Elevated serum sialic acid in pregnancy

Pregnancy-induced differential expression of SARS-CoV-2 and influenza a viral entry factors in the lower respiratory tract

Despite differences in the clinical presentation of coronavirus disease-19 and pandemic influenza in pregnancy, fundamental mechanistic insights are currently lacking because of the difficulty in recruiting critically ill pregnant subjects for research studies. Therefore, to better understand host-pathogen interaction during pregnancy, we performed a series of foundational experiments in pregnant rats at term gestation to assess the expression of host entry factors for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and influenza A virus (IAV) and genes associated with innate immune response in the lower respiratory tract. We report that pregnancy is characterized by a decrease in host factors mediating SARS-CoV-2 entry and an increase in host factors mediating IAV entry. Furthermore, using flow cytometric assessment of immune cell populations and immune provocation studies, we show an increased prevalence of plasmacytoid dendritic cells and a Type I interferon-biased environment in the lower respiratory tract of pregnancy, contrary to the expected immunological indolence. Our findings, therefore, suggest that the dissimilar clinical presentation of COVID-19 and pandemic influenza A in pregnancy could partly be due to differences in the extent of innate immune activation from altered viral tropism and indicate the need for comparative mechanistic investigations with live virus studies.

Upregulated influenza A viral entry factors and enhanced interferon-alpha response in the nasal epithelium of pregnant rats

Despite the increased severity of influenza A infection in pregnancy, knowledge about the expression of cell entry factors for influenza A virus (IAV) and the innate immune response in the nasal epithelium, the primary portal of viral entry, is limited. Here, we compared the expression of IAV cell entry factors and the status of the innate immune response in the nasal epithelium of pregnant vs. non-pregnant female rats. IAV cell entry factors — sialic acid [SA] α-2,3- and α-2,6-linked glycans for avian and human IAV, respectively — were detected and quantified with lectin-based immunoblotting and flow cytometry. Baseline frequencies of innate immune cell phenotypes in single cell suspensions of the nasal epithelium were studied with flow cytometry. Subsequently, the magnitude of interferon and cytokine responses was studied with ELISA and cytokine arrays after intranasal resiquimod, a Toll-like receptor 7/8 agonist that mimics IAV infection. We noted substantially increased expression of cell entry factors for both avian and human IAV in the nasal epithelium during pregnancy. Assessment of the innate immune state of the nasal epithelium during pregnancy revealed two previously unreported features: (i) increased presence of tissue-resident plasmacytoid dendritic cells, and (ii) markedly enhanced release of interferon-α but not of the other interferons or cytokines 2 h after intranasal resiquimod. Collectively, our findings challenge the conventional notion of pregnancy-induced immunosuppression as a cause for severe influenza A disease and suggest the need for focused studies on viral tropism during pregnancy to better understand the proximate cause for the observed immunopathology.

Maternal Neu5Ac Supplementation During Pregnancy Improves Offspring Learning and Memory Ability in Rats

Sialic acids are postulated to improve cognitive abilities. This study aimed to evaluate the effects of sialic acid on behavior when administered in a free form as N-acetylneuraminic acid (Neu5Ac) to pregnant mothers or rat pups. The experiment involved 40 male 21-day-old rat pups and 20 15-day-pregnant rats that were randomized into four Neu5Ac treated groups: 0 (control), or 10, 20, and 40 mg/kg. Morris water maze test and shuttle box test were performed on the rat pups and maternal Neu5Ac-supplemented offspring on day 100 to evaluate their cognitive performance. The Neu5Ac levels in the cerebral cortex and hippocampus were tested with high-performance liquid chromatography-fluorescence detection (HPLC-FLD). We found that the maternal Neu5Ac-supplemented offspring showed better cognitive performance, less escape latency in the Morris water maze test, and less electric shock time shuttle box test, compared with the untreated control. In the meantime, the Neu5Ac level in the cerebral cortex and hippocampus of the offspring was higher in the Neu5Ac treatment group than that in the untreated control group. However, no significant differences were observed between rat pups in the treated and the untreated control groups in terms of cognitive performance and Neu5Ac content in the cerebral cortex and hippocampus. Maternal Neu5Ac supplementation during pregnancy could effectively promote the brain Neu5Ac content of the offspring and enhance their cognitive performance, but Neu5Ac had no such effect on rat pups while directly supplemented with Neu5Ac.

