Chitosan/siRNA Nanoparticle–mediated TNF-α Knockdown in Peritoneal Macrophages for Anti-inflammatory Treatment in a Murine Arthritis Model
Secretion of tumor necrosis factor-α (TNF-α) by macrophages plays a predominant role in the development and progression of rheumatoid arthritis. We demonstrate that knockdown of TNF-α expression in systemic macrophages by intraperitoneal (i.p.) administration of chitosan/small interfering RNA (siRNA) nanoparticles in mice downregulates systemic and local inflammation. Chitosan nanoparticles containing an unmodified anti-TNF-α Dicer-substrate siRNA (DsiRNA) mediated TNF-α knockdown (~66%) in primary peritoneal macrophages in vitro. The presence of Cy3-labeled nanoparticles within peritoneal macrophages and specific TNF-α knockdown (~44%) with TNF-α siRNA after i.p. injection supports our therapeutic approach. Downregulation of TNF-α-induced inflammatory responses arrested joint swelling in collagen-induced arthritic (CIA) mice dosed i.p. with anti-TNF-α DsiRNA nanoparticles. The use of 2′-O-Me-modified DsiRNA resulted in the lowest arthritic scores and correlated with reduced type I interferon (IFN) activation in macrophages in vivo compared with unmodified DsiRNA. Histological analysis of joints revealed minimal cartilage destruction and inflammatory cell infiltration in anti-TNF-α-treated mice. The onset of arthritis could be delayed using a prophylactic dosing regime. This work demonstrates nanoparticle-mediated TNF-α knockdown in peritoneal macrophages as a method to reduce both local and systemic inflammation, thereby presenting a novel strategy for arthritis treatment. Secretion of tumor necrosis factor-α (TNF-α) by macrophages plays a predominant role in the development and progression of rheumatoid arthritis. We demonstrate that knockdown of TNF-α expression in systemic macrophages by intraperitoneal (i.p.) administration of chitosan/small interfering RNA (siRNA) nanoparticles in mice downregulates systemic and local inflammation. Chitosan nanoparticles containing an unmodified anti-TNF-α Dicer-substrate siRNA (DsiRNA) mediated TNF-α knockdown (~66%) in primary peritoneal macrophages in vitro. The presence of Cy3-labeled nanoparticles within peritoneal macrophages and specific TNF-α knockdown (~44%) with TNF-α siRNA after i.p. injection supports our therapeutic approach. Downregulation of TNF-α-induced inflammatory responses arrested joint swelling in collagen-induced arthritic (CIA) mice dosed i.p. with anti-TNF-α DsiRNA nanoparticles. The use of 2′-O-Me-modified DsiRNA resulted in the lowest arthritic scores and correlated with reduced type I interferon (IFN) activation in macrophages in vivo compared with unmodified DsiRNA. Histological analysis of joints revealed minimal cartilage destruction and inflammatory cell infiltration in anti-TNF-α-treated mice. The onset of arthritis could be delayed using a prophylactic dosing regime. This work demonstrates nanoparticle-mediated TNF-α knockdown in peritoneal macrophages as a method to reduce both local and systemic inflammation, thereby presenting a novel strategy for arthritis treatment. IntroductionRheumatoid arthritis is a chronic inflammatory disease affecting ~1% of the population. Joint destruction associated with this autoimmune condition results from synovial infiltration by helper T cells, and mono-polymorphonuclear leukocytes eliciting local proinflammatory and regulatory cytokine effects,1Arend WP Physiology of cytokine pathways in rheumatoid arthritis.Arthritis Rheum. 2001; 45: 101-106Crossref PubMed Google Scholar modulated predominantly by tumor necrosis factor-α (TNF-α) secreted by systemic-derived macrophages. Intervention of the inflammation cascade in mice with anti-TNF-α,2Williams RO Feldmann M Maini RN Anti-tumor necrosis factor ameliorates joint disease in murine collagen-induced arthritis.Proc Natl Acad Sci USA. 1992; 89: 9784-9788Crossref PubMed Scopus (941) Google Scholar CD4+ T-cell receptor,3Williams RO Mason LJ Feldmann M Maini RN Synergy between anti-CD4 and anti-tumor necrosis factor in the amelioration of established collagen-induced arthritis.Proc Natl Acad Sci USA. 1994; 91: 2762-2766Crossref PubMed Scopus (194) Google Scholar and interleukin (IL)-1 (ref. 4Williams RO Marinova-Mutafchieva L Feldmann M Maini RN Evaluation of TNF-α and IL-1 blockade in collagen-induced arthritis and comparison with combined anti-TNF-α/anti-CD4 therapy.J Immunol. 