Effects of dietary supplementation on autoimmunity in the MRL/lpr mouse: a preliminary investigation

Crystalline silica-induced pulmonary inflammation and autoimmunity in mature adult NZBW/f1 mice: age-related sensitivity and impact of omega-3 fatty acid intervention

OBJECTIVE

Occupational exposure to respirable crystalline silica (cSiO2) has been linked to lupus development. Previous studies in young lupus-prone mice revealed that intranasal cSiO2 exposure triggered autoimmunity, preventable with docosahexaenoic acid (DHA). This study explores cSiO2 and DHA effects in mature lupus-prone adult mice, more representative of cSiO2-exposed worker age.

METHODS

Female NZBWF1 mice (14-week old) were fed control (CON) or DHA-supplemented diets. After two weeks, mice were intranasally instilled saline (VEH) or 1 mg cSiO2 weekly for four weeks. Cohorts were then analyzed 1- and 5-weeks postinstillation for lung inflammation, cell counts, chemokines, histopathology, B- and T-cell infiltration, autoantibodies, and gene signatures, with results correlated to autoimmune glomerulonephritis onset.

RESULTS

VEH/CON mice showed no pathology. cSiO2/CON mice displayed significant ectopic lymphoid tissue formation in lungs at 1 week, increasing by 5 weeks. cSiO2/CON lungs exhibited elevated cellularity, chemokines, CD3+ T-cells, CD45R + B-cells, IgG + plasma cells, gene expression, IgG autoantibodies, and glomerular hypertrophy. DHA supplementation mitigated all these effects.

DISCUSSION

The mature adult NZBWF1 mouse used here represents a life-stage coincident with immunological tolerance breach and one that more appropriately represents the age (20-30 yr) of cSiO2-exposed workers. cSiO2-induced robust pulmonary inflammation, autoantibody responses, and glomerulonephritis in mature adult mice, surpassing effects observed previously in young adults. DHA at a human-equivalent dosage effectively countered cSiO2-induced inflammation/autoimmunity in mature mice, mirroring protective effects in young mice.

CONCLUSION

These results highlight life-stage significance in this preclinical lupus model and underscore omega-3 fatty acids' therapeutic potential against toxicant-triggered autoimmune responses.

An update on diet and nutritional factors in systemic lupus erythematosus management

Systemic lupus erythematosus (SLE) is a chronic inflammatory and autoimmune disease characterised by multiple organ involvement and a large number of complications. SLE management remains complicated owing to the biological heterogeneity between patients and the lack of safe and specific targeted therapies. There is evidence that dietary factors can contribute to the geoepidemiology of autoimmune diseases such as SLE. Thus, diet therapy could be a promising approach in SLE owing to both its potential prophylactic effects, without the side effects of classical pharmacology, and its contribution to reducing co-morbidities and improving quality of life in patients with SLE. However, the question arises as to whether nutrients could ameliorate or exacerbate SLE and how they could modulate inflammation and immune function at a molecular level. The present review summarises preclinical and clinical experiences to provide the reader with an update of the positive and negative aspects of macro- and micronutrients and other nutritional factors, including dietary phenols, on SLE, focusing on the mechanisms of action involved.

Dietary extra virgin olive oil attenuates kidney injury in pristane-induced SLE model via activation of HO-1/Nrf-2 antioxidant pathway and suppression of JAK/STAT, NF-κB and MAPK activation

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by a widespread organ involvement. Recent studies have suggested that extra virgin olive oil (EVOO) might possess preventive effects on this immunoinflammation-related disease. However, its role in SLE remained unknown. In this work, we evaluated the effects of EVOO diet in a pristane-induced SLE model in mice. Three-month-old mice received an injection of pristane or saline solution and were fed with different experimental diets: sunflower oil diet or EVOO diet. After 24weeks, mice were sacrificed, spleens were collected and kidneys were removed for immunoinflammatory detections. The kidney expression of microsomal prostaglandin E synthase 1, heme oxygenase 1 (HO-1), nuclear factor E2-related factor 2 (Nrf-2), mitogen-activated protein kinases (MAPKs), Janus kinase/signal transducer and activator of transcription (JAK/STAT) and nuclear transcription factor-kappa B (NF-κB) pathways were studied by western blotting. In addition to macroscopic and histological analyses, serum matrix metalloproteinase 3 (MMP-3) levels and proinflammatory cytokines production in splenocytes were evaluated by enzyme-linked immunoassay. We have demonstrated that EVOO diet significantly reduced renal damage and decreased MMP-3 serum and PGE2 kidney levels as well as the proinflammatory cytokines production in splenocytes. Our data indicate that Nrf-2 and HO-1 protein expressions were up-regulated in those mice fed with EVOO and the activation of JAK/STAT, MAPK and NF-κB pathways were drastically ameliorated. These results support the interest of EVOO as a beneficial functional food exerting a preventive/palliative role in the management of SLE.

