Using Imaging Mass Cytometry to Develop Mechanistic Understanding of Glomerulonephritis

• Applicant: Dr. Marlene Weiss
• Subject Area: Nephrology
• Term: from 2019 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 434349493

Both ANCA-associated vasculitis (AAV) and lupus nephritis (LN) are autoimmune diseases in which inflammatory and immunological activation result in kidney damage. Current diagnostic approaches rely on pathologic tissue section analysis, and typically lead to non-specific immunosuppressive therapies such as glucocorticoids and cytotoxic agents. While the disease entities themselves entail a high morbidity, mortality and relapse rate, the common treatment agents cause secondary complications such as atherosclerosis and susceptibility to infections. The proposed research project aims to better characterize these disease entities by quantitatively analyzing morphological, immunological and activation state markers in both the glomerulus and the renal parenchyma, and to use this to identify specific pathogenic pathways for development of targeted therapies with less off-target side effects. Imaging Mass Cytometry (IMC) is a new multiplexed imaging technique available for analyzing multiple antigens in a single tissue section. It provides a good platform to investigate cellular and morphological changes in autoimmune disease as well as pathogenic questions regarding the immune infiltrate and mechanisms of injury. IMC utilizes mass spectrometry with laser ablation to simultaneously identify up to 44 heavy metal labeled antibodies. The concurrent spatial preservation can determine which agents and immunological markers secreted by the antigen-presenting cells directly lead to specific immune responses and subsequent paracrine signaling to renal resident cells. By providing digital data rather than image data, the method lends itself to accurate quantification.The technique has been used by several scientific research groups worldwide to characterize healthy and diseased tissue. While others have focused on the human pancreas and tumor tissue, my host laboratory has developed a validated antibody panel and analysis pipeline for mapping of the healthy human kidney, based on a machine-learning approach. Using this as the starting point, I will validate a set of new antibodies targeted to define immunologic and cell activation states, conjugate them with metal ions and incorporate them into the existing 26 antibody panel. Suitable biopsy tissues of AAV and LN will be identified with help of the underlying clinical data and the renal pathologist at Yale. Subsequently, IMC will be performed using the expanded antibody panel. I will then analyze the resulting data according to the imaging and analysis pipeline. In a second step, the results will be correlated with clinical data and compared both to healthy kidney samples and among themselves. Comparing AAV and LN class III and IV will be of particular interest to point out differences in immunological and inflammatory pathogenesis between the two groups. Achieving greater knowledge of the molecular differences between these diseases is predicted to help establish more individualized therapeutic concepts.

• DFG Programme: Research Fellowships
• International Connection: USA
• Host: Professor Dr. Lloyd Cantley