Optimization of cytokine stability in stored amniotic fluid

Development of a free cytokine immunoassay to maintain binding and dissociation equilibrium in vitro

Using competitive ELISA to detect free cytokines is limited as it can only reflect relative trends rather than accurately determine the real state and quantity of cytokines due to the dynamic equilibrium between dissociation and binding. This imprecise quantification adversely affects the usage of clinical medication and the validity assessment. In this study, we have developed a novel cytokine immunoassay that utilizes Rosetta molecular docking prediction technique, we screened two specific antibody pairs binding IL-1β and Durg respectively and then established the Total IL-1β and Total Drug ELISA assay. Protein A column could separate bound IL-1β and free IL-1β, and the bound IL-1β occupied for about 90% of the total. This innovative approach ensures the maintenance of equilibrium between the free cytokines and complex. We have developed a free cytokine content detection method that combines ELISA and solid phase extraction, which can detect the true concentration of free cytokines without destroying the free-binding dynamic equilibrium. It can be used to verify the accuracy of clinical PK/PD and other data, evaluate the applicability of detection methods, and guide clinical drug use and drug efficacy evaluation.

Proteomic Analysis and Cell Viability of Nine Amnion, Chorion, Umbilical Cord, and Amniotic Fluid-Derived Products

OBJECTIVE

Amnion products are used in various musculoskeletal surgeries and as injections for joint pain with conflicting reports of cell viability and protein contents. The objective of this study was to determine the full proteome and examine cell viability in 9 commercial amnion products using an unbiased bottom-up shotgun proteomics approach and confocal microscopy.

DESIGN

Products were subjected to liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis and searched against a UniProt Homo sapiens database. Relative protein abundance was determined for each sample. Based on proteomics results, lumican was measured by enzyme-linked immunosorbent assay (ELISA) and Western blot analysis was performed for interleukin-1 receptor antagonist (IL-1Ra) and tissue inhibitor of matrix metalloproteinase-2 (TIMP-2). Cell viability was determined by calcein AM (live) and ethidium homodimer (dead) staining and confocal microscopy.

RESULTS

Proteomic analysis revealed 919 proteins in the nine products. Proteins were primarily collagens, keratin, and albumin. Lumican, a small leucine-rich proteoglycan (SLRP) was found in all samples. Western blot analysis for IL-1Ra and TIMP-2 indicated presence of both proteins, with nonspecific antibody binding also present in all samples. No live cells were identified in any product.

CONCLUSIONS

Several novel proteins were identified through proteomics that might impart the beneficial effects of amnion products, including SLRPs, collagens, and regulators of fibroblast activity. IL-1Ra and TIMP-2 were identified, but concentrations measured by ELISA may be falsely increased due to nonspecific antibody binding. The concept that the amnion tissues provide live cells to aid in tissue regeneration cannot be supported by the findings of this study.

Bacteria in the amniotic fluid without inflammation: early colonization vs. contamination

OBJECTIVES

Intra-amniotic infection, defined by the presence of microorganisms in the amniotic cavity, is often accompanied by intra-amniotic inflammation. Occasionally, laboratories report the growth of bacteria or the presence of microbial nucleic acids in amniotic fluid in the absence of intra-amniotic inflammation. This study was conducted to determine the clinical significance of the presence of bacteria in amniotic fluid samples in the absence of intra-amniotic inflammation.

METHODS

A retrospective cross-sectional study included 360 patients with preterm labor and intact membranes who underwent transabdominal amniocentesis for evaluation of the microbial state of the amniotic cavity as well as intra-amniotic inflammation. Cultivation techniques were used to isolate microorganisms, and broad-range polymerase chain reaction coupled with electrospray ionization mass spectrometry (PCR/ESI-MS) was utilized to detect the nucleic acids of bacteria, viruses, and fungi.

RESULTS

Patients whose amniotic fluid samples evinced microorganisms but did not indicate inflammation had a similar perinatal outcome to those without microorganisms or inflammation [amniocentesis-to-delivery interval (p=0.31), spontaneous preterm birth before 34 weeks (p=0.83), acute placental inflammatory lesions (p=1), and composite neonatal morbidity (p=0.8)].

