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RGS4 inhibits angiotensin II signaling and macrophage localization during renal reperfusion injury independent of vasospasm.

Pang P, Jin X, Proctor BM, Farley M, Roy N, Chin MS, von Andrian UH, Vollmann E, Perro M, Hoffman RJ, Chung J, Chauhan N, Mistri M, Muslin AJ, Bonventre JV, Siedlecki AM - Kidney Int. (2014)

Bottom Line: Angiotensin II stimulated pre-glomerular vascular smooth muscle cells (VSMCs) to secrete the macrophage chemoattractant RANTES, a process decreased by angiotensin II R2 (AT2) inhibition.However, RANTES increased when RGS4 expression was suppressed implicating Gα protein activation in an AT2-RGS4-dependent pathway.Thus, RGS4 expression, specific to renal VSMC, inhibits angiotensin II-mediated cytokine signaling and macrophage recruitment during reperfusion, distinct from vasomotor regulation.

View Article: PubMed Central - PubMed

Affiliation: Renal Division, Department of Internal Medicine, Brigham and Women's Hospital, Harvard Medical School, Harvard Institutes of Medicine, Boston, Massachusetts, USA.

ABSTRACT
Vascular inflammation is a major contributor to the severity of acute kidney injury. In the context of vasospasm-independent reperfusion injury we studied the potential anti-inflammatory role of the Gα-related RGS protein, RGS4. Transgenic RGS4 mice were resistant to 25 min injury, although post-ischemic renal arteriolar diameter was equal to the wild type early after injury. A 10 min unilateral injury was performed to study reperfusion without vasospasm. Eighteen hours after injury, blood flow was decreased in the inner cortex of wild-type mice with preservation of tubular architecture. Angiotensin II levels in the kidneys of wild-type and transgenic mice were elevated in a sub-vasoconstrictive range 12 and 18 h after injury. Angiotensin II stimulated pre-glomerular vascular smooth muscle cells (VSMCs) to secrete the macrophage chemoattractant RANTES, a process decreased by angiotensin II R2 (AT2) inhibition. However, RANTES increased when RGS4 expression was suppressed implicating Gα protein activation in an AT2-RGS4-dependent pathway. RGS4 function, specific to VSMC, was tested in a conditional VSMC-specific RGS4 knockout showing high macrophage density by T2 MRI compared with transgenic and non-transgenic mice after the 10 min injury. Arteriolar diameter of this knockout was unchanged at successive time points after injury. Thus, RGS4 expression, specific to renal VSMC, inhibits angiotensin II-mediated cytokine signaling and macrophage recruitment during reperfusion, distinct from vasomotor regulation.

No MeSH data available.


Related in: MedlinePlus

T2 imaging of injured kidneys in the coronal plane 18 hours after MION-47 injection and 10 minute unilateral ischemia injury. (A) SMMHC-Cre undergoing sham procedure (Cre+S), RGS4 overexpressor undergoing sham procedure (Tg+S), SMMHC-Cre rgs4  undergoing sham procedure (CKO+S), SMMHC-Cre undergoing 10 minute unilateral ischemia (Cre+10UI), RGS4 overexpressor undergoing 10 minute unilateral ischemia (Tg+10UI), SMMHC-Cre rgs4  undergoing 10 minute unilateral ischemia (CKO+10UI), SMMHC-Cre rgs4  treated with PD123319 undergoing 10 minute unilateral ischemia (CKO+10UI+PD123). (B) T2 signal decay curves were measured subsequent to 10 minute microvascular clamping and 18 hrs of reperfusion. Regions of interest selected at the corticomedullary junction (red crosshairs). Calculated T2 signal in kidney (T2k) was compared to calculated T2 signal in adjacent psoas muscle (T2m). Cre+10UI (0.37±0.03) (n=7) vs TG+10UI (0.57±0.03) (n=7) (*, p=1.2×10−6); CKO+10UI (0.11±0.02) (n=7) vs CKO+10UI+PD123319 (0.46±0.02) (n=7) (**, p=2.3×10−8).
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Figure 10: T2 imaging of injured kidneys in the coronal plane 18 hours after MION-47 injection and 10 minute unilateral ischemia injury. (A) SMMHC-Cre undergoing sham procedure (Cre+S), RGS4 overexpressor undergoing sham procedure (Tg+S), SMMHC-Cre rgs4 undergoing sham procedure (CKO+S), SMMHC-Cre undergoing 10 minute unilateral ischemia (Cre+10UI), RGS4 overexpressor undergoing 10 minute unilateral ischemia (Tg+10UI), SMMHC-Cre rgs4 undergoing 10 minute unilateral ischemia (CKO+10UI), SMMHC-Cre rgs4 treated with PD123319 undergoing 10 minute unilateral ischemia (CKO+10UI+PD123). (B) T2 signal decay curves were measured subsequent to 10 minute microvascular clamping and 18 hrs of reperfusion. Regions of interest selected at the corticomedullary junction (red crosshairs). Calculated T2 signal in kidney (T2k) was compared to calculated T2 signal in adjacent psoas muscle (T2m). Cre+10UI (0.37±0.03) (n=7) vs TG+10UI (0.57±0.03) (n=7) (*, p=1.2×10−6); CKO+10UI (0.11±0.02) (n=7) vs CKO+10UI+PD123319 (0.46±0.02) (n=7) (**, p=2.3×10−8).