Further evidence for the anti-inflammatory activity of oleocanthal: inhibition of MIP-1α and IL-6 in J774 macrophages and in ATDC5 chondrocytes

AIMS

Given the relevance of degenerative joint diseases in our society, the development of a novel pharmacologic intervention is a critically important public health goal. Recently, oleocanthal, a polyphenolic natural compound from extra virgin olive oil, has emerged as a potential therapeutic weapon for the treatment of inflammatory degenerative diseases. The goal of this study was to further evaluate the anti-inflammatory activity of oleocanthal in murine macrophages J774 and murine chondrocytes ATDC5 with a particular focus on the inhibition of gene expression of pro-inflammatory factors such as MIP-1α and IL-6.

MAIN METHODS

ATDC5 murine chondrogenic cells and murine macrophages J774 were used. J774 macrophages were tested with different doses of oleocanthal and cell viability was evaluated using the MTT assay. Western blot analysis was carried on in J774 cells using anti NOS2 antibody. Nitrite accumulation was determined in culture supernatant using the Griess reaction. MIP-1α and IL-6 mRNA levels were determined using SYBR Green-based quantitative RT-PCR. MIP-1α and IL-6 protein levels were evaluated using specific ELISA assay. Several cytokines, involved in the inflammatory response, were also tested by BioPlex assay.

KEY FINDINGS

First, oleocanthal inhibits LPS-induced NO production in J774 macrophages, without affecting cell viability. Moreover, it inhibits MIP-1α and IL-6 mRNA expression, as well as protein synthesis, in both ATDC5 chondrocytes and J774 macrophages. Oleocanthal also inhibits IL-1β, TNF-α and GM-CSF protein synthesis from LPS-stimulated macrophages.

SIGNIFICANCE

Our data confirm a clear potent role of oleocanthal as anti-inflammatory therapeutic agent for future treatment of arthritis or other inflammatory diseases.

Effect of oleocanthal and its derivatives on inflammatory response induced by lipopolysaccharide in a murine chondrocyte cell line

OBJECTIVE

In joint diseases, cartilage homeostasis is disrupted by mechanisms that are driven by combinations of biologic factors that vary according to the disease process. In osteoarthritis (OA), biomechanical stimuli predominate, with up-regulation of both catabolic and anabolic factors. Likewise, OA progression is characterized by increased nitric oxide (NO) production, which has been associated with cartilage degradation. Given the relevance of cartilage degenerative diseases in our society, the development of a novel pharmacologic intervention is a critically important public health goal. Recently, oleocanthal isolated from extra virgin olive oil was found to display nonsteroidal antiinflammatory drug activity similar to that of ibuprofen, a drug widely used in the therapeutic management of joint inflammatory diseases. We undertook this study to evaluate the effect of oleocanthal and its derivatives on the modulation of NO production in chondrocytes.

METHODS

Cultured ATDC-5 chondrocytes were tested with different doses of oleocanthal and its derivatives. Cell viability was evaluated using the MTT assay. Nitrite accumulation was determined in culture supernatant using the Griess reaction. Inducible NO synthase (NOS2) protein expression was examined using Western blotting analysis.

RESULTS

Oleocanthal and its derivatives decreased lipopolysaccharide-induced NOS2 synthesis in chondrocytes without significantly affecting cell viability at lower concentrations. Among the derivatives we examined, derivative 231 was the most interesting, since its inhibitory effect on NOS2 was devoid of cytotoxicity even at higher concentrations.

CONCLUSION

This class of molecules shows potential as a therapeutic weapon for the treatment of inflammatory degenerative joint diseases.

Antioxidants and fatty acids in the amelioration of rheumatoid arthritis and related disorders

