Ronald Wong - Academia.edu (original) (raw)

Papers by Ronald Wong

Birth Defects Research, Jul 15, 2015

Background-Spina bifida is the most common form of neural tube defects (NTDs). Etiologies of NTDs... more Background-Spina bifida is the most common form of neural tube defects (NTDs). Etiologies of NTDs are multifactorial, and oxidative stress is believed to play a key role in NTD development. Heme oxygenase (HO), the rate-limiting enzyme in heme degradation, has multiple protective properties including mediating antioxidant processes, making it an ideal candidate for study. The inducible HO isoform (HO-1) has two functional genetic polymorphisms: (GT) n dinucleotide repeats and A(−413)T SNP (rs2071746), both of which can affect its promoter activity. However, no study has investigated a possible association between HO-1 genetic polymorphisms and risk of NTDs. Methods-This case-control study included 152 spina bifida cases (all myelomeningoceles) and 148 non-malformed controls obtained from the California Birth Defects Monitoring Program reflecting births during 1990-99. Genetic polymorphisms were determined by PCR and AFLP/ RFLP using genomic DNA extracted from archived newborn blood spots. Genotype and haplotype frequencies of two HO-1 promoter polymorphisms between cases and controls were compared. Results-For (GT)n dinucleotide repeat lengths and the A(−413)T SNP, no significant differences in allele frequencies or genotypes were found. Linkage disequilibrium was observed between the HO-1 polymorphisms (D': 0.833); however, haplotype analyses did not show increased risk of spina bifida overall or by race/ethnicity. Conclusion-Although, an association was not found between HO-1 polymorphisms and risk of spina bifida, we speculate that the combined effect of low HO-1 expression and exposures to known environmental oxidative stressors (low folate status or diabetes), may overwhelm antioxidant defenses and increase risk of NTDs and warrants further study.

Pediatric Research, Jul 2, 2018

Background: Bilirubin-induced neurologic dysfunction (BIND) is a spectrum of preventable neurolog... more Background: Bilirubin-induced neurologic dysfunction (BIND) is a spectrum of preventable neurological sequelae in jaundiced newborns. Current total plasma bilirubin (B T) concentration thresholds for phototherapy and/or exchange transfusion poorly predict BIND. Methods: The unbound (free) bilirubin (B f) measured at these B T thresholds provides additional information about the risk for BIND. B f can be readily adapted to clinical use by determining B f population parameters at current B T thresholds. These parameters can be established using a plasma bilirubin binding panel (BBP) consisting of B T , B f , and two empiric constants, the maximum B T (B Tmax) and the corresponding equilibrium association bilirubin constant (K). Results: B Tmax and K provide the variables needed to accurately estimate B f at B T < B Tmax to obtain B f at threshold B T in patient samples. Once B f population parameters are known, the BBP in a newborn can be used to identify poor bilirubin binding (higher B f at the threshold B T compared with the population) and increased risk of BIND. Conclusion: The BBP can also be used in jaundice screening to better identify the actual B T at which intervention would be prudent. The BBP is used with current B T thresholds to better identify the risk of BIND and whether and when to intervene.

