Rbp4, or Retinol-binding protein 4, is a member of the lipocalin family and acts as a specific carrier protein that delivers retinol (vitamin A) from the liver to the peripheral tissues [3]. It is predominantly secreted in the liver and adipose tissues and has gained attention in metabolism research [1].

In recent years, numerous studies have explored the role of Rbp4 in various diseases. Elevated serum levels of Rbp4 in obese experimental animals and human subjects are associated with cardiometabolic diseases (CMD) such as obesity, insulin resistance, and hyperlipidemia [1]. Rbp4 has also been identified as a controversial adipokine, potentially linking obesity with its comorbidities like insulin resistance, type 2 diabetes (T2D), and components of the metabolic syndrome, though clinical data are conflicting [2]. In gestational diabetes mellitus (GDM), circulating Rbp4 levels are consistently higher in affected cases compared to non-GDM controls, suggesting its potential as a biomarker [3]. In T2DM patients with kidney diseases, Rbp4 concentrations are significantly higher in those with micro-or macro-albuminuria, and levels are positively correlated with the albumin-to-creatinine ratio but negatively correlated with the estimated glomerular filtration rate, indicating it could be a reliable biomarker for kidney diseases in T2DM [4]. Bariatric surgery in obese individuals impacts Rbp4 levels, and it may improve insulin sensitivity post-surgery, suggesting its potential as a pharmacotherapeutic target [5]. In hyperuricemia-induced rats and patients with hyperuricemia, Rbp4 may be involved in hyperuricemia-induced insulin resistance by inhibiting IRS/PI3K/Akt phosphorylation [6].

In conclusion, Rbp4 is crucial for retinol transport and has significant implications in multiple disease areas. Its role in cardiometabolic diseases, diabetes-related complications, and other conditions like hyperuricemia-induced insulin resistance has been increasingly recognized. The study of Rbp4 in these disease contexts helps in understanding disease mechanisms and potentially developing new therapeutic strategies. [1-6]

References:

1. Oluwamodupe, Cecilia, Adeleye, Adesola Oluwaseun. 2023. Targeting Retinol-Binding Protein 4 (RBP4) in the Management of Cardiometabolic Diseases. In Cardiovascular toxicology, 23, 285-294. doi:10.1007/s12012-023-09803-8. https://pubmed.ncbi.nlm.nih.gov/37587250/

2. Kotnik, Primoz, Fischer-Posovszky, Pamela, Wabitsch, Martin. 2011. RBP4: a controversial adipokine. In European journal of endocrinology, 165, 703-11. doi:10.1530/EJE-11-0431. https://pubmed.ncbi.nlm.nih.gov/21835764/

3. Leca, Bianca M, Kite, Chris, Lagojda, Lukasz, Randeva, Harpal S, Kyrou, Ioannis. 2024. Retinol-binding protein 4 (RBP4) circulating levels and gestational diabetes mellitus: a systematic review and meta-analysis. In Frontiers in public health, 12, 1348970. doi:10.3389/fpubh.2024.1348970. https://pubmed.ncbi.nlm.nih.gov/38532976/

4. Zhang, Li, Cheng, Yan-Li, Xue, Shuai, Xu, Zhong-Gao. 2020. The Role of Circulating RBP4 in the Type 2 Diabetes Patients with Kidney Diseases: A Systematic Review and Meta-Analysis. In Disease markers, 2020, 8830471. doi:10.1155/2020/8830471. https://pubmed.ncbi.nlm.nih.gov/33082885/

5. Bidares, Matin, Safari-Kish, Borna, Malekzadeh-Shoushtari, Hesam, Nosouhi, Golnaz, Aziz, Mahsa. 2024. Assessing the Impact of Bariatric Surgery on Retinol-Binding Protein 4 (RBP4): A Systematic Review and Meta-Analysis. In Obesity surgery, 34, 1855-1865. doi:10.1007/s11695-024-07140-5. https://pubmed.ncbi.nlm.nih.gov/38451368/

6. Liu, Chan, Zhou, Xiao-Rong, Ye, Mu-Yao, Liu, Hong, Huang, Xian-Zhe. 2021. RBP4 Is Associated With Insulin Resistance in Hyperuricemia-Induced Rats and Patients With Hyperuricemia. In Frontiers in endocrinology, 12, 653819. doi:10.3389/fendo.2021.653819. https://pubmed.ncbi.nlm.nih.gov/34177800/