Publication numbers, subject area, and type of articles
There are 566 published articles on Akkermansia in the Scopus, 311 of which are open accesses and 255 were assigned in others. The great majority of which are original articles (n=353, 62.3%), followed by 140 review articles (24.7%), 30 notes (5.3%), 12 editorials (2.1%), 11 letters (1.9 %), 8 short surveys (1.4 %), 5 book chapters (0.9%), 4 errata (0.7%) and 3 conference papers (0.5%) (Fig. 1a). These articles published in four different languages including 556 articles in English, 4 in French, 4 in Chinese and 2 in Russian.
The global Akkermansia research output during 2004–2019 has been published in the context of 21 different subfields. 326 documents had published in the area of Medicine that considered as the most focused subject area in this field , followed by Biochemistry, Genetics and Molecular Biology (n=187), Immunology and Microbiology (n=151), Agricultural and Biological Sciences (n=102), Nursing (n=62), Pharmacology, Toxicology and Pharmaceutics (n=27), Chemistry (n=18), Environmental Sciences (n=15), Neurosciences (n=12), Chemical engineering (n=11), Engineering (n=6), Physic and Astronomy (n=5), Veterinary (n=5), Computer sciences (n=4), Mathematics (n=3), Psychology (n=2), Dentistry (n=1), Economics, Econometrics and Finance (n=1), Energy (n=1), Health Professions (n=1) and 43 documents have multidisciplinay approach (Fig. 1b).
The distribution of Akkermansia articles based on the study design, targeted population and conditions/diseases
We screened the titles and abstracts of all 353 original articles and determined the targeted population of each study and revealed that majority of these studies were conducted in animal population (n=186 research), followed by human studies (n=108), in vitro studies (n=44), in silico studies (n=6), both animal and in vitro studies (n=4), both human and animal studies (n=3), both in vivo and in silico study (n=1) and one study was conducted in three phases of in vitro, animal and human.
Then, we categorized the type of animals that were utitlized in only animal studies or both animal and other population studies (n=194) and found that 155 studies were performed in mice, 29 in rat, 2 in poultry and 1 study were performed in each of the following animal population: dog, foals, hamster, marine fish, pig, rabbit and zebrafish.
In addition, we found that Akkermansia articles were conducted on 51 various diseases (Supplementary Table S1) that the diseases that have attracted the most attention in this regard are as follows: obesity (54 articles), type 2 diabetes (29 articles), inflammatory bowel disease (28 articles) and metabolic disorders (12 articles).
Year distribution of articles
The year publication pattern of original articles and reviews on Akkermansia is presented in Fig. 2. As shown, the first article indexed in Scopus was published in 2004 in which just 2 articles had been published. After the experience of steady pattern in publication for 9 years, the number of publications in this field had gradually increased and reached 13 articles in 2013 and since then the number of publications remarkably increased and reached top numbers of 168 articles in 2019.
Citation numbers of published articles and top-cited articles
The total citation number is another main factor for the evaluation of the Akkermansia articles in the literature. The lowest citations belonged to the articles in 2004 and the highest was experienced by the articles in 2019 with 6318 citations. The citation number of articles had increased gradually from 2004 to 2014 and then, Annually published articles on Akkermansia have received a rapidly growing number of citations (The citations referred to all citations during one specific year for all articles published up to that point). The citation number of each year is depicted in Supplementary Fig. S1. In addition, Table 1 demonstrated the characteristics of the 5 top-cited articles on Akkermansia. As presented, the top one was published in 2013 in the PNAS journal (Proceedings of the National Academy of Sciences) and cited 1523 times, more information about these articles listed in the table.
The top active journals in publication
The journals’ contribution (the top-ranked journals) in the field of Akkermansia is displayed in Table 2. As seen, the Frontiers in Microbiology, PLoS ONE, Nutrients, Scientific reports and Gut with 23, 17, 16, 15 and 12 articles are the top-ranked journals in the publication of Akkermansia articles. Moreover, the trend of publication of three top-ranked journals is presented in Supplementary Fig. S2. Both PLoS ONE and Frontiers in Microbiology journals started to publish articles in the field of Akkermansia in 2011 with one publication. Then PLoS ONE sharply increased its publications in this field to reach a peak in 2013 with 4 articles. Then it experienced some fluctuation to reached 2 publications in 2018. Meanwhile, Frontiers in Microbiology had published one article per each year of 2014 and 2015 and then started to rise up and reached a hike in 2017 with 7 articles. Besides, the juvenile and member of the top-ranked journal in this field is Nutrients which started to publish in 2015 (just five years ago) with 1 article. Then it has a growing trend and increasingly raise the number of its publication each year and reached 12 publications in 2019.
The profile of top-ranked countries
The number of publications of the top 5 countries is as follows: the USA with 132 articles is the leading country publishing articles on this domain, followed by China with 95 articles, The Netherland with 54 articles, Finland with 47 articles and France with 34 articles. (Table 3).