Pediatric Research, May 11, 2012

Articles Translational Investigation nature publishing group Background: Neonatal hyperbilirubine... more Articles Translational Investigation nature publishing group Background: Neonatal hyperbilirubinemia arises from increased bilirubin production and decreased bilirubin elimination. Although phototherapy safely and effectively reduces bilirubin levels, recent evidence shows that it has adverse effects. Therefore, alternative treatments are warranted. Metalloporphyrins, competitive inhibitors of heme oxygenase (hO), the rate-limiting enzyme in bilirubin production, effectively reduce bilirubin formation; however, many are photoreactive. here, we investigated possible photosensitizing effects of chromium mesoporphyrin (crMP) and zinc deuteroporphyrin bis-glycol (ZnBG). Methods and results: Administration of crMP or ZnBG to 3-d-old mouse pups (3.75-30.0 µmol/kg intraperitoneally) and exposure to cool white (F20T12cW) and blue (TL20W/52) fluorescent lights (+L) for 3 h, resulted in a dose-dependent mortality (50% lethal dose (LD50) = 21.5 and 19.5 µmol/kg, respectively). In contrast to ZnBG, there was no significant difference in survival between the crMP+L and crMP groups. Following 30 µmol/kg ZnBG+L, we found significant weight loss, decreased liver antioxidant capacities, and increased aspartate aminotransaminase levels. At 6-d post-light exposure, ZnBG+L-treated pups showed gross and histologic skin changes at doses >7.5 µmol/kg. No lethality was observed following treatment with 30 µmol ZnBG/kg plus exposure to blue light-emitting diodes. Phototoxicity of ZnBG was dependent on light source, emission spectrum, and irradiance. conclusion: Low doses of ZnBG (<3.75 µmol/kg) retained maximal hO inhibitory potency without photosensitizing effects, and therefore are potentially useful in treating neonatal hyperbilirubinemia.

Frontiers in Pediatrics, Dec 14, 2020

In recent years, there have been major advances in the application of non-invasive techniques to ... more In recent years, there have been major advances in the application of non-invasive techniques to predict pregnancy-related complications, for example by measuring cell-free RNA (cfRNA) in maternal blood. In contrast to cell-free DNA (cfDNA), which is already in clinical use to diagnose fetal aneuploidy, circulating RNA levels can correspond with tissue-specific gene expression and provide a snapshot of prenatal health across gestation. Here, we review the physiologic origins of cfRNA and its novel applications and corresponding challenges to monitor fetal and maternal health and predict pregnancy-related complications.

Pediatric Research, May 23, 2018

BACKGROUND: Sepsis in preterm infants is associated with systemic inflammatory responses. The str... more BACKGROUND: Sepsis in preterm infants is associated with systemic inflammatory responses. The stress-response protein heme oxygenase-1 (HO-1) has protective anti-inflammatory properties. Recently, we reported a protective role of HO-1 using our nonsurgical cecal slurry (CS) model in wild-type (WT) mouse pups. Here, we extend these findings to investigate the association of HO-1 deficiency with sepsis severity. METHODS: Adapting the Wynn model, we induced sepsis in 4-day-old HO-1-deficient (HO-1 +/− , Het) pups to determine if HO-1 deficiency affected survival rates at the LD40 (2.0 mg/g) of WT pups. To see if HO-1 induction affected sepsis severity, we gave 30μmol heme/kg subcutaneously to 3-day-old mice 24 h prior to sepsis induction. RESULTS: Post-sepsis induction, Het pups had a mortality of 85.0% (n = 20) and increased expression of the pro-inflammatory gene in the livers and affected hematologic profiles. Heme treatment 24 h prior to sepsis induction significantly increased liver HO activity, reduced mortality to 24.5% (n = 17), attenuated inflammatory responses, reduced spleen bacterial counts, and significantly increased peripheral neutrophils. CONCLUSIONS: A partial deficiency in HO-1 increased the progression and mortality in sepsis. Furthermore, induction of HO-1 significantly reduced the mortality even in Het pups. Thus, we conclude that HO-1 plays an important role in the protection against preterm sepsis.

Biochemical and Biophysical Research Communications, Mar 1, 2007

Tin mesoporphyrin (SnMP), a competitive heme oxygenase (HO) inhibitor, also induces HO-1 mRNA and... more Tin mesoporphyrin (SnMP), a competitive heme oxygenase (HO) inhibitor, also induces HO-1 mRNA and protein expression by a mechanism that is not fully understood. We examined whether the induction by SnMP is mediated by a de-repression of Bach1, a transcription factor that suppresses the HO-1 gene. Incubation of NIH3T3-HO-1-luc cells with SnMP attenuated HO activity with a concomitant increase in HO-1 mRNA and protein and a decrease in Bach1 and HO-2 proteins, which was not due to transcriptional down-regulation, but accelerated protein decay. Similarly, HO-1 protein degradation was increased by SnMP, despite of an elevation in HO-1 transcription. Transfection of Bach1 shRNA in Hepa cells raised basal HO-1 expression significantly, and SnMP treatment further increased HO-1 mRNA. In conclusion, SnMP induces HO-1 expression not only by de-repressing the HO-1 promoter by binding Bach1, but also by accelerating Bach1 degradation.