Mentions: We inferred that RGS4 depletion in VSMC would exacerbate AngII-induced monocyte localization because of the above findings including decreased ED1+ cell density in RGS4 overexpressors and RGS4-dependent modulation of RANTES secretion. Therefore we injected monocrystalline iron oxide nanoparticles (MION-47) intravenously to localize phagocytic cells, primarily macrophages (31), in live animals. Using 10 minute unilateral kidney injury (10UI) we then measured macrophage localization in the late reperfusion period (i.e. 18 hours of reperfusion). In vivo MR imaging of the injured kidney identified nanoparticles in CKO kidneys 18 hours after 10UI. Particle density was greater in CKO kidneys after 10UI than Cre controls undergoing the same procedure (Figure 10A). Injured Tg animals had less nanoparticle density compared to injured Cre controls (Figure 10B). CKO animals treated with PD123319 followed by 10UI had reduced nanoparticle density approaching that of Tg+10UI (Figure 10B). Increased density of ED1+ cells (Figure 11A, C) and Prussian blue + cells (Figure 11B, C) was coincident with a shorter normalized T2 relaxation time in CKO (Figure 10B). ED1 probing and Prussian blue staining were also decreased in CKO treated with PD123319.


RGS4 inhibits angiotensin II signaling and macrophage localization during renal reperfusion injury independent of vasospasm.

Pang P, Jin X, Proctor BM, Farley M, Roy N, Chin MS, von Andrian UH, Vollmann E, Perro M, Hoffman RJ, Chung J, Chauhan N, Mistri M, Muslin AJ, Bonventre JV, Siedlecki AM - Kidney Int. (2014)

