Harshwardhan M Thaker

Columbia University, New York City, NY, United States

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Publications (21)63.1 Total impact

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    ABSTRACT: Attempts to enhance patients' immune responses to malignancies have been largely unsuccessful. We now describe an immune-escape mechanism mediated by the inhibitory receptor Ig-like transcript 3 (ILT3) that may be responsible for such failures. Using a humanized SCID mouse model, we demonstrate that soluble and membrane ILT3 induce CD8(+) T suppressor cells and prevent rejection of allogeneic tumor transplants. Furthermore, we found that patients with melanoma, and carcinomas of the colon, rectum, and pancreas produce the soluble ILT3 protein, which induces the differentiation of CD8(+) T suppressor cells and impairs T cell responses in MLC. These responses are restored by anti-ILT3 mAb or by depletion of soluble ILT3 from the serum. Immunohistochemical staining of biopsies from the tumors and metastatic lymph nodes suggests that CD68(+) tumor-associated macrophages represent the major source of soluble ILT3. Alternative splicing, resulting in the loss of the ILT3 transmembrane domain, may contribute to the release of ILT3 in the circulation. These data suggest that ILT3 depletion or blockade is crucial to the success of immunotherapy in cancer. In contrast, the inhibitory activity of soluble ILT3 on T cell alloreactivity in vitro and in vivo suggests the potential usefulness of rILT3 for immunosuppressive treatment of allograft recipients or patients with autoimmune diseases.
    The Journal of Immunology 07/2007; 178(11):7432-41. · 5.52 Impact Factor
  • Laxmi Baxi, Stephen Brown, Harshwardhan M Thaker
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    ABSTRACT: In the literature, conflicting reports on the significance of false-positive maternal serum multiple marker testing for trisomy 18 are encountered; however, the biology of this finding is discussed infrequently. We present such a case in association with Bloom's syndrome in the fetus. The fetus had intrauterine growth restriction, seen early in the second trimester, oligohydramnios, and was delivered at 34 weeks of gestation for impending fetal compromise. We propose that the adverse outcome of the pregnancy with false-positive serum analyte testing for trisomy 18 might result from a small-sized placenta and perhaps pathology at receptor level.
    Fetal Diagnosis and Therapy 02/2007; 22(4):318-20. · 1.90 Impact Factor
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    ABSTRACT: Glycogen storage disease type IV (GSD-IV) is a rare autosomal recessive disorder due to mutations in the GBE1 gene causing deficiency of the glycogen branching enzyme (GBE). Prenatal diagnosis has occasionally been performed by the measurement of the GBE activity in cultured chorionic villi (CV) cells. Two unrelated probands with severe hypotonia at birth and death during the neonatal period were diagnosed with GSD-IV on the basis of postmortem histological findings. DNA analysis revealed truncating GBE1 mutations in both families. Prenatal diagnosis was performed in subsequent pregnancies by determination of branching enzyme activity and DNA analysis of CV or cultured amniocytes. Detailed autopsies of the affected fetuses at 14 and 24 weeks of gestation demonstrated intracellular inclusions of abnormal glycogen characteristic of GSD-IV. Prenatal diagnosis of GSD-IV by DNA analysis is highly accurate in genetically confirmed cases.
    Prenatal Diagnosis 11/2006; 26(10):951-5. · 2.68 Impact Factor
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    ABSTRACT: We sought to determine the accuracy of antenatal diagnosis of twin chorionicity at a single tertiary care center and assess the consequences of incorrect diagnoses. Twins with chorionicity diagnosed by ultrasound < or = 24 weeks' gestation were retrospectively reviewed. Chorionicity was assigned by sonographic findings including placental location(s), the lambda and T-signs, and/or fetal gender(s). Postnatal diagnosis was determined by placental histopathologic examination. Medical records of antenatal-postnatal discordant chorionicities were reviewed for adverse sequelae. Chorionicity was correctly assigned antenatally in 392/410 (95.6%) twins. The sensitivity, specificity, and positive and negative predictive values of monochorionicity assessed < or = 14 weeks were 89.8%, 99.5%, 97.8%, and 97.5%. Corresponding statistical values for the second trimester were 88.0%, 94.7%, 88.0%, and 94.7%. Two cases of inaccurate antenatal diagnoses affected patient counseling or were associated with adverse clinical outcomes. Antenatal assessment of chorionicity is accurate; however, incorrect diagnoses do occur and can affect reliable patient counseling and management.