2000; 165: 7240-7245Crossref PubMed Scopus (97) Google Scholar) monoclonal antibodies provides the basis for present clinical immunotherapy treatments;5Taylor PC Williams RO Maini RN Immunotherapy for rheumatoid arthritis.Curr Opin Immunol. 2001; 13: 611-616Crossref PubMed Scopus (61) Google Scholar however, cost and possible auto-immunity to antibodies and side-effects associated with standard methotrexate and corticosteroid combinational therapy necessitates different approaches.Small interfering RNA (siRNA)-mediated knockdown of proinflammatory cytokines at the messenger RNA (mRNA) level (termed RNA interference),6Lieberman J Song E Lee SK Shankar P Interfering with disease: opportunities and roadblocks to harnessing RNA interference.Trends Mol Med. 2003; 9: 397-403Abstract Full Text Full Text PDF PubMed Scopus (93) Google Scholar offers an alternative therapeutic strategy to overcome inflammatory conditions. In this process, double-stranded RNAs are cleaved by the cellular nuclease Dicer into short 21–22mer fragments referred to as siRNA, which enter a ribonuclear protein complex termed the RNA-induced silencing complex. Guided by the antisense strand of the siRNA, this complex mediates a specific degradation of the corresponding mRNA.7Elbashir SM Harborth J Yalcin A Weber K Tuschl T Duplexes of 21-nucleotide RNAs mediate RNA interference in cultured mammalian cells.Nature. 2001; 411: 494-498Crossref PubMed Scopus (8079) Google ScholarDirect intra-articular injection of TNF-α-specific siRNA has been reported to reduce joint inflammation in murine collagen-induced arthritis (CIA) and supports the use of siRNA-based therapies.8Schiffelers RM Xu J Storm G Woodle MC Scaria PV Effects of treatment with small interfering RNA on joint inflammation in mice with collagen-induced arthritis.Arthritis Rheum. 2005; 52: 1314-1318Crossref PubMed Scopus (132) Google Scholar Furthermore, systemic delivery of TNF-α-specific siRNA using cationic lipid-based nanoparticles show effective anti-inflammatory effects in arthritic mice.9Khoury M Louis-Plence P Escriou V Noel D Largeau C Cantos C et al.Efficient new cationic liposome formulation for systemic delivery of small interfering RNA silencing tumor necrosis factor α in experimental arthritis.Arthritis Rheum. 2006; 54: 1867-1877Crossref PubMed Scopus (171) Google Scholar Delivery is a key determinant as to whether or not RNAi-based therapeutics will have clinical relevance. In this regard, delivery describes extracellular transport to target cells, intracellular RNA trafficking, and processing. The recruitment of systemic macrophages to local sites and pivotal role during inflammation10Simon J Surber R Kleinstauber G Petrow PK Henzgen S Kinne RW et al.Systemic macrophage activation in locally-induced experimental arthritis.J Autoimmun. 2001; 17: 127-136Crossref PubMed Scopus (39) Google Scholar,11Kinne RW Brauer R Stuhlmuller B Palombo-Kinne E in rheumatoid arthritis.Arthritis 2000; PubMed Scopus Google Scholar an target for RNAi-based TNF-α We have reported knockdown of in primary macrophages using a et interference in and in vivo using a novel 2006; Full Text Full Text PDF PubMed Scopus Google Scholar however, systemic delivery of by the is by and to the M D et to and of delivery with a and of 2000; PubMed Scopus Google K et of of cationic on the of by with 2000; PubMed Scopus Google Scholar an i.p. injection delivery into a This has been as a strategy to systemic TNF-α in mice using for the treatment of murine M M silencing by systemic delivery of in Mol 2003; PubMed Scopus Google Scholar and in in P PV E necrosis factor mice of or PubMed Scopus Google Scholar RNA which are in termed Dicer-substrate siRNA M et is by Dicer of short 2005; PubMed Scopus Google S Dicer and 2005; PubMed Scopus Google Scholar have been to silencing to by Dicer RNA-induced silencing complex of G Lee I of siRNA silencing in 2006; 13: Full Text Full Text PDF PubMed Scopus Google Scholar in Dicer-substrate L C M et with Dicer-substrate small interfering PubMed Scopus Google Scholar and strand M et is by Dicer