The generation of reactive oxygen species (free radicals) is an important factor in the development and maintenance of rheumatoid arthritis in humans and animal models. One source of free radicals is nitric oxide produced within the synoviocytes and chondrocytes and giving rise to the highly toxic radical peroxynitrite. Several cytokines, including tumour necrosis factor-alpha (TNFalpha) are involved in the formation of free radicals, partly by increasing the activity of nitric oxide synthase. Indeed, nitric oxide may mediate some of the deleterious effects of cytokines on bone resorption. Aspirin, tetracyclines, steroids and methotrexate can suppress nitric oxide synthase. Dietary antioxidants include ascorbate and the tocopherols and beneficial effects of high doses have been reported especially in osteoarthritis. There is also evidence for beneficial effects of beta-carotene and selenium, the latter being a component of the antioxidant enzyme glutathione peroxidase. The polyunsaturated fatty acids (PUFA) include the n-3 compounds, some of which are precursors of eicosanoid synthesis, and the n-6 group which can increase formation of the pro-inflammatory cytokines TNFalpha and interleukin-6, and of reactive oxygen species. Some prostaglandins, however, suppress cytokine formation, so that n-3 PUFA often oppose the inflammatory effects of some n-6-PUFA. gamma-linolenic acid (GLA) is a precursor of prostaglandin E1, a fact which may account for its reported ability to ameliorate arthritic symptoms. Fish oil supplements, rich in n-3 PUFA such as eicosapentaenoic acid have been claimed as beneficial in rheumatoid arthritis, possibly by suppression of the immune system and its cytokine repertoire. Some other oils of marine origin (e.g. from the green-lipped mussel) and a range of vegetable oils (e.g. olive oil and evening primrose oil) have indirect anti-inflammatory actions, probably mediated via prostaglandin E1. Overall, there is a growing scientific rationale for the use of dietary supplements as adjuncts in the treatment of inflammatory disorders such as rheumatoid arthritis and osteoarthritis.

The Role of Environmental Antigens in the Spontaneous Development of Autoimmunity in MRL-lpr Mice

It has been proposed that the “normal” stimulation of the immune system that occurs from interactions with environmental stimuli, whether infectious or dietary, is necessary for the initiation and/or continuation of autoimmunity. We tested this hypothesis by deriving a group of MRL-lpr mice into a germfree (GF) environment. At 5 mo of age, no differences between GF and conventional MRL-lpr mice were noted in lymphoproliferation, flow cytometric analysis of lymph node cells (LN), or histologic analysis of the kidneys. Autoantibody levels were comparably elevated in both groups. A second experiment tested the role of residual environmental stimuli by contrasting GF mice fed either a low m.w., ultrafiltered Ag-free (GF-AF) diet or an autoclaved natural ingredient diet (GF-NI). At 4 mo of age, both groups showed extensive lymphoproliferation and aberrant T cell formation, although the GF-AF mice had ∼50% smaller LNs compared with sex-matched GF-NI controls. Autoantibody formation was present in both groups. Histologic analysis of the kidneys revealed that GF-AF mice had much lower levels of nephritis, while immunofluorescence analysis demonstrated no difference in Ig deposits but did reveal a paucity of C3 deposition in the kidneys of GF-AF mice.

These data do not support a role for infectious agents in the induction of lymphoproliferation and B cell autoimmunity in MRL-lpr mice. Furthermore, they suggest that autoantibodies do not originate from B cells that were initially committed to exogenous Ags. They do suggest a possible contributory role for dietary exposure in the extent of lymphoproliferation and development of nephritis in this strain.

Dietary fish oil supplementation alters LTB4:LTB5 ratios but does not affect the expression of acute graft versus host disease in mice

One of the mechanisms by which corticosteroids may modify acute graft vs host disease (GvHD) is via inhibition of arachidonic acid (AA) metabolism. Leukotriene B4 (LTB4) is a product of that pathway which may take part in the pathogenesis of GvHD through the stimulation of T-lymphopoiesis and T-lymphocyte activation. LTB4 is a metabolite of AA (20:4n-6). Alternate dietary sources of polyunsaturated fatty acids (PUFA), specifically eicosapenteinoic acid (20:5n-3) (EPA) and docosahexaenoic acid (22:6n-3) (DHA), shift the LTs formed with a decrease in LTB4 an increase in LTB5. LTB5 is a less potent agonist than LTB4 and this results in a theoretical decrease of LTB4 mediated events. Supplementation of in vitro bone marrow cultures with EPA or DHA had no detrimental effect on myeloid colony formation. Dietary EPA/DHA supplementation in mice with induced GvHD appeared to be safe and well tolerated. The LTB4:LTB5 ratio shifted from 7.65 +/- 1.75 in control-fed animals to 1.03 +/- 0.18. Fish-oil-supplementation did not compromise engraftment or stem cell content. Alone, this therapy was unable to modify GvHD.

