Low circulating maternal adiponectin in patients with pyelonephritis: adiponectin at the crossroads of pregnancy and infection

A biomarker for bacteremia in pregnant women with acute pyelonephritis: soluble suppressor of tumorigenicity 2 or sST2

Objective: Sepsis is a leading cause of maternal death, and its diagnosis during the golden hour is critical to improve survival. Acute pyelonephritis in pregnancy is a risk factor for obstetrical and medical complications, and it is a major cause of sepsis, as bacteremia complicates 15-20% of pyelonephritis episodes in pregnancy. The diagnosis of bacteremia currently relies on blood cultures, whereas a rapid test could allow timely management and improved outcomes. Soluble suppression of tumorigenicity 2 (sST2) was previously proposed as a biomarker for sepsis in non-pregnant adults and children. This study was designed to determine whether maternal plasma concentrations of sST2 in pregnant patients with pyelonephritis can help to identify those at risk for bacteremia.Study design: This cross-sectional study included women with normal pregnancy (n = 131) and pregnant women with acute pyelonephritis (n = 36). Acute pyelonephritis was diagnosed based on a combination of clinical findings and a positive urine culture. Patients were further classified according to the results of blood cultures into those with and without bacteremia. Plasma concentrations of sST2 were determined by a sensitive immunoassay. Non-parametric statistics were used for analysis.Results: The maternal plasma sST2 concentration increased with gestational age in normal pregnancies. Pregnant patients with acute pyelonephritis had a higher median (interquartile range) plasma sST2 concentration than those with a normal pregnancy [85 (47-239) ng/mL vs. 31 (14-52) ng/mL, p < .001]. Among patients with pyelonephritis, those with a positive blood culture had a median plasma concentration of sST2 higher than that of patients with a negative blood culture [258 (IQR: 75-305) ng/mL vs. 83 (IQR: 46-153) ng/mL; p = .03]. An elevated plasma concentration of sST2 ≥ 215 ng/mL had a sensitivity of 73% and a specificity of 95% (area under the receiver operating characteristic curve, 0.74; p = .003) with a positive likelihood ratio of 13.8 and a negative likelihood ratio of 0.3 for the identification of patients who had a positive blood culture.Conclusion: sST2 is a candidate biomarker to identify bacteremia in pregnant women with pyelonephritis. Rapid identification of these patients may optimize patient care.

Adiponectin alleviated renal cell apoptosis and inflammation via inactivation of JAK2/STAT3 signal pathway in an acute pyelonephritis mouse model

Background

Acute pyelonephritis (APN), an acute and severe kidney infection, is usually treated with antibiotics. However, APN treatment has become increasingly challenging because of bacterial resistance. Adiponectin, an adipokine, has recently been reported to exhibit profound anti-inflammatory and anti-apoptotic effects. However, the effect of adiponectin on the outcomes of APN treatment remains unclear. In this study, we aimed to investigate the effects of adiponectin on APN and the mechanisms underlying these effects.

Methods

Wild-type C57 mice and adiponectin-knockout (KO) mice were divided into 6 groups: the wild-type control group, the wild-type model group, the wild-type adiponectin intervention group, the KO control group, the KO model group, and the adiponectin-KO intervention group. We measured white blood cell (WBC) and neutrophil counts (NC) using a multispecies hematology analyzer; tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) using enzyme-linked immunosorbent assay (ELISA); blood urea nitrogen (BUN) and serum creatinine (SCr) levels using colorimetry; and the protein levels of JAK2, STAT3, p-JAK2, p-STAT3, Bcl-2, and Bax in renal tissues using western blot analysis. Apoptotic cells were detected using the transferase-mediated dUTP nick end labelling (TUNEL) assay.

Results

Compared to the wild-type mice, the KO mice showed a more severe inflammatory response and kidney damage after Escherichia coli infection. After treatment with exogenous adiponectin injection, the inflammatory response, oxidative stress, and kidney damage were partly alleviated. Adiponectin KO led to JAK2/STAT3 signaling activation, and exogenous adiponectin administration inactivated JAK2/STAT3 signaling in the APN model. APN can lead to an increase in the level of the protein Bax and a decrease in the level of the bcl-2 protein, thereby increasing apoptosis; this effect was inhibited by adiponectin.

