3,5-dihydroxyheptane; abbreviated as HMDD) from this herb that exhibited potent agonistic activity on β2-adrenergic receptors (β2 adrenoreceptor) that are present on airway smooth muscle cells. In this work, we used chemically synthesized HMDD compound, and confirmed its bioactivity on β2 adrenoreceptors. Then by a proteomics study and anti-inflammatory evaluation detections, we found that HMDD downregulated the nucleotide-binding oligomerization domain (NOD)-like receptor (NLR) signaling pathway and suppressed the NLRP3 receptor expression in RAW264.7 macrophages and in a COPD model in A549 lung carcinoma cells. HMDD also decreased nitric oxide production levels, and impacted other interleukins and the phosphorylation of NF-κB and ERK pathways. We performed molecular docking of HMDD on β2 adrenoreceptor and NLRP3 protein models. This work reports the anti-inflammatory effects of HMDD and suggests a dual-targeting mechanism of β2-adrenoreceptor agonism and NLRP3 inhibition. Such a mechanism scientifically supports the clinical uses of Curcuma zedoaria (Christm.) Roscoe in treating COPD, as it can simultaneously relieve persistent breathlessness and inflammation. HMDD can be considered as a potential non-steroidal anti-inflammatory drug in novel therapy design for the treatment of COPD and other inflammatory diseases.

Immunomodulatory Effects and Mechanisms of Curcuma Species and Their Bioactive Compounds: A Review

Curcuma species (family: Zingiberaceae) are widely utilized in traditional medicine to treat diverse immune-related disorders. There have been many scientific studies on their immunomodulating effects to support their ethnopharmacological uses. In this review, the efficacy of six Curcuma species, namely, C. longa L., C. zanthorrhiza Roxb., C. mangga Valeton & Zijp, C. aeruginosa Roxb. C. zedoaria (Christm.) Roscoe, and C. amada Roxb., and their bioactive metabolites to modulate the immune system, their mechanistic effects, and their potential to be developed into effective and safe immunomodulatory agents are highlighted. Literature search has been carried out extensively to gather significant findings on immunomodulating activities of these plants. The immunomodulatory effects of Curcuma species were critically analyzed, and future research strategies and appropriate perspectives on the plants as source of new immunomodulators were discussed. Most of the pharmacological investigations to evaluate their immunomodulatory effects were in vivo and in vitro experiments on the crude extracts of the plants. The extracts were not chemically characterized or standardized. Of all the Curcuma species investigated, the immunomodulatory effects of C. longa were the most studied. Most of the bioactive metabolites responsible for the immunomodulating activities were not determined, and mechanistic studies to understand the underlying mechanisms were scanty. There are limited clinical studies to confirm their efficacy in human. Of all the bioactive metabolites, only curcumin is undergoing extensive clinical trials based on its anti-inflammatory properties and main use as an adjuvant for the treatment of cancer. More in-depth studies to understand the underlying mechanisms using experimental in vivo animal models of immune-related disorders and elaborate bioavailability, preclinical pharmacokinetics, and toxicity studies are required before clinical trials can be pursued for development into immunomodulatory agents.

Protective effect of Lycium barbarum polysaccharide on ethanol-induced injury in human hepatocyte and its mechanism

The purpose of this research is to study the effect of Lycium barbarum polysaccharide on ethanol-induced liver injury and its mechanism. The cell survival rate, the apoptosis rate, and the intracellular ROS level was detected by MTT assay, flow cytometry, laser confocal microscopy, and fluorescence spectrophotometry, respectively. The antioxidative indices were determined by ELISA kits and the protein level was detected by western blot. The result showed Lycium barbarum polysaccharide could protect ethanol-induced cell injury by reducing cell apoptosis and regulating the levels of indicators related to oxidative stress, such as ROS, MDA, SOD, etc. In addition, LBP could increase the nuclear expression of Nrf2 protein and significantly up-regulate the expression levels of Nrf2 protein and its downstream proteins, such as HO-1, NQO1, and GCLC in the cell nucleus. Therefore, Lycium barbarum polysaccharide has a protective effect on ethanol-induced liver cell injury and it plays the role in cell apoptosis pathway and oxidative stress pathway. PRACTICAL APPLICATIONS: Lycium barbarum is a kind of food that can be used as food and medicine in China. The result showed that Lycium barbarum polysaccharide could protect ethanol-induced liver cell injury, which is beneficial to the application of LBP in functional food.