of short 2005; PubMed Scopus Google Scholar type I interferon by RNA T D M P R et basis for between and double-stranded RNAs in mammalian 2006; PubMed Scopus Google Scholar and that is with work a novel treatment for arthritis using on systemic knockdown of TNF-α for in inflammation at local sites by i.p. of macrophages. into knockdown of TNF-α in peritoneal macrophages is by of TNF-α silencing and type I on macrophages after i.p. administration using and unmodified DsiRNA The as a therapeutic and prophylactic treatment strategy in a type murine arthritis by arthritic and joint macrophage for the strategy in this work is an to TNF-α in peritoneal macrophages. We have knockdown of protein in peritoneal macrophages from a protein with the et interference in and in vivo using a novel 2006; Full Text Full Text PDF PubMed Scopus Google Scholar nanoparticles between DsiRNA TNF-α or siRNA and from to in for in and in vivo silencing The in TNF-α by in the of peritoneal macrophages as the determinant for RNA interference in vitro. We of TNF-α knockdown at and after with nanoparticles containing unmodified compared to A in TNF-α in the siRNA nanoparticles after into the of nanoparticles to siRNA into peritoneal macrophage in mice. containing Cy3-labeled DsiRNA within peritoneal macrophages after injection with a to not not in the of correlated with intracellular using this et interference in and in vivo using a novel 2006; Full Text Full Text PDF PubMed Scopus Google and TNF-α knockdown in murine peritoneal macrophages in The of nanoparticles to and TNF-α in peritoneal macrophages after i.p. in macrophages after i.p. administration of nanoparticles Cy3-labeled siRNA of Cy3-labeled siRNA and TNF-α by to macrophages to in peritoneal macrophages after i.p. administration of of nanoparticles containing of anti-TNF-α DsiRNA or unmodified anti-TNF-α DsiRNA or TNF-α Dicer-substrate siRNA in mice to are of type I expression in macrophages in to macrophages to for unmodified siRNA is in vivo silencing of peritoneal macrophage TNF-α with unmodified and TNF-α DsiRNA at after i.p. injection of the peritoneal macrophages and for vivo to macrophage and to in the TNF-α level in the of peritoneal macrophages revealed for both unmodified and and and compared to the and siRNA The knockdown be a of macrophages or of macrophages from the during the This is by knockdown in peritoneal macrophages after not The of responses as type I by the RNA and nanoparticle-mediated delivery into a in the macrophages. from mice with nanoparticles containing DsiRNA revealed of type I in comparison with both siRNA and unmodified DsiRNA with the DsiRNA formulation reduced of type I in comparison with which of The as and and of siRNA in both that the reduced type I is to type therapeutic of silencing TNF-α in systemic macrophages with nanoparticles in a type arthritic Mol 2003; Google Scholar of arthritis as joint inflammation at after and on an arthritic in swelling of inflammation in for and arthritis of this arthritic in i.p. with that resulted in reduced the of the of the of inflammation. The arthritic scores mice to the The dosed and i.p. with of containing unmodified or TNF-α DsiRNA or DsiRNA at an arthritic in in inflammation during the arthritic at with DsiRNA compared to the which at the dosing development of inflammation with the formulation after the the unmodified and siRNA to The with the siRNA formulation during the dosing a from the to of siRNA nanoparticles and mice with The reduced arthritic of the anti-TNF-α siRNA mice compared to with siRNA nanoparticles the between siRNA nanoparticles and mice This specific TNF-α silencing effects of the effects in collagen-induced arthritic (CIA) mice after i.p. administration of nanoparticles. The therapeutic of i.p. administration of nanoparticles on the clinical progression of established collagen-induced arthritis. for clinical using an arthritic method for level of joint inflammation swelling of inflammation in for to onset of arthritis and to treatment dosed i.p. on and with nanoparticles containing unmodified or anti-TNF-α DsiRNA or DsiRNA siRNA, or dosed analysis of on by comparison for siRNA is The of treatment on in in from of the a between with TNF-α DsiRNA nanoparticles and