RETRACTED: Refining siRNA in vivo transfection: Silencing SPHK1 reveals its key role in C5a-induced inflammation in vivo

Pushparaj, Peter Natesan; H'ng, Shiau Chen; Melendez, Alirio J.

doi:10.1016/j.biocel.2008.01.015

Cited by 21 publications

(29 citation statements)

References 30 publications

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“…200 g/kg of SphK1 siRNA or scrambled siRNA as control on days 20 -22 and then once every 2 days until day 36 as described in Materials and Methods. The siRNA dose chosen is consistent with our previous in vivo murine studies (typically 4 -8 g/animal) where we observed that SphK1 protein expression in lysates of PBMC, spleen, lung, and liver was effectively suppressed by administration of SphK1 siRNA (28,49). To determine the levels of SphK1 protein inhibition, spleen cells were isolated from mice (n ϭ 5) 24 h after the last treatment of SphK1 siRNA as described above, and they were found to be significant reduced when compared with mice that received scrambled control siRNA, while its isoenzyme, SphK2, remains unaffected (data not shown).…”

Section: Sphk1 Sirna Attenuated the Development Of Murine Ciasupporting

confidence: 68%

“…Control mice received scramble siRNA at the same time points. The dose of SphK1 siRNA chosen is consistent with our previous in vivo murine studies (typically 4 -8 g/animal) where SphK2 protein expression remains unaffected (28,49). The level of SphK1 inhibition was assessed by Western blot in spleen cells freshly isolated from mice treated with either SphK1 or scrambled control siRNA.…”

Section: Treatment Protocolsmentioning

confidence: 87%

“…Thus, blockade of SphK in normal animals may lead to modulation of inflammatory responses. To this end we have recently validated that SphK1 plays a critical role in vivo in a model of acute inflammation (49).…”

Section: Discussionmentioning

confidence: 99%

“…The level of SphK1 inhibition was assessed by Western blot in spleen cells freshly isolated from mice treated with either SphK1 or scrambled control siRNA. Mice were sacrificed 24 h after the last treatment and cell lysates were separated by 10% SDS-PAGE, transferred onto membrane, and probed with anti-SphK1 or anti-SphK2 Abs as previously described (28,49).…”

Section: Treatment Protocolsmentioning

confidence: 99%

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Anti-Inflammatory Effects of Sphingosine Kinase Modulation in Inflammatory Arthritis

Lai

Irwan

Goh

et al. 2008

The Journal of Immunology

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121

126

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Sphingosine kinase (SphK) is a key enzyme in the sphingolipid metabolic pathway responsible for phosphorylating sphingosine into sphingosine-1-phosphate (S1P). SphK/S1P play a critical role in angiogenesis, inflammation, and various pathologic conditions. Recently, S1P1 receptor was found to be expressed in rheumatoid arthritis (RA) synovium, and S1P signaling via S1P1 enhances synoviocyte proliferation, COX-2 expression, and prostaglandin E2 production. Here, we examined the role of SphK/S1P in RA using a potent SphK inhibitor, N,N-dimethylsphingosine (DMS), and a molecular approach against one of its isoenzymes, SphK1. We observed that levels of S1P in the synovial fluid of RA patients were significantly higher than those of osteoarthritis patients. Additionally, DMS significantly reduced the levels of TNF-α, IL-6, IL-1β, MCP-1, and MMP-9 in cell-contact assays using both Jurkat-U937 cells and RA PBMCs. In a murine collagen-induced arthritis model, i.p. administration of DMS significantly inhibited disease severity and reduced articular inflammation and joint destruction. Treatment of DMS also down-regulated serum levels IL-6, TNF-α, IFN-γ, S1P, and IgG1 and IgG2a anti-collagen Ab. Furthermore, DMS-treated mice also displayed suppressed proinflammatory cytokine production in response to type II collagen in vitro. Moreover, similar reduction in incidence and disease activity was observed in mice treated with SphK1 knock-down via small interfering RNA approach. Together, these results demonstrate SphK modulation may provide a novel approach in treating chronic autoimmune conditions such as RA by inhibiting the release of pro-inflammatory cytokines.

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Section: Sphk1 Sirna Attenuated the Development Of Murine Ciasupporting

confidence: 68%

Section: Treatment Protocolsmentioning

confidence: 87%

Section: Discussionmentioning

confidence: 99%

Section: Treatment Protocolsmentioning

confidence: 99%

See 2 more Smart Citations

Anti-Inflammatory Effects of Sphingosine Kinase Modulation in Inflammatory Arthritis

Lai

Irwan

Goh

et al. 2008

The Journal of Immunology

Self Cite

121

126

View full text Add to dashboard Cite

show abstract

“…Control mice received scramble siRNA at the same time points. The dose of siRNA chosen is consistent with our previous in vivo murine studies (typically 4 -8 g/animal) (23,24). The level of SphK1 and Sphk2 inhibition was assessed by Western blot in spleen cells freshly isolated from mice treated with either SphK1, SphK2, or scrambled control siRNA.…”

Section: Treatment Protocolsmentioning

confidence: 98%

Distinct Roles of Sphingosine Kinase 1 and 2 in Murine Collagen-Induced Arthritis

Lai

Irwan

Goh

et al. 2009

The Journal of Immunology

Self Cite

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Sphingosine kinase (SphK) phosphorylates sphingosine into sphingosine-1-phosphate (S1P). S1P plays a critical role in angiogenesis, inflammation, and various pathologic conditions. To date, two mammalian isoenzymes, SphK1 and SphK2, have been identified. Although both SphK1 and SphK2 share overall homology and produce the common product, S1P, it has been proposed they display different unique and separate functions. In this study, we examined the role of SphK1 and SphK2 in a murine collagen-induced arthritis model by down-regulating each isoenzyme via specific small interfering RNA (siRNA). Prophylactic i.p. administration of SphK1 siRNA significantly reduced the incidence, disease severity, and articular inflammation compared with control siRNA recipients. Treatment of SphK1 siRNA also down-regulated serum levels of S1P, IL-6, TNF-α, IFN-γ, and IgG2a anti-collagen Ab. Ex vivo analysis demonstrated significant suppression of collagen-specific proinflammatory/Th1 cytokine (IL-6, TNF-α, IFN-γ) release in SphK siRNA-treated mice. Interestingly, mice received with SphK2 siRNA develop more aggressive disease; higher serum levels of IL-6, TNF-α, and IFN-γ; and proinflammatory cytokine production to collagen in vitro when compared with control siRNA recipients. Together, these results demonstrate the distinct immunomodulatory roles of SphK1 and SphK2 in the development of inflammatory arthritis by regulating the release of proinflammatory cytokines and T cell responses. These findings raise the possibility that drugs which specifically target SphK1 activity may play a beneficial role in the treatment of inflammatory arthritis.

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Oligonucleotides as Recognition and Catalytic Elements

Herold

Rasooly²

2009

Recognition Receptors in Biosensors

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RETRACTED: Refining siRNA in vivo transfection: Silencing SPHK1 reveals its key role in C5a-induced inflammation in vivo

Cited by 21 publications

References 30 publications

Anti-Inflammatory Effects of Sphingosine Kinase Modulation in Inflammatory Arthritis

Anti-Inflammatory Effects of Sphingosine Kinase Modulation in Inflammatory Arthritis

Distinct Roles of Sphingosine Kinase 1 and 2 in Murine Collagen-Induced Arthritis

Oligonucleotides as Recognition and Catalytic Elements

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