CONCLUSIONS

The isolation of microorganisms from a sample of amniotic fluid in the absence of intra-amniotic inflammation is indicative of a benign condition, which most likely represents contamination of the specimen during the collection procedure or laboratory processing rather than early colonization or infection.

Amniotic fluid: Source of trophic factors for the developing intestine

The gastrointestinal tract (GIT) is a complex system, which changes in response to requirements of the body. GIT represents a barrier to the external environment. To achieve this, epithelial cells must renew rapidly. This renewal of epithelial cells starts in the fetal life under the influence of many GIT peptides by swallowing amniotic fluid (AF). Development and maturation of GIT is a very complex cascade that begins long before birth and continues during infancy and childhood by breast-feeding. Many factors like genetic preprogramming, local and systemic endocrine secretions and many trophic factors (TF) from swallowed AF contribute and modulate the development and growth of the GIT. GIT morphogenesis, differentiation and functional development depend on the activity of various TF in the AF. This manuscript will review the role of AF borne TF in the development of GIT.

Child intellectual development in relation to cytokine levels in umbilical cord blood

Although cytokines play a dual role in the developing neurologic system and in prenatal immune reactions, relations between fetal cytokine levels and child intellectual development remain unknown. The authors investigated associations between umbilical cord serum cytokine concentrations and intellectual outcomes in 369 children within a prospective cohort study, the Eunice Kennedy Shriver National Institute of Child Health and Human Development-University of Alabama Infant Growth Study (1985-1988). Concentrations of interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), and interleukins 4, 10, and 12p70 were determined. The Wechsler Preschool and Primary Scale of Intelligence-Revised was administered at age 5 years, producing verbal and performance intelligence quotients (VIQ and PIQ); associations with each cytokine were evaluated using linear and logistic regression. Log-unit increases in IFN-γ (adjusted odds ratio (aOR) = 0.67, 95% confidence interval (CI): 0.46, 0.98) and interleukin-12p70 (aOR = 0.43, 95% CI: 0.21, 0.87) were inversely associated with low PIQ (score <70). One log-unit increase in TNF-α was associated with a reduced odds ratio for low VIQ (score <70) among preterm children (aOR = 0.11, 95% CI: 0.01, 0.94) and an elevated odds ratio for low VIQ among small-for-gestational-age children (aOR = 3.96, 95% CI: 0.99, 15.9). IFN-γ, which is involved in neurogenesis and perinatal adaptive immunity, may be related to fetal neurologic development overall, while TNF-α may be a marker of intellectual development in vulnerable subgroups.

Impact of cryopreservation on serum concentration of matrix metalloproteinases (MMP)-7, TIMP-1, vascular growth factors (VEGF) and VEGF-R2 in Biobank samples

BACKGROUND

Blood biomarkers are subject to pre-analytical variability. In many cases, the stability of important new tissue biomarkers during freeze cycles and storage has not been studied sufficiently.

METHODS

To test the stability of matrix metalloproteinases-7 (MMP-7) and their tissue inhibitors (TIMP-1), vascular growth factors (VEGF) and VEGF-receptor, serum samples were frozen and then thawed up to six times. The impact of storage temperature was investigated using an accelerated stability testing protocol. Stability at -20°C and -75°C was calculated using the Arrhenius equation.

RESULTS

The average concentration of TIMP-1 was stable, even after six freeze/thaw cycles. One thawing did not change the concentration of MMP-7 and VEGF-receptor. However, repeated freeze/thaw cycles increased the measured values significantly. Decreases in VEGF concentrations were dramatic, even after the first freeze/thaw cycle. According to the Arrhenius calculation, MMP-7 showed excellent stability, at least 5 years at -20°C and several 100 years at -75°C. The VEGF-receptor maintains 90% of its initial concentration at -20°C over 3 months, and decades at -75°C. TIMP-1 and VEGF showed poor stability with cryopreservation, even at -75°C.

CONCLUSIONS

The stability of MMP-7, TIMP-1, VEGF or VEGF-receptor in biobanking is highly variable, and this should be taken into account in the interpretation of results. A temperature -20°C is unsuitable for prolonged storage of the biomarkers investigated, and repeated thawing of sera is not recommended. VEGF is especially unstable and should be quantitated using serum that has never been frozen.