Glycosaminoglycan from Apostichopus japonicus induces immunomodulatory activity in cyclophosphamide-treated mice and in macrophages

This study was designed to systematically elucidate the immunomodulation effect of glycosaminoglycan from Apostichopus japonicus (AHG) in cyclophosphamide (CY)-induced immunosuppression model and potential mechanism responsible for the activation of macrophages. The results showed that the treatment with AHG could increase natural killer (NK) cell cytotoxicity, carbon clearance and marker enzymes activities in CY-induced immunosuppression mice, indicating that the innate immunity experienced recovery to some extent. Moreover, CY-induced reductions in thymus and spleen indices, serum levels of cytokines, immunoglobulins and hemolysin, as well as the ratio of spleen lymphocyte subsets were recovered by AHG, suggesting that AHG could improve the adaptive immunity through cellular immunity and humoral immunity. Delightedly, it was found that AHG at 10 mg/kg body weight could restore the CY-induced immunosuppression in mice to normal level on both innate and adaptive immunity. Furthermore, AHG also promoted both the expression of NO, TNF-α, IL-6, IL-1β, IL-18 and MCP-1 protein and related mRNA in macrophages. It was revealed that AHG activated macrophages through the phosphorylation of mitogen-activated protein kinase (MAPK) and nuclear factor-B (NF-κB). In conclusion, AHG exerts remarkable immunomodulatory activities in both innate and adaptive immune system. These findings should have great value for further study on the immunopotentiating mechanisms of this biomacromolecule.

Green synthesis of silver nanoparticles using transgenic Nicotiana tabacum callus culture expressing silicatein gene from marine sponge Latrunculia oparinae

In the present investigation, transgenic tobacco callus cultures and plants overexpressing the silicatein gene LoSilA1 from marine sponge Latrunculia oparinae were obtained and their bioreduction behaviour for the synthesis of silver nanoparticles (AgNPs) was studied. Synthesized nanoparticles were characterized using UV-visible spectroscopy, Fourier transformed infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), atomic flame electron microscopy (AFM) and nanoparticle tracking analysis (NTA). Our measurements showed that the reduction of silver nitrate produced spherical AgNPs with diameters in the range of 12-80 nm. The results of XRD analysis proved the crystal nature of the obtained AgNPs. FTIR analysis indicated that particles are reduced and stabilized in solution by the capping agent, which is likely to be proteins present in the callus extract. Interestingly, the reduction potential of LoSiLA1-transgenic callus line was increased three-fold compared with the empty vector-transformed calli. The synthesized AgNPs were found to exhibit strong antibacterial activity against Escherichia coli and Agrobacterium rhizogenes. The present study reports the first evidence for using genetic engineering for activation of the reduction potential of plant cells for synthesis of biocidal AgNPs.

Chemical constituents and biological research on plants in the genus Curcuma

Curcuma, a valuable genus in the family Zingiberaceae, includes approximately 110 species. These plants are native to Southeast Asia and are extensively cultivated in India, China, Sri Lanka, Indonesia, Peru, Australia, and the West Indies. The plants have long been used in folk medicine to treat stomach ailments, stimulate digestion, and protect the digestive organs, including the intestines, stomach, and liver. In recent years, substantial progress has been achieved in investigations regarding the chemical and pharmacological properties, as well as in clinical trials of certain Curcuma species. This review comprehensively summarizes the current knowledge on the chemistry and briefly discusses the biological activities of Curcuma species. A total of 720 compounds, including 102 diphenylalkanoids, 19 phenylpropene derivatives, 529 terpenoids, 15 flavonoids, 7 steroids, 3 alkaloids, and 44 compounds of other types isolated or identified from 32 species, have been phytochemically investigated. The biological activities of plant extracts and pure compounds are classified into 15 groups in detail, with emphasis on anti-inflammatory and antitumor activities.