Conclusions

Through use of a pyelonephritis mouse model, we demonstrated that adiponectin might alleviate renal cell apoptosis and inflammatory response by inactivating the JAK2/STAT3 signaling pathway.

Intra-amniotic administration of lipopolysaccharide induces spontaneous preterm labor and birth in the absence of a body temperature change

OBJECTIVE

Intra-amniotic infection is associated with spontaneous preterm labor. In most cases, the infection is subclinical and bacteria are detected in the amniotic cavity rather than in the chorioamniotic membranes. The aims of this study were to establish a model of intra-amniotic lipopolysaccharide (LPS)-induced preterm labor/birth that resembles the subclinical syndrome and to compare this model to two established models of LPS-induced preterm labor/birth.

METHODS

Pregnant B6 mice received an intra-amniotic, intra-uterine, or intra-peritoneal injection of LPS (100 ng/amniotic sac, 15 μg/25 μL, and 15 μg/200 μL respectively) or PBS (control). Following injection, body temperature (every two hours for a 12-h period), gestational age, and the rate of preterm labor/birth were recorded.

RESULTS

An intra-amniotic injection of LPS resulted in preterm labor/birth [LPS 80 ± 24.79% (8/10) versus PBS 0% (0/8); p = 0.001] without causing maternal hypothermia. Intra-peritoneal [LPS 100% (8/8) versus PBS 0% (0/8); p < 0.001)] and intra-uterine [LPS 100% (8/8) versus PBS 28.57 ± 33.47% (2/7); p =0 .007] injections of LPS induced preterm labor/birth; yet, maternal hypothermia was observed.

CONCLUSION

Intra-amniotic injection of LPS induces preterm labor/birth in the absence of a body temperature change, which resembles the subclinical syndrome.

Characterization of visceral and subcutaneous adipose tissue transcriptome in pregnant women with and without spontaneous labor at term: implication of alternative splicing in the metabolic adaptations of adipose tissue to parturition

OBJECTIVE

The aim of this study was to determine gene expression and splicing changes associated with parturition and regions (visceral vs. subcutaneous) of the adipose tissue of pregnant women.

STUDY DESIGN

The transcriptome of visceral and abdominal subcutaneous adipose tissue from pregnant women at term with (n=15) and without (n=25) spontaneous labor was profiled with the Affymetrix GeneChip Human Exon 1.0 ST array. Overall gene expression changes and the differential exon usage rate were compared between patient groups (unpaired analyses) and adipose tissue regions (paired analyses). Selected genes were tested by quantitative reverse transcription-polymerase chain reaction.

RESULTS

Four hundred and eighty-two genes were differentially expressed between visceral and subcutaneous fat of pregnant women with spontaneous labor at term (q-value <0.1; fold change >1.5). Biological processes enriched in this comparison included tissue and vasculature development as well as inflammatory and metabolic pathways. Differential splicing was found for 42 genes [q-value <0.1; differences in Finding Isoforms using Robust Multichip Analysis scores >2] between adipose tissue regions of women not in labor. Differential exon usage associated with parturition was found for three genes (LIMS1, HSPA5, and GSTK1) in subcutaneous tissues.

CONCLUSION

We show for the first time evidence of implication of mRNA splicing and processing machinery in the subcutaneous adipose tissue of women in labor compared to those without labor.

Characterization of Visceral and Subcutaneous Adipose Tissue Transcriptome and Biological Pathways in Pregnant and Non-Pregnant Women: Evidence for Pregnancy-Related Regional-Specific Differences in Adipose Tissue

Objective

The purpose of this study was to compare the transcriptome of visceral and subcutaneous adipose tissues between pregnant and non-pregnant women.

Study Design

The transcriptome of paired visceral and abdominal subcutaneous adipose tissues from pregnant women at term and matched non-pregnant women (n = 11) was profiled with the Affymetrix Human Exon 1.0 ST array. Differential expression of selected genes was validated with the use of quantitative reverse transcription–polymerase chain reaction.

