Clinical, Endoscopic, and Histopathologic Gastrointestinal Disease in an American Cohort With Behçet's Disease

INTRODUCTION

Behçet's disease (BD) is a chronic systemic vasculitis characterized by oral and genital ulcers, uveitis, and skin lesions. Patients with BD may develop gastrointestinal (GI) disease; however, characterization of GI disease in American cohorts is lacking. In this article, we present clinical, endoscopic, and histopathologic GI findings in an American cohort of patients with BD.

METHODS

Patients with established BD were evaluated prospectively at the National Institutes of Health. Demographic and clinical data were collected including BD manifestations and GI symptoms. Endoscopy with histopathologic sampling was performed for both clinical and research indications with written consent.

RESULTS

Eighty-three patients were evaluated. The majority were female (83.1%) and white (75.9%). Mean age was 36 ± 14.8 years. GI symptoms were reported in 75% of cohort with nearly half of reporting abdominal pain (48.2%) and significant numbers reporting acid reflux, diarrhea, and nausea/vomiting. Esophagogastroduodenoscopy was performed in 37 patients; erythema and ulcers were the most common found abnormalities. Colonoscopy was performed in 32 patients with abnormalities including polyps, erythema, and ulcers. Endoscopy was normal in 27% of esophagogastroduodenoscopies and 47% of colonoscopies. Vascular congestion was demonstrated on the majority of random biopsies throughout the GI tract. Inflammation was not highly prevalent on random biopsies except in the stomach. Wireless capsule endoscopy was performed on 18 patients; ulcers and strictures were the most common abnormalities.

DISCUSSION

GI symptoms were common in this cohort of American patients with BD. Endoscopic examination was often normal; however, histopathologic examination demonstrated vascular congestion throughout the GI tract.

Estimating quality of life: A spatial microsimulation model of well-being in Aotearoa New Zealand

Quality of life is a complex concept characterised by several dualities, it has many definitions depending on the field of research and an abundance of diverse objective and subjective measures. The latter often represents the extent of perceived (dis)satisfaction with various domains of life experienced by individuals or groups, and research is increasingly focusing on subjective measures of well-being to better understand personal drivers related to quality of life. A better understanding of these factors at a local level has potential to shed light on an often-overlooked aspect of the mental health landscape in Aotearoa New Zealand. Individual-level data on adults (15+ years) is sourced from the New Zealand Attitudes and Values Study 2018 (N = 47,949) and aggregate-level data from the Census 2018 (N = 3,775,854). