Background: Type I interferon signature is one of the most important features of systemic lupus erythematosus (SLE), which indicates an active immune response to antigen invasion. Characteristics of type I interferon-stimulated genes (ISGs) in SLE patients have not been well described thus far. Methods: We analyzed 35,842 cells of PBMC single-cell RNA sequencing data of five SLE patients and three healthy controls. Thereafter, 178 type I ISGs among DEGs of all cell clusters were screened based on the Interferome Database and AUCell package was used for ISGs activity calculation. To determine whether common ISG features exist in PBMCs and kidneys of patients with SLE, we analyzed kidney transcriptomic data from patients with lupus nephritis (LN) from the GEO database. MRL/lpr mice model were used to verify our findings. Findings: We found that monocytes, B cells, dendritic cells, and granulocytes were significantly increased in SLE patients, while subsets of T cells were significantly decreased. Neutrophils and low-density granulocytes (LDGs) exhibited the highest ISG activity. GO and pathway enrichment analyses showed that DEGs focused on leukocyte activation, cell secretion, and pathogen infection. Thirty-one common ISGs were found expressed in both PBMCs and kidneys; these ISGs were also most active in neutrophils and LDGs. Transcription factors including PLSCR1, TCF4, IRF9 and STAT1 were found to be associated to ISGs expression. Consistently, we found granulocyte infiltration in the kidneys of MRL/lpr mice. Granulocyte inhibitor Avacopan reduced granulocyte infiltration and reversed renal conditions in MRL/lpr mice. Interpretation: This study shows for the first time, the use of the AUCell method to describe ISG activity of granulocytes in SLE patients. Moreover, Avacopan may serve as a granulocyte inhibitor for treatment of lupus patients in the future.

Objectives: Ischemia-reperfusion injury (IRI) is a major cause of chronic renal fibrosis.Currently, numerous therapies have shown a minimal effect on the blockade of fibrosis progression. Here, the therapeutic potential of peptide-based TGF-β1 inhibitor P144 in IRI-induced renal fibrosis and the underlying mechanism were analyzed. Materials and Methods: The unilateral ischemia-reperfusion injury with the contralateral nephrectomy model was established, and the P144 was administered intravenously 1d/14d after the onset of IRI. The histopathology and immunofluorescence staining were used to detect renal fibrosis and macrophage infiltration. The in vivo fluorescence imaging was used to measure the bio-distribution of P144. The transwell assays were used to observe the migration of macrophages. RT-qPCR and western blot were used to analyze TGF-β1 signaling. Results: P144 ameliorated the accumulation of extracellular matrix in the kidney and improved the renal function in the unilateral ischemia-reperfusion injury plus contralateral nephrectomy model. Mechanistically, P144 downregulated the TGF-β1-Smad3 signaling at both the transcriptional and translational levels and further reduced the TGF-β1-dependent infiltration of macrophages to the injured kidney. Additionally, P144 blocked the polarization of macrophages to an M2-like phenotype induced by TGF-β1 in vitro, but showed no effect on their proliferation. Conclusions: Our study showed that the TGF-β1 peptide-based inhibitor P144 decreased renal fibrosis through the blockade of the TGF-β1-Smad3 signaling pathway and the modulation of macrophage polarization, suggesting its potential therapeutic use in IRI-induced renal fibrosis. Delun Li and Jian Zhang contributed equally as co-first authors.