Results

Six hundred forty-four transcripts from 633 known genes were differentially expressed (false discovery rate (FDR) <0.1; fold-change >1.5), while 42 exons from 36 genes showed differential usage (difference in FIRMA scores >2 and FDR<0.1) between the visceral and subcutaneous fat of pregnant women. Fifty-six known genes were differentially expressed between pregnant and non-pregnant subcutaneous fat and three genes in the visceral fat. Enriched biological processes in the subcutaneous adipose tissue of pregnant women were mostly related to inflammation.

Conclusion

The transcriptome of visceral and subcutaneous fat depots reveals pregnancy-related gene expression and splicing differences in both visceral and subcutaneous adipose tissue. Furthermore, for the first time, alternative splicing in adipose tissue has been associated with regional differences and human parturition.

The peripheral whole-blood transcriptome of acute pyelonephritis in human pregnancya

OBJECTIVE

Human pregnancy is characterized by activation of the innate immune response and suppression of adaptive immunity. The former is thought to provide protection against infection for the mother, and the latter, tolerance against paternal antigens expressed in fetal cells. Acute pyelonephritis is associated with an increased risk of acute respiratory distress syndrome and sepsis in pregnant (vs. nonpregnant) women. The objective of this study was to describe the gene expression profile (transcriptome) of maternal whole blood in acute pyelonephritis.

METHOD

A case-control study was conducted to include pregnant women with acute pyelonephritis (n=15) and women with a normal pregnancy (n=34). Affymetrix HG-U133 Plus 2.0 arrays (Affymetrix, Santa Clara, CA, USA) were used for gene expression profiling. A linear model was used to test the association between the presence of pyelonephritis and gene expression levels while controlling for white blood cell count and gestational age. A fold change of 1.5 was considered significant at a false discovery rate of 0.1. A subset of differentially expressed genes (n=56) was tested with real-time quantitative reverse transcription-polymerase chain reaction (qRT-PCR) (cases, n=19; controls, n=59). Gene ontology and pathway analyses were applied.

RESULTS

A total of 983 genes were differentially expressed in acute pyelonephritis: 457 were upregulated and 526 were downregulated. Significant enrichment of 300 biological processes and 63 molecular functions was found in pyelonephritis. Significantly impacted pathways in pyelonephritis included (a) cytokine-cytokine receptor interaction, (b) T-cell receptor signaling, (c) Jak-STAT signaling, and (d) complement and coagulation cascades. Of 56 genes tested by qRT-PCR, 48 (85.7%) had confirmation of differential expression.

CONCLUSION

This is the first study of the transcriptomic signature of whole blood in pregnant women with acute pyelonephritis. Acute infection during pregnancy is associated with the increased expression of genes involved in innate immunity and the decreased expression of genes involved in lymphocyte function.

The frequency of meconium-stained amniotic fluid increases as a function of the duration of labor

OBJECTIVE

The purpose of this study was to determine whether there is a relationship between the frequency of meconium-stained amniotic fluid (MSAF) and the duration of labor in term singleton gestation.

METHODS

The clinical characteristics of women who delivered term singleton live newborns between 2001 and 2006 were examined. The cases involving neonates with major congenital anomalies were excluded.

RESULTS

(1) The frequency of MSAF in term pregnancies was 18.4% (806/4376); (2) MSAF was found in only 2.8% (28/1008) of women who delivered by elective cesarean, but in 23.1% (778/3368) of women who delivered after the onset of labor (p < 0.001); (3) The longer the duration of labor (first stage, second stage, or total), the higher the frequency of MSAF (p < 0.001 for each); this remained significant after adjusting for other confounding variables such as parity, duration of rupture of membranes, gestational age at delivery, and mode of delivery (p < 0.001 for each).

CONCLUSION

MSAF was found in only 2.8% (28/1008) of women who delivered before the onset of labor, but in 23.1% (778/3368) of women who delivered after the onset of labor. The longer the duration of labor, the higher the risk of MSAF in term singleton gestation.

Fragment Bb: evidence for activation of the alternative pathway of the complement system in pregnant women with acute pyelonephritis

OBJECTIVE

Pyelonephritis during pregnancy is associated with a more severe course than in the non-pregnant state. This has been attributed to an increased susceptibility of pregnant women to microbial products. The complement system is part of innate immunity and its alternative pathway is activated mainly by microorganisms. The purpose of this study was to determine if activation of the alternative pathway of the complement system (determined by maternal fragment Bb concentrations) occurs in pregnant women with acute pyelonephritis.