Long-term treatment of the MRL/lpr mouse with methotrexate and 10-deazaaminopterin

Female MRL/lpr mice were treated with I.P. doses of methotrexate (MTX) and 10-deazaaminopterin (DAAM) in the range of 1 to 100 mg/kg body weight/week, in two equally divided doses. Treatment began at 7 weeks of age and continued to 30 weeks of age. Joint histopathology scores were tightly correlated with skin lesion-proteinuria scores at 30 weeks of age. MTX at levels of 5, 25, and 100 mg/kg body weight/week and DAAM at a level of 25 mg/kg body weight/week significantly reduced skin lesion-proteinuria scores below controls in a dose dependent manner. Animals receiving MTX at 25 mg/kg body weight/week had a significantly longer median life span and animals receiving MTX at 100 mg/kg body weight/week had a greater than 15% suppression of growth when compared with controls. Longevity and skin lesion-proteinuria scores appeared to be good indicators of drug efficacy while growth suppression appeared to be a good indicator of drug toxicity.

Dietary fish oil and the severity of symptoms in patients with systemic lupus erythematosus

A prospective, double blind, cross over study assessing the effects of a low fat, high marine oil diet in 27 patients with active systemic lupus erythematosus has been performed. The patients were given 20 g daily of MaxEPA (eicosapentaenoic acid) or 20 g of olive oil (placebo) in matching capsules added to a standardised isoenergetic low fat diet. When individual outcome measures of the 17 patients who completed the full 34 week study were considered 14 who were receiving MaxEPA achieved useful or ideal status, whereas 13 receiving placebo were rated as worse or no change. The difference between the two types of capsule was statistically significant. No major side effects were noted, and it is suggested that dietary modification with additional marine oil may be a useful way of modifying disease activity in systemic lupus erythematosus.

Dietary fish oil and olive oil supplementation in patients with rheumatoid arthritis. Clinical and immunologic effects

Forty-nine patients with active rheumatoid arthritis completed a 24-week, prospective, double-blind, randomized study of dietary supplementation with 2 different dosages of fish oil and 1 dosage of olive oil. Clinical evaluations were performed at baseline and every 6 weeks thereafter, and immunologic variables were measured at baseline and after 24 weeks of study. The 3 groups of patients were matched for age, sex, disease severity, and use of disease-modifying antirheumatic drugs (DMARDs). Subjects continued receiving DMARDs and other background medications without change during the study. Twenty patients consumed daily dietary supplements of n3 fatty acids containing 27 mg/kg eicosapentaenoic acid (EPA) and 18 mg/kg docosahexaenoic acid (DHA) (low dose), 17 patients ingested 54 mg/kg EPA and 36 mg/kg DHA (high dose), and 12 patients ingested olive oil capsules containing 6.8 gm of oleic acid. Significant improvements from baseline in the number of tender joints were noted in the low-dose group at week 24 (P = 0.05) and in the high-dose group at week 18 (P = 0.04) and 24 (P = 0.02). Significant decreases from baseline in the number of swollen joints were noted in the low-dose group at weeks 12 (P = 0.003), 18 (P = 0.002), and 24 (P = 0.001) and in the high-dose group at weeks 12 (P = 0.0001), 18 (P = 0.008), and 24 (P = 0.02). A total of 5 of 45 clinical measures were significantly changed from baseline in the olive oil group, 8 of 45 in the low-dose fish oil group, and 21 of 45 in the high-dose fish oil group during the study (P = 0.0002). Neutrophil leukotriene B4 production decreased by 19% from baseline in the low-dose fish oil group (P = 0.0003) and 20% in the high-dose group (P = 0.03), while macrophage interleukin-1 production decreased by 38.5% in the olive oil group (P not significant), 40.6% in the low-dose group (P = 0.06), and 54.7% in the high-dose group (P = 0.0005). Tritiated thymidine incorporation in peripheral blood mononuclear cells after stimulation with concanavalin A increased significantly in all 3 groups after 24 weeks, compared with baseline values. We conclude that the clinical benefits of dietary supplementation with omega-3 fatty acids are more commonly observed in patients consuming higher dosages of fish oil for time intervals that are longer than those previously studied. Dietary supplementation with olive oil is also associated with certain changes in immune function, which require further investigation.

The therapeutic effects of dietary fatty acid supplementation in the autoimmune disease of the MRL-mp-lpr/lpr mouse

The effect of dietary fatty acids on the spontaneous autoimmune disease systemic lupus erythematosus of the MRL-mp-lpr/lpr mouse was investigated after onset of disease. Parameters monitored included auto-antibody levels (by ELISA), proteinuria, body weights, clinical appearance and survival. The preliminary study (using five mice per group) showed that dietary restriction improved survival (P less than 0.001) per se, and further that all mice receiving the fish oil diet benefited considerably (P less than 0.005), whilst males on the fish oil/evening primrose oil diet also lived longer than expected (P less than 0.005).