Identification of a Role for Monocytes in Murine Lupus Associated Diffuse Alveolar Hemorrhage By Mass Cytometry

Nathan Nelson-Maney¹, Pui Lee², Anais Levescot³, Yuelong Huang⁴ and Peter Nigrovic⁵, ¹Division of Rheumatology, Immunology, and Allergy, Brigham and Women's Hospital, Boston, MA, ²Harvard Medical School, Boston, MA, ³Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Harvard Medical School, boston, MA, ⁴Brigham and Women's Hospital, Boston, MA, ⁵Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Boston, MA

Meeting: 2018 ACR/ARHP Annual Meeting

Keywords: Animal models, monocytes, pulmonary complications and systemic lupus erythematosus (SLE)

Session Information

Date: Tuesday, October 23, 2018

Title: Systemic Lupus Erythematosus – Animal Models Poster

Session Type: ACR Poster Session C

Session Time: 9:00AM-11:00AM

Background/Purpose:

Diffuse alveolar hemorrhage (DAH) is a life-threatening pulmonary complication of systemic lupus erythematosus. The inciting pathology is thought to be pulmonary capillaritis but the pathogenic cell population(s) that elicits inflammation and tissue destruction remains unclear. Mice treated intraperitoneally with the hydrocarbon pristane develop features of human SLE including autoantibodies, glomerulonephritis and DAH.

We used mass cytometry complemented with studies in informative marrow transplantation and genetic deletions to identify pathogenic cellular populations in DAH.

Methods: Wild-type and transplanted/transgenic mice (6-8 weeks of age) were treated with 0.5 mL of pristane intraperitoneally and analyzed after 2 weeks. Lung sections were analyzed by H&E staining. Lung tissue was digested using collagenase and analyzed by mass cytometry (CyTOF) and flow cytometry.

Results: Mass cytometry using heavy-metal isotopes was superior to fluorescence-based flow cytometry for unambiguous identification of cell subsets in strongly autofluorescent lung tissue digest. Using a 25-antibody mass cytometry panel, we found that alveolar macrophages and eosinophils were significantly reduced in DAH while both Ly6C^hi and Ly6C^lo monocytes increased markedly. Dendritic cells and interstitial macrophages were minimally affected by pristane treatment. Using bone marrow transplant, we found that the expanded lung monocytes in DAH are bone marrow-derived and differentiate into macrophage-like cells. The incidence of DAH was reduced in Ccr2 (CC-chemokine receptor 2)-deficient mice with impaired monocyte egress from the bone marrow (11/15 in wild-type vs. 3/15 in Ccr2-/-, p < 0.01). Furthermore, Irf8 (interferon regulatory factor 8)-deficient mice with absent Ly6C^hi monocyte development were strongly protected against the development of DAH (21/25 in wild-type vs. 1/25 in Irf8^-/-, p < 0.001).

Conclusion: We demonstrate the utility of mass cytometry for unambiguous identification of immune cells in DAH. We found that monocytes infiltrate the lungs in pristane-treated mice and play an essential role in the development of DAH. These findings suggest that monocytes could represent a therapeutic target in SLE-associated human DAH.

Disclosure: N. Nelson-Maney, None; P. Lee, None; A. Levescot, None; Y. Huang, None; P. Nigrovic, Novartis, AbbVie, Sobi, 2,Novartis, AbbVie, Sobi, UCB, Pfizer, 5,UpToDate, American Academy of Pediatrics, 7.

To cite this abstract in AMA style:

Nelson-Maney N, Lee P, Levescot A, Huang Y, Nigrovic P. Identification of a Role for Monocytes in Murine Lupus Associated Diffuse Alveolar Hemorrhage By Mass Cytometry [abstract]. Arthritis Rheumatol. 2018; 70 (suppl 9). https://acrabstracts.org/abstract/identification-of-a-role-for-monocytes-in-murine-lupus-associated-diffuse-alveolar-hemorrhage-by-mass-cytometry/. Accessed .

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