METHODS

This cross-sectional study included the following groups: (1) normal pregnant women (n=62) and (2) pregnant women with pyelonephritis (n=38). Maternal plasma fragment Bb concentrations were determined by ELISA. Non-parametric statistics were used for analyses.

RESULTS

(1) Pregnant women with pyelonephritis had a higher median plasma concentration of fragment Bb than those with a normal pregnancy (1.3 μg/ml, IQR: 1.1-1.9 vs. 0.8 μg/ml, IQR: 0.7-0.9; p<0.001); (2) No significant differences were observed in the median maternal plasma concentration of fragment Bb between pregnant women with pyelonephritis who had a positive blood culture and those with a negative blood culture (1.4 μg/ml, IQR: 1.1-3.5 vs. 1.3 μg/ml, IQR: 1.1-1.9; p=0.2).

CONCLUSIONS

Pregnant women with acute pyelonephritis have evidence of activation of the alternative pathway of the complement system, regardless of the presence or absence of a positive blood culture.

Maternal and neonatal circulating visfatin concentrations in patients with pre-eclampsia and a small-for-gestational age neonate

OBJECTIVE

Maternal circulating visfatin concentrations are higher in patients with a small-for-gestational-age (SGA) neonate than in those who delivered an appropriate-for-gestational age (AGA) neonate or in those with pre-eclampsia. It has been proposed that enhanced transfer of visfatin from the foetal to maternal circulation may account for the high concentrations of maternal visfatin observed in patients with an SGA neonate. The aims of this study were: (1) to determine whether cord blood visfatin concentrations differ between normal neonates, SGA neonates and newborns of pre-eclamptic mothers; and (2) to assess the relationship between maternal and foetal circulating visfatin concentrations in patients with an SGA neonate and those with pre-eclampsia.

STUDY DESIGN

This cross-sectional study included 88 pregnant women and their neonates, as well as 22 preterm neonates in the following groups: (1) 44 normal pregnant women at term and their AGA neonates; (2) 22 normotensive pregnant women and their SGA neonates; (3) 22 women with pre-eclampsia and their neonates; and (4) 22 preterm neonates delivered following spontaneous preterm labour without funisitis or histologic chorioamnionitis, matched for gestational age with infants of pre-eclamptic mothers. Maternal plasma and cord blood visfatin concentrations were determined by ELISA. Non-parametric statistics were used for analyses.

RESULTS

(1) The median visfatin concentration was lower in umbilical cord blood than in maternal circulation, in normal pregnancy, SGA and pre-eclampsia groups (p<0.001 for all comparisons); (2) the median cord blood visfatin concentrations did not differ significantly between term AGA or SGA neonates, infants of mothers with pre-eclampsia and their gestational-age-matched preterm AGA neonates; (3) maternal and cord blood visfatin concentrations correlated only in the normal term group (r=0.48, p=0.04).

CONCLUSION

Circulating visfatin concentrations are lower in the foetal than in the maternal circulation and did not significantly differ between the study groups. Thus, it is unlikely that the foetal circulation is the source of the high maternal visfatin concentrations reported in patients with an SGA neonate.

Could alterations in maternal plasma visfatin concentration participate in the phenotype definition of preeclampsia and SGA?

OBJECTIVE

Women with preeclampsia and those who delivered a small-for-gestational-age (SGA) neonate share several mechanisms of disease, including chronic uteroplacental ischemia and failure of physiologic transformation of the spiral arteries. However, the clinical manifestation of these obstetrical syndromes is remarkably different. It has been proposed that an altered maternal metabolic state, as well as a unique circulating cytokines milieu, predispose women to develop either preeclampsia or SGA. Compelling evidence suggests that adipose tissue orchestrates both metabolic pathways and immunological responses via the production of adipokines. Visfatin is a novel adipocytokine with metabolic and immunomodulating properties. The objective of this study was to determine whether preeclampsia and SGA are associated with alterations in maternal circulating visfatin concentrations.