    American journal of obstetrics and gynecology 09/2006; 195(3):863-7. · 3.28 Impact Factor
  • Xiangyuan Wang, Laxmi Baxi, Debra Wolgemuth, Harshwardhan Thaker
    American Journal of Obstetrics and Gynecology - AMER J OBSTET GYNECOL. 01/2006; 195(6).
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    ABSTRACT: Imprinted genes control fetal and placental growth in mice and in rare human syndromes, but the role of these genes in sporadic intrauterine growth restriction (IUGR) is less well-studied. We measured the ratio of mRNA from a maternally expressed imprinted gene, PHLDA2, to that from a paternally expressed imprinted gene, MEST, by Northern blotting in 38 IUGR-associated placentae and 75 non-IUGR placentae and found an increase in the PHLDA2/MEST mRNA ratio in IUGR (p=0.0001). Altered expression of PHLDA2 and MEST was not accompanied by changes in DNA methylation within their imprinting centers, and immunohistochemistry showed PHLDA2 protein appropriately restricted to villous and intermediate cytotrophoblast in the IUGR placentae. We next did a genome-wide survey of mRNA expression in 14 IUGR placentae with maternal vascular under-perfusion compared to 15 non-IUGR placentae using Affymetrix U133A microarrays. In this series six imprinted genes were differentially expressed by ANOVA with a Benjamini-Hochberg false discovery rate of 0.05, with increased expression of PHLDA2 and decreased expression of MEST, MEG3, GATM, GNAS and PLAGL1 in IUGR placentae. At lower significance, we found IGF2 mRNA decreased and CDKN1C mRNA increased in the IUGR cases. We confirmed the significant reduction in MEG3 non-translated RNA in IUGR placentae by Northern blotting. In addition to imprinted genes, the microarray data highlighted non-imprinted genes acting in endocrine signaling (LEP, CRH, HPGD, INHBA), tissue growth (IGF1), immune modulation (INDO, PSG-family genes), oxidative metabolism (GLRX), vascular function (AGTR1, DSCR1) and metabolite transport (SLC-family solute carriers) as differentially expressed in IUGR vs. non-IUGR placentae.
    Placenta 01/2006; 27(6-7):540-9. · 3.12 Impact Factor
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    ABSTRACT: Down syndrome (DS) is caused by trisomy 21 (+21), but the aberrations in gene expression resulting from this chromosomal aneuploidy are not yet completely understood. We used oligonucleotide microarrays to survey mRNA expression in early- and late-passage control and +21 fibroblasts and mid-gestation fetal hearts. We supplemented this analysis with northern blotting, western blotting, real-time RT-PCR, and immunohistochemistry. We found chromosome 21 genes consistently over-represented among the genes over-expressed in the +21 samples. However, these sets of over-expressed genes differed across the three cell/tissue types. The chromosome 21 gene MX1 was strongly over-expressed (mean 16-fold) in senescent +21 fibroblasts, a result verified by northern and western blotting. MX1 is an interferon target gene, and its mRNA was induced by interferons present in +21 fibroblast conditioned medium, suggesting an autocrine loop for its over-expression. By immunohistochemistry the p78MX1 protein was induced in lesional tissue of alopecia areata, an autoimmune disorder associated with DS. We found strong over-expression of the purine biosynthesis gene GART (mean 3-fold) in fetal hearts with +21 and verified this result by northern blotting and real-time RT-PCR. Different subsets of chromosome 21 genes are over-expressed in different cell types with +21, and for some genes this over-expression is non-linear (>1.5X). Hyperactive interferon signaling is a candidate pathway for cell senescence and autoimmune disorders in DS, and abnormal purine metabolism should be investigated for a potential role in cardiac defects.
