Pulmonary delivery of docosahexaenoic acid mitigates bleomycin-induced pulmonary fibrosis
© Zhao et al.; licensee BioMed Central Ltd. 2014
Received: 13 December 2013
Accepted: 8 April 2014
Published: 18 April 2014
Pulmonary fibrosis is an untreatable, fatal disease characterized by excess deposition of extracellular matrix and inflammation. Although the etiology of pulmonary fibrosis is unknown, recent studies have implicated dysregulated immune responses and wound healing. Since n-3 polyunsaturated fatty acids (n-3 PUFAs) may beneficially modulate immune responses in a variety of inflammatory disorders, we investigated the therapeutic role of docosahexaenoic acid (DHA), a single n-3 PUFA, in lung fibrosis.
Intratracheal DHA or PBS was administered to mouse lungs 4 days prior to intratracheal bleomycin treatment. Body weight and survival were monitored for 21 days. Bronchoalveolar fluid (BALF) and lung inflammatory cells, cytokines, eicosanoids, histology and lung function were determined on serial days (0, 3, 7, 14, 21) after bleomycin injury.
Intratracheal administration of DHA mitigated bleomycin-induced lung injury. Mice pretreated with DHA had significantly less weight loss and mortality after bleomycin injury. The lungs from DHA-pretreated mice had markedly less fibrosis. DHA pretreatment also protected the mice from the functional changes associated with bleomycin injury. Bleomycin-induced cellular inflammation in BALF and lung tissue was blunted by DHA pretreatment. These advantageous effects of DHA pretreatment were associated with decreased IL-6, LTB4, PGE2 and increased IL-10.
Our findings demonstrate that intratracheal administration of DHA, a single PUFA, protected mice from the development of bleomycin-induced pulmonary inflammation and fibrosis. These results suggest that further investigations regarding the role of n-3 polyunsaturated fatty acids in fibrotic lung injury and repair are needed.
Idiopathic Pulmonary fibrosis (IPF) is a relentless and progressive disease characterized by lung inflammation and subsequent fibrosis [1, 2]. A critical barrier to treating this disease is the lack of understanding of the pathophysiology driving the fibrosis. In pulmonary fibrosis, the normally self-limiting lung inflammation that results in healing and restoration of tissue integrity becomes an unremitting inflammation characterized by persistent inflammatory cell infiltration, fibroblast recruitment and ensuing fibrosis [3, 4]. Although the etiology of this persistent inflammation is unclear, it is clear that this disease is associated with the persistence of pro-inflammatory cytokines and chemokines. Specifically, TNF-α, TGF-β, and both CXC chemokines (IL-8, MIG, IP-10, I-TAC) as well as CC chemokines (MIP-1, MCP-1) . Recently, inflammatory lipid eicosanoid mediators, such as prostaglandins (PGs) and leukotrienes (LTs), have also been linked to pulmonary fibrosis [6–10].
Fish oil, a complex mixture of polyunsaturated fatty acids as well as a range of other unsaturated and saturated fatty acids, has been deemed beneficial in a wide variety of human chronic ailments [11–16]. Unfortunately, due to the complex mixture of fats in the fish oil, many of the purported benefits have been recently questioned [17–26]. Thus, investigating a single, pure polyunsaturated fatty acid (PUFA) is pivotal in understanding its role in diseases. Recent studies have showed that a pure n-3 PUFA may exert beneficial effects in inflammatory ailments [27–31]. The pure n-3 PUFAs have been noted to reduce inflammatory cells, regulate key inflammatory cytokines such as IL-6 and TNF-α and suppress the production of prostaglandins (PGs) and leukotrienes (LTs) [31–35]. It is believed that the beneficial effects of n-3 PUFAs are due in part to the replacement of arachidonic acid in the membrane phospholipids of inflammatory cells with the n-3 PUFAs thus leading to a reduced capacity of immune cells to synthesize LTs and PGs [36, 37]. At present, the specific effects of n-3 PUFAs on pulmonary fibrosis have not been studied. In this study, we demonstrate that DHA, one best-known n-3 PUFA, protects mice from bleomycin-induced pulmonary inflammation and fibrosis. Intratracheal DHA mitigated bleomycin induced mortality, weight loss, inflammation, histological damage and loss of lung function. Overall these findings provide insight into the disease process as well as suggest a novel therapeutic approach for pulmonary fibrosis.
DHA was purchased from Sigma-Alrich (St. Louis, MO), bleomycin from Hospira (Lake Forest, IL) and antibodies from eBiosceice (San Diego, CA) and Cayman (Ann Arbor, MI).
In this study, 8 week old female C57BL/6 mice were purchased from Jackson Laboratories (Bar Harbor, ME), housed in a pathogen-free sterile facility at the Johns Hopkins School of Public Health and allowed water and food ad libitum. All animal experiments were approved by the Johns Hopkins Animal Care and Use Committee.