and or the siRNA nanoparticles and and Histological analysis on from treatment after and for joint destruction as cartilage and and joint inflammation that of the synovial and cellular infiltration of this arthritic Joint and cartilage in with nanoparticles containing unmodified anti-TNF-α DsiRNA and effects to the in this by inflammatory In with siRNA and cartilage and destruction by and mice with anti-TNF-α DsiRNA of cartilage and of cellular infiltration This is by for cartilage and inflammation in however, siRNA and scores the is possible that dosing with the of joints from mice dosed i.p. with nanoparticles. Histological from mice. after treatment with nanoparticles containing unmodified anti-TNF-α DsiRNA or siRNA and and for cartilage and and cellular infiltration as of joint inflammation. of the different are cartilage and cellular are in A and Histological Histological scores for cartilage and cellular infiltration are for the different using a prophylactic of TNF-α silencing in the The for this to TNF-α during the of arthritis to after to the onset of inflammation. dosed i.p. with or siRNA nanoparticles in and after on and siRNA nanoparticles and mice of joint inflammation with scores of and compared to the formulation after of the mice from TNF-α DsiRNA progression of joint inflammation resulted arthritic from on to by compared to the siRNA nanoparticles and during the effects in mice after i.p. administration of nanoparticles. The of i.p. administration of nanoparticles on the onset of collagen-induced arthritis. for clinical using an arthritic method for level of joint inflammation in dosed i.p. with nanoparticles containing of anti-TNF-α DsiRNA or siRNA and after on and is from work describes a novel for inflammatory in rheumatoid arthritis by TNF-α silencing in peritoneal macrophages. arthritis is a systemic inflammatory as of the from to chronic rheumatoid systemic-derived cellular infiltration and cytokine that cellular and activation for cartilage and WP Physiology of cytokine pathways in rheumatoid arthritis.Arthritis Rheum. 2001; 45: 101-106Crossref PubMed Google Scholar S et of arthritis by Rheum. 2005; 52: PubMed Scopus Google M S M K et necrosis factor α of inflammatory responses by in Rheum. PubMed Scopus Google Scholar a predominant role this by expression in the joints of and and secreted IL-1 and of expression in the RW Brauer R Stuhlmuller B Palombo-Kinne E in rheumatoid arthritis.Arthritis 2000; PubMed Scopus Google Scholar inflammation in an arthritic by systemic and joint macrophages with supports as therapeutic Williams RM Williams synovial inflammation and ameliorates joint destruction in PubMed Scopus Google Scholar Furthermore, the in clinical effects with PC Williams RO Maini RN Immunotherapy for rheumatoid arthritis.Curr Opin Immunol. 2001; 13: 611-616Crossref PubMed Scopus (61) Google Scholar provides the for the TNF-α target in this TNF-α knockdown in in primary murine peritoneal macrophages and after with nanoparticles compared to and siRNA nanoparticles. A in TNF-α level with the formulation not in is to effects or macrophage activation to in peritoneal T M M T T T of macrophage activation by 2005; PubMed Scopus Google Scholar and TNF-α in macrophage cell with J L of in PubMed Scopus Google Scholar The of TNF-α-specific however, this to target macrophages after administration is by the of M D et to and of delivery with a and of 2000; PubMed Scopus Google Scholar is to nanoparticles into the peritoneal to delivery into a in peritoneal macrophages in systemic of and TNF-α in peritoneal macrophages during the and chronic of murine J Surber R Kleinstauber G Petrow PK Henzgen S Kinne RW et al.Systemic macrophage activation in locally-induced experimental arthritis.J Autoimmun. 