    BMC Medical Genetics 01/2006; 7:24. · 2.54 Impact Factor
  • J McMinn, M Wei, Y Sadovsky, H M Thaker, B Tycko
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    ABSTRACT: The PEG1 gene (a.k.a. MEST) is expressed in human placental trophoblast and endothelium, and data from knockout mice show that this gene regulates placental and fetal growth. Isoform 1 of PEG1 mRNA initiates from exon 1c and produces the long form of the MEST protein. This isoform is imprinted, with expression only from the paternal allele in many human and mouse organs, including placenta. In contrast, PEG1 isoform 2, initiating from exon 1a and producing the short form of MEST protein, is biallelically expressed (non-imprinted) in several non-placental organs. Here we show that PEG1 isoform 2 is in fact imprinted in a large subset of human placentae. A CpG island overlapping PEG1 exon 1a is unmethylated in various fetal and adult non-placental tissues, but is often substantially methylated in the placenta, with the extent of methylation in a large series approximating a normal distribution. Bisulfite conversion/sequencing indicates that the inter-individual differences reflect the relative representation of heavily methylated vs. unmethylated alleles, and RT-PCR/RFLP analysis shows strongly biased allelic expression of PEG1 isoform 2 mRNA in a majority of placentae with a high proportion of methylated alleles. These data highlight PEG1 isoform 2 as a marker for future studies of inter-individual epigenetic variation and its relation to placental and fetal growth in humans.
    Placenta 01/2006; 27(2-3):119-26. · 3.12 Impact Factor
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    ABSTRACT: To understand genetic and epigenetic pathways in Wilms' tumors, we carried out a genome scan for loss of heterozygosity (LOH) using Affymetrix 10K single nucleotide polymorphism (SNP) chips and supplemented the data with karyotype information. To score loss of imprinting (LOI) of the IGF2 gene, we assessed DNA methylation of the H19 5' differentially methylated region (DMR). Few chromosomal regions other than band 11p13 (WT1) were lost in Wilms' tumors from Denys-Drash and Wilms' tumor-aniridia syndromes, whereas sporadic Wilms' tumors showed LOH of several regions, most frequently 11p15 but also 1p, 4q, 7p, 11q, 14q, 16q, and 17p. LOI was common in the sporadic Wilms' tumors but absent in the syndromic cases. The SNP chips identified novel centers of LOH in the sporadic tumors, including a 2.4-Mb minimal region on chromosome 4q24-q25. Losses of chromosomes 1p, 14q, 16q, and 17p were more common in tumors presenting at an advanced stage; 11p15 LOH was seen at all stages, whereas LOI was associated with early-stage presentation. Wilms' tumors with LOI often completely lacked LOH in the genome-wide analysis, and in some tumors with concomitant 16q LOH and LOI, the loss of chromosome 16q was mosaic, whereas the H19 DMR methylation was complete. These findings confirm molecular differences between sporadic and syndromic Wilms' tumors, define regions of recurrent LOH, and indicate that gain of methylation at the H19 DMR is an early event in Wilms' tumorigenesis that is independent of chromosomal losses. The data further suggest a biological difference between sporadic Wilms' tumors with and without LOI.
    Molecular Cancer Research 10/2005; 3(9):493-502. · 4.35 Impact Factor
  • American Journal of Obstetrics and Gynecology - AMER J OBSTET GYNECOL. 01/2005; 193(6).
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    ABSTRACT: We describe the clinical and pathologic features of an unusual case of alpha-thalassemia major in a patient who survived to term and lived for 9 days. The neonate was nonhydropic and the clinical picture was dominated by severe hypoxia with pulmonary hypertension. The diagnosis was not suspected until postnatal examination of the blood smear, which prompted the performance of hemoglobin electrophoresis and subsequent molecular confirmation. This case illustrates that alpha-thalassemia major should be in the differential diagnosis of hypoxic neonates even in the absence of hydrops.
    Pediatric and Developmental Pathology 01/2005; 8(6):706-9. · 0.86 Impact Factor
  • Harshwardhan M Thaker
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    ABSTRACT: The presence of a fetus in a molar pregnancy is usually an indication that it is a partial, rather than a complete, hydatidiform mole. The underlying reason for this is a basic difference in the genetic composition of the 2 types of mole. Complete moles are ‘‘androgenetic’’ conceptions, i.e., their genome is entirely paternal in origin [1]. The total absence of a maternal genetic contribution results in unopposed action of paternally expressed genes, leading to excessive trophoblastic proliferation and a very early cessation of embryonic development. Partial moles are almost all ‘‘diandric’’ triploids, with 1 maternal set and 2 paternal sets of chromosomes. The excess paternal genetic dose causes trophoblastic proliferation but is presumably kept in check by the maternal genetic contribution, which also permits the fetus to develop much further than in complete moles, sometimes well into the second trimester [2]. This marked difference in fetal viability between complete and partial moles has resulted in the dictum that ‘‘if it is a mole and if there is a fetus, then it must be a partial mole.’’ However, there are 2 important exceptions. First, the villi of early complete moles can show histologic evidence of fetal tissue, including endothelial cells, nucleated red cells, an amnion, and a yolk sac [3]. Second, a complete mole may be part of a dizygotic twin pregnancy in which the other conceptus is a normal well-developed fetus with its own nonmolar pla
    Pediatric and Developmental Pathology 01/2005; 8(2):146-7. · 0.86 Impact Factor
  • Sara E Monaco, Welton M Gersony, Harshwardhan M Thaker
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    ABSTRACT: We describe an infant with hypoplasia of the left heart diagnosed prenatally who, at birth, had signs of severe pulmonary venous obstruction. Echocardiography indicated normally connecting pulmonary veins, and showed a paradoxical right-to-left shunt across a patent oval foramen. Postmortem examination revealed that the obstruction was due to a divided left atrium, or cor triatriatum sinister, with an imperforate muscular diaphragm separating completely the two components of the divided atrium.