Pulmonary fibrosis model
8 week old female C57BL/6 mice were anesthetized by intraperitoneal injection of 75 mg/kg ketamine and 5 mg/kg xylazine, intubated and given 50 μl of PBS or DHA (6.25 mg/kg body weight) diluted in PBS intratacheally. 4 days after DHA or PBS treatment, mice were again anesthesized, intubated and given intratracheal bleomycin (1.5 U/kg or 2.5 U/kg) in 50 μl PBS. Body weight and survival were monitored. Mice were sacrificed for bronchoalveolar lavage, FACS, histology and lung function measurements at days 0, 3, 7, 14 and 21 after bleomycin. Day 0 represents baseline, i.e. 4 days after DHA or PBS, but prior to bleomycin.
BALF cell count
BALF differential cell counts were carried out through cytopspin preparation (Thermo Scientific, Waltham, MA) and Diff-Quick Staining (Dade Behring; Germany).
All flow cytometry of lung cells was performed on a Facs Caliber, BD Biosciences (San Jose, CA). FACS antibodies were purchased from eBiosceice (San Diego, CA).
IFN-γ, TNF-α, IL-1, IL-6, IL-10 and IL-33 were measured in BALF by ELISA according to the manufacturer’s protocol (eBioscience, San Diego, CA). Leukotriene B4 (LTB4), and prostaglandin E2 (PGE2) were measured with immunoassays per protocol from Cayman (Ann Arbor, MI).
Lung function measurement
Using the forced oscillation technique, tissue elastance (H) and tissue damping (G) that reflect the severity of pulmonary fibrosis were measured [10, 38]. All dynamic measurements were performed in vivo on anesthetized mice (intraperitoneal 100 mg/kg ketamine and 10 mg/kg xylazine) with an intact chest wall. After animals were anesthetized, tracheotomy and intubation was performed and the animals were ventilated by a computerized Flexivent system (SCIREQ Scientific respiratory equipment, Montreal, Quebec, Canada) with a tidal volume of 0.2 ml of 100% oxygen at a rate of 150 breaths/min. After administration of succinylcholine (2 mg/kg), a deep inspiration (DI) was given and held for 5 seconds, prior to returning to normal ventilation. One minute after the DI, measurement was performed and data were fit into constant phase model to determine G and H.
Histology and imaging
Following assessment of lung function, the lungs were inflated at a pressure of 25 cmH2O with formalin, sectioned and stained with Hematoxylin-eosin (H&E) for lung morphology and Masson’s trichrome to observe collagen deposition. The sections were photographed at 20X magnification to create panorama images which were scored for fibrosis by Ashcroft method as previously described .
Data were and analyzed with the Mann–Whitney U-test running Prism software (GraphPad Inc., San Diego, CA). P values < 0.05 were considered significant. Survival curves (Kaplan-Meier plots) were compared using a log rank test.
Intratracheal DHA enhances survival following bleomycin injury
Intratracheal DHA mitigates bleomycin-induced lung fibrosis
DHA prevents bleomycin-induced lung inflammation
Similar results were also noted for the cellular infiltrate in the total lung parenchyma as analyzed by flow cytometry (Figure 4E-I). Compared with the PBS-treated mice, DHA-pretreated mice revealed a blunted response in T cells (both CD4+ and CD8+) and neutrophils (Ly6G+) (Figure 4E-I). Interestingly, we also noted a significant decrease in lung dendritic cells (CD11Chi MHC-IIhi) after DHA exposure (Figure 4H). Thus, DHA pre-treatment blunted bleomycin-induced cellular inflammation in BALF and lung tissue most notably by inhibiting accumulations of neutrophils, T cells and dendritic cells.
DHA inhibits bleomycin-induced inflammatory cytokines and eicosanoids
Pulmonary fibrosis is a chronic, progressive interstitial lung disease with a poor prognosis for which there is no effective treatment [1, 43]. The lack of therapy is in part due to the limited knowledge concerning the pathogenesis of the disease. However, many recent studies have implicated dysregulated immune responses and aberrant wound healing as playing key roles in the etiology of lung fibrosis. As n-3 polyunsaturated fatty acids, such as DHA (docosahexaenoic acid), have the capacity to modulate immune responses with beneficial effects, we hypothesized they may have a therapeutic role in lung fibrosis. We demonstrate the ability of intratracheal DHA to mitigate bleomycin-induced lung injury. Specifically, mice pretreated with DHA have significantly less weight loss, mortality, lung inflammation, histology damage and physiologic derangements in lung function. Mechanistically, DHA pretreatment appears to mitigate lung damage by suppressing lung inflammatory cells, decreasing IL-6, LTB4, PGE2 and increasing IL-10. Thus, our findings demonstrate that intra-tracheal administration of the n-3 polyunsaturated fatty acid, DHA, protected mice from the development of bleomycin-induced pulmonary inflammation and fibrosis. Our data suggest further investigations into the role of n-3 polyunsaturated fatty acids in the treatment of lung fibrosis.