Pregnancy in GNE myopathy patients: a nationwide repository survey in Japan

BACKGROUND

GNE myopathy is an autosomal recessive adult-onset distal myopathy. While a few case reports have described the progression of GNE myopathy during pregnancy, to our knowledge, none have examined disease progression after delivery or obstetric complications.

OBJECTIVE

This study aimed to reveal maternal complications, newborn complications, and the impact of pregnancy on disease progression in GNE myopathy patients.

METHODS

We conducted a questionnaire survey on pregnancy, delivery, and newborns involving female GNE myopathy patients who are currently registered in a national registry in Japan.

RESULTS

The response rate for the questionnaire survey was 60.0% (72/120). Of the 72 respondents, 44 (61.1%) had pregnancy experience (average, 1.8 pregnancies; 53 pregnancies before onset and 28 after onset). The incidence of threatened abortion was 26.9% among post-onset pregnancies, which was higher compared to those of the general Japanese population (p = 0.03). No other maternal or infant complications were commonly observed. Over 80% were unaware of changes in disease progression during pregnancy (mean age, 32.8 ± 3.5 years) or after delivery (32.9 ± 3.8 years), while 19.0% experienced disease exacerbation within a year after delivery (30.0 ± 1.0 years). Six patients developed myopathy within a year after delivery (29.7 ± 4.6 years), while none developed myopathy during pregnancy.

CONCLUSIONS

There were no serious maternal or newborn complications, and subjective progression did not differ during or after delivery in the majority of GNE myopathy patients. However, our findings suggest the importance of considering the possibility of threatened abortion and disease progression after delivery.

Evaluation of Total and Lipid Bound Sialic Acid in Serum in Oral Leukoplakia

INTRODUCTION

Oral cancer has become the most common cause of cancer related mortality which may be preceded by oral potentially malignant disorders. Altered glycosylation of glycoconjugates, such as sialic acid are one of the most important molecular changes accompanied during malignant transformation in precancerous lesions like Oral Leukoplakia (OL), and correlating them histopathologically with grades of epithelial dysplasia which will serve clinical significance.

AIM

The aim of this study was to evaluate the significance of serum Total Sialic Acid (TSA) and serum Lipid Bound Sialic Acid (LSA) as a prognostic serum marker in Oral Leukoplakia.

MATERIALS AND METHODS

Blood samples were collected from 30 patients diagnosed with OL and 30 healthy controls. Serum sialic acid (total and lipid bound) levels were measured using spectrophotometer. Tissue samples were histopathologically typed and were graded for epithelial dysplasia. Data were analysed using Independent t-test and Kruskal Wallis method.

RESULTS

Serum levels of both total and lipid bound sialic acids were found to be increased in OL when compared to healthy controls. The mean TSA levels among those in the OL group (45.3±4.2) were significantly greater than healthy controls (29±2.2). On multiple comparison the highest mean TSA level was found in severe OL compared to moderate and mild OL (p<0.05). The mean levels of LSA were found to be statistically non-significant between the groups.

CONCLUSION

The present study showed that the serum levels of both TSA and LSA were found to be increased in OL when compared to apparently healthy controls. We also found that with increasing grades of epithelial dysplasia TSA levels were found to be gradually increasing which was significant for this study serving as an early indicator for the detection of malignant transformation in OL.

The effect of proanthocyanidin on formaldehyde-induced toxicity in rat testes

BACKGROUND/AIM

This study investigated the effect of proanthocyanidin (PA) against formaldehyde (FA)-induced lipid peroxidation damage and morphological changes in rat testes.

MATERIALS AND METHODS

Twenty-one Wistar albino rats were randomized into 3 groups: control, FA, and FA + PA groups. Plasma and tissue malondialdehyde (MDA) and total sialic acid (TSA) levels were measured. Testes tissues were observed by light and electron microscopy.