METHODS

This cross-sectional study included pregnant women in the following groups: (1) normal pregnancy (n = 158); (2) patients with preeclampsia (n = 43) of which 32 had an AGA and 11 had an SGA neonate; (3) patients without preeclampsia who delivered an SGA neonate (n = 55). Maternal plasma visfatin concentrations were measured by ELISA. Nonparametric tests and multiple linear regression analysis were used.

RESULTS

(1) Women who delivered an SGA neonate had a higher median maternal plasma visfatin concentration than those with a normal pregnancy (20.0 ng/ml, interquartile range: 17.2-24.6 vs. 15.2 ng/ml, 12.1-19.2, respectively; P < 0.001) and than those with preeclampsia (14.5 ng/ml, 12.5-18.7; P < 0.001); (2) the median maternal plasma visfatin concentration did not differ significantly between patients with preeclampsia and those with a normal pregnancy (P = 0.8); (3) among patients with preeclampsia, there was no significant difference in the median maternal plasma visfatin concentration between those with or without an SGA neonate (P = 0.5); (4) in a linear regression model, delivery of an SGA neonate and pregestational body mass index were independently associated with increased visfatin concentration after adjustment for confounding factors (maternal age, smoking, gestational age at blood collection and the presence of preeclampsia or SGA).

CONCLUSION

(1) Patients with SGA, but not those with preeclampsia, had a higher maternal plasma visfatin concentration than those with a normal pregnancy; (2) this finding suggests differential involvement of visfatin in SGA and preeclampsia; (3) we propose that changes in circulating maternal visfatin concentration may be implicated in the phenotypic definitions and distinction of preeclampsia and SGA.

Maternal plasma retinol binding protein 4 in acute pyelonephritis during pregnancy

OBJECTIVE

Adipokines have been implicated in metabolic regulation and the immune response thus providing a molecular mechanism for the interaction between these two systems. Retinol binding protein 4 (RBP4) is a novel adipokine that plays a role in the pathophysiology of obesity-induced insulin resistance, as well as in the modulation of inflammation. The aim of this study was to determine whether there are changes in maternal plasma concentrations of RBP4 in pregnant women with acute pyelonephritis.

STUDY DESIGN

This cross-sectional study included pregnant women in the following groups: 1) normal pregnancy (n=80); 2) pyelonephritis (n=39). Maternal plasma RBP4 concentrations were determined by enzyme-linked immunoassays. Non-parametric statistics were used for analyses.

RESULTS

1) The median maternal plasma RBP4 concentration was lower in patients with acute pyelonephritis than in those with a normal pregnancy (3709.6 ng/mL, interquartile range (IQR) 2917.7-5484.2 vs. 9167.6 ng/mL, IQR 7496.1- 10,384.1, P<0.001; 2) the median maternal plasma RBP4 concentration did not differ significantly between patients with acute pyelonephritis who had a positive blood culture and those with a negative culture (3285.3 ng/mL, IQR 2274.1-4741.1 vs. 3922.6 ng/mL, IQR 3126.8-5547.1, respectively, P=0.2); and 3) lower maternal plasma RBP4 concentrations were independently associated with pyelonephritis after adjustment for confounding factors.

CONCLUSIONS

In contrast to what has been reported in preeclampsia, acute pyelonephritis during pregnancy is associated with lower maternal plasma RBP4 concentrations than in normal pregnancy. This finding suggests that the acute maternal inflammatory process associated with pyelonephritis is fundamentally different from that of the chronic systemic inflammatory process suggested in preeclampsia, in which RBP4 concentrations were found to be elevated.

Hyperresistinemia - a novel feature in systemic infection during human pregnancy

PROBLEM

Resistin, originally described as an adipokine, has emerged as a potent pro-inflammatory protein associated with both acute and chronic inflammation. Moreover, resistin has been proposed as a powerful marker of sepsis severity, as well as a predictor of survival of critically ill non-pregnant patients. The aim of this study was to determine whether pyelonephritis during pregnancy is associated with changes in maternal plasma resistin concentrations.

METHODS OF STUDY

This cross-sectional study included the following groups: (i) normal pregnant women (n = 85) and (ii) pregnant women with pyelonephritis (n = 40). Maternal plasma resistin concentrations were determined by ELISA. Non-parametric statistics was used for analyses.