While many studies claimed the beneficial effects of fish oil, we chose to look only at the pure n-3 PUFA. Given the contradictory results of many recent studies using fish oil, a complex mixture of polyunsaturated fatty acids as well as a range of other unsaturated and saturated fats, a study of such a complex material would have little chance to define specific protective pathways in lung fibrosis. Indeed, similar discrepancy also occurred in the studies about the effect of fish oil on bleomycin-induced pulmonary fibrosis [44, 45]. Although the mechanism by which n-3 PUFAs decreased inflammation is unclear, changes in the composition of the cell membrane have been implicated. The cell membrane composition of inflammatory cells in subjects fed n-3 PUFA-rich diets demonstrate increased amount of n-3 PUFAs thus altering the fatty acid composition of cellular phospholipids [36, 46, 47]. Although little is known about the effects of these cellular modifications by DHA, Fan et al. have suggested that the impacts of n-3 PUFAs on membrane micro-domains may regulate intracellular signal transduction (18). Our study is unique in that we directly administered the DHA to the target organ, the lungs. We gave the DHA 4 days before the bleomycin to allow significant time for the n-3 PUFA to integrate into the membrane phospholipid and mitigate any effect due only to the intratracheal instillation itself. As previous studies have demonstrated that the integration of the DHA into the membrane is stable for at least 8 weeks, thus the impact of the DHA on membrane composition would still be maintained during the 21 days after bleomycin injury .
Although no animal model of lung fibrosis is perfect, the bleomycin model is a well-established, extensively studied, reproducible model of murine lung fibrosis that can be interrogated to reveal potential mechanisms underlying human fibrotic lung disorders [48–51]. DHA pretreatment significantly mitigated the fibrotic changes induced by bleomycin on examination of histology, lung function and mortality. Both panorama and high power images of lung tissue demonstrate a clear decrease in fibrosis in the DHA-treated animals. The ability of n-3 PUFAs to inhibit inflammation has been suggested in numerous diseases such as Crohn’s Desease and rheumatoid arthritis [11, 13]. Indeed, we demonstrate that DHA also prevented the bleomycin-induced inflammatory cells in both BALF and lung tissue, in particular there was a marked decrease in lymphocytes and neutrophils in the lungs of DHA-pretreated animals.
We also demonstrate a change in the inflammatory cytokine profile in DHA-pretreated bleomycin injured mice. While there is a marked rise in the IL-6 level of PBS-bleomycin-treated mice, the DHA-pretreated mice have no increase in IL-6 levels. This is in keeping with recent studies displaying that DHA inhibited macrophage IL-6 production [31, 34]. Although the role of IL-6 in pulmonary fibrosis is only emerging, Saito et al. have reported less severe bleomycin-induced lung injury in IL-6-deficient mice . Additionally IL-6 has been implicated in mediating the phenotypic conversion of fibroblast to myofibroblast via up-regulation of α-SMA . As lung myofibroblasts appear to play a role in lung fibrosis, DHA may be mitigating the development of fibrosis by inhibiting bleomycin induced IL-6 [54–56]. Lastly, blocking of IL-6 receptor has also been shown to alleviate bleomycin-induced skin fibrosis .
In addition, we also demonstrate changes in IL-10 expression in DHA-treated animals. In the PBS-bleomcyin-treated controls, the IL-10 levels progressively decrease as the inflammation and fibrosis develop and are quite low by day 21. However, in the DHA-bleomcyin-treated animals, although the IL-10 levels dip on day 3, they begin to increase thereafter and are back to or above baseline levels by days 14 and 21. The exact role of IL-10 in pulmonary fibrosis is unclear. While gene delivery of IL-10 has been showed to attenuate pulmonary fibrosis other investigators have found it only inhibited inflammation, but not fibrosis [58, 59]. Regardless, in our study we see both preserved IL-10 levels at late time points correlating with decreased inflammation and fibrosis in the DHA-pretreated animals.
Leukotrienes (LTs) and prostaglandin (PGs) belong to a family of bioactive lipids, called eicosanoids that are produced from arachidonic acid by 5-lipoxygenase and cyclo-oxygenase . Eicosanoid mediators have been suggested to be involved in a host of inflammatory diseases, and their potential role in pulmonary fibrosis has been increasingly recognized [6, 10, 60]. Incorporation of n-3 PUFAs, in place of arachdonic acid into cell membranes, results in decreased production of eicosanoid mediators as n-3 PUFAs are poor substrates for 5-lipoxygenase and cyclo-oxygenase [36, 37]. Several human studies reveal that dietary n-3 PUFA supplementation significantly decreased PGE2 and LTs production by human immune cells [36, 61]. Indeed, our data demonstrating decreased PGE2 at later time points after bleomycin injury in the DHA-treated animals is consistent with studies demonstrating that DHA inhibit PGE2 synthesis [27, 32, 33, 35].
Currently, the role of PGE2 in pulmonary fibrosis is unclear. Both human and animal studies alike have demonstrated seemingly contradictory data concerning the beneficial or detrimental effects of prostaglandins in lung fibrosis [9, 10, 62–65]. While several investigators have demonstrated that exogenously increasing PGE2 levels protected mice from bleomycin-induced lung injury, others have suggested that PGI2, not PGE2, is the protective prostaglandin [9, 10, 63]. Our finding of lower levels of PGE2 in DHA-treated mice on days 14 and 21, as the acute inflammation recedes and the fibrosis begins, may indicate that PGE2 may be pathogenic in the fibrotic process. Our study differs from other studies purporting the benefits of PGE2 in mitigating lung fibrosis in many ways. We are administering the DHA, not PGE2, thus affecting upstream pathways not just PGE2 levels. We measure PGE2 in BALF at many time points during the acute inflammation and subsequent fibrosis. Other studies either do not measure PGE2 content or only at early time points where we too see no difference [9, 63, 66]. Finally we are administering the DHA directly to the lungs thus avoiding any of the off target anti-inflammatory effects of administering PGE2 via subcutaneous pumps [9, 63] Although Ivanova et al. did administer PGE2 by aerosolized liposomes, no BALF levels were reported making it difficult to compare directly to our data .