Anticancer Activity of Curcumin and Its Analogues: Preclinical and Clinical Studies

Curcumin has been shown to have a wide variety of therapeutic effects, ranging from anti-inflammatory, chemopreventive, anti-proliferative, and anti-metastatic. This review provides an overview of the recent research conducted to overcome the problems with the bioavailability of curcumin, and of the preclinical and clinical studies that have reported success in combinatorial strategies coupling curcumin with other treatments. Research on the signaling pathways that curcumin treatment targets shows that it potently acts on major intracellular components involved in key processes such as genomic modulations, cell invasion and cell death pathways. Curcumin is a promising molecule for the prevention and treatment of cancer.

Cytopiloyne, a polyacetylenic glucoside from Bidens pilosa, acts as a novel anticandidal agent via regulation of macrophages

ETHNOPHARMACOLOGICAL RELEVANCE

Bidens pilosa, a tropical and sub-tropical herbal plant, is used as an ethnomedicine for bacterial infection or immune modulation in Asia, America and Africa. It has been demonstrated that cytopiloyne (CP), a bioactive polyacetylenic glucoside purified from B. pilosa, increases the percentage of macrophages in the spleen but the specific effects on macrophages remain unclear.

AIM OF THE STUDY

The aim of this study was to evaluate the effects of CP on macrophage activity and host defense in BALB/c mice with Candida parapsilosis infection and investigate the likely mechanisms.

MATERIALS AND METHODS

RAW264.7 cells, a mouse macrophage cell line, were used to assess the effects of CP on macrophage activity by phagocytosis assay, colony forming assay and acridine orange/crystal violet stain. To evaluate the activity of CP against C. parapsilosis, BALB/c mouse infection models were treated with/without CP and histopathological examination was performed. The role of macrophages in the infection model was clarified by treatment with carrageenan, a selective macrophage-toxic agent. RAW264.7 macrophage activities influenced by CP were further investigated by lysosome staining, phagosomal acidification assay, lysosome enzyme activity and PKC inhibitor GF109203X.

RESULTS

The results showed that CP in vitro enhances the ability of RAW264.7 macrophages to engulf and clear C. parapsilosis. In the mouse model, CP treatment improved the survival rate of Candida-infected mice and lowered the severity of microscopic lesions in livers and spleens via a macrophage-dependent mechanism. Furthermore, with CP treatment, the fusion and acidification of phagolysosomes were accelerated and the lysosome enzyme activity of RAW264.7 macrophages was elevated. PKC inhibitor GF109203X reversed the increase in phagocytic activity by CP demonstrating that the PKC pathway is involved in the macrophage-mediated phagocytosis of C. parapsilosis.

CONCLUSIONS

Our data suggested that CP, as an immunomodulator, enhances macrophage activity against C. parapsilosis infections.

Structure of β-Glucan Oligomer from Laminarin and Its Effect on Human Monocytes to Inhibit the Proliferation of U937 Cells

We analyzed the human monocyte-stimulating ability of laminarin from Eisenia bicyclis, lichenan from Cetraria islandica, and their oligomers depolymerized with endo-1,3-beta-glucanase from Arthrobacter sp. The respective beta-glucan oligomers with different degrees of polymerization (DP) were fractionated from hydrolytic products of laminarin and lichenan using gel-filtration chromatography. The monocyte-conditioned medium pre-cultured in the presence of a fraction of beta-glucan oligomer (DP>/=8) from laminarin exhibited inhibitory activity against the proliferation of human myeloid leukemia U937 cells, while those pre-cultured with other beta-glucan oligomers and the original laminarin and lichenan showed little or no activity. NMR analysis indicated that the beta-glucan oligomer (DP>/=8) has an average DP value of 13, and its ratio of beta-1,3- to beta-1,6-linkages in glucopyranose units was estimated to be 1.3:1. These results indicate that the beta-1,3-glucan oligomer with a higher content of beta-1,6-linkage stimulates monocytes to inhibit the proliferation of U937 cells.

