miRNA-23b as a biomarker of culture-positive neonatal sepsis

Abstract

Background: Neonatal sepsis remains an important cause of morbidity and mortality. The ability to quickly and accurately diagnose neonatal sepsis based on clinical assessments and laboratory blood tests remains difficult, where haemoculture is the gold standard for detecting bacterial sepsis in blood culture. It is also very difficult to study because neonatal samples are lacking.

Methods: Forty-eight newborns suspected of sepsis admitted to the Neonatology Department of the Mother-Child Specialized Hospital of Tlemcen. From each newborn, a minimum of 1-2 ml of blood was drawn by standard sterile procedures for blood culture. The miRNA-23b level in haemoculture was evaluated by RT-qPCR.

Results: miR-23b levels increased in premature and full-term newborns in early onset sepsis (p < 0.001 and p < 0.005 respectively), but lowered in late onset sepsis in full-term neonates (p < 0.05) compared to the respective negative controls. miR-23b levels also increased in late sepsis in the negative versus early sepsis negative controls (p < 0.05). miR-23b levels significantly lowered in the newborns who died from both sepsis types (p < 0.0001 and p < 0.05 respectively). In early sepsis, miR-23b and death strongly and negatively correlated (correlation coefficient = - 0.96, p = 0.0019). In late sepsis, miRNA-23b and number of survivors (correlation coefficient = 0.70, p = 0.506) positively correlated.

Conclusions: Lowering miR-23b levels is an important factor that favours sepsis development, which would confirm their vital protective role, and strongly suggest that they act as a good marker in molecular diagnosis and patient monitoring.

Keywords: Early-onset sepsis; Haemoculture; Late-onset sepsis; Newborns; miR-23b.

Fig. 1

Changes in the miRNA-23b expression levels in early onset sepsis. Scatter plot values a on the left represent the miR-23b level for EOS in the at-term newborns, measured by (2^-ΔΔCT). While that scatter plot in b on the right represent the miR-23b level in the premature newborns. The line inside the boxes corresponds to the median values. For the at-term patients, Co/NH (n = 9), DP/PH (n = 2), SP/PH (n = 7). For the premature patients, Co/NH (n = 4), DP/PH (n = 3), SP/PH (n = 2). Co/NH: negative haemoculture, DP/PH: positive haemoculture in dead newborns, SP/PH: positive haemoculture in the newborns who survived. KW: Kruskal-Wallis. The sharp indicate significant differences highlighted between all groups using the Kruskal-Wallis test: ### p < 0.001

Fig. 2

Changes in the miR-23b expression levels in late onset sepsis. Scatter plot values represent the miR-23b level for LOS in at-term newborns, measured by (2^-ΔΔCT). The line inside the boxes corresponds to the median values. Co/NH (n = 6), DP/NH (n = 2), SP/PH (n = 12), DP/PH (n = 1). Co/NH: negative haemoculture, DP/NH: negative haemoculture in the dead newborns, DP/PH: positive haemoculture in the newborns who died, SP/PH: positive haemoculture in the newborns who survived, KW: Kruskal-Wallis. The sharp indicate significant differences highlighted between all groups using the Kruskal-Wallis test: # p < 0.05

Fig. 3

Change in the miRNA-23b expression levels in newborns at two different stages. Scatter plot values represent the miR-23b level for the negative control of EOS (n = 9) and the negative control of LOS (n = 6) in terms of the newborns, measured by (2^-ΔΔCT). The line inside the boxes corresponds to the median values. LOS/ Bac-: negative haemoculture in LOS, Co/NH before 72 h: negative haemoculture in EOS, where patients’ age was less than 72 h, Co/NH / before 72 h: negative haemoculture in LOS, where patients’ age was more than 72 h. *p = 0.011 via the Mann-Whitney U test

Fig. 4

Correlation between miRNA-23b expression and dead newborns with sepsis. Individual values represent the correlation with the miR-23b level, survivor and dead in newborns with sepsis. a: in early onset sepsis in at-term newborns, b: early onset sepsis in premature newborns, c: late onset sepsis in at-term newborns. Control: patients with negative haemoculture, dead: dead patients with sepsis, survivor: survivor patients with sepsis, r: correlation coefficient