Furthermore, in a model of bleomycin-induced skin fibrosis, investigators showed mice lacking the PGE2 (mPGES-1 null mice) were resistant to bleomycin-induced skin fibrosis . In our study, we see similar levels of PGE2 in the first 7 days after bleomycin injury but these levels markedly decrease in the DHA-treated mice at late time points. Although the decreased PGE2 levels may be mirroring the decreased inflammation and fibrosis at later time points, the relative lack of it may also prevent fibrosis as suggested in the studies showing less bleomycin-induced skin fibrosis in PGE2-deficient mice. Interestingly, our data also suggested there is less LTB4 in the DHA-pretreated mice. This is in keeping with the literature that demonstrated decreased bleomcyin-induced fibrosis in mice deficient in leukotrienes or in those mice where LTB4 receptor is blocked [7, 60]. Thus, as DHA is known to modify cell membrane composition and thus eicosanoids metabolism, in our model DHA pre-treatment may be mitigating the bleomycin-induced lung inflammation and fibrosis by altering the eicosanoids, LTB4 and PGE2.
In conclusion, our findings demonstrate that intra-tracheal administration of the n-3 polyunsaturated fatty acid, DHA, protected mice from the development of bleomycin-induced pulmonary inflammation and fibrosis. Our data suggest further investigations into the role of n-3 polyunsaturated fatty acids in the treatment of lung fibrosis.
The authors thank Richard Rabold and Guo Xing for their technical assistance.
- Katzenstein AL, Myers JL: Idiopathic pulmonary fibrosis: clinical relevance of pathologic classification. Am J Respir Crit Care Med. 1998, 157: 1301-1315. 10.1164/ajrccm.157.4.9707039.View ArticlePubMedGoogle Scholar
- Raghu G, Weycker D, Edelsberg J, Bradford WZ, Oster G: Incidence and prevalence of idiopathic pulmonary fibrosis. Am J Respir Crit Care Med. 2006, 174: 810-816. 10.1164/rccm.200602-163OC.View ArticlePubMedGoogle Scholar
- Kuhn C: The pathogenesis of pulmonary fibrosis. Churg A and Katzenstein A-LA (Eds.), The Lung Current Concepts (Series: Monographs in Pathology; no. 36). 1993, Baltimore: Williams & Wilkins, 78-92.Google Scholar
- Martinet Y, Menard O, Vaillant P, Vignaud JM, Martinet N: Cytokines in human lung fibrosis. Arch Toxicol Suppl. 1996, 18: 127-139. 10.1007/978-3-642-61105-6_14.View ArticlePubMedGoogle Scholar
- Agostini C, Gurrieri C: Chemokine/cytokine cocktail in idiopathic pulmonary fibrosis. Proc Am Thorac Soc. 2006, 3: 357-363. 10.1513/pats.200601-010TK.View ArticlePubMedGoogle Scholar
- Charbeneau RP, Peters-Golden M: Eicosanoids: mediators and therapeutic targets in fibrotic lung disease. Clin Sci (Lond). 2005, 108: 479-491. 10.1042/CS20050012.View ArticleGoogle Scholar
- Izumo T, Kondo M, Nagai A: Effects of a leukotriene B4 receptor antagonist on bleomycin-induced pulmonary fibrosis. Eur Respir J. 2009, 34: 1444-1451. 10.1183/09031936.00143708.View ArticlePubMedGoogle Scholar
- Stratton R, Shiwen X: Role of prostaglandins in fibroblast activation and fibrosis. J Cell Commun Signal. 2010, 4: 75-77. 10.1007/s12079-010-0089-8.View ArticlePubMedPubMed CentralGoogle Scholar
- Dackor RT, Cheng J, Voltz JW, Card JW, Ferguson CD, Garrett RC, Bradbury JA, DeGraff LM, Lih FB, Tomer KB, Flake GP, Travlos GS, Ramsey RW, Edin ML, Morgan DL, Zeldin DC: Prostaglandin E(2) protects murine lungs from bleomycin-induced pulmonary fibrosis and lung dysfunction. Am J Physiol Lung Cell Mol Physiol. 2011, 301: L645-L655. 10.1152/ajplung.00176.2011.View ArticlePubMedPubMed CentralGoogle Scholar
- Lovgren AK, Jania LA, Hartney JM, Parsons KK, Audoly LP, Fitzgerald GA, Tilley SL, Koller BH: COX-2-derived prostacyclin protects against bleomycin-induced pulmonary fibrosis. Am J Physiol Lung Cell Mol Physiol. 2006, 291: L144-L156. 10.1152/ajplung.00492.2005.View ArticlePubMedGoogle Scholar
- Cleland LG, James MJ: Fish oil and rheumatoid arthritis: antiinflammatory and collateral health benefits. J Rheumatol. 2000, 27: 2305-2307.PubMedGoogle Scholar