Comparative Evaluation of Anti-Inflammatory Activity of Curcuminoids, Turmerones, and Aqueous Extract of Curcuma longa

Curcuma longa is widely known for its anti-inflammatory activity in traditional system of medicine for centuries and has been scientifically validated extensively. The present study was conducted to evaluate the anti-inflammatory activity of curcuminoids and oil-free aqueous extract (COFAE) of C. longa and compare it with that of curcuminoids and turmerones (volatile oil), the bioactive components of C. longa that are proven for the anti-inflammatory potential. The activity against inflammation was evaluated in xylene-induced ear edema, cotton pellet granuloma models in albino Swiss mice and albino Wistar rats, respectively. The results showed that COFAE of C. longa at three dose levels significantly (P ≤ 0.05) inhibited inflammation in both models, as evidenced by reduction in ear weight and decrease in wet as well as dry weights of cotton pellets, when compared to the vehicle control. The COFAE of C. longa showed considerable anti-inflammatory effects against acute and chronic inflammation and the effects were comparable to those of curcuminoids and turmerones.

Immune-stimulatory and anti-inflammatory activities of Curcuma longa extract and its polysaccharide fraction

Background:

While curcuminoids have been reported to possess diverse biological activities, the anti-inflammatory activity of polar extracts (devoid of curcuminoids) of Curcuma longa (C. longa) has seldom been studied. In this study, we have investigated immune-stimulatory and anti-inflammatory activities of an aqueous based extract of C. longa (NR-INF-02) and its fractions in presence and absence of mitogens.

Materials and Methods:

Effects of NR-INF-02 (Turmacin™, Natural Remedies Pvt. Ltd., Bangalore, India) on proliferation, nitric oxide (NO), monocyte chemotactic protein-1 (MCP-1), interleukins (ILs) and prostaglandin (PGE₂) levels of mouse splenocytes and mouse macrophage (RAW264.7) cells were determined.

Results:

NR-INF-02 increased splenocytes number in presence and absence of lipopolysaccharide (LPS) or concanavalin A. Treatment of NR-INF-02 showed a significant increase of NO, IL-2, IL-6, IL-10, IL-12, interferon (IFN) gamma, tumor necrosis factor (TNF) alpha and MCP-1 production in unstimulated mouse splenocytes and mouse macrophages. Interestingly, NR-INF-02 showed potent inhibitory effect towards release of PGE₂ and IL-12 levels in LPS stimulated mouse splenocytes. Further, NR-INF-02 was fractionated into polysaccharide fraction (F1) and mother liquor (F2) to study their immune-modulatory effects. F1 was found to be more potent than F2 toward inhibiting PGE₂ and IL-12 in LPS stimulated splenocytes.

Conclusion:

Present findings revealed the novel anti-inflammatory property of NR-INF-02 and its polysaccharide fraction by inhibiting the secretion of IL-12 and PGE₂in vitro.

Antitumour Effects of Isocurcumenol Isolated from Curcuma zedoaria Rhizomes on Human and Murine Cancer Cells

Curcuma zedoaria belonging to the family Zingiberaceae has been used in the traditional system of medicine in India and Southwest Asia in treating many human ailments and is found to possess many biological activities. The rationale of the present study was to isolate, identify, and characterize antitumour principles from the rhizomes of Curcuma zedoaria, to assess its cytotoxic effects on human and murine cancer cells, to determine its apoptosis inducing capacity in cancer cells, and to evaluate its tumour reducing properties in in vivo mice models. Isocurcumenol was characterized as the active compound by spectroscopy and was found to inhibit the proliferation of cancer cells without inducing significant toxicity to the normal cells. Fluorescent staining exhibited the morphological features of apoptosis in the compound-treated cancer cells. In vivo tumour reduction studies revealed that a dose of 35.7 mg/kg body weight significantly reduced the ascitic tumour in DLA-challenged mice and increased the lifespan with respect to untreated control mice.

Immunostimulatory activities of polysaccharide extract isolated from Curcuma longa

Several curcuminoids and sesquiterpenoids isolated from Curcuma longa (CL) have been shown to have many pharmacological activities. In the present study, the immunomodulatory activities of the polar fractions of CL hot water extracts were investigated using human peripheral blood mononuclear cells (PBMC). Our results showed that the high polarity fraction of the hot water extract exhibited stimulatory effects on PBMC proliferation as shown in [methyl-(3)H]-thymidine incorporation assay. In an attempt to isolate the active components responsible for the activities, further partition with ethyl acetate, n-butanol and ethanol, progressively were performed. The cytokine productions (TGF-beta, TNF-alpha, GM-CSF, IL-1alpha, IL-5, IL-6, IL-8, IL-10, IL-13, etc.) have been modulated by a polysaccharide-enriched fraction as shown in ELISA and cytokine protein array. The proportion of CD14 positive stained PBMC was increased by such fraction. The composition of monosaccharide of the active fraction has been determined by GC-MS and gel permeation chromatography. The immunostimulatory effects of C. longa polysaccharides on PBMC were shown for the first time. The findings revealed the potential use of C. longa crude extract (containing curcuminoids and polysaccharides) as an adjuvant supplement for cancer patients, whose immune activities were suppressed during chemotherapies.

