Table 1.

Summary of macrophage polarization studies in kidney injury

Factor tested	Injury type	Major findings	Effect on macrophages	Ref
Relaxin	UUO AKI	Relaxin administration lowers TLR4 expression Increased renal function and attenuated injury and fibrosis	Increased M2 polarization	[74]
PRDX6	LPS AKI	PRDX6 overexpression decreased mortality and renal injury by lowering ROS via decreasing p38 MAPK and JNK.	Overall lower macrophage infiltration	[75]
Gpnmb	IR AKI	Gpnmb is highly expressed in M2. Knocking down Gpnmb results in higher IL-1B and TNFa. Gpmb induces M2 activation via IL-4/STAT6	Required for IL-4/STAT6 dependent M2 activation	[76]
IL-4/IL-13	DT AKI; IR AKI	IL-4/IL-13 activate JAK3/STAT6 Deletion of IL-4/13 results in worsened fibrosis	Required for M2a activation	[77]
EPO	RI AKI	EPO administration increases macrophage polarization reduces macrophage recruitment, increased phenotype switch to M2, repressed M1 and increases Jak2/STAT3/STAT6 pathway	Overall lower macrophage infiltration; higher ratio of M2 activation	[36]
RA	I/R AKI	RA synthesis (Raldh3) is activated in recruited renal macrophages All-Trans Retinoic Acid reduces post-AKI fibrosis RTEC-specific RAR knockdown results reduces M2 polarization in mice	RTEC-specific RA required for M2 activation	[34]
EPO	I/R AKI	EPO administration resulted in increased function Increased expression of Wnt7b, B-Cat, downregulation of miR-21, −214,−210, −199a	EPO lowers renal macrophage infiltration	[78]
CSF-1	I/R AKI	CSF-1 depletion results in reduced M2 polarization, delayed functional, structural recovery, increased fibrosis	Required for M2 polarization	[79]
GM-CSF	I/R AKI	GM-CSF secreted by RTECs increase STAT5 activation and increases RTEC proliferation	Required for M2 polarization	[24]
SOCS-3	RI AKI; I/R AKI	SOCS-3 KO in RTECs resulted in increased proliferation and attenuated injury	Inhibits M2 polarization	[80]
MSC	RI AKI	Increased renal function and injury attenuation function and injury attenuation.	Increases M2 polarization	[37]

UUO - unilateral uretral obstruction

LPS - Lipopolysaccharide

DT - diphtheria toxin

RI - Rhabdomyolysis induced

I/R - Ischemia/reperfusion

PRDX6 - Peroxiredoxin 6

Gpnmb - Glycoprotein non-metastatic melanoma protein b

EPO - Erythropoietin

RA - Retinoic Acid

CSF-1 - Colony Stimulating Factor-1

GM-CSF - Granulocyte-macrophage colony-stimulating factor

SOCS-3 - suppressor of cytokine signaling 3

MSC - Mesenchymal Stem Cells