- Broughton KS, Johnson CS, Pace BK, Liebman M, Kleppinger KM: Reduced asthma symptoms with n-3 fatty acid ingestion are related to 5-series leukotriene production. Am J Clin Nutr. 1997, 65: 1011-1017.PubMedGoogle Scholar
- Belluzzi A, Brignola C, Campieri M, Pera A, Boschi S, Miglioli M: Effect of an enteric-coated fish-oil preparation on relapses in Crohn’s disease. N Engl J Med. 1996, 334: 1557-1560. 10.1056/NEJM199606133342401.View ArticlePubMedGoogle Scholar
- Calder PC: N-3 polyunsaturated fatty acids and inflammation: from molecular biology to the clinic. Lipids. 2003, 38: 343-352. 10.1007/s11745-003-1068-y.View ArticlePubMedGoogle Scholar
- Thies F, Garry JM, Yaqoob P, Rerkasem K, Williams J, Shearman CP, Gallagher PJ, Calder PC, Grimble RF: Association of n-3 polyunsaturated fatty acids with stability of atherosclerotic plaques: a randomised controlled trial. Lancet. 2003, 361: 477-485. 10.1016/S0140-6736(03)12468-3.View ArticlePubMedGoogle Scholar
- Baggio B, Musacchio E, Priante G: Polyunsaturated fatty acids and renal fibrosis: pathophysiologic link and potential clinical implications. J Nephrol. 2005, 18: 362-367.PubMedGoogle Scholar
- Thien FCK, De Luca S, Woods RK, Thien FC, Abramson MJ: Dietary marine fatty acids (fish oil) for asthma in adults and children. Cochrane Database Syst Rev. 2002, CD001283-doi:10.1002/14651858.CD001283, 2Google Scholar
- Rauch B, Schiele R, Schneider S, Diller F, Victor N, Gohlke H, Gottwik M, Steinbeck G, del Castillo U, Sack R, Worth H, Katus H, Spitzer W, Sabin G, Senges J, OMEGA Study Group: OMEGA, a randomized, placebo-controlled trial to test the effect of highly purified omega-3 fatty acids on top of modern guideline-adjusted therapy after myocardial infarction. Circulation. 2010, 122: 2152-2159. 10.1161/CIRCULATIONAHA.110.948562.View ArticlePubMedGoogle Scholar
- Galan P, Kesse-Guyot E, Czernichow S, Briancon S, Blacher J, Hercberg S: Effects of B vitamins and omega 3 fatty acids on cardiovascular diseases: a randomised placebo controlled trial. BMJ. 2010, 341: c6273-10.1136/bmj.c6273.View ArticlePubMedPubMed CentralGoogle Scholar
- Hooper L, Thompson RL, Harrison RA, Summerbell CD, Ness AR, Moore HJ, Worthington HV, Durrington PN, Higgins JP, Capps NE, Riemersma RA, Ebrahim SB, Davey Smith G: Risks and benefits of omega 3 fats for mortality, cardiovascular disease, and cancer: systematic review. BMJ. 2006, 332: 752-760. 10.1136/bmj.38755.366331.2F.View ArticlePubMedPubMed CentralGoogle Scholar
- Root M, Collier SR, Zwetsloot KA, West KL, McGinn MC: A randomized trial of fish oil omega-3 fatty acids on arterial health, inflammation, and metabolic syndrome in a young healthy population. Nutr J. 2013, 12: 40-10.1186/1475-2891-12-40.View ArticlePubMedPubMed CentralGoogle Scholar
- Bosco N, Brahmbhatt V, Oliveira M, Martin FP, Lichti P, Raymond F, Mansourian R, Metairon S, Pace-Asciak C, Bastic Schmid V, Rezzi S, Haller D, Benyacoub J: Effects of increase in fish oil intake on intestinal eicosanoids and inflammation in a mouse model of colitis. Lipids Health Dis. 2013, 12: 81-10.1186/1476-511X-12-81.View ArticlePubMedPubMed CentralGoogle Scholar
- Mercer DF, Hobson BD, Fischer RT, Talmon GA, Perry DA, Gerhardt BK, Grant WJ, Botha JF, Langnas AN, Quiros-Tejeira RE: Hepatic fibrosis persists and progresses despite biochemical improvement in children treated with intravenous fish oil emulsion. J Pediatr Gastroenterol Nutr. 2013, 56: 364-369. 10.1097/MPG.0b013e31827e208c.View ArticlePubMedGoogle Scholar
- Pot GK, Brouwer IA, Enneman A, Rijkers GT, Kampman E, Geelen A: No effect of fish oil supplementation on serum inflammatory markers and their interrelationships: a randomized controlled trial in healthy, middle-aged individuals. Eur J Clin Nutr. 2009, 63: 1353-1359. 10.1038/ejcn.2009.63.View ArticlePubMedGoogle Scholar