Chemically-modified polysaccharide extract derived from Leucaena leucocephala alters Raw 264.7 murine macrophage functions

In this study, a chemical modification of the polysaccharides extract (E) derived from Leucaena leucocephala seeds was performed to prepare C-glycosidic 2-propanol derivative (PE), and its sulphated derivative (SPE). This study aimed to characterize immunomodulatory activities of the original extract and its derivatives by exploring their effects on Raw macrophage 264.7 functions and their antioxidant activity. Our results indicated that PE was an effective radical scavenger to hydroxyl, peroxyl, and superoxide anion radicals, and SPE was a peroxyl radical scavenger. PE and SPE were found to influence the macrophage functions. Both of PE and SPE enhanced the macrophage proliferation and phagocytosis of FITC-zymosan; PE inhibited nitric oxide (NO) generation and tumor necrosis factor-alpha (TNF-alpha) secretion in lipopolysaccharide (LPS)-stimulated Raw macrophage 264.7. In contrast, SPE over-induced NO generation and TNF-alpha secretion. Moreover, PE strongly inhibited the binding affinity of FITC-LPS to Raw 264.7, as indicated by flow cytometry analysis. These findings revealed that PE may act as a potent anti-inflammatory agent; however SPE may act as an inducer of macrophage functions against pathogens.

Cancer chemopreventive and anti-inflammatory activities of chemically modified guar gum

Guar gum (G) is a simple characterized branched polysaccharide, which is frequently used in food industries. We prepared the gum C-glycosylated derivative (GG), and its sulphated derivative (SGG), aiming to characterize their cancer chemopreventive, and anti-inflammatory properties. Estimation of cancer chemopreventive activity, specifically anti-initiation, including the modulation of carcinogen metabolism and the antioxidant capacity, revealed that GG was a potent anti-initiator, where it inhibited not only the carcinogen activator enzyme, cytochrome P450 1A (CYP1A), but also induced the carcinogen detoxification enzymes glutathione-S-transferases (GSTs), while SGG inhibited both CYP1A and GSTs. SGG was an effective radical scavenger than GG against hydroxyl, peroxyl, and superoxide anion radicals. GG and SGG were found to modulate the macrophage functions into an anti-inflammatory pattern. Thus, both enhanced the macrophage proliferation and phagocytosis of fluorescein isothiocyanate (FITC)-zymosan; however, they also inhibited strongly the nitric oxide generation and tumor necrosis factor-alpha secretion in lipopolysaccharide (LPS)-stimulated RAW macrophage 264.7. Unexpectedly, both GG and SGG dramatically inhibited the binding affinity of FITC-LPS to RAW 264.7, as indicated by flow cytometry analysis. GG and SGG exhibited a significant anti-proliferative activity against human hepatocellular carcinoma cells (Hep G2), and only SGG was specifically cytotoxic for human breast carcinoma cells (MCF-7), but neither was significantly cytotoxic for human lymphoblastic leukemia cells (1301). SGG led to a major disturbance in cell cycle phases of Hep G2 cells as indicated by concomitant arrest in S- and G2/M-phases, a disturbance that was associated with an induced cell death as a result of necrosis, but not apoptosis in both GG- and SGG-treated cells. Taken together, the modified gums could be used as an alternative of G in health food industries to provide cancer prevention in risk populations.

