Kidney Week

Abstract: SA-OR021

Clonal Hematopoiesis in ANCA-Associated Vasculitis

Session Information

• ANCA It Is
  November 09, 2019 | Location: 207, Walter E. Washington Convention Center
  Abstract Time: 04:30 PM - 04:42 PM

Category: Glomerular Diseases

• 1202 Glomerular Diseases: Immunology and Inflammation

Authors

• Weiss, Marlene, Charité Berlin, Germany, Berlin, Germany

Marlene Weiss, DrMed



I studied medicine in Munich, Germany, and started residency in internal medicine at Charité Hospital Berlin in 2016, being employed in the Division of Nephrology and Internal Intensive Care Medicine. As a clinicial scientist, I was part of the laboratory of Dr. Adrian Schreiber with focus on ANCA-associated vasculitis and worked on a joint project with Dr. Frederik Damm’s laboratory. Since April of this year, I am pursuing a postdoc at Yale University in the laboratory of Dr. Lloyd Cantley where I use the technique of Imaging Mass Cytometry (IMC) to develop a mechanistic understanding of glomerulonephritis.

• Rousselle, Anthony, ECRC, Berlin, Germany

Anthony Rousselle,

• Bullinger, Lars, Charité University Medicine, Berlin, Germany

Lars Bullinger,

• Eckardt, Kai-Uwe, Charité – Universitätsmedizin Berlin, Berlin, Germany

Kai-Uwe Eckardt,

• Kettritz, Ralph, Universitatsmedizin Berlin, Berlin, Germany

Ralph Kettritz,

• Damm, Frederik, Charité Universitätsmedizin Berlin, Berlin, Germany

Frederik Damm,

• Schreiber, Adrian, Charite Berlin, Berlin, Germany

Adrian Schreiber,

Background

Antineutrophil cytoplasmic autoantibodies (ANCA)-associated vasculitides (AAV) are induced by binding of ANCA IgG to myeloid cells and their subsequent activation. Autoantigen expression has been described to be dysregulated on both molecular and protein expression level in AAV patients. Recently, clonal hematopoiesis of indeterminate potential (CHIP), which is defined by the presence of a somatic mutation in the peripheral blood of individuals without evidence of hematologic neoplasms, has been linked with increased risk of hematologic cancer and cardiovascular disease. Here we aimed to characterize CHIP in patients with AAV.

Methods

112 patients with AAV (median age 64, range 18-84) were screened for CHIP using targeted sequencing. mRNA expression of PR3 and MPO in peripheral blood leukocytes was quantified by qPCR, ANCA autoantigen expression and neutrophil reactive oxygen generation were measured by flow-cytometry.

Results

CHIP was discovered in 34 out of 112 AAV patients (in total of 46 somatic mutations), which is a higher prevalence than expected in age-matched healthy controls (30.4% vs. 13.5%, p<0.001). The overall frequency of CHIP increased with age, however, 18.2% of patients <55 years had CHIP. The most frequently mutated genes were DNMT3A (19/46=39.1%), TET2 (7/46=15.2%), and ASXL1 (4/46=8.7%). CHIP was not associated with disease activity, ANCA subtype, or therapy. No differences in blood counts, creatinine levels, comorbidities, the development of malignancies, disease activity status, and AAV relapse risk were observed. However, disease manifestation patterns differed: CHIP^positive GPA patients showed less renal (68.2% vs. 88.5%, p=0.049) and nervous system involvements (0% vs. 19.2%, p=0.028). Longitudinal analysis of 23 CHIP clones in 19 selected patients revealed that more than 25% of patients showed an increase in clone size over time. Finally, a downregulation of both PR3 and MPO mRNA in peripheral blood leukocytes and significant less ROS production after ANCA IgG stimulation of neutrophils from CHIP^positive AAV patients compared to CHIP^negative patients (stimulation-index aMPO 7.8±5.4 vs. 15.5±9.3 and aPR3 6.8±3.1 vs. 13.2±7.7) was found.

Conclusion

Our findings provide novel experimental evidence of CHIP in AAV patients. Additionally, we found a functional impact of CHIP on ANCA-related neutrophil functions.