ASN's Mission

To create a world without kidney diseases, the ASN Alliance for Kidney Health elevates care by educating and informing, driving breakthroughs and innovation, and advocating for policies that create transformative changes in kidney medicine throughout the world.

learn more

Contact ASN

1401 H St, NW, Ste 900, Washington, DC 20005

email@asn-online.org

202-640-4660

The Latest on Twitter

Kidney Week

Abstract: FR-PO118

Polymyxin and Neomycin (P+N) Attenuates Inflammation and Fibrosis in Unilateral Ureteral Obstructed (UUO) Kidney by Altering Macrophage Phenotype

Session Information

Category: CKD (Non-Dialysis)

  • 1903 CKD (Non-Dialysis): Mechanisms

Authors

  • Ghosh, Siddhartha S., VCU Medical Ctr, Richmond, Virginia, United States
  • Gonzalez, Austin J., Virginia Commonwealth University, Fredericksburg, Virginia, United States
  • Krieg, Richard, VCU, Richmond, Virginia, United States
  • Gehr, Todd W., Virginia Commonwealth University, Fredericksburg, Virginia, United States
  • Ghosh, Shobha, VCU, Richmond, Virginia, United States
Background

Gut bacteria have been shown to modulate inflammation in both acute and chronic kidney injury. P+N are non-absorbable antibiotics that are used to sterilize the gut. UUO mice develop acute inflammation in one kidney after surgery which progresses to fibrosis within 7 days. We wanted to investigate if gut sterilization by P+N can affect inflammation and fibrosis in UUO mice.

Methods

UUO surgery was done by the method adapted from Vanderbilt O’Brien Center. One group of mice was treated with P+N 7 days before UUO. One group was untreated (UT). Control mice did not receive surgery or treatment (C). Mice were sacrificed 3 days (n=5/group) and 10 days (n=5/group) after UUO. Macrophage (Mo) and macrophage phenotype M1 and M2 were determined by flow cytometry. Inflammation markers MCP1, IL1β, and fibrosis marker α-smooth muscle actin (SMA) were assessed by immunoblot. Lipopolysaccharide (LPS) was measured by LAL assay.

Results

3 Days post UUO: P+N treatment did decrease Mo influx in kidney but not Mo phenotype (Table). Only MCP1 increased in UT kidney compared to C, and P+N significantly lowered it (p<0.05). 10 Days post UUO: Although Mo in the kidneys of both groups was significantly higher, UT had more M1 and less M2 compared to P+N (Table). High levels of MCP1, IL-1β and SMA were lowered by P+N. Average plasma LPS in 5 normal mice (C) was 0.8 EU/ml. LPS of UT mice was 3.7±0.32 EU/ml, 3 days after UUO and remained high (3.1±0.3 EU/ml) even after 10 days of UUO. In contrast, LPS levels of P+N group (1.1±.3 EU/ml) after 10 days was not different from group C.

Conclusion

LPS is known to modulate inflammation and Mo phenotype. M1 and M2 phenotypes are known to modulate fibrosis and inflammation respectively. Increased inflammation and fibrosis in UT (10 days) can be attributed to increased M1 and decreased M2. A decrease in inflammatory markers and fibrosis in P+N corresponds to the increased M2 and decreased M1 in this group. P+N can only act at the intestinal level and reduction of systemic LPS by this treatment implies that the gut might be a source of kidney inflammation.

Table
 CD45+CD11b (Mo)CD45+ CD11b Ly6Chi (M1)CD45+ CD11b Ly6Clo (M2)
 UTP+NUTP+NUTP+N
3 day UUO30.8± 22.35.7±0.4*73.4±17.959.7±12.225.2±17.639.5±7.5
10 day UUO95.5±3.783.1±11.382.5±6.761.3±17.4*15.5±5.536.9±10.5*

*p<0.05 compared to UT