2001; 17: 127-136Crossref PubMed Scopus (39) Google K D M J Brauer R Kinne RW monoclonal treatment in and chronic on macrophage PubMed Scopus Google Scholar Chitosan nanoparticles within macrophages from the after injection to lipid-based i.p. delivery of M delivery of in 2003; PubMed Scopus Google T L SK T et delivery and using intraperitoneal macrophages as a cellular 2006; PubMed Scopus Google M P E J and in and in vivo delivery of Dicer 2006; PubMed Scopus Google Scholar This the of nanoparticles for by of the K et of of cationic on the of by with 2000; PubMed Scopus Google Scholar by by peritoneal macrophages i.p. for T L SK T et delivery and using intraperitoneal macrophages as a cellular 2006; PubMed Scopus Google Scholar TNF-α knockdown in peritoneal after i.p. administration of unmodified and 2′-O-Me-modified anti-TNF-α DsiRNA nanoparticles compared to and our this is the of TNF-α knockdown in peritoneal macrophages after i.p. knockdown with the unmodified formulation that an from the The knockdown could be to activation of the macrophages that macrophage to macrophage during Xu P A S et the of macrophage during the of peritoneal Med. PubMed Scopus Google Scholar This and possible recruitment of macrophages to in an of TNF-α I in macrophages from mice with unmodified TNF-α-specific and siRNA This macrophage activation by TNF-α in vivo and in with unmodified from mice with anti-TNF-α however, type I an siRNA of the unmodified The in this have been to the of to by Dicer for M et is by Dicer of short 2005; PubMed Scopus Google M P E J and in and in vivo delivery of Dicer 2006; PubMed Scopus Google Scholar A of inflammatory responses as type I are associated with double-stranded RNA with the by delivery of using nanoparticles. The of of or into the strand as a method to reduce and associated G Lee I of siRNA silencing in 2006; 13: Full Text Full Text PDF PubMed Scopus Google Scholar is by our in this work for therapeutic and prophylactic is a and T-cell arthritis rheumatoid Mol 2003; Google Scholar after arthritic onset with a of of and and nanoparticles arthritic scores the mice with the siRNA nanoparticles or The joint inflammation, by a arthritic at the of that therapeutic is in a The disease of this results in a to and in This the for of the in the siRNA and the that to be the This the of analysis and in to the arthritic in the could be to the inflammatory effects of This could of the in the a of joint destruction the In in the have scores for joint destruction and inflammation. 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PubMed Scopus Google Scholar of arthritic onset with DsiRNA and the of arthritis. of joint inflammation after treatment the effects of TNF-α after to inflammatory in from anti-TNF-α Maini RN Feldmann M A P et therapy with monoclonal to necrosis factor α in with rheumatoid 1994; PubMed Scopus Google Scholar treatment to in arthritic onset in of this with show inflammation the and which anti-inflammatory of Chitosan inflammatory effects in macrophage PubMed Scopus Google Scholar or of arthritis in mice that with the of the inflammatory TNF-α has been as an effective treatment in rheumatoid PC Williams RO Maini RN Immunotherapy for rheumatoid arthritis.Curr Opin Immunol. 2001; 13: 611-616Crossref PubMed Scopus (61) Google Scholar however, macrophage cytokines as and (ref. WP Physiology of cytokine pathways in rheumatoid arthritis.Arthritis Rheum. 2001; 45: 101-106Crossref PubMed Google Scholar) be in the for our approach. In to possible effects using a anti-TNF-α DsiRNA a different of RNA effects not for regulatory that from the of the RNA with results from an will this The i.p. is in the treatment of a of a for rheumatoid arthritis in work with nanoparticles and that of using M M silencing by systemic delivery of in Mol 2003; PubMed Scopus Google P PV E necrosis factor mice of or PubMed Scopus Google Scholar the i.p. for of systemic anti-inflammatory have local RM Xu J Storm G Woodle MC Scaria PV Effects of treatment with small interfering RNA on joint inflammation in mice with collagen-induced arthritis.Arthritis Rheum. 2005; 52: 1314-1318Crossref PubMed Scopus (132) Google Scholar and systemic M Louis-Plence P Escriou V Noel D Largeau C Cantos C et al.Efficient new cationic liposome formulation for systemic delivery of small interfering RNA silencing tumor necrosis factor α in experimental arthritis.Arthritis Rheum. 2006; 54: 1867-1877Crossref PubMed Scopus (171) Google Scholar administration of for arthritis treatment in a murine In the by et RM Xu J Storm G Woodle MC Scaria PV Effects of treatment with small interfering RNA on joint inflammation in mice with collagen-induced arthritis.Arthritis Rheum. 