Frontiers in Pharmacology, Jan 14, 2015

Pregnancy can be defined as a "permissible" process, where a semi-allogeneic fetus and placenta a... more Pregnancy can be defined as a "permissible" process, where a semi-allogeneic fetus and placenta are allowed to grow and survive within the mother. Similarly, in tumor growth, antigen-specific malignant cells proliferate and evade into normal tissues of the host. The microenvironments of the placenta and tumors are amazingly comparable, sharing similar mechanisms exploited by fetal or cancer cells with regard to surviving in a hypoxic microenvironment, invading tissues via degradation and vasculogenesis, and escaping host attack through immune privilege. Heme oxygease-1 (HO-1) is a stress-response protein that has antioxidative, anti-apoptotic, pro-angiogenic, and anti-inflammatory properties. Although a large volume of research has been published in recent years investigating the possible role(s) of HO-1 in pregnancy and in cancer development, the molecular mechanisms that regulate these "yin-yang" processes have still not been fully elucidated. Here, we summarize and compare pregnancy and cancer development, focusing primarily on the function of HO-1 in cellular invasion, cytoprotection, angiogenesis, and immunomodulation. Due to the similarities of both processes, a thorough understanding of the molecular mechanisms of each process may reveal and guide the development of new approaches to prevent not only pregnancy disorders; but also, to study cancer.

Placenta, Oct 1, 2009

Heme oxygenase (HO) is the rate-limiting enzyme in the heme catabolic pathway and highly expresse... more Heme oxygenase (HO) is the rate-limiting enzyme in the heme catabolic pathway and highly expressed in the placenta. Deficiencies in HO-1, the inducible isoform, have been associated with pregnancy disorders, such as recurrent miscarriages, intrauterine growth retardation, and preeclampsia. The aim of this study was to identify if a deficiency in HO-1 affects placental development using a mouse model. When HO-1 heterozygote (Het, HO-1 +/−) mice were cross-bred, an extremely low birth rate in homozygote (Mut, HO-1 −/−) offspring (2.4%) and small litter sizes were observed. Placentas and fetuses from Het cross-breedings were relatively smaller and weighed less than those from wild-type (WT) cross-breedings at E12.5 and E15.5. Furthermore, Het placentas had significantly less HO-1 mRNA and protein levels than WT placentas, but no significant differences in placental HO activity. Interestingly, HO-2, the constitutive HO isoform, as well as iNOS and eNOS expression were significantly upregulated in Het placentas. Histological examination showed that the junctional zone (JZ) of Het placentas were markedly thinner than those of WT placentas and appeared to be due to an increase in apoptosis. Immunohistochemistry revealed that HO-1-expressing cells were located primarily in the JZ of Het placentas, specifically in the spongiotrophoblast layer. In addition, diastolic blood pressures and plasma soluble VEGFR-1 (sFlt-1) levels were significantly elevated in pregnant Het mice. We conclude that a partial deficiency in HO-1 is associated with morphological changes in the placenta and elevations in maternal diastolic blood pressure and plasma sFlt-1 levels, despite a compensatory increase in HO-2 expression.

