Plasma Insulin-like Growth Factor-Binding Protein-2 of Critically Ill Patients Is Related to Disease Severity and Survival

Plasma Insulin-Like Growth Factor-Binding Protein-2 Levels Predict Severe Septic Acute Kidney Injury: A Mendelian Randomization Analysis

BACKGROUND

 Sepsis-associated acute kidney injury (SA-AKI) currently lacks highly sensitive biomarkers for early detection, resulting in delayed identification and intervention during its early stages and an independent risk of death.

OBJECTIVE

 This study aimed to investigate the relationship between insulin-like growth factor-binding protein-2 (IGFBP-2) levels and the occurrence of sepsis-induced kidney injury and to evaluate the causal relationship between the two through Mendelian randomization (MR) analysis.

METHODS

 This study employed a single-center, prospective cohort design involving 79 sepsis patients from the Intensive Care Unit (ICU) at the First Affiliated Hospital of Xinjiang Medical University, Ürümqi, China. The patients were divided into two groups, the SA-AKI group and the non-SA-AKI group, on the basis of whether they developed SA-AKI. The primary endpoint was whether SA-AKI occurred within 48 hours of admission. MR and sensitivity analyses were conducted to explore the causal relationships.

RESULTS

 The IGFBP-2 level had high diagnostic value for the prediction of SA-AKI. Receiver operating characteristic (ROC) curve analysis revealed that IGFBP-2 alone predicted SA-AKI, with an area under the curve (AUC) of 0.8994, a cut-off value of 709.004, a sensitivity of 88.64%, and a specificity of 85.71%. The combined prediction of the IGFBP-2 score, acute physiology and chronic health evaluation (APACHE) II score, sequential organ failure assessment (SOFA) score, and use of vasopressors had an AUC of 0.9604, a sensitivity of 93.18%, and a specificity of 82.86%. MR analysis revealed no causal relationship between genetically predicted IGFBP-2 levels and AKI (OR: 1.1507, 95% CI: 0.88-1.50, p = 0.2995).

CONCLUSION

 Plasma IGFBP-2 levels can predict the occurrence of SA-AKI in sepsis patients. However, MR analysis suggests that there is no direct causal relationship between plasma IGFBP-2 levels and septic kidney injury, and the underlying mechanisms need to be further investigated in randomized controlled trials.

IGFBP-2 in Critical Illness: A Prognostic Marker in the Growth Hormone/Insulin-like Growth Factor Axis

Critical illness (CI) triggers complex disruptions in the growth hormone (GH)/insulin-like growth factor (IGF) axis, significantly affecting the dynamics of insulin-like growth-factor-binding proteins (IGFBPs). Among these, IGFBP-2 shows a sustained elevation during CI, which inversely correlates with serum levels of IGF-1, IGFBP-3, and the acid-labile subunit (ALS). Although IGFBP-2 does not directly interact with ALS, it may influence the availability of IGFs by competing with other IGFBPs for binding to IGF-1 and IGF-2. Research suggests that this persistent elevation of IGFBP-2 is largely driven by cytokine activity during CI, reflecting an adaptive response rather than a direct result of GH/IGF axis dysregulation. The clinical importance of IGFBP-2 is emphasized by its correlation with disease severity in conditions like sepsis and coronavirus disease 2019 (COVID-19), where its levels are markedly elevated compared to healthy controls and are similar to those observed in sepsis from various causes. Beyond its role in endocrine regulation, IGFBP-2 appears to play a part in metabolic and inflammatory pathways. Elevated IGFBP-2 levels have been linked to increased mortality and longer hospital stays, indicating its potential utility as a prognostic marker. Furthermore, measuring plasma IGFBP-2 may have other diagnostic applications, aiding in the assessment of CI when traditional biomarkers are inconclusive.

Serum Insulin-like Growth Factor-Binding Protein-2 as a Prognostic Factor for COVID-19 Severity

Insulin-like growth factor-binding protein (IGFBP)-2 is a regulator of anabolic pathways, which become inactivated in severe illness. Here, we measured the serum IGFBP-2 levels of COVID-19 patients with moderate and severe disease as well as healthy controls to identify the associations of serum IGFBP-2 levels with disease severity. Patients with severe COVID-19 had higher serum IGFBP-2 levels than those with moderate disease and healthy controls, who had similar levels. Non-survivors of COVID-19 tended to have elevated serum IGFBP-2 levels compared to survivors. Increased serum IGFBP-2 levels were observed in patients requiring dialysis and vasopressor therapy. Serum IGFBP-2 was positively correlated with procalcitonin in both patient groups. Bacterial co-infection in severe COVID-19 patients did not influence serum IGFBP-2 levels. Patients with liver cirrhosis and obesity, showing increased and decreased serum IGFBP-2 levels, respectively, were excluded from the study. The present analysis showed that higher serum IGFBP-2 levels are associated with increased disease severity in COVID-19 patients. The similarity in serum IGFBP-2 levels between patients with moderate COVID-19 and healthy controls suggests that elevated IGFBP-2 is associated with critical illness rather than SARS-CoV-2 infection itself.