Wang Ting, Kuley Runa, Hermanson Payton, Chu Peirou, Pohlmeyer Christopher, Ravichandar Jayamary Divya, Lopez David, Min-Oo Gundula, Crellin Natasha, Shang Ching, Lood Christian
Division of Rheumatology, University of Washington, Seattle, WA, United States.
Centre for Life Sciences, Mahindra University, Hyderabad, India.
Front Immunol. 2024 Dec 24;15:1515469. doi: 10.3389/fimmu.2024.1515469. eCollection 2024.
Neutrophil activation is important in systemic lupus erythematosus (SLE). We previously demonstrated that ribonucleoprotein (RNP) immune complexes (ICs) promoted neutrophil activation in a TLR7/8-dependent manner. However, it remains unclear if this mechanism occurs in patients. Here, we investigated the role of RNA recognition by evaluating TLR7/8 in plasma-mediated neutrophil activation in SLE.
Plasma levels of neutrophil activation markers and ICs were measured by ELISA and flow cytometry in SLE patients (n=151) and healthy controls (HCs, n=31). Neutrophils were incubated with plasma and assessed for CD66b and CD11b up-regulation by flow cytometry in the presence of select inhibitors to define the mechanisms of neutrophil activation by SLE plasma.
SLE plasma induced higher levels of CD66b (p=0.0002) and CD11b (p=0.01) expression than plasma from HCs. Blocking FcγRIIA, targeting RNA sensing by adding RNase, or blocking TLR7/8, TLR8 only, or IRAK4, decreased plasma-mediated neutrophil activation (p<0.05). Consistent with the ability of selective TLR8 inhibitor to block plasma-mediated neutrophil activation, TLR8 agonists, but not TLR7 agonists induced robust neutrophil activation. Further, neutrophil mRNA expression of TLR8 was higher than TLR7. Finally, patients with plasma samples inducing neutrophil activation in RNA-dependent manner had increased levels of interferon alpha, IP-10 (p<0.05), ICs (p<0.05), and reduced complement C3 levels (p<0.01), indicative of IC-driven disease.
The data support IC-driven RNA-sensing by TLR8 in neutrophils is a key mechanism of neutrophil activation in SLE. Patients with elevated neutrophil activation and presence of RNA-containing ICs, may benefit from TLR8 inhibition and other strategies targeting RNA removal.
中性粒细胞活化在系统性红斑狼疮（SLE）中很重要。我们之前证明核糖核蛋白（RNP）免疫复合物（ICs）以TLR7/8依赖性方式促进中性粒细胞活化。然而，该机制是否在患者中发生仍不清楚。在此，我们通过评估TLR7/8在SLE血浆介导的中性粒细胞活化中的作用来研究RNA识别的作用。
通过酶联免疫吸附测定（ELISA）和流式细胞术测量SLE患者（n = 151）和健康对照（HCs，n = 31）中中性粒细胞活化标志物和ICs的血浆水平。将中性粒细胞与血浆一起孵育，并在存在选择抑制剂的情况下通过流式细胞术评估CD66b和CD11b的上调，以确定SLE血浆激活中性粒细胞的机制。
与HCs的血浆相比，SLE血浆诱导更高水平的CD66b（p = 0.0002）和CD11b（p = 0.01）表达。阻断FcγRIIA、通过添加核糖核酸酶靶向RNA传感、或阻断TLR7/8、仅阻断TLR8或阻断IRAK4，均可降低血浆介导的中性粒细胞活化（p < 0.05）。与选择性TLR8抑制剂阻断血浆介导的中性粒细胞活化的能力一致，TLR8激动剂而非TLR7激动剂可诱导强烈的中性粒细胞活化。此外，中性粒细胞中TLR8的mRNA表达高于TLR7。最后，血浆样本以RNA依赖性方式诱导中性粒细胞活化的患者，其α干扰素、IP - 10水平升高（p < 0.05）、ICs水平升高（p < 0.05）且补体C3水平降低（p < 0.01），提示IC驱动的疾病。
数据支持TLR8在中性粒细胞中由IC驱动的RNA传感是SLE中中性粒细胞活化的关键机制。中性粒细胞活化升高且存在含RNA的ICs的患者，可能受益于TLR8抑制和其他靶向RNA清除的策略。
