Comments on Research Trends of Macrophage Polarization: A Bibliometric Analysis
Macrophages—your body’s versatile immune cells—play a huge role in everything from fighting infections to regulating metabolism. Their ability to “polarize” (shift between pro-inflammatory “M1” and anti-inflammatory “M2” states) is a hot topic in medical research, but how do we track the trends in this field? A 2018 study tried to answer that—but a new comment argues its methods might have missed the mark.
In 2018, researchers Gao H, Huang FY, and Wang ZP published “Research Trends of Macrophage Polarization: A Bibliometric Analysis” in the Chinese Medical Journal. They used the Web of Science Core Collection (SCI-E) to search for papers between 2007–2016 using the query: “TS = (macrophage AND polarization).” They found 3064 articles—and used that data to map trends in macrophage polarization research.
But Yuh-Shan Ho, a researcher at the Trend Research Centre at Asia University in Taiwan, says the method has a critical flaw: the Web of Science Core Collection is built for finding literature, not for rigorous bibliometric analysis. Ho’s team previously proposed a better filter: the “front page” of a paper (title, abstract, and author keywords). Why? Because relying on the “TS” (topic) field— which includes full texts, references, and more—can pull in papers that only mention the terms in passing, not those focused on the topic.
Ho tested Gao’s method and found 3079 articles—but when he applied the “front page” filter, only 1557 papers actually included both “macrophage” and “polarization” in their title, abstract, or author keywords. Even more striking: 13% of the original results (390 articles) didn’t mention either term on their front page at all.
To make this concrete, Ho pointed to two highly cited papers that should be included in macrophage polarization research:
- A 2011 Science study (“Eosinophils Sustain Adipose Alternatively Activated Macrophages Associated with Glucose Homeostasis”) by Wu et al., which links M2 macrophages to metabolism.
- A 2009 Diabetes study (“Regulatory Mechanisms for Adipose Tissue M1 and M2 Macrophages in Diet-Induced Obese Mice”) by Fujisaka et al., which explores how diet affects macrophage polarization in obesity.
These papers are central to the field—but Ho’s analysis suggests the original method might have included unrelated work and missed key studies. The problem, he argues, is the search query: “TS = (macrophage AND polarization)” is too broad. He also notes that researchers should account for variations in keywords (like “macrophages” instead of “macrophage,” or “polarized” instead of “polarization”) to get a more accurate picture.
The takeaway? Bibliometric studies— which help researchers understand where a field is going—need precise methods. Using the “front page” filter, Ho says, would have given Gao’s team more reliable results.
Gao H, Huang FY, Wang ZP. Research trends of macrophage polarization: a bibliometric analysis. Chin Med J 2018;131:2968–2975.
Ho YS. Comment on: “A bibliometric analysis and visualization of medical big data research” Sustainability 2018, 10, 166. Sustainability 2018;10:4851.
Fu HZ, Wang MH, Ho YS. The most frequently cited adsorption research articles in the Science Citation index (expanded). J Colloid Interf Sci 2012;379:148–156.
Hsu YHE, Ho YS. Highly cited articles in health care sciences and services field in Science Citation index expanded: a bibliometric analysis for 1958-2012. Method Inform Med 2014;53:446–458.
Wu D, Molofsky AB, Liang HE, et al. Eosinophils sustain adipose alternatively activated macrophages associated with glucose homeostasis. Science 2011;332:243–247.
Fujisaka S, Usui I, Bukhari A, et al. Regulatory mechanisms for adipose tissue M1 and M2 macrophages in diet-induced obese mice. Diabetes 2009;58:2574–2582.
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