2005; 52: 1314-1318Crossref PubMed Scopus (132) Google Scholar joint injection of TNF-α siRNA joint however, as a method to siRNA cellular et have therapeutic in inflammation administration of a cationic M Louis-Plence P Escriou V Noel D Largeau C Cantos C et al.Efficient new cationic liposome formulation for systemic delivery of small interfering RNA silencing tumor necrosis factor α in experimental arthritis.Arthritis Rheum. 2006; 54: 1867-1877Crossref PubMed Scopus (171) Google Scholar the therapeutic however, for TNF-α silencing in macrophages in vivo not in (termed within that reduce of the approach. i.p. this and delivery to work is the of a novel treatment for arthritis by TNF-α knockdown in systemic macrophages by nanoparticles. as administration siRNA target and of the in this are for development of RNAi-based anti-inflammatory and and Chitosan by TNF-α-specific and siRNA by TNF-α the antisense the antisense and TNF-α siRNA the and antisense antisense protein siRNA containing a Cy3-labeled strand for cellular antisense RNA are are a a and a and type from and from TNF-α TNF-α and from of nanoparticles. Chitosan in to a and to for in vivo of siRNA in to of and for specific as the of a of for RNA and of at in on nanoparticles. The of nanoparticles by using a at in in with and analysis to knockdown in murine peritoneal macrophages in vitro. to mice by and (i.p.) with of with and The the and and the using a The for and the in with and The on a cell at in The macrophages to for containing the the and with and nanoparticles at siRNA and with containing or the with and TNF-α by an and TNF-α knockdown in murine peritoneal macrophages in of nanoparticles or TNF-α or DsiRNA or Cy3-labeled i.p. into mice. macrophages to the after injection and in or with of Cy3-labeled siRNA by a TNF-α in the of macrophages after injection to the by an in in with at in of or murine as the to the and the for The as of The by with antibodies and in type arthritic mice after i.p. administration of nanoparticles. The type arthritic to the anti-inflammatory of mice on with of to the The of the mice for clinical of arthritis at and mice arthritic scores into of i.p. dosed with of nanoparticles unmodified or TNF-α DsiRNA or on and is onset of The after administration to the peritoneal on with as a for clinical from to using a standard for of joint inflammation. using a on on of inflammation which in and for of joint inflammation. prophylactic dosed i.p. with TNF-α DsiRNA or DsiRNA nanoparticles in and after on and to the compared using analysis of on by comparison P IntroductionRheumatoid arthritis is a chronic inflammatory disease affecting ~1% of the population. Joint destruction associated with this autoimmune condition results from synovial infiltration by helper T cells, and mono-polymorphonuclear leukocytes eliciting local proinflammatory and regulatory cytokine effects,1Arend WP Physiology of cytokine pathways in rheumatoid arthritis.Arthritis Rheum. 2001; 45: 101-106Crossref PubMed Google Scholar modulated predominantly by tumor necrosis factor-α (TNF-α) secreted by systemic-derived macrophages. Intervention of the inflammation cascade in mice with anti-TNF-α,2Williams RO Feldmann M Maini RN Anti-tumor necrosis factor ameliorates joint disease in murine collagen-induced arthritis.Proc Natl Acad Sci USA. 1992; 89: 9784-9788Crossref PubMed Scopus (941) Google Scholar CD4+ T-cell receptor,3Williams RO Mason LJ Feldmann M Maini RN Synergy between anti-CD4 and anti-tumor necrosis factor in the amelioration of established collagen-induced arthritis.Proc Natl Acad Sci USA. 1994; 91: 2762-2766Crossref PubMed Scopus (194) Google Scholar and interleukin (IL)-1 (ref. 4Williams RO Marinova-Mutafchieva L Feldmann M Maini RN Evaluation of TNF-α and IL-1 blockade in collagen-induced arthritis and comparison with combined anti-TNF-α/anti-CD4 therapy.J Immunol. 2000; 165: 7240-7245Crossref PubMed Scopus (97) Google Scholar) monoclonal antibodies provides the basis for present clinical immunotherapy treatments;5Taylor PC Williams RO Maini RN Immunotherapy for rheumatoid arthritis.Curr Opin Immunol. 