Botanical polysaccharides: macrophage immunomodulation and therapeutic potential

Botanical polysaccharides exhibit a number of beneficial therapeutic properties, and it is thought that the mechanisms involved in these effects are due to the modulation of innate immunity and, more specifically, macrophage function. In this review, we summarize our current state of understanding of the macrophage modulatory effects of botanical polysaccharides isolated from a wide array of different species of flora, including higher plants, mushrooms, lichens and algae. Overall, the primary effect of botanical polysaccharides is to enhance and/or activate macrophage immune responses, leading to immunomodulation, anti-tumor activity, wound-healing and other therapeutic effects. Furthermore, botanical and microbial polysaccharides bind to common surface receptors and induce similar immunomodulatory responses in macrophages, suggesting that evolutionarily conserved polysaccharide structural features are shared between these organisms. Thus, the evaluation of botanical polysaccharides provides a unique opportunity for the discovery of novel therapeutic agents and adjuvants that exhibit beneficial immunomodulatory properties.

Metal-induced oxidative damage in cultured hepatocytes and hepatic lysosomal fraction: beneficial effect of a curcumin/absinthium compound

OBJECTIVE

Metals undergo redox cycling and there is increasing evidence of free radical generation and oxidative injury in the pathogenesis of liver injury and fibrosis in metal storage diseases. The aim of the present study was to test a natural hepatoprotective compound in metal-induced liver injury.

METHODS

Hepatocytes were isolated from Wistar rats by collagenase perfusion method and cultured as such and also with alpha-linolenic acid (LNA)-bovine serum albumin (BSA). Hepatocytes were then cultured with a graded dilution of PN-M001 (100 microg/mL and 200 microg/mL), which is a curcuma/absinthium-containing compound, or sylibin (100 microg/mL) dissolved in dimethyl sulfoxide for 10 min before the addition of metallic salts (iron, copper and vanadium). Lysosomal fractions were prepared for lysosome fragility tests in which beta-galactosidase activity and lactate dehydrogenase (LDH) leakage were measured, as well as oxidative damage tests in the presence of hydrophilic and lipophilic free radical generators. Quenching activity by 1,1-diphenyl-2-picrylhydrazyl (DPPH) was also assessed.

RESULTS

Malonildialdehyde accumulation in the medium showed a direct time-course increase with incubation time. Both PN-M001 and sylibin showed a significant protective effect against all challenge metal ions, as expressed by the half inhibition concentration (IC(50)) against lipid peroxidation. However, on a molar ratio, sylibin seemed to be more effective than PN-M001 in Fe-induced peroxidative damage (P < 0.05). Both test compounds, irrespective of the concentration, significantly reduced the LDH and beta-galactosidase concentration in the lysosomal fractions. As compared with untreated lysosomal fractions challenged with the two peroxide radicals generators, either PN-M001 or sylibin exerted significant protection However, PN-M001 was significantly better than sylibin in suppressing acid phosphatase enzyme activity. Both compounds showed comparable and significant DPPH radical-scavenging activity.

CONCLUSION

These data support the potential clinical application of curcumin-containing compounds.

Glucosamine and chondroitin sulfate: biological response modifiers of chondrocytes under simulated conditions of joint stress

OBJECTIVE

To test the hypothesis that chondrocytes are more responsive to the chondroprotective agents, glucosamine (glcN) and chondroitin sulfate (CS), under in vitro conditions simulating in vivo joint stress.

DESIGN

Synthetic and anticatabolic activities of bovine articular cartilage were assayed using 35-sulfate labeling and assaying the specific activity of glycosaminoglycans (GAGs) under the conditions of enzyme-induced matrix depletion, heat stress, mechanical compression and cytokine stress.

RESULTS

The response of cartilage to simulated conditions of in vivo stress varies, depending on the type stress and age of the animal. Cartilage from aged animals was more responsive to stress and to glcN and CS. Pronase-induced matrix depletion and mechanical stress increased proteoglycan synthetic activity. Exposure to glcN and CS significantly enhanced this stress response from 85 to 191% and from 40 to 1000%, respectively. Heat stress and stromelysin digestion decreased synthetic activity, which was reversed or normalized on exposure to glcN and CS. Cartilage from young joints was somewhat refractory to the level of stress imposed and to treatment with glcN and CS.

CONCLUSION

The metabolic response of cartilage from aged animals to glcN and CS under simulated conditions of in vivo stress is significantly greater than that seen in nonstressed or young tissue. By enhancing the "protective" metabolic response of chondrocytes to stress, glcN and CS may improve its ability for repair and regeneration. These observations suggest that these compounds function as biological response modifiers (BRMs), agents which boost natural protective responses of tissues under adverse environmental conditions.