- Kirkhus B, Lamglait A, Eilertsen KE, Falch E, Haider T, Vik H, Hoem N, Hagve TA, Basu S, Olsen E, Seljeflot I, Nyberg L, Elind E, Ulven SM: Effects of similar intakes of marine n-3 fatty acids from enriched food products and fish oil on cardiovascular risk markers in healthy human subjects. Br J Nutr. 2011, 107: 1339-1349.View ArticlePubMedGoogle Scholar
- Rizos EC, Ntzani EE, Bika E, Kostapanos MS, Elisaf MS: Association between omega-3 fatty acid supplementation and risk of major cardiovascular disease events: a systematic review and meta-analysis. JAMA. 2012, 308: 1024-1033. 10.1001/2012.jama.11374.View ArticlePubMedGoogle Scholar
- Correia M, Michel V, Matos AA, Carvalho P, Oliveira MJ, Ferreira RM, Dillies MA, Huerre M, Seruca R, Figueiredo C, Machado JC, Touati E: Docosahexaenoic acid inhibits Helicobacter pylori growth in vitro and mice gastric mucosa colonization. PLoS One. 2012, 7: e35072-10.1371/journal.pone.0035072.View ArticlePubMedPubMed CentralGoogle Scholar
- Titos E, Rius B, Gonzalez-Periz A, Lopez-Vicario C, Moran-Salvador E, Martinez-Clemente M, Arroyo V, Claria J: Resolvin D1 and its precursor docosahexaenoic acid promote resolution of adipose tissue inflammation by eliciting macrophage polarization toward an M2-like phenotype. J Immunol. 2011, 187: 5408-5418. 10.4049/jimmunol.1100225.View ArticlePubMedGoogle Scholar
- Schwab JM, Chiang N, Arita M, Serhan CN: Resolvin E1 and protectin D1 activate inflammation-resolution programmes. Nature. 2007, 447: 869-874. 10.1038/nature05877.View ArticlePubMedPubMed CentralGoogle Scholar
- Aoki H, Hisada T, Ishizuka T, Utsugi M, Kawata T, Shimizu Y, Okajima F, Dobashi K, Mori M: Resolvin E1 dampens airway inflammation and hyperresponsiveness in a murine model of asthma. Biochem Biophys Res Commun. 2008, 367: 509-515. 10.1016/j.bbrc.2008.01.012.View ArticlePubMedGoogle Scholar
- Weldon SM, Mullen AC, Loscher CE, Hurley LA, Roche HM: Docosahexaenoic acid induces an anti-inflammatory profile in lipopolysaccharide-stimulated human THP-1 macrophages more effectively than eicosapentaenoic acid. J Nutr Biochem. 2007, 18: 250-258. 10.1016/j.jnutbio.2006.04.003.View ArticlePubMedGoogle Scholar
- Denkins Y, Kempf D, Ferniz M, Nileshwar S, Marchetti D: Role of omega-3 polyunsaturated fatty acids on cyclooxygenase-2 metabolism in brain-metastatic melanoma. J Lipid Res. 2005, 46: 1278-1284. 10.1194/jlr.M400474-JLR200.View ArticlePubMedGoogle Scholar
- Kirkup SE, Cheng Z, Elmes M, Wathes DC, Abayasekara DR: Polyunsaturated fatty acids modulate prostaglandin synthesis by ovine amnion cells in vitro. Reproduction. 2010, 140: 943-951. 10.1530/REP-09-0575.View ArticlePubMedGoogle Scholar
- Oliver E, McGillicuddy FC, Harford KA, Reynolds CM, Phillips CM, Ferguson JF, Roche HM: Docosahexaenoic acid attenuates macrophage-induced inflammation and improves insulin sensitivity in adipocytes-specific differential effects between LC n-3 PUFA. J Nutr Biochem. 2012, 23: 1192-1200. 10.1016/j.jnutbio.2011.06.014.View ArticlePubMedGoogle Scholar
- Li X, Yu Y, Funk CD: Cyclooxygenase-2 induction in macrophages is modulated by docosahexaenoic acid via interactions with free fatty acid receptor 4 (FFA4). FASEB J. 2013, 27: 4987-4997. 10.1096/fj.13-235333.View ArticlePubMedGoogle Scholar
- Calder PC: Immunomodulation by omega-3 fatty acids. Prostaglandins Leukot Essent Fatty Acids. 2007, 77: 327-335. 10.1016/j.plefa.2007.10.015.View ArticlePubMedGoogle Scholar
- Stulnig TM: Immunomodulation by polyunsaturated fatty acids: mechanisms and effects. Int Arch Allergy Immunol. 2003, 132: 310-321. 10.1159/000074898.View ArticlePubMedGoogle Scholar
- Manali ED, Moschos C, Triantafillidou C, Kotanidou A, Psallidas I, Karabela SP, Roussos C, Papiris S, Armaganidis A, Stathopoulos GT, Maniatis NA: Static and dynamic mechanics of the murine lung after intratracheal bleomycin. BMC Pulm Med. 2011, 11: 33-10.1186/1471-2466-11-33.View ArticlePubMedPubMed CentralGoogle Scholar
- Ashcroft T, Simpson JM, Timbrell V: Simple method of estimating severity of pulmonary fibrosis on a numerical scale. J Clin Pathol. 1988, 41: 467-470. 10.1136/jcp.41.4.467.View ArticlePubMedPubMed CentralGoogle Scholar