    Cardiology in the Young 11/2004; 14(5):553-6. · 0.95 Impact Factor
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    ABSTRACT: Hydatidiform moles are pregnancies characterized by abnormal development of both embryonic and extraembryonic tissues and are associated with the misexpression of imprinted genes. The vast majority of complete hydatidiform moles are diploid and androgenetic, whereas partial hydatidiform moles are triploid, with an extra set of chromosomes of paternal origin. Here, we present an unusual complete mole that showed strong expression of two imprinted, maternally transcribed genes, CDKN1C (encoding p57(KIP2)) and PHLDA2 (TSSC3/IPL), both part of a large imprinted gene domain on chromosome 11. Using microsatellite genotyping and fluorescent in situ hybridization, we show that this paradoxical gene expression was due to retention of a maternal copy of chromosome 11 in addition to the two paternal copies normally present in complete moles. These findings demonstrate that, despite being predominantly androgenetic, some complete moles contain small amounts of DNA of maternal origin. Furthermore, these results provide an explanation for rare false negatives that can arise when p57(KIP2) is used as a diagnostic marker for complete moles.
    Modern Pathology 10/2004; 17(9):1155-60. · 5.25 Impact Factor
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    ABSTRACT: To determine if immunohistochemistry for PHLDA2 (also known as IPL and TSSC3), the product of a paternally imprinted, maternally expressed gene, can be used as a tool in the differential diagnosis of molar gestations. Twenty-five cases (15 complete moles, 5 partial moles and five hydropic abortions) were stained by immunohistochemistry for PHLDA2 and scored (without knowledge of the diagnosis) for positivity in the villous cytotrophoblast and then compared to adjacent sections stained by p57KIP2 immunohistochemistry. All partial moles and hydropic abortions were positive for PHLDA2 and p57KIP2. There was strong PHLDA2 staining of the cytoplasm in virtually all cells of the villous cytotrophoblast, while p57KIP2 was localized to the nucleus in a subset of those cells. All complete moles were negative for both markers in the villous cytotrophoblast. Immunohistochemistry for PHLDA2 serves as a practical and reliable diagnostic marker for the discrimination of complete mole from partial mole and hydropic abortion. Since the immunohistochemical diagnosis of complete mole is based on a negative result, absence of staining, the use of both markers (PHLDA2 and p57KIP2) together could increase the level of confidence when making this prognostically important distinction.
    The Journal of reproductive medicine 09/2004; 49(8):630-6. · 0.75 Impact Factor
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    ABSTRACT: Endothelial dysfunction characterizes heart failure (HF). Simvastatin (Sim) increases endothelial nitric oxide (NO) independent of lipid-lowering. We evaluated the effect of Sim on cardiac function, apoptosis, and NO availability in HF. Five-month-old cardiomyopathic (CM) hamsters were divided into 2 groups: Sim (20 mg/kg, 6 weeks, n = 6) and Untreated (n = 6). Age-matched normal hamsters served as controls (n = 6). Serial echocardiograms were performed to measure LV function. Myocardial apoptosis, eNOS, and capillary density were measured at 6 weeks. Cardiomyopathic hamsters had lower LV shortening fraction (SF) compared with controls (17 +/- 3% vs 59 +/- 2%), higher LV end-diastolic volume (30 +/- 3 vs 6 +/- 2 mL/m2), and lower LV mass/volume ratio (0.5 +/- 0.04 vs 0.72 +/- 0.02 mg/ml, P < 0.001). During follow-up, SF decreased (9 +/- 2%) and LV volume increased (38 +/- 1 mL/m2) in untreated hamsters (P < 0.05 from baseline) but did not change significantly in the Sim group (P < 0.05 vs untreated). Myocardial caspase-3 activity was higher and apoptotic nuclear density was lower in Sim compared with untreated CM hamsters (0.072 +/- 0.02% vs 0.107 +/- 0.03%, P < 0.01). Myocardial capillary density was highest in the Sim group (P < 0.05). eNOS expression was not different between groups. Sim retards the progression of HF in CM hamsters. This may be related to an increase in coronary microvasculature, increase in NO availability, and decreased apoptosis.
