Dampened Inflammation and Improved Survival After CXCL5 Administration in Murine Lupus via Myeloid and Neutrophil Pathways.

OBJECTIVE: To determine the efficacy of CXCL5 administration in lupus-prone MRL/lpr (Faslpr ) mice and elucidate its working mechanisms. METHODS: CXCL5 expression in blood (obtained from SLE patients and Faslpr mice) and major internal organs (obtained from Faslpr mice) was examined by Luminex, real-time polymerase chain reaction, and immunofluorescent staining analyses. Pharmacokinetic studies were performed in Faslpr mice and healthy Institute of Cancer Research mice. Efficacy of CXCL5 administration was demonstrated in Faslpr mice, and the working mechanism of CXCL5 treatment was elucidated by flow cytometry, Luminex, and RNA sequencing. RESULTS: In SLE patients, serum CXCL5 levels were significantly lower than in healthy individuals (P < 0.0001) and negatively correlated with disease activity (P = 0.004). In Faslpr mice, disease severity progressed with age and was negatively associated with plasma CXCL5 levels. Intravenous administration of CXCL5 to Faslpr mice restored endogenous circulatory CXCL5, improved mice survival, and reduced anti-double-stranded DNA antibodies, proteinuria, lupus nephritis activity and chronicity indices, renal complements, and neutrophil extracellular traps over short-term (10 weeks) and long-term (2 years) time periods. In vitro and in vivo assays demonstrated that CXCL5 dictated neutrophil trafficking and suppressed neutrophil activation, degranulation, proliferation, and renal infiltration. Renal and splenic RNA sequencing further showed that CXCL5-mediated immunomodulation occurred by promoting energy production in renal-infiltrated immune cells, activating certain T cells, and reducing tissue fibrosis, granulocyte extravasation, complement components, and interferons. Further factorial design results indicated that CXCL5 appears to enhance host tolerability to cyclophosphamide in vulnerable individuals. CONCLUSION: We found that serum CXCL5 levels were significantly lower in SLE patients than in healthy individuals and were negatively correlated with disease activity. By administering CXCL5 intravenously in a mouse model of lupus, mouse survival improved, and indices of disease activity reduced significantly. Taken together, these findings indicate CXCL5 administration may represent a novel myeloid/neutrophil-targeting therapy for SLE.

Intraperitoneally Delivered Umbilical Cord Lining Mesenchymal Stromal Cells Improve Survival and Kidney Function in Murine Lupus via Myeloid Pathway Targeting.

To determine the therapeutic efficacy of human umbilical cord lining mesenchymal stromal cells (CL-MSCs) (US Patent number 9,737,568) in lupus-prone MRL/lpr (Faslpr) mice and elucidate its working mechanisms. A total of 4 doses of (20-25) × 106 cells/kg of CL-MSCs was given to 16-week-old female Faslpr mice by intraperitoneal injection. Three subsequent doses were given on 17 weeks, 18 weeks, and 22 weeks, respectively. Six-week-old Faslpr mice were used as disease pre-onset controls. Mice were monitored for 10 weeks. Mouse kidney function was evaluated by examining complement component 3 (C3) deposition, urinary albumin-to-creatinine ratio (ACR), and lupus nephritis (LN) activity and chronicity. Working mechanisms were elucidated by flow cytometry, Luminex/ELISA (detection of anti-dsDNA and isotype antibodies), and RNA sequencing. CL-MSCs improved mice survival and kidney function by reducing LN activity and chronicity and lymphocyte infiltration over 10 weeks. CL-MSCs also reduced urinary ACR, renal complement C3 deposition, anti-dsDNA, and isotype antibodies that include IgA, IgG1, IgG2a, IgG2b, and IgM. Immune and cytokine profiling demonstrated that CL-MSCs dampened inflammation by suppressing splenic neutrophils and monocytes/macrophages, reducing plasma IL-6, IL-12, and CXCL1 and stabilizing plasma interferon-γ and TNF-α. RNA sequencing further showed that CL-MSCs mediated immunomodulation via concerted action of pro-proinflammatory cytokine-induced chemokines and production of nitric oxide in macrophages. CL-MSCs may provide a novel myeloid (neutrophils and monocytes/macrophages)-targeting therapy for SLE.

Mesenchymal Stromal Cell (MSC)-Derived Combination of CXCL5 and Anti-CCL24 Is Synergistic and Superior to MSC and Cyclosporine for the Treatment of Graft-versus-Host Disease.

The immunosuppressive properties of mesenchymal stromal cells (MSCs) have been clinically proven to be effective in treating graft-versus-host disease (GVHD). However, MSC therapy is limited by the need for laborious and expensive manufacturing processes that are fraught with batch-to-batch variability. Substitution of MSC therapy with key MSC-mediated immunomodulatory factors could be an option for GVHD treatment. Using a simulated in vitro model of the immunosuppressive effects of MSC on allogeneic graft reactions, a synergistic 2-factor combination (2FC) of CXCL5 and anti-CCL24 was identified from a panel of over 100 immunomodulatory factors as being superior to MSCs in the modulation of mixed lymphocyte reactions. This 2FC was superior to cyclosporine in ameliorating both moderate and severe GVHD while being equivalent to MSCs in moderate GVHD and superior to MSCs in severe GVHD. Its immunosuppressive efficacy could be further improved by extended treatment. Mechanistic studies revealed that in vitro the 2FC could only reduce the proliferation of Th 1 and Th 17, whereas in vivo CXCL5 acts in concert with anti-CCL24 antibody to reduce not only transplanted Th 1 and Th 17 but also cytotoxic T lymphocytes and natural killer cells to increase mouse immunosuppressive neutrophils without affecting human hematopoietic stem cell reconstitution. Concurrently, it reduced circulating human proinflammatory cytokines IFN-γ, IL-6, IL-17A, IL-8, macrophage inflammatory protein-1ß, and monocyte chemoattractant protein-1. Both in vitro and in vivo data suggest that CXCL5 and anti-CCL24 antibody act in concert to ameliorate GVHD via suppression of Th 1 and Th 17 responses. We propose that this novel 2FC could substitute for MSC therapy in GVHD treatment.