- Awada M, Soulage CO, Meynier A, Debard C, Plaisancie P, Benoit B, Picard G, Loizon E, Chauvin MA, Estienne M, Peretti N, Guichardant M, Lagarde M, Genot C, Michalski MC: Dietary oxidized n-3 PUFA induce oxidative stress and inflammation: role of intestinal absorption of 4-HHE and reactivity in intestinal cells. J Lipid Res. 2012, 53: 2069-2080. 10.1194/jlr.M026179.View ArticlePubMedPubMed CentralGoogle Scholar
- Musto AE, Gjorstrup P, Bazan NG: The omega-3 fatty acid-derived neuroprotectin D1 limits hippocampal hyperexcitability and seizure susceptibility in kindling epileptogenesis. Epilepsia. 2011, 52: 1601-1608. 10.1111/j.1528-1167.2011.03081.x.View ArticlePubMedGoogle Scholar
- Hantos Z, Daroczy B, Suki B, Nagy S, Fredberg JJ: Input impedance and peripheral inhomogeneity of dog lungs. J Appl Physiol. 1992, 72: 168-178. 10.1063/1.352153.View ArticlePubMedGoogle Scholar
- Raghu G, Collard HR, Egan JJ, Martinez FJ, Behr J, Brown KK, Colby TV, Cordier JF, Flaherty KR, Lasky JA, Lynch DA, Ryu JH, Swigris JJ, Wells AU, Ancochea J, Bouros D, Carvalho C, Costabel U, Ebina M, Hansell DM, Johkoh T, Kim DS, King TE, Kondoh Y, Myers J, Müller NL, Nicholson AG, Richeldi L, Selman M, Dudden RF, et al: An official ATS/ERS/JRS/ALAT statement: idiopathic pulmonary fibrosis: evidence-based guidelines for diagnosis and management. Am J Respir Crit Care Med. 2011, 183: 788-824. 10.1164/rccm.2009-040GL.View ArticlePubMedGoogle Scholar
- Silva LP, Lemos AP, Curi R, Azevedo RB: Effects of fish oil treatment on bleomycin-induced pulmonary fibrosis in mice. Cell Biochem Funct. 2006, 24: 387-396. 10.1002/cbf.1237.View ArticlePubMedGoogle Scholar
- Baybutt RC, Rosales C, Brady H, Molteni A: Dietary fish oil protects against lung and liver inflammation and fibrosis in monocrotaline treated rats. Toxicology. 2002, 175: 1-13. 10.1016/S0300-483X(02)00063-X.View ArticlePubMedGoogle Scholar
- Rees D, Miles EA, Banerjee T, Wells SJ, Roynette CE, Wahle KW, Calder PC: Dose-related effects of eicosapentaenoic acid on innate immune function in healthy humans: a comparison of young and older men. Am J Clin Nutr. 2006, 83: 331-342.PubMedGoogle Scholar
- Healy DA, Wallace FA, Miles EA, Calder PC, Newsholm P: Effect of low-to-moderate amounts of dietary fish oil on neutrophil lipid composition and function. Lipids. 2000, 35: 763-768. 10.1007/s11745-000-0583-1.View ArticlePubMedGoogle Scholar
- Chua F, Gauldie J, Laurent GJ: Pulmonary fibrosis: searching for model answers. Am J Respir Cell Mol Biol. 2005, 33: 9-13. 10.1165/rcmb.2005-0062TR.View ArticlePubMedGoogle Scholar
- Moore BB, Hogaboam CM: Murine models of pulmonary fibrosis. Am J Physiol Lung Cell Mol Physiol. 2008, 294: L152-L160.View ArticlePubMedGoogle Scholar
- Wilson KS, Worth A, Richards AG, Ford HS: Low-dose bleomycin lung. Med Pediatr Oncol. 1982, 10: 283-288. 10.1002/mpo.2950100309.View ArticlePubMedGoogle Scholar
- Moeller A, Ask K, Warburton D, Gauldie J, Kolb M: The bleomycin animal model: a useful tool to investigate treatment options for idiopathic pulmonary fibrosis?. Int J Biochem Cell Biol. 2008, 40: 362-382. 10.1016/j.biocel.2007.08.011.View ArticlePubMedGoogle Scholar
- Saito F, Tasaka S, Inoue K, Miyamoto K, Nakano Y, Ogawa Y, Yamada W, Shiraishi Y, Hasegawa N, Fujishima S, Takano H, Ishizaka A: Role of interleukin-6 in bleomycin-induced lung inflammatory changes in mice. Am J Respir Cell Mol Biol. 2008, 38: 566-571. 10.1165/rcmb.2007-0299OC.View ArticlePubMedGoogle Scholar
- Melendez GC, McLarty JL, Levick SP, Du Y, Janicki JS, Brower GL: Interleukin 6 mediates myocardial fibrosis, concentric hypertrophy, and diastolic dysfunction in rats. Hypertension. 2010, 56: 225-231. 10.1161/HYPERTENSIONAHA.109.148635.View ArticlePubMedPubMed CentralGoogle Scholar
- Phan SH: The myofibroblast in pulmonary fibrosis. Chest. 2002, 122: 286S-289S. 10.1378/chest.122.6_suppl.286S.View ArticlePubMedGoogle Scholar
