Induction of macrophages matriptase and activation of macrophage stimulating protein 1 in sickle cell anemia - related chronic kidney disease

BACKGROUND: More than 50% of sickle cell anemia (SCA) patients develop chronic kidney disease (CKD). The mechanism of CKD is multifactorial and is not yet fully understood. SCA is a vasculopathy associated with multiple mechanisms driven by cell-free mutated hemoglobin (HbS). We have demonstrated that activation of recepteur d'origine nantais (RON) kinase contributes to the renal endothelial injury in SCA mouse model. Inhibition of RON reduces endothelial injury and ameliorates renal disease. Macrophage-stimulating protein 1 (MSP1) is the only known ligand for RON. MSP1 is synthesized by the liver and released in the circulation as biologically inactive pro-MSP1 protein that is activated by proteolytic cleavage. Macrophage membrane matriptase (MT-SP1) cleaves MSP1, making it able to bind RON receptor. The levels of plasma MSP1 and macrophage MT-SP1 in SCA have not been investigated. OBJECTIVES: To evaluate MT-SP1 expression and serum MSP1 levels in SCA patients and mouse model. HYPOTHESIS: The level of circulating MSP1 is reduced in SCA patients and mice due to its accumulation in organs. METHODS: The study was approved by Howard University IRB.All subjects provided written informed consent. Whole blood samples were obtained from 44 SCA patients enrolled at HU CSCD Registry study and 6 healthy control individuals. SCA mice (Townes) were housed in Howard University; the animal protocol was approved by the IACUC. ELISA kits were used to test human and mouse MSP1. Human THP-1 promonocytic cells were differentiated into macrophages with 25 nM PMA for 72 hrs and treated with either purified HbS or HbA (5 μM). Total RNA was used for RNA Seq. Comparisons were conducted using Dragen differential expression software v. 3.6.3 (Illumina), and gene counts were normalized using DESeq2 package from Bioconductor. RESULTS: RNA Seq results demonstrated increased levels of MT-SP1 in THP-1-derived macrophages after treatment with HbS compared to treatment with normal hemoglobin (HbA) (p=0.036). The results were further confirmed by real-time RT-PCR. The levels of plasma MSP1 were about 7-fold lower in SCD patients compared to non-SCD controls (146.8±111.7 ng/ml, N=6 in control vs. 20.6 ng/ml, N=44 in SCD, p=3.97x10-10). Log2 (MSP1) slightly correlated with albuminuria log2 (ALB/CRE) (r=0.1243, R2=0.0154, p=0.4216, N=44). This correlation was more profound in females (r=0.3158, R2=0.0997, p=0.1632, N=21). No correlation was found in males. We found moderate inverted correlation between eGFR and log2 (MSP1) (r=-0.3313, R2=0.1094, p=0.0280, N=44). In SCA patients with renal disease, MSP1 levels positively correlated with stages of CKD (r=0.3990, R2=0.1592, p=0.0320, N=29). In mouse, serum MSP1 levels were about 2.3-fold reduced in SCA compared to control mice (441.0±97.98 ng/ml, N=5 in control vs. 192.2 ±27.02, N=7 in SCD, p=0.0173). Immunostaining demonstrated the high levels of MSP1 accumulation on the surface of endothelial cells in the ki This work was supported by NIH Research Grants SC1HL150685, P50HL118006, R01HL125005, and G12MD007597. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.