RESULTS

TSA (plasma and tissue) levels decreased and MDA (plasma) significantly increased (P < 0.05) in rats treated with FA compared to the controls. Tissue MDA levels were not significantly different. Several necrotic changes were observed in testes tissues by light and electron microscopy. Disordering in epithelia of seminiferous tubules, vacuolization between germinal epithelium cells, and separated basement membranes were observed by light microscope. Immunopositivity in Leydig cells decreased in the FA group (P < 0.05). In the FA + PA group there were more immune Leydig cells reacting immune-positively than in the FA group (P < 0.05). Ultrastructurally, FA also caused disorganization and loss of mitochondrial cristae, and dilatation in endoplasmic reticulum in testes.

CONCLUSION

The results suggest that PA has a protective effect on FA toxicity in testes.

Progesterone receptor-mediated regulation of N-acetylneuraminate pyruvate lyase (NPL) in mouse uterine luminal epithelium and nonessential role of NPL in uterine function

N-acetylneuraminate pyruvate lyase (NPL) catalyzes N-acetylneuraminic acid, the predominant sialic acid. Microarray analysis of the periimplantation mouse uterine luminal epithelium (LE) revealed Npl being the most downregulated (35×) gene in the LE upon embryo implantation. In natural pregnant mouse uterus, Npl expression increased 56× from gestation day 0.5 (D0.5) to D2.5. In ovariectomized mouse uterus, Npl was significantly upregulated by progesterone (P4) but downregulated by 17β-estradiol (E2). Progesterone receptor (PR) antagonist RU486 blocked the upregulation of Npl in both preimplantation uterus and P4-treated ovariectomized uterus. Npl was specifically localized in the preimplantation D2.5 and D3.5 uterine LE. Since LE is essential for establishing uterine receptivity, it was hypothesized that NPL might play a critical role in uterine function, especially during embryo implantation. This hypothesis was tested in the Npl^(−/−) mice. No significant differences were observed in the numbers of implantation sites on D4.5, gestation periods, litter sizes, and postnatal offspring growth between wild type (WT) and Npl^(−/−) females from mating with WT males. Npl^(−/−)xNpl^(−/−) crosses produced comparable little sizes as that from WTxWT crosses. Comparable mRNA expression levels of several genes involved in sialic acid metabolism were observed in D3.5 uterus and uterine LE between WT and Npl^(−/−), indicating no compensatory upregulation in the D3.5 Npl^(−/−) uterus and LE. This study demonstrates PR-mediated dynamic expression of Npl in the periimplantation uterus and dispensable role of Npl in uterine function and embryo development.

Does oxidative stress play a role in altered plasma protein homeostasis in pregnancy-induced hypertension?

BACKGROUND

Pregnancy-induced hypertension (PIH) is associated with oxidative stress and low plasma proteins. This study explored the effect of oxidative stress on plasma protein level in PIH.

METHODS

Serum total proteins (TP), albumin, globulin, malondialdehyde, protein carbonyls (PC) and protein bound sialic acid (PBSA) were measured in gestational hypertensive, pre-eclamptic, eclamptic and healthy pregnant women (n=20/group). Serum proteins were separated by electrophoresis for assessing protein damage.

RESULTS

Serum TP and albumin decreased and malondialdehyde, PC & PBSA increased significantly in all PIH subgroups as compared to healthy pregnant subjects. Serum globulin levels decreased only in eclampsia. Malondialdehyde and PC negatively correlated with albumin level. Protein fragmentation and aggregation in eclampsia were evident from electrophoretogram.

CONCLUSION

We conclude that oxidative damages to proteins contribute to decreased serum protein levels in PIH and hypersialylation of plasma proteins is probably body’s protective mechanism to combat oxidative protein damage in PIH.

Salivary lipid peroxidation and total sialic acid levels during healthy gestation and postpartum: a longitudinal study

OBJECTIVES

This study investigated salivary lipid peroxidation (LPO) as an oxidative stress marker and salivary total sialic acid (TSA) as an inflammatory response during gestation and postpartum.