Reproductive Sciences, Jun 13, 2022

Racial disparity exists for hypertensive disorders in pregnancy (HDP), which leads to disparate m... more Racial disparity exists for hypertensive disorders in pregnancy (HDP), which leads to disparate morbidity and mortality worldwide. The enzyme heme oxygenase-1 (HO-1) is encoded by HMOX1, which has genetic polymorphisms in its regulatory region that impact its expression and activity and have been associated with various diseases. However, studies of these genetic variants in HDP have been limited. The objective of this study was to examine HMOX1 as a potential genetic contributor of ancestral disparity seen in HDP. First, the 1000 Genomes Project (1 KG) phase 3 was utilized to compare the frequencies of alleles, genotypes, and estimated haplotypes of guanidine thymidine repeats (GTn; containing rs3074372) and A/T SNP (rs2071746) among females from five ancestral populations (Africa, the Americas, Europe, East Asia, and South Asia, N = 1271). Then, using genomic DNA from women with a history of HDP, we explored the possibility of HMOX1 variants predisposing women to HDP (N = 178) compared with an equivalent ancestral group from 1 KG (N = 263). Both HMOX1 variants were distributed differently across ancestries, with African women having a distinct distribution and an overall higher prevalence of the variants previously associated with lower HO-1 expression. The two HMOX1 variants display linkage disequilibrium in all but the African group, and within EUR cohort, LL and AA individuals have a higher prevalence in HDP. HMOX1 variants demonstrate ancestral differences that may contribute to racial disparity in HDP. Understanding maternal genetic contribution to HDP will help improve prediction and facilitate personalized approaches to care for HDP.

American Journal of Obstetrics and Gynecology, 2018

Pediatric Research, Oct 10, 2022

Immunoperinatology is an emerging field. Transdisciplinary efforts by physicians, physician-scien... more Immunoperinatology is an emerging field. Transdisciplinary efforts by physicians, physician-scientists, basic science researchers, and computational biologists have made substantial advancements by identifying unique immunologic signatures of specific diseases, discovering innovative preventative or treatment strategies, and establishing foundations for individualized neonatal intensive care of the most vulnerable neonates. In this review, we summarize the immunobiology and immunopathology of pregnancy, highlight omics approaches to study the maternal-fetal interface, and their contributions to pregnancy health. We examined the importance of transdisciplinary, multiomic (such as genomics, transcriptomics, proteomics, metabolomics, and immunomics) and machinelearning strategies in unraveling the mechanisms of adverse pregnancy, neonatal, and childhood outcomes and how they can guide the development of novel therapies to improve maternal and neonatal health.

Pediatric Research, Nov 1, 2011

Infants with hemolytic diseases frequently develop hyperbilirubinemia and are treated with photot... more Infants with hemolytic diseases frequently develop hyperbilirubinemia and are treated with phototherapy, which only eliminates bilirubin after its production. A better strategy might be to directly inhibit heme oxygenase (HO), the rate-limiting enzyme in bilirubin production. Metalloporphyrins (Mps) are heme analogs that competitively inhibit HO activity in vitro and in vivo and suppress plasma bilirubin levels in vivo. A promising Mp, zinc deuteroporphyrin bis glycol (ZnBG), is orally absorbed and effectively inhibits HO activity at relatively low doses. We determined the I 50 (the dose needed to inhibit HO activity by 50%) of orally administered ZnBG in vivo and then evaluated ZnBG's effects on in vivo bilirubin production, HO activity, HO protein levels, and HO-1 gene expression in newborn mice after heme loading, a model analogous to a hemolytic infant. The I 50 of ZnBG was found to be 4.0 mol/kg body weight (BW). At a dose of 15 mol/kg BW, ZnBG reduced in vivo bilirubin production, inhibited heme-induced liver HO activity and spleen HO activity to and below baseline, respectively, transiently induced liver and spleen HO-1 gene transcription, and induced liver and spleen HO-1 protein levels. We conclude that ZnBG may be an attractive compound for treating severe neonatal hyperbilirubinemia caused by hemolytic disease.