Umbilical cord serum cytokine levels and risks of small-for-gestational-age and preterm birth

While elevated levels of proinflammatory cytokines are clearly associated with preterm birth, the relation between cytokines and fetal growth is unclear. The authors examined associations between umbilical cord serum cytokine concentrations and risk of small-for-gestational-age (SGA) and preterm birth. This cross-sectional analysis was nested within a National Institute of Child Health and Human Development-University of Alabama population-based cohort study of high-risk prenatal care patients in Jefferson County, Alabama. Patients were enrolled between 1985 and 1988. For 370 singletons, umbilical cord serum concentrations of interferon gamma (IFN-gamma), tumor necrosis factor alpha, and interleukins 12p70, 4, and 10 were determined. Associations between each cytokine and SGA and preterm delivery were evaluated using log binomial regression. Increasing log concentration of tumor necrosis factor alpha was associated with an increased risk of preterm birth (risk ratio (RR) = 2.00, 95% confidence interval (CI): 1.31, 3.06). IFN-gamma was associated with a decreased risk of SGA birth (RR = 0.78, 95% CI: 0.61, 1.01). After stratification for preterm birth status, the association between IFN-gamma concentration and SGA birth was pronounced among preterm babies (RR = 0.56, 95% CI: 0.31, 1.01). The observations regarding IFN-gamma, which is involved in the activation of adaptive immune responses and regulation of trophoblast function, suggest that IFN-gamma levels at birth may be related to fetal growth restriction.

Ionizing radiation-induced gene modulations, cytokine content changes and telomere shortening in mouse fetuses exhibiting forelimb defects

Several lines of evidence have linked limb teratogenesis to radiation-induced apoptosis and to the p53 status in murine fetuses. In previous reports, we studied the occurrence of various malformations after intrauterine irradiation and showed that these malformations were modulated by p53-deficiency as well as by the developmental stage at which embryos were irradiated. In this new study, we focused onto one particular phenotype namely forelimb defects to further unravel the cellular and molecular mechanisms underlying this malformation. We measured various parameters expected to be directly or indirectly influenced by irradiation damage. The mouse fetuses were irradiated at day 12 p.c. (post conception) and examined for forelimb defects on gestational days 15, 16, 17 and 19 of development. The release of inflammatory cytokines was determined in the amniotic fluid on day 16 p.c. and the mean telomere lengths assessed at days 12, 13 and 19 p.c. Differential gene expression within the forelimb bud tissues was determined using Real Time quantitative PCR (RTqPCR) 24 h following irradiation. Apoptosis was investigated in the normal and malformed fetuses using the TUNEL assay and RTqPCR. First, we found that irradiated fetuses with forelimb defects displayed excessive apoptosis in the predigital regions. Besides, overexpression of the pro-apoptotic Bax gene indicates a mitochondrial-mediated cell death. Secondly, our results showed overexpression of MKK3 and MKK7 (members of the stress-activated MAP kinase family) within the malformed fetuses. The latter could be involved in radiation-induced apoptosis through activation of the p38 and JNK pathways. Thirdly, we found that irradiated fetuses exhibiting forelimb defects showed a marked telomere shortening. Interestingly, telomere shortening was observed as the malformations became apparent. Fourthly, we measured cytokine levels in the amniotic fluid and detected a considerable inflammatory reaction among the irradiated fetuses as evidenced by the increase in pro-inflammatory cytokine levels. Altogether, our data suggest that transcriptional modulations of apoptotic, inflammation, stress, and DNA damage players are early events in radiation-induced forelimb defects. These changes resulted in harsh developmental conditions as indicated by a marked increase in cytokine levels in the amniotic fluid and telomere shortening, two features concomitant with the onset of the forelimb defect phenotype in our study.

Systemic immune response to Trichomonas vaginalis infection during pregnancy

OBJECTIVE

The objective of this study was to characterize the systemic immune response in women with trichomoniasis in pregnancy as compared with uninfected women.