DESIGN AND METHODS

Salivary LPO and TSA levels, using the Ledwozyw and Warren methods respectively, were obtained in healthy pregnant women followed up during gestation and 6-8 weeks postpartum, and in healthy non-pregnant controls. All were with good oral health.

RESULTS

LPO was significantly higher than controls during all trimesters and postpartum and in the second trimester than in the third trimester and postpartum. TSA in the second trimester was significantly higher than in any other group. First trimester levels were significantly higher than postpartum . Oral health indices remained within normal levels for the duration.

CONCLUSION

The salivary LPO profile followed plasma gestation and postpartum profiles in the literature but the salivary TSA differed in that after the 2nd trimester, rather than persisting, it decreased.

Sialic acid is an essential nutrient for brain development and cognition

The rapid growth of infant brains places an exceptionally high demand on the supply of nutrients from the diet, particularly for preterm infants. Sialic acid (Sia) is an essential component of brain gangliosides and the polysialic acid (polySia) chains that modify neural cell adhesion molecules (NCAM). Sia levels are high in human breast milk, predominately as N-acetylneuraminic acid (Neu5Ac). In contrast, infant formulas contain a low level of Sia consisting of both Neu5Ac and N-glycolylneuraminic acid (Neu5Gc). Neu5Gc is implicated in some human inflammatory diseases. Brain gangliosides and polysialylated NCAM play crucial roles in cell-to-cell interactions, neuronal outgrowth, modifying synaptic connectivity, and memory formation. In piglets, a diet rich in Sia increases the level of brain Sia and the expression of two learning-related genes and enhances learning and memory. The purpose of this review is to summarize the evidence showing the importance of dietary Sia as an essential nutrient for brain development and cognition.

Pregnancy-related factors and the risk of isolated systolic hypertension

BACKGROUND

Isolated systolic hypertension (ISH) is known to be a strong predictor of cerebrovascular and cardiac events, especially in women. Metabolic and hormonal changes associated with reproductive history may contribute to the development of cardiovascular diseases. The aim of this study was to identify associations between pregnancy-related factors and ISH.

METHODS

A cross-sectional study based on a random sample of 3937 Finnish women aged 30-99 was carried out. Associations between pregnancy-related factors and ISH were analyzed using multivariate analyses.

RESULTS

Of 3470 subjects, 26% had ISH. Younger age at first delivery predicted a higher risk of ISH (odds ratio after adjustment for age, education, smoking, height and weight = 1.31, 95% CI 1.07-1.61). Age at first and last delivery was significantly associated with age, education, marital status and use at any time of hormone replacement therapy (HRT); age at first delivery was also associated with toxemia in any pregnancy, weight and body mass index (BMI). In the univariate analyses, ISH was significantly associated with age, height, weight, BMI, education, marital status, oral contraceptive pills use at any time and HRT use at any time.

CONCLUSION

This population-based study showed that early age at first delivery increased the risk of ISH, which may in turn increase cerebrovascular and cardiac events after menopause. Age at first delivery is heavily dependent on education, which may be linked to the risk of developing of cardiovascular disease throughout adulthood. The other plausible mechanism may be adiposity due to pregnancy.

Detection of alcohol consumption during pregnancy—Current and future biomarkers

Alcohol, one of the most frequently reported addictions, is a significant public health problem in the USA. Early identification is important and would aid in intervention for the pregnant woman who continues to drink and for the affected infant. To date, there isn't a definitive test which identifies either alcohol abuse during pregnancy or newborns exposed to alcohol prenatally. The existing biomarkers can detect varying degrees of alcohol exposure but further research is needed to improve sensitivity/specificity and to validate these markers.