Pediatric Research, Oct 21, 2015

Basic Science Investigation nature publishing group Background: Increased bilirubin production du... more Basic Science Investigation nature publishing group Background: Increased bilirubin production due to hemolysis can lead to neonatal hyperbilirubinemia. Inhibition of heme oxygenase (HO), the rate-limiting enzyme in heme catabolism, by metalloporphyrins (Mps) may be an ideal preventive strategy for neonatal hemolytic disease. Zinc protoporphyrin (ZnPP) is a naturally occurring Mp, potent, not phototoxic, with minimal HO-1 upregulation, but is not orally absorbed. Recently, we designed a lipid-based ZnPP formulation (ZnPP-Lipid), which is orally absorbed by newborn mice. Here, we evaluated the efficacy of ZnPP-Lipid in heme-loaded newborn mice, a model analogous to hemolytic infants. Methods: After 24 h of heme administration (30 µmol/kg s.c.), 4-d-old mice were given 30 µmol ZnPP-Lipid/kg via intragastric injections. After 3 h, liver and brain HO activity were measured. HO-1 upregulation was assessed by determinations of HO-1 protein, promoter activity, and mRNA by Western blot, in vivo bioluminescence imaging, and RT-PCR, respectively. results: After heme loading, liver HO activity significantly increased ~1.6-fold, which was inhibited in a dose-dependent manner by ZnPP-Lipid. A dose of 30 µmol/kg returned activity to control levels. Brain HO activity was not inhibited. No significant increases in liver and brain HO-1 protein, promoter activity, and mRNA were observed. conclusion: ZnPP-Lipid is effective and thus has potential for treating neonatal hyperbilirubinemia due to hemolysis.

JCI insight, Feb 13, 2020

PLOS ONE, Feb 19, 2016

Heme oxygenase-1 (HO-1), the rate-limiting enzyme in heme degradation, is a cytoprotective enzyme... more Heme oxygenase-1 (HO-1), the rate-limiting enzyme in heme degradation, is a cytoprotective enzyme upregulated in the vasculature by increased flow and inflammatory stimuli. Human genetic data suggest that a diminished HO-1 expression may predispose one to abdominal aortic aneurysm (AAA) development. In addition, heme is known to strongly induce HO-1 expression. Utilizing the porcine pancreatic elastase (PPE) model of AAA induction in HO-1 heterozygous (HO-1 +/-, HO-1 Het) mice, we found that a deficiency in HO-1 leads to augmented AAA development. Peritoneal macrophages from HO-1 +/mice showed increased gene expression of pro-inflammatory cytokines, including MCP-1, TNF-alpha, IL-1beta, and IL-6, but decreased expression of anti-inflammatory cytokines IL-10 and TGF-beta. Furthermore, treatment with heme returned AAA progression in HO-1 Het mice to a wild-type profile. Using a second murine AAA model (Ang II-ApoE-/-), we showed that low doses of the HMG-CoA reductase inhibitor rosuvastatin can induce HO-1 expression in aortic tissue and suppress AAA progression in the absence of lipid lowering. Our results support those studies that suggest that pleiotropic statin effects might be beneficial in AAA, possibly through the upregulation of HO-1. Specific targeted therapies designed to induce HO-1 could become an adjunctive therapeutic strategy for the prevention of AAA disease.

Seminars in fetal & neonatal medicine, Jun 1, 2010

Neonatal jaundice in the first week of life is a common problem in newborns. It is due to an imba... more Neonatal jaundice in the first week of life is a common problem in newborns. It is due to an imbalance of bilirubin production and its elimination, which can lead to significantly elevated levels of circulating bilirubin or hyperbilirubinemia. Use of phototherapy and/or exchange transfusion are the current modes for treating neonatal hyperbilirubinemia and preventing any neurologic damage. These strategies, however, only remove bilirubin that has already been formed. Preventing the production of excess bilirubin may be a more logical approach. Synthetic heme analogs, metalloporphyrins, are competitive inhibitors of heme oxygenase (HO), the ratelimiting enzyme in bilirubin production, and their use has been proposed as an attractive alternative strategy for preventing or treating severe hyperbilirubinemia.