- Kuhn C, McDonald JA: The roles of the myofibroblast in idiopathic pulmonary fibrosis. Ultrastructural and immunohistochemical features of sites of active extracellular matrix synthesis. Am J Pathol. 1991, 138: 1257-1265.PubMedPubMed CentralGoogle Scholar
- Wynn TA: Cellular and molecular mechanisms of fibrosis. J Pathol. 2008, 214: 199-210. 10.1002/path.2277.View ArticlePubMedPubMed CentralGoogle Scholar
- Kitaba S, Murota H, Terao M, Azukizawa H, Terabe F, Shima Y, Fujimoto M, Tanaka T, Naka T, Kishimoto T, Katayama I: Blockade of interleukin-6 receptor alleviates disease in mouse model of scleroderma. Am J Pathol. 2012, 180: 165-176. 10.1016/j.ajpath.2011.09.013.View ArticlePubMedGoogle Scholar
- Nakagome K, Dohi M, Okunishi K, Tanaka R, Miyazaki J, Yamamoto K: In vivo IL-10 gene delivery attenuates bleomycin induced pulmonary fibrosis by inhibiting the production and activation of TGF-beta in the lung. Thorax. 2006, 61: 886-894. 10.1136/thx.2005.056317.View ArticlePubMedPubMed CentralGoogle Scholar
- Kradin RL, Sakamoto H, Jain F, Zhao LH, Hymowitz G, Preffer F: IL-10 inhibits inflammation but does not affect fibrosis in the pulmonary response to bleomycin. Exp Mol Pathol. 2004, 76: 205-211. 10.1016/j.yexmp.2003.12.010.View ArticlePubMedGoogle Scholar
- Peters-Golden M, Bailie M, Marshall T, Wilke C, Phan SH, Toews GB, Moore BB: Protection from pulmonary fibrosis in leukotriene-deficient mice. Am J Respir Crit Care Med. 2002, 165: 229-235. 10.1164/ajrccm.165.2.2104050.View ArticlePubMedGoogle Scholar
- Kelley DS, Taylor PC, Nelson GJ, Schmidt PC, Ferretti A, Erickson KL, Yu R, Chandra RK, Mackey BE: Docosahexaenoic acid ingestion inhibits natural killer cell activity and production of inflammatory mediators in young healthy men. Lipids. 1999, 34: 317-324. 10.1007/s11745-999-0369-5.View ArticlePubMedGoogle Scholar
- Stratton R, Shiwen X, Martini G, Holmes A, Leask A, Haberberger T, Martin GR, Black CM, Abraham D: Iloprost suppresses connective tissue growth factor production in fibroblasts and in the skin of scleroderma patients. J Clin Invest. 2001, 108: 241-250. 10.1172/JCI12020.View ArticlePubMedPubMed CentralGoogle Scholar
- Failla M, Genovese T, Mazzon E, Fruciano M, Fagone E, Gili E, Barera A, la Rosa C, Conte E, Crimi N, Cuzzocrea S, Vancheri C: 16,16-Dimethyl prostaglandin E2 efficacy on prevention and protection from bleomycin-induced lung injury and fibrosis. Am J Respir Cell Mol Biol. 2009, 41: 50-58. 10.1165/rcmb.2007-0438OC.View ArticlePubMedGoogle Scholar
- Kowal-Bielecka O, Kowal K, Distler O, Rojewska J, Bodzenta-Lukaszyk A, Michel BA, Gay RE, Gay S, Sierakowski S: Cyclooxygenase- and lipoxygenase-derived eicosanoids in bronchoalveolar lavage fluid from patients with scleroderma lung disease: an imbalance between proinflammatory and antiinflammatory lipid mediators. Arthritis Rheum. 2005, 52: 3783-3791. 10.1002/art.21432.View ArticlePubMedGoogle Scholar
- Wilborn J, Crofford LJ, Burdick MD, Kunkel SL, Strieter RM, Peters-Golden M: Cultured lung fibroblasts isolated from patients with idiopathic pulmonary fibrosis have a diminished capacity to synthesize prostaglandin E2 and to express cyclooxygenase-2. J Clin Invest. 1995, 95: 1861-1868. 10.1172/JCI117866.View ArticlePubMedPubMed CentralGoogle Scholar
- Ivanova V, Garbuzenko OB, Reuhl KR, Reimer DC, Pozharov VP, Minko T: Inhalation treatment of pulmonary fibrosis by liposomal prostaglandin E2. Eur J Pharm Biopharm. 2012, 84: 335-344.View ArticlePubMedPubMed CentralGoogle Scholar
- McCann MR, Monemdjou R, Ghassemi-Kakroodi P, Fahmi H, Perez G, Liu S, Shi-Wen X, Parapuram SK, Kojima F, Denton CP, Abraham DJ, Martel-Pelletier J, Crofford LJ, Leask A, Kapoor M: mPGES-1 null mice are resistant to bleomycin-induced skin fibrosis. Arthritis Res Ther. 2011, 13: R6-10.1186/ar3226.View ArticlePubMedPubMed CentralGoogle Scholar
- The pre-publication history for this paper can be accessed here:http://www.biomedcentral.com/1471-2466/14/64/prepub
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.