Separation methods for sialic acids and critical evaluation of their biologic relevance

Sialic acids are biosynthesized by almost all organisms as a 9-carbon carboxylated monosaccharide and are integral components of glycoconjugates. More than 40 naturally occurring sialic acid derivatives of the three main forms of sialic acids, the N-acetyl- and N-glycolylneuraminic acid and 2-keto-3-deoxy-nonulosonic acid have been identified. Due to the great importance of sialic acids as key mediators in a plethora of cellular events, including cell-cell recognition and cell-matrix interactions, their analysis in biologic samples is useful for a deeper understanding of the various (patho)physiological processes and of value in disease diagnosis and monitoring. In this review we summarize the methodology developed to isolate and liberate sialic acids from biologic samples as well as the chromatographic, electromigration and hyphenated techniques available for their separation and analysis. A critical evaluation of the biological relevance of the results obtained by analyzing sialic acids in biologic samples is also presented.

Total sialic acid and associated elements of the metabolic syndrome in women with and without previous gestational diabetes

OBJECTIVE

Inflammatory markers predict type 2 diabetes and relate to the metabolic syndrome. Gestational diabetes mellitus (GDM) predicts type 2 diabetes and may be part of this syndrome. To examine the association of inflammatory markers with GDM, we investigated total sialic acid (TSA) in women with and without previous GDM.

RESEARCH DESIGN AND METHODS

All women with GDM and a random sample of women from one center of the Brazilian Study of Gestational Diabetes were invited to return 7 years after their index pregnancy. After an interview, an oral glucose tolerance test and anthropometry were performed. A total of 46 women with and 50 women without previous GDM completed the protocol.

RESULTS

Mean TSA was significantly higher in women with (71.8 +/- 11.1 mg/dl) than without (67.5 +/- 9.8 mg/dl) previous GDM (P < 0.05). In a linear regression model, TSA was 4 mg/dl (P < 0.05) higher in women with previous GDM, after adjustment for BMI, fasting insulin sensitivity, and number of years spent in school. In a similar model, current 2-h plasma glucose levels were associated with higher TSA levels after adjustment for waist-to-hip ratio and the log of triglycerides. TSA was strongly correlated with individual components and aggregates (r = 0.55, P < 0.001) of the metabolic syndrome.

CONCLUSIONS

Increased TSA levels are associated with previous GDM and are strongly linked to the metabolic syndrome. These findings in young women suggest that a chronic mild systemic inflammatory response is an early feature of the metabolic syndrome and that GDM may be a window for its investigation.

Total serum sialic acid is a general disease marker rather than a specific tumour marker in dogs

The aim of the present study was to examine the levels of total sialic acid (TSA) in serum of clinically healthy dogs and dogs with various diseases to evaluate the usefulness of TSA as a tumour marker. TSA levels in clinically healthy dogs were not different between sexes, but pregnant and lactating dogs had higher mean (+/- standard deviation (SD)) TSA levels than clinically healthy female dogs (642 +/- 78 vs. 495 +/- 73 mg/l, P < 0.001). Eighty-eight dogs with different tumours (54 malignant and 34 benign tumours of different tissues) had higher mean TSA levels than 148 clinically healthy dogs (675 +/- 143 vs. 498 +/- 75 mg/l, P < 0.01). Fifty dogs with other diseases excluding tumours (skin, urinary system, and gastrointestinal diseases, pyometra, other inflammatory diseases, and Cushing's syndrome) had slightly higher TSA levels than the tumour-bearing dogs (730 +/- 159 mg/l, P = 0.02). TSA levels in dogs with malignant tumours did not differ from dogs with benign tumours (682 +/- 144 vs. 664 +/- 142 mg/l, P = 0.73). A receiver-operating characteristic (ROC) plot revealed a maximum sensitivity and specificity combination of 69% and 91% (TSA cut-off concentration 595 mg/l) in distinguishing between healthy dogs and dogs with tumours. When evaluating TSA measurements to distinguish dogs with other diseases from dogs with tumours, a maximum sensitivity and specificity combination of 50% and 75% was found (cut-off concentration 761 mg/l). WHO staging of mammary tumours revealed an increase in TSA levels with increasing stage (P < 0.0001, rs, = 0.62). In conclusion, the nonspecificity of increases makes TSA determinations unsuitable as a tumour marker. TSA levels seem instead to be a general disease marker. Whether serial TSA measurements could be used in the follow-up of dogs operated for malignant tumours should be further investigated.