Enzyme-cytochemically detectable glucose-6-phosphate dehydrogenase in human villous macrophages (Hofbauer cells)

Hofbauer Cells: Placental Macrophages of Fetal Origin

Pregnancy complications such as preterm birth, miscarriage, maternal and/or neonatal morbidities, and mortality can be manifestations of underlying placental pathology. Hofbauer cells refer to a heterogeneous population of fetal macrophages that reside within the functional unit of the placenta known as the chorionic villus. Hofbauer cells can be detected within the connective tissue matrix of the placenta as early as 4 weeks post-conception and are present throughout pregnancy. These cells are implicated in a wide array of functions important for a successful pregnancy including placental morphogenesis, immune regulation, control of stromal water content, and the transfer of ions and serum proteins across the maternal-fetal barrier. Derangements in Hofbauer cell homeostasis are associated with placental pathologies involving infection, inflammation, and inadequate placental development. Despite a growing body of evidence that these cells are important, our knowledge about Hofbauer cell function in both normal and dysfunctional pregnancy is rudimentary. The goal of this chapter is to provide an overview of what is known about Hofbauer cell origins and their potential roles in normal and complicated pregnancy. We also review established and emerging methodologies available for the study of Hofbauer cells during in vitro and in vivo conditions.

Characterization of cytokine production by human term placenta macrophages in vitro

PROBLEM

Macrophages are apparently the only immune cells within placenta villi, yet functions of these cells remain obscure. It has been postulated that placental macrophages accomplish regulatory roles at the fetal-maternal interface by means of wide variety of secreted cytokines. We attempt to analyze the patterns of cytokine production in an isolated population of placental macrophages.

METHOD OF STUDY

Macrophages were obtained from term placentas in the absence of spontaneous labor. The basal and lipopolysaccharide (LPS)-stimulated levels of intracellular cytokines were detected by flow cytometry. The basal cytokine secretion was determined by BD Cytometry Bead Array (BD Biosciences, San Diego, CA, USA).

RESULTS

Intracellular IL-1alpha, IL-1beta, IL-6, and TNFalpha were detected in 31, 27, 4, and 3% CD68+ cells, respectively. Stimulation with LPS increased the proportions of cytokine-producing CD68+ cells to 48, 50, 28, and 49%, respectively. Under basal conditions, levels of released TNFalpha and IL-6, respectively, were 20- and 25-fold higher when compared with IL-1b while IL-10 was secreted in small but detectable amounts. When a secretory activity was estimated for cytokine-producing cells, the secretion rate for TNFalpha and IL-6 overwhelmingly surpassed that for IL-1beta (TNFalpha:IL-6:IL-1beta ratio was 192:145:1).

CONCLUSION

These results suggest functional heterogeneity of the placental macrophage population and contribute to the elucidation of regulatory roles of these cells in gestation.

Multi-mutational analysis of fifteen common mutations of the glucose 6-phosphate dehydrogenase gene in the Mediterrranean population

BACKGROUND

Glucose-6-phosphate dehydrogenase (G6PD) is a cytosolic enzyme encoded by a housekeeping X-linked gene whose main function is to produce NADPH, a key electron donor in the defence against oxidizing agents and in reductive biosynthetic reactions. Many variants of G6PD have been described, mostly produced from missense mutations, with wide ranging levels of enzyme activity and associated clinical symptoms.

METHOD

A single base extension assay is used, yielding a single base difference of the extended products. Primers are designed to amplify products of different sizes with distinct fluorescent dyes in order to accurately distinguish all possible combinations of genotypes (homozygous and heterozygous for each mutation) in a multiplex PCR analysis.

RESULTS

We present the first application of a multiplex multicolour assay to detect 15 of the most frequent G6PD-related mutations in Spain, which are studied in three multiplex reactions. Capillary electrophoresis analysis of the amplified products enables easy, rapid, unambiguous and high-resolution discrimination between wild-type and mutant alleles, even though various mutations may be present in the multiplex analysis.

CONCLUSION

The analytical method described herein offers greater diagnostic power in Spanish and Mediterranean populations and would facilitate automated genotyping in routine molecular diagnostics and large-scale genetic studies (e.g., newborn screening programs).

A comprehensive study on the major mutations in glucose-6-phosphate dehydrogenase-deficient polymorphic variants identified in the coastal provinces of Caspian Sea in the north of Iran

BACKGROUND

The aim of this study was the molecular analysis of G6PD patients for G6PD mutations in the coastal provinces of the Caspian Sea in north of Iran.

METHODS

Studies on G6PD deficiency in the coastal provinces of the Caspian Sea in Iran were performed in 248 patients with a history of favism, in Mazandaran, Golestan and Gillan provinces, which contributed 74, 71 and 103 samples, respectively. Three different major polymorphic variants were determined by molecular analysis, using SSCP, sequencing and PCR-RFLP methods. Firstly, all Mazandaranian samples were searched for the Mediterranean mutation by PCR-RFLP method. The remaining samples of the Mazandaran province were analysed by SSCP followed by sequencing for other mutations. Then, our research was expanded in two other provinces, Golestan and Gillan, by the PCR-RFLP method.

RESULTS

Three different major polymorphic variants were found: G6PD Mediterranean 75.4% (187 out of 248), G6PD Chatham 19.76% (49 out of 248), G6PD Cosenza 2.02% (5 out of 248) and 7 samples out of 248 remained unknown. Also, there was no significant difference in the incidence of various G6PD polymorphic variants with mean age, and various blood work values such as Hb, WBC and MCV between two major variants (p>0.20).