    Journal of Cardiovascular Pharmacology 03/2004; 43(3):454-61. · 2.38 Impact Factor
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    ABSTRACT: Radiofrequency ablation is a minimally invasive technique that has been used in selective reduction of acardiac twins. We report a case in which radiofrequency ablation was used to selectively reduce a monochorionic twin discordant for an abnormality.
    American Journal of Obstetrics and Gynecology 03/2004; 190(2):575-6. · 3.88 Impact Factor
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    ABSTRACT: Human and mouse paralogues of the evolutionarily conserved mammalian HRAD9 and Mrad9 cell cycle checkpoint control genes have been isolated and called HRAD9B and Mrad9B, respectively. HRAD9B encodes a protein that is 414 amino acids long and is 55% similar and 35% identical to the HRAD9 gene product. The Mrad9B protein is 398 amino acids long and is 50% similar and 35% identical to its paralogue. We demonstrate that the encoded human protein is nuclear and can physically interact with checkpoint proteins HRAD1, HRAD9, HHUS1, and HHUS1B, much like HRAD9. Northern blot analysis to detect tissue specificity indicates that the human and mouse genes are expressed predominantly in the testis. The abundance of HRAD9B RNA, as judged by quantitative reverse transcription-PCR, is very low in most testicular tumors, particularly those of germ cell origin, i.e., seminomas, relative to normal testis control, nonseminomas, or Leydig tumor cells. RNA levels corresponding to HRAD17, another checkpoint control gene, demonstrated a similar pattern, but in general, higher quantities of this message were detected in samples. Furthermore, normal/tumor tissue differences were not as dramatic or consistent from sample to sample, especially for the seminomas. Our results demonstrate for the first time that HRAD9 and Mrad9 are part of a gene family and reveal a new genetic element encoding a product that interacts with multiple, known cell cycle checkpoint control proteins. The findings also indicate that HRAD9B can serve as a biomarker in particular for testicular seminomas and might be causally related to the disease.
    Cancer Research 10/2003; 63(17):5291-8. · 8.65 Impact Factor
  • American Journal of Kidney Diseases 05/2003; 41(4):891-6. · 5.29 Impact Factor
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    ABSTRACT: The IPL/TSSC3 gene is expressed nearly exclusively from the maternal allele, and its protein product acts to limit placental growth in mice. This protein specifically marks Type II trophoblast in the labyrinthine layer of the mouse placenta. To investigate mouse-human homologies, we carried out immunohistochemistry with antibodies against human IPL. There was strong expression of IPL in villous cytotrophoblast of the human placenta, contrasting with complete lack of expression in syncytiotrophoblast. Staining for IPL was weak in cells of the villous mesenchyme and extravillous trophoblast, including the cytotrophoblast columns in the basal plate and the intervillous trophoblast islands. The IPL and p57(KIP2)/CDKN1C genes are closely linked and coordinately imprinted, and immunostaining showed that their protein products are co-expressed in villous cytotrophoblast. However, other cell types, including extravillous cytotrophoblast and cells in various non-placental tissues, expressed p57(KIP2), but not IPL. IPL protein was absent in both of two cases of androgenetic complete hydatidiform mole examined by immunostaining, and IPL mRNA was absent in an additional three cases of this neoplasm examined by northern blotting. In the mouse, Ipl-expressing cells disappear at mid- to late-gestation when placental growth ceases, but persistent IPL mRNA and protein expression was observed throughout human gestation, correlating with the continuous growth of the human placenta. These findings highlight dosage regulation of human IPL by imprinting and, more generally, suggest homology between Type II labyrinthine trophoblast in the mouse and villous cytotrophoblast in humans, both of which are proliferative stem cell-like compartments.
    Placenta 01/2003; 24(8-9):835-42. · 3.12 Impact Factor