Gulate synovial inflammation during the first phase of AIA. Both genes are specific markers for murine M2 macrophages [31]. Arginase 1 is an enzyme that competes with iNOS for L-arginine and reduces the accumulation of reactive oxygen species (ROS) [32]. The physiological role of Ym1 is not clear but a role in promotion of cytokines is suggested [32]. Expression of Ym1 (but not Arg1) was raised by Lip-PLP Fexinidazole web treatment of macrophages in vitro but also in the synovium after 1 day of treatment of AIA. Ym1 promotes Th2 cytokine expression like IL-4 and IL-13 by inhibiting 12/15 lipoxygenase [33]. These cytokines are expressed during AIA and have been shown to strongly regulate synovial inflammation within this model [34]. In direct response to IL-4 and IL-13, Ym1 is strongly upregulated in murine macrophages in a STAT-6 dependent manner [35] thereby forming a positive feedback loop which may drive further Th2 differentiation. Unlike Ym1, other mediators of M2 macrophages like IL-10, TGF-b, IL-1RII, CD206 and FIZZ1 remained at the same level and were not altered by Lip-PLP treatment whereas in contrast M1 markers were strongly downregulated. Altogether this 25331948 suggests that there is no shift towards the M2 as the dominant phenotype within the synovium after treatment with Lip-PLP. In AIA, we have found evidence of favoring M2 by decreasing M1 markers whereas in the ICA there is more an overall nonspecific decrease in M1 and M2 markers. An explanation for this discrepancy may be that under in vivo conditions macrophages which have taken up PLP-liposomes meet additional triggers like ICs and T-cells which prevent an effective differentiation towards an M2 status. ICs that drive joint inflammation in ICA can stimulate macrophages into an M1 phenotype by binding to activating FccR. In the AIA joint, apart from ICs also Th2 cells meet synovial macrophages which produce cytokines like IL-4 and IL-13 which may counteract the IC effects. Previous studies in our lab have shown that overexpression of either IL-4 [36] or IL-13 [37] during ICA strongly Pentagastrin chemical information diminished joint inflammation and destruction, probably by differentiating macrophages into an M2 phenotype. Treatment of arthritis with a single systemic injection of PLPliposomes has been shown to be much more effective than free corticosteroids. This study clearly shows that selective targeting of PLP-liposomes to synovial intimal macrophages strongly suppressed M1 in both arthritis models whereas M2 was lower in ICA and not altered in AIA. Suppression of the M1 signature by liposomal PLP may drive the inflammatory status in the synovium towards a more positive and more efficient treatment for patients suffering from auto-immune disease.PLP Liposomes Inhibit M1 Macrophage ActivationAuthor ContributionsConceived and designed the experiments: WH PvL WvdB. Performed the experiments: WH. Analyzed the data: WH PvL RS. Contributed reagents/materials/analysis tools: WH GS. Wrote the paper: PvL WH WvdB GS RS.
Polyamines, found in the cells of most species, play vital roles in cell proliferation and many physiological functions [1]. Thus, cellular polyamine homeostasis is strictly maintained by regulation of its anabolic and catabolic pathways [2]. In mammals, the interconversion pathway enhances control of cellular polyamine. Spermidine/spermine N1-acetyltransferase 1 (Ssat1) is the key enzyme in the rate-determining reactions of this pathway, by which spermine or spermidine accepts the acetyl group from acetyl-CoA t.Gulate synovial inflammation during the first phase of AIA. Both genes are specific markers for murine M2 macrophages [31]. Arginase 1 is an enzyme that competes with iNOS for L-arginine and reduces the accumulation of reactive oxygen species (ROS) [32]. The physiological role of Ym1 is not clear but a role in promotion of cytokines is suggested [32]. Expression of Ym1 (but not Arg1) was raised by Lip-PLP treatment of macrophages in vitro but also in the synovium after 1 day of treatment of AIA. Ym1 promotes Th2 cytokine expression like IL-4 and IL-13 by inhibiting 12/15 lipoxygenase [33]. These cytokines are expressed during AIA and have been shown to strongly regulate synovial inflammation within this model [34]. In direct response to IL-4 and IL-13, Ym1 is strongly upregulated in murine macrophages in a STAT-6 dependent manner [35] thereby forming a positive feedback loop which may drive further Th2 differentiation. Unlike Ym1, other mediators of M2 macrophages like IL-10, TGF-b, IL-1RII, CD206 and FIZZ1 remained at the same level and were not altered by Lip-PLP treatment whereas in contrast M1 markers were strongly downregulated. Altogether this 25331948 suggests that there is no shift towards the M2 as the dominant phenotype within the synovium after treatment with Lip-PLP. In AIA, we have found evidence of favoring M2 by decreasing M1 markers whereas in the ICA there is more an overall nonspecific decrease in M1 and M2 markers. An explanation for this discrepancy may be that under in vivo conditions macrophages which have taken up PLP-liposomes meet additional triggers like ICs and T-cells which prevent an effective differentiation towards an M2 status. ICs that drive joint inflammation in ICA can stimulate macrophages into an M1 phenotype by binding to activating FccR. In the AIA joint, apart from ICs also Th2 cells meet synovial macrophages which produce cytokines like IL-4 and IL-13 which may counteract the IC effects. Previous studies in our lab have shown that overexpression of either IL-4 [36] or IL-13 [37] during ICA strongly diminished joint inflammation and destruction, probably by differentiating macrophages into an M2 phenotype. Treatment of arthritis with a single systemic injection of PLPliposomes has been shown to be much more effective than free corticosteroids. This study clearly shows that selective targeting of PLP-liposomes to synovial intimal macrophages strongly suppressed M1 in both arthritis models whereas M2 was lower in ICA and not altered in AIA. Suppression of the M1 signature by liposomal PLP may drive the inflammatory status in the synovium towards a more positive and more efficient treatment for patients suffering from auto-immune disease.PLP Liposomes Inhibit M1 Macrophage ActivationAuthor ContributionsConceived and designed the experiments: WH PvL WvdB. Performed the experiments: WH. Analyzed the data: WH PvL RS. Contributed reagents/materials/analysis tools: WH GS. Wrote the paper: PvL WH WvdB GS RS.
Polyamines, found in the cells of most species, play vital roles in cell proliferation and many physiological functions [1]. Thus, cellular polyamine homeostasis is strictly maintained by regulation of its anabolic and catabolic pathways [2]. In mammals, the interconversion pathway enhances control of cellular polyamine. Spermidine/spermine N1-acetyltransferase 1 (Ssat1) is the key enzyme in the rate-determining reactions of this pathway, by which spermine or spermidine accepts the acetyl group from acetyl-CoA t.
