Global trends and emerging hotspots of macrophage research in kidney transplantation: a bibliometric and visualization analysis

Background Macrophages are plastic innate immune cells that couple inflammatory signaling with microvascular injury and alloimmune responses, thereby shaping rejection phenotypes and chronic allograft dysfunction after kidney transplantation. Yet, the mechanistic knowledge structure and emerging hotspots of this field remain insufficiently synthesized. Methods Publications on kidney transplantation and macrophage-related research (2000–2025) were retrieved from the Web of Science Core Collection (n=538) and PubMed (n=385). Bibliometric and visualization analyses were performed using Microsoft Excel 2021, VOSviewer, CiteSpace, Charticulator, and Scimago Graphica, including trend analysis, collaboration mapping, journal and reference impact assessment, keyword co-occurrence and clustering, and burst detection. PubMed keyword analysis was used to validate and complement the WoSCC-based findings. Results A total of 538 publications were identified, showing a steady increase over time. The United States and China were the major contributors, with extensive international collaboration networks. Co-citation and keyword analyses revealed that the research focus has evolved from early studies on graft injury and immune mechanisms to more recent hotspots such as immune infiltration, polarization, ferroptosis, transcriptomics, and machine learning. The timeline analysis further indicated a shift from foundational immunological mechanisms to mechanistic expansion and, more recently, to technology-driven and clinically oriented research, highlighting increasing emphasis on diagnosis, precision monitoring, and translational applications in kidney transplantation. Conclusion Macrophage-focused kidney transplantation research is moving toward cell-state–resolved and technology-driven mechanistic frameworks that connect rejection pathology to long-term graft outcomes, providing a roadmap for biomarker development and targeted immunomodulation.