RESULTS

(i) The median maternal plasma resistin concentration was higher in patients with pyelonephritis than in those with a normal pregnancy (P < 0.001); (ii) among patients with pyelonephritis, the median maternal resistin concentration did not differ significantly between those with and without a positive blood culture (P = 0.3); (iii) among patients with pyelonephritis who were diagnosed with systemic inflammatory response syndrome (SIRS), those who fulfilled > or =3 criteria for SIRS had a significantly higher median maternal plasma resistin concentration than those who met only two criteria; and (iv) maternal WBC count positively correlated with circulating resistin concentration (r = 0.47, P = 0.02).

CONCLUSION

Hyperresistinemia is a feature of acute pyelonephritis during pregnancy. The results of this study support the role of resistin as an acute-phase protein in the presence of bacterial infection during pregnancy.

Evidence for differential regulation of the adipokine visfatin in the maternal and fetal compartments in normal spontaneous labor at term

OBJECTIVE

Visfatin, a novel adipokine with metabolic and immunoregulatory properties, has been implicated in the regulation of fetal growth, as well as in preterm labor. A gap in knowledge is whether spontaneous labor at term is associated with changes in the maternal and fetal concentrations of visfatin. The aim of this study was to determine if the presence of labor at term is associated with alterations in maternal and neonatal plasma visfatin concentrations.

STUDY DESIGN

This cross-sectional study included 50 normal pregnant women at term and their appropriate-for-gestational age (AGA) neonates in the following groups: 1) 25 mother-neonate pairs delivered by elective cesarean section without spontaneous labor, and 2) 25 mother-neonate pairs who delivered vaginally following spontaneous labor. Maternal plasma and cord blood visfatin concentrations were determined by ELISA. Non-parametric statistics were used for analyses.

RESULTS

1) The median visfatin concentration was higher in umbilical cord plasma of neonates born following a spontaneous labor at term than that of those who were born by an elective cesarean section (P=0.02); 2) in contrast, the median maternal plasma visfatin concentration did not differ significantly between patients with and without labor (P=0.44); and 3) there was a significant correlation between umbilical cord plasma concentration of visfatin and both maternal visfatin concentration (r=0.54, P=0.005) and gestational age (GA) at delivery (r=0.58; P=0.002) only in the absence of labor.

CONCLUSION

Term labor is associated with increased fetal, but not maternal, circulating visfatin concentrations. Previous reports indicate that preterm labor leading to preterm delivery is characterized by an increase in maternal plasma concentrations of visfatin. The observations reported herein support the view that there are fundamental differences in the endocrine and metabolic adaptations in normal labor at term and preterm labor.

Retinol-binding protein 4: a novel adipokine implicated in the genesis of LGA in the absence of gestational diabetes mellitus

OBJECTIVE

Adipokines (cytokines produced by adipose tissue) play a major role in the control of body weight and energy distribution. Retinol-binding protein 4 (RBP4), only recently recognized as an adipokine, has been proposed to modulate systemic insulin sensitivity. The goal of this study was to determine whether there is an association between maternal plasma RBP4 concentration and the birth of a large-for-gestational-age (LGA) newborn in women with and without gestational diabetes mellitus (GDM).

STUDY DESIGN

This cross-sectional study included pregnant women at term in the following groups: 1) normal pregnancy with an appropriate-for-gestational-age (AGA) neonate (n=64); 2) normal pregnancy with an LGA neonate (n=44); 3) GDM with an AGA neonate (n=55); and 4) GDM with an LGA neonate (n=42). Maternal plasma RBP4 concentration was determined by ELISA. Parametric and non-parametric statistics were used for analyses.

RESULTS

1) Patients with GDM, either with AGA or LGA neonates, had a higher median plasma concentration of RBP4 than normal pregnant women who delivered an AGA neonate (P=0.01 and P=0.008, respectively); 2) mothers without GDM but with LGA neonates had a higher median plasma concentration of RBP4 than those with normal pregnancy and AGA newborns (P=0.001); 3) these findings remained significant after adjusting for maternal age, body mass index and gestational age at blood sampling.

CONCLUSION

GDM is characterized by alterations in maternal circulating RBP4 concentrations akin to those of Type 2 diabetes mellitus. RBP4 concentrations in maternal plasma may play a role in accelerated fetal growth in the absence of overt carbohydrate intolerance.