Session Type: Poster Session A
Session Time: 8:30AM-10:30AM
Background/Purpose: The alternative complement pathway has been implicated in the pathogenesis of ANCA-associated vasculitis (AAV), however it is not clear whether activation of complement occurs systemically or in affected organs such as the kidney. This study measured levels of urinary and plasma complement fragment Ba (uBa and pBa respectively) at multiple timepoints in patients with AAV.
Methods: Ba was measured by ELISA in serial samples of urine (uBa) and plasma (pBa) from 20 AAV patients who developed a renal flare, 20 who developed a non-renal flare, and 20 in long-term remission. Changes in Ba levels were modeled using linear mixed effect models.
Results: Cohort characteristics are given in Figure.1. uBa levels increased at renal flare, but did not increase at non-renal flare, and remained stable in long-term remission (Figure 2a). pBa levels were stable over time in all groups (Figure 2b). uBa correlated with renal AAV activity measured as the renal component of the BVAS score (R2= 0.33, p< 0.01) (Figure 3a), but did not correlate with the overall BVAS score during renal flare (R2= 0.13, p=0.12) or non-renal flare (R2= 0.10, p=0.22) (Figure 3b,c).
Conclusion: Urine, but not plasma, Ba levels increase at the time of a flare of renal disease in AAV, suggesting intra-renal alternative complement pathway activation. uBa has the potential for use as a surveillance biomarker of renal vasculitis.
To cite this abstract in AMA style:Almaani S, Song H, Sthanithra M, Toy C, Levesque A, Fussner L, Meara A, Nagaraja H, Cuthbertson D, Khalidi N, KOENING C, Langford C, McAlear C, Moreland L, Pagnoux C, Seo P, Sreih A, Warrington K, Monach P, Merkel P, Rovin B, Birmingham D. Urine and Plasma Complement Ba Levels During Flares of Nephritis in Patients with ANCA-Associated Vasculitis [abstract]. Arthritis Rheumatol. 2021; 73 (suppl 10). https://acrabstracts.org/abstract/urine-and-plasma-complement-ba-levels-during-flares-of-nephritis-in-patients-with-anca-associated-vasculitis/. Accessed January 25, 2022.
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/urine-and-plasma-complement-ba-levels-during-flares-of-nephritis-in-patients-with-anca-associated-vasculitis/