STUDY DESIGN

A nested case control study was performed on 195 serum samples. Serum concentrations of cytokines, chemokines, and C-reactive protein (CRP) were compared between infected and uninfected women. Cytokines and chemokines were measured using a multiplex bead assay. The CRP concentrations were determined using a standard enzyme-linked immunosorbent assay method.

RESULTS

The median serum concentration of granulocyte-macrophage colony-stimulating factor (GM-CSF) was significantly higher in the trichomonas-infected group compared with the uninfected group (8.9 pg/mL vs. 5.7 pg/mL; P <0.001). The mean log-transformed CRP values were higher in the infected group compared with the uninfected group (1.66 vs. 1.27; P = 0.03).

CONCLUSIONS

The results of this study suggest that trichomoniasis during pregnancy can lead to a systemic immune response in some women as exhibited by elevation in the serum concentrations of both GM-CSF and CRP.

Amniotic fluid: not just fetal urine anymore

Amniotic fluid (AF) is a complex substance essential to fetal well-being. This article reviews recent discoveries and the current understanding of the origin and circulation of AF and its nutritive, protective, and diagnostic functions. Future directions for AF research are also discussed.

Amniotic Fluid and Maternal Blood Characteristics in Severe Mid-Trimester Twin–Twin Transfusion Syndrome

OBJECTIVE

To investigate the concentrations of metabolic variables in the amniotic fluid of the recipient twin and maternal blood and to correlate them with clinical features, which are characteristic for the course of pregnancies with twin-twin transfusion syndrome (TTS).

MATERIALS AND METHODS

In 109 pregnancies with severe mid-trimester TTS, we measured the concentrations of interleukin-6 (IL-6), alpha-fetoprotein (AFP), sodium, potassium, total protein, beta2-microglobulin and osmolality in the amniotic fluid of the recipient twin prior to laser coagulation of the vascular anastomoses and compared them to a control group of 92 singleton pregnancies. We measured the pulsatility index (PI) of ductus venosus flow velocity waveforms in the recipient twin and performed a retrospective chart analysis for complete maternal blood count before and after the procedure.

RESULTS

All variables, except osmolality, IL-6 and AFP were significantly lower in the TTS group. There was a significant positive correlation between PI in the ductus venosus and the amniotic fluid AFP concentrations (r = 0.355; p < 0.001). There was a significant fall in complete maternal blood count after laser therapy (p < 0.001) and a significant correlation between the amount of amniotic fluid drained and the fall of maternal Hb (r = -0.261; p = 0.03) and hematocrit (r = -0.212; p = 0.01).

CONCLUSION

Pathophysiologic changes in TTS do not only occur at the inter-twin level of placental vascular anastomoses but also at the materno-fetal level of fluid exchanges. AFP is correlated to the severity of congestive heart failure of the recipient twin.

Intrapartum fever at term: serum and histologic markers of inflammation

OBJECTIVE

This study was undertaken to determine whether intrapartum fevers at term are associated with markers of acute inflammation in maternal, fetal, and placental compartments.

STUDY DESIGN

Term cases with intrapartum fever (temperature >/=100.4 degrees F) were recruited with gestational age-matched controls. Maternal serum and umbilical vein blood were collected and assayed for interleukin-6 (IL-6) levels. Placentas were examined for histologic chorioamnionitis. Demographic and clinical data were collected and compared between cases and controls.

RESULTS

Forty-seven case-control pairs were analyzed. Maternal IL-6 levels were higher in cases than in controls (median of 145 pg/mL vs 42 pg/mL, P <.0001). Umbilical vein IL-6 levels also were higher in cases than controls (median 9 pg/mL vs 3.5 pg/mL, P =.01), but more than half of levels in cases were below 11 pg/mL. Only 31.1% of febrile cases had moderate or severe histologic chorioamnionitis. Multivariable logistic regression identified maternal serum IL-6 levels, nulliparity, and number of vaginal examinations as the major predictors of intrapartum fever at term.

CONCLUSION

The maternal inflammatory response as measured by maternal serum IL-6 levels is a strong marker for term intrapartum fever. The much weaker association of fetal and placental inflammatory responses suggest a smaller than expected contribution of intra-amniotic inflammation to term intrapartum fevers.