Top productive institutions in the publication
The most productive institutes based on the number of Akkermansia publications are listed in Table 4. Wageningen University and Research Centre was nominated as the most productive and active institution in the publication of Akkermansia articles as it has supported 43 documents in this field. The other top productive institutes are Helsingin Yliopisto, Universite Catholique de Louvain, University of Copenhagen and Inserm with 36, 20, 18 and 16 articles, respectively.
Funding sponsors
The most active sponsors for Akkermansia research are as follows: the National Natural Science Foundation of China, the National Institutes of Health in the USA, European Research Council in Belgium, European Commission in Belgium and Netherlands Organisation for Scientific Research with 49, 49, 32, 10 and 9 articles, respectively (Supplementary Table S2).
Profile of the most active authors
The most active authors are as follows: De Vos, W.M. with 41 publications is ranked as the first, then Belzer C, Cani P.D, Salminen S. and Nielsen D.S with 25, 17, 13 and 11 publications, respectively are the next most active authors publishing Akkermansia documents (Table 5). Additionally, the activity of the three top authors during these years is depicted in Supplementary Fig. S3.
The most co-occurrences author’s keywords
When a criteria of 10 as the minimum number of occurrences for keywords was imposed, 16 of all 967 keywords meet this threshold that include “gut microbiota” (n=110 co-occurrences), “Akkermansia muciniphila” (n=80), obesity (n=62), microbiota (n=48), microbiome (n=36), probiotics (n=27), inflammation (n=26), “intestinal microbiota” (n=18), “metabolic syndrome” (n=17), dysbiosis (n=17) and “gut microbiome” (n=17). From these keywords, it is clearly can be seen that the most co-occurrences keywords of authors are more related to gut microbiota and its relevant terms (Fig.3).
The most co-occurrences terms
The most co-occurrences terms in the Akkermansia articles were Mouse (n=586 co-occurrences), “Gut microbiota” (n=576), Study (n=438), “Akkermansia muciniphila” (n=416), Effect (n=362), Bacterium (n=359), “A. muciniphila” (n=332), Obesity (n=322), Patient (n=306), Microbiota (n=298) and Disease (n=293). These terms were achieved when a minimum number of occurrences for a term was imposed as 30. Thereafter from the 12129 terms, 105 meet the threshold. These co-occurrences terms were categorized into 5 different clusters that is demonstrated in Fig. 4.
Co-authorship of authors and countries
The author co-authorship in the publication of Akkermansia is displayed in Fig. 5a. To exclude some co-authorships, the minimum number of documents of an author is selected as 10 documents and from 2891 authors, 6 meet the threshold that one of them were excluded due to no co-authorship with other 5 authors. Furthermore, the countries partnership in the publication of Akkermansia is displayed in Fig. 5b. To achieve such results, the numbers of collaborative published articles were analyzed and 10 documents were selected as a minimum number of documents of a country and from 61 countries, 20 of which met the threshold. Moreover, the collaborations between 20 countries resulted in 100 contributions (Fig. 5b).
High Frequent Burst words in titles, abstracts, and author keywords
As can be seen in the temporal bar graph of Fig. 6a, based on the burst detection of the words in titles of Akkermansia documents, there were 8 bursting words in this domain. The top bursting words from the beginning to the end can be categorized into two periods. In the first period, from the beginning (2004) to 2011, there were 4 top bursting words including “degrade” (2004-2011), “human” (2004-2014), “mucin” (2004-2011) and “divers” (2007-2015) that among these bursting words, the weight of mucin is more than other words that indicate the word of “mucin” had been appeared in the titles of Akkermansia articles more than other words based on the duration of its usage and its frequency. In the second period, 2011-2019, “analysis”, “host”, “profile” and “cancer” were the top bursting words that weighted 3.21, 3.34,3.32, and 3.26, respectively. This analysis revealed that the latest works focused on profiling, analysis methods and the relation between Akkermansia and cancer. Regarding bursting words in abstract, visualize analyzing of abstracts extracted 10 bursting words, which most of them were between 2009 to 2014. After 2014 there were no bursting words. “Speci”, started from 2004 to 2013, was the longest bursting word in the abstracts and based on the weight, the “influence” had the highest weight of 4.87 (Fig. 6b). In the author's keywords analysis, “gastrointestine” had been burst for a long period of time; from the beginning (2004) to 2015. Also, the latest bursting word was “metagenome” which has the highest weight of 3.99. By introducing advanced high throughput techniques like next-generation sequencing (NGS), a new line of research has been raised and metagenome is one of that approaches which by studying genetic materials presents a large amount of information for researchers (Fig. 6c). The weight of top bursting words in the titles, abstracts and the author keywords of Akkermansia articles with their starting and ending time were summarized in Table 6.