2001; 13: 611-616Crossref PubMed Scopus (61) Google Scholar however, cost and possible auto-immunity to antibodies and side-effects associated with standard methotrexate and corticosteroid combinational therapy necessitates different approaches.Small interfering RNA (siRNA)-mediated knockdown of proinflammatory cytokines at the messenger RNA (mRNA) level (termed RNA interference),6Lieberman J Song E Lee SK Shankar P Interfering with disease: opportunities and roadblocks to harnessing RNA interference.Trends Mol Med. 2003; 9: 397-403Abstract Full Text Full Text PDF PubMed Scopus (93) Google Scholar offers an alternative therapeutic strategy to overcome inflammatory conditions. In this process, double-stranded RNAs are cleaved by the cellular nuclease Dicer into short 21–22mer fragments referred to as siRNA, which enter a ribonuclear protein complex termed the RNA-induced silencing complex. Guided by the antisense strand of the siRNA, this complex mediates a specific degradation of the corresponding mRNA.7Elbashir SM Harborth J Yalcin A Weber K Tuschl T Duplexes of 21-nucleotide RNAs mediate RNA interference in cultured mammalian cells.Nature. 2001; 411: 494-498Crossref PubMed Scopus (8079) Google ScholarDirect intra-articular injection of TNF-α-specific siRNA has been reported to reduce joint inflammation in murine collagen-induced arthritis (CIA) and supports the use of siRNA-based therapies.8Schiffelers RM Xu J Storm G Woodle MC Scaria PV Effects of treatment with small interfering RNA on joint inflammation in mice with collagen-induced arthritis.Arthritis Rheum. 2005; 52: 1314-1318Crossref PubMed Scopus (132) Google Scholar Furthermore, systemic delivery of TNF-α-specific siRNA using cationic lipid-based nanoparticles show effective anti-inflammatory effects in arthritic mice.9Khoury M Louis-Plence P Escriou V Noel D Largeau C Cantos C et al.Efficient new cationic liposome formulation for systemic delivery of small interfering RNA silencing tumor necrosis factor α in experimental arthritis.Arthritis Rheum. 2006; 54: 1867-1877Crossref PubMed Scopus (171) Google Scholar Delivery is a key determinant as to whether or not RNAi-based therapeutics will have clinical relevance. In this regard, delivery describes extracellular transport to target cells, intracellular RNA trafficking, and processing. The recruitment of systemic macrophages to local sites and pivotal role during inflammation10Simon J Surber R Kleinstauber G Petrow PK Henzgen S Kinne RW et al.Systemic macrophage activation in locally-induced experimental arthritis.J Autoimmun. 2001; 17: 127-136Crossref PubMed Scopus (39) Google Scholar,11Kinne RW Brauer R Stuhlmuller B Palombo-Kinne E in rheumatoid arthritis.Arthritis 2000; PubMed Scopus Google Scholar an target for RNAi-based TNF-α We have reported knockdown of in primary macrophages using a et interference in and in vivo using a novel 2006; Full Text Full Text PDF PubMed Scopus Google Scholar however, systemic delivery of by the is by and to the M D et to and of delivery with a and of 2000; PubMed Scopus Google K et of of cationic on the of by with 2000; PubMed Scopus Google Scholar an i.p. injection delivery into a This has been as a strategy to systemic TNF-α in mice using for the treatment of murine M M silencing by systemic delivery of in Mol 2003; PubMed Scopus Google Scholar and in in P PV E necrosis factor mice of or PubMed Scopus Google Scholar RNA which are in termed Dicer-substrate siRNA M et is by Dicer of short 2005; PubMed Scopus Google S Dicer and 2005; PubMed Scopus Google Scholar have been to silencing to by Dicer RNA-induced silencing complex of G Lee I of siRNA silencing in 2006; 13: Full Text Full Text PDF PubMed Scopus Google Scholar in Dicer-substrate L C M et with Dicer-substrate small interfering PubMed Scopus Google Scholar and strand M et is by Dicer of short 2005; PubMed Scopus Google Scholar type I interferon by RNA T D M P R et basis for between and double-stranded RNAs in mammalian 2006; PubMed Scopus Google Scholar and that is with work a novel treatment for arthritis using on systemic knockdown of TNF-α for in inflammation at local sites by i.p. of macrophages. into knockdown of TNF-α in peritoneal macrophages is by of TNF-α silencing and type I on macrophages after i.p. administration using and unmodified DsiRNA The as a therapeutic and prophylactic treatment strategy in a type murine arthritis by arthritic and joint