CONCLUSIONS

These results which are the first molecular investigation in north of Iran indicate a higher prevalence of G6PD Chatham in this large Iranian population than anywhere else in the world. The distribution of these G6PD variants is more similar to that found in an Italian population (80-84% for Mediterranean, 20% for Chatham and 1.9% for Cosenza mutation). Although the origin of Iranian population is rather uncertain, the closer similarity of the mutation spectrum to Italian rather than Middle Eastern population may indicate that these populations have a common ancestral origin.

The overexpression of NADPH-producing enzymes counters the oxidative stress evoked by gallium, an iron mimetic

Gallium (Ga), an iron (Fe) mimetic promoted an oxidative environment and elicited an antioxidative response in Pseudomonas fluorescens. Ga-stressed P. fluorescens was characterized by higher amounts of oxidized lipids and proteins compared to control cells. The oxidative environment provoked by Ga was nullified by increased synthesis of NADPH. The activity and expression glucose 6-phosphate dehydrogenase (G6PDH) and isocitrate dehydrogenase-NADP (ICDH) were stimulated in Ga-cultures. The induction of isoenzymes of these dehydrogenases was also evident in the Ga-stressed cells. Although superoxide dismutase (SOD) activity was significantly enhanced in Ga-stressed cultures, catalase activity experienced a marked diminution. Fe metabolism appeared to be severely impeded by Ga toxicity. This is the first demonstration of the oxidative stress evoked by Ga to be neutralized by a reductive environment generated via the overexpression of NADPH-producing enzymes.

Detection and purification of glucose 6-phosphate dehydrogenase, malic enzyme, and NADP-dependent isocitrate dehydrogenase by blue native polyacrylamide gel electrophoresis

We describe a blue native polyacrylamide gel electrophoretic technique that allows the facile detection, quantitation and purification of three NADPH-producing enzymes. Glucose 6-phosphate dehydrogenase, malic enzyme and NADP-dependent isocitrate dehydrogenase were detected simultaneously. Activity staining based on the formation of NADPH from the respective substrates and the subsequent precipitation of formazan enabled the relative quantitation of enzymatic activities, while Coomassie staining on one-dimensional or two-dimensional gels helped monitor the amount of protein associated with these enzymatic activities. This technique provides a simple and effective route to obtain homogeneous protein for further analyses and also enables the screening of these NADPH-producing enzymes in various cellular systems.

Pathophysiological basis for the prophylaxis of preeclampsia through early supplementation with antioxidant vitamins

Preeclampsia (PE) is a multisystem disorder that remains a major cause of maternal and foetal morbidity and death. To date, no treatment has been found that prevents the development of the disease. Endothelial dysfunction is considered to underlie its clinical manifestations, such as maternal hypertension, proteinuria, and edema; however, the precise biochemical pathways involved remain unclear. A current hypothesis invokes the occurrence of oxidative stress as pathogenically important, as suggested by the fact that in PE, the placental and circulating levels of lipid peroxidation products (F2-isoprostanes and malondialdehyde [MDA]) are increased and endothelial cells are activated. A potential mechanism for endothelial dysfunction may occur via nuclear transcription factor kappa B (NF-kappaB) activation by oxidative stress. Alternatively, the idea that the antiangiogenic placental soluble fms-like tyrosine kinase 1 factor (sFlt1) is involved in the pathogenesis of this disease is just emerging; however, other pathophysiological events seem to precede its increased production. This review is focused on evidence providing a pathophysiological basis for the beneficial effect of early antioxidant therapy in the prevention of PE, mainly supported by the biological effects of vitamins C and E.

Hofbauer cell activation and its increased glucose-6-phosphate dehydrogenase activity in second trimester-spontaneous abortion: an ultrastructural dual staining enzyme-cytochemical study

PROBLEM

While activated/phagocytosing phagocytes infiltrating to the chorioamnion are considered to be one of the causal agents of preterm labor onset, whether placental villous macrophages (Hofbauer cells) are activated/phagocytosing in this condition is not known.

METHOD OF STUDY

We concomitantly localized two important phagocytosis-related enzymes, acid phosphatase (ACP) and glucose-6-phosphate dehydrogenase (G6PD), in Hofbauer cells in second trimester placental villi, and compared them with those from infection-related second trimester-spontaneous abortion (miscarriage) placentas.

RESULTS

There were two types of Hofbauer cells. The first cells exhibited ACP stainings confined to the lysosomes, suggesting that they are dormant/non-activated cells. Approximately two-thirds of these cells showed weak G6PD labeling on the cytosolic side of endoplasmic reticula, and G6PD labeling was hardly recognizable in the remaining one-third. The second cells, possessing large phagosomes, showed marked ACP labeling in the phagosomes, suggesting that they are activated/phagocytosing cells. All these cells exhibited G6PD labeling, and in 'bursting cells' (possibly hyperactivated cells) G6PD deposits were marked. The percentage of activated cells in miscarriage placentas was significantly higher (44.8 +/- 6.0%) than that in gestational age-matched controls (17.4 +/- 5.3%).

CONCLUSIONS

These observations indicated that (1) G6PD activity increased in activated/phagocytosing Hofbauer cells, and (2) the percentage of phagocytosing cells increased in infection-related miscarriage placentas. Hofbauer activation and G6PD may play an role in the pathogenesis/pathophysiology of preterm labor onset.