T2 imaging of injured kidneys in the coronal plane 18 hours after MION-47 injection and 10 minute unilateral ischemia injury. (A) SMMHC-Cre undergoing sham procedure (Cre+S), RGS4 overexpressor undergoing sham procedure (Tg+S), SMMHC-Cre rgs4  undergoing sham procedure (CKO+S), SMMHC-Cre undergoing 10 minute unilateral ischemia (Cre+10UI), RGS4 overexpressor undergoing 10 minute unilateral ischemia (Tg+10UI), SMMHC-Cre rgs4  undergoing 10 minute unilateral ischemia (CKO+10UI), SMMHC-Cre rgs4  treated with PD123319 undergoing 10 minute unilateral ischemia (CKO+10UI+PD123). (B) T2 signal decay curves were measured subsequent to 10 minute microvascular clamping and 18 hrs of reperfusion. Regions of interest selected at the corticomedullary junction (red crosshairs). Calculated T2 signal in kidney (T2k) was compared to calculated T2 signal in adjacent psoas muscle (T2m). Cre+10UI (0.37±0.03) (n=7) vs TG+10UI (0.57±0.03) (n=7) (*, p=1.2×10−6); CKO+10UI (0.11±0.02) (n=7) vs CKO+10UI+PD123319 (0.46±0.02) (n=7) (**, p=2.3×10−8).
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Figure 10: T2 imaging of injured kidneys in the coronal plane 18 hours after MION-47 injection and 10 minute unilateral ischemia injury. (A) SMMHC-Cre undergoing sham procedure (Cre+S), RGS4 overexpressor undergoing sham procedure (Tg+S), SMMHC-Cre rgs4 undergoing sham procedure (CKO+S), SMMHC-Cre undergoing 10 minute unilateral ischemia (Cre+10UI), RGS4 overexpressor undergoing 10 minute unilateral ischemia (Tg+10UI), SMMHC-Cre rgs4 undergoing 10 minute unilateral ischemia (CKO+10UI), SMMHC-Cre rgs4 treated with PD123319 undergoing 10 minute unilateral ischemia (CKO+10UI+PD123). (B) T2 signal decay curves were measured subsequent to 10 minute microvascular clamping and 18 hrs of reperfusion. Regions of interest selected at the corticomedullary junction (red crosshairs). Calculated T2 signal in kidney (T2k) was compared to calculated T2 signal in adjacent psoas muscle (T2m). Cre+10UI (0.37±0.03) (n=7) vs TG+10UI (0.57±0.03) (n=7) (*, p=1.2×10−6); CKO+10UI (0.11±0.02) (n=7) vs CKO+10UI+PD123319 (0.46±0.02) (n=7) (**, p=2.3×10−8).
Mentions: We inferred that RGS4 depletion in VSMC would exacerbate AngII-induced monocyte localization because of the above findings including decreased ED1+ cell density in RGS4 overexpressors and RGS4-dependent modulation of RANTES secretion. Therefore we injected monocrystalline iron oxide nanoparticles (MION-47) intravenously to localize phagocytic cells, primarily macrophages (31), in live animals. Using 10 minute unilateral kidney injury (10UI) we then measured macrophage localization in the late reperfusion period (i.e. 18 hours of reperfusion). In vivo MR imaging of the injured kidney identified nanoparticles in CKO kidneys 18 hours after 10UI. Particle density was greater in CKO kidneys after 10UI than Cre controls undergoing the same procedure (Figure 10A). Injured Tg animals had less nanoparticle density compared to injured Cre controls (Figure 10B). CKO animals treated with PD123319 followed by 10UI had reduced nanoparticle density approaching that of Tg+10UI (Figure 10B). Increased density of ED1+ cells (Figure 11A, C) and Prussian blue + cells (Figure 11B, C) was coincident with a shorter normalized T2 relaxation time in CKO (Figure 10B). ED1 probing and Prussian blue staining were also decreased in CKO treated with PD123319.

Bottom Line: Angiotensin II stimulated pre-glomerular vascular smooth muscle cells (VSMCs) to secrete the macrophage chemoattractant RANTES, a process decreased by angiotensin II R2 (AT2) inhibition.However, RANTES increased when RGS4 expression was suppressed implicating Gα protein activation in an AT2-RGS4-dependent pathway.Thus, RGS4 expression, specific to renal VSMC, inhibits angiotensin II-mediated cytokine signaling and macrophage recruitment during reperfusion, distinct from vasomotor regulation.

View Article: PubMed Central - PubMed

Affiliation: Renal Division, Department of Internal Medicine, Brigham and Women's Hospital, Harvard Medical School, Harvard Institutes of Medicine, Boston, Massachusetts, USA.

ABSTRACT
Vascular inflammation is a major contributor to the severity of acute kidney injury. In the context of vasospasm-independent reperfusion injury we studied the potential anti-inflammatory role of the Gα-related RGS protein, RGS4. Transgenic RGS4 mice were resistant to 25 min injury, although post-ischemic renal arteriolar diameter was equal to the wild type early after injury. A 10 min unilateral injury was performed to study reperfusion without vasospasm. Eighteen hours after injury, blood flow was decreased in the inner cortex of wild-type mice with preservation of tubular architecture. Angiotensin II levels in the kidneys of wild-type and transgenic mice were elevated in a sub-vasoconstrictive range 12 and 18 h after injury. Angiotensin II stimulated pre-glomerular vascular smooth muscle cells (VSMCs) to secrete the macrophage chemoattractant RANTES, a process decreased by angiotensin II R2 (AT2) inhibition. However, RANTES increased when RGS4 expression was suppressed implicating Gα protein activation in an AT2-RGS4-dependent pathway. RGS4 function, specific to VSMC, was tested in a conditional VSMC-specific RGS4 knockout showing high macrophage density by T2 MRI compared with transgenic and non-transgenic mice after the 10 min injury. Arteriolar diameter of this knockout was unchanged at successive time points after injury. Thus, RGS4 expression, specific to renal VSMC, inhibits angiotensin II-mediated cytokine signaling and macrophage recruitment during reperfusion, distinct from vasomotor regulation.

No MeSH data available.


Related in: MedlinePlus