Biology of Reproduction, Nov 1, 2011

The placental vasculature is critical for nutrient, gas, and waste exchange between the maternal ... more The placental vasculature is critical for nutrient, gas, and waste exchange between the maternal and fetal systems. Its development depends on the proper expression and interaction of angiogenesis and associated growth factors. Heme oxygenase (HMOX), the enzyme for heme degradation, plays a role in angiogenesis and is highly expressed in the placenta. To evaluate the role of maternal HMOX1, the inducible HMOX isozyme, on placental vasculature formation, mice with a partial deficiency in Hmox1 (Hmox1 +/À) were used. Three-dimensional images of placental vasculatures as well as spiral arteries from Hmox1 +/+ or Hmox1 +/À placentas were created by vascular corrosion casting technique and imaged by micro-computerized tomography (microCT). The structures and morphologies of fetomaternal interfaces were observed by histological staining and the ultrastructure of uterine natural killer (uNK) cells, a major regulator in spiral artery remodeling, was analyzed by transmission electron microscopy. A group of growth factors and angiogenic factors from the decidua/mesometrial lymphoid aggregate of pregnancy (MLAp) as well as labyrinth regions were quantified using an angiogenesis PCR array kit and compared between Hmox1 +/+ or Hmox1 +/À placentas. In conclusion, a partial deficiency of maternal Hmox1 resulted in the malformation of fetomaternal interface, insufficiency of spiral artery remodeling, and alteration of uNK cell differentiation and maturation. These changes were independent of the fetal genotype, but relied on the maternal HMOX1 level, which determined the balance of expression levels of pro-and antiangiogenic factors in the decidua/MLAp region. These results implied that Hmox1 polymorphisms among the human population might contribute to some unexplained cases of pregnancy disorders, such as fetal growth retardation and preeclampsia. angiogenesis, heme oxygenase 1, intrauterine growth restriction (IUGR), placenta, spiral artery remodeling, uterine natural killer (uNK) cell

Frontiers in Pharmacology, Apr 24, 2015

Normal pregnancy is an immunotolerant state. Many factors, including environmental, socioeconomic... more Normal pregnancy is an immunotolerant state. Many factors, including environmental, socioeconomic, genetic, and immunologic changes by infection and/or other causes of inflammation, may contribute to inter-individual differences resulting in a normal or pathologic pregnancy. In particular, imbalances in the immune system can cause many pregnancy-related diseases, such as infertility, abortions, pre-eclampsia, and preterm labor, which result in maternal/fetal death, prematurity, or small-for-gestational age newborns. New findings imply that myeloid regulatory cells and regulatory T cells (Tregs) may mediate immunotolerance during normal pregnancy. Effector T cells (Teffs) have, in contrast, been implicated to cause adverse pregnancy outcomes. Furthermore, fetomaternal tolerance affects the developing fetus. It has been shown that the Treg/Teff balance affects litter size and adoptive transfer of pregnancy-induced Tregs can prevent fetal rejection in the mouse. Heme oxygenase-1 (HO-1) has a protective role in many conditions through its anti-inflammatory, anti-apoptotic, antioxidative, and anti-proliferative actions. HO-1 is highly expressed in the placenta and plays a role in angiogenesis and placental vascular development and in regulating vascular tone in pregnancy. In addition, HO-1 is a major regulator of immune homeostasis by mediating crosstalk between innate and adaptive immune systems. Moreover, HO-1 can inhibit inflammation-induced phenotypic maturation of immune effector cells and pro-inflammatory cytokine secretion and promote anti-inflammatory cytokine production. HO-1 may also be associated with T-cell activation and can limit immune-based tissue injury by promoting Treg suppression of effector responses. Thus, HO-1 and its byproducts may protect against pregnancy complications by its immunomodulatory effects, and the regulation of HO-1 or its downstream effects has the potential to prevent or treat pregnancy complications and prematurity.

Journal of Perinatology, Dec 1, 2001

International Journal of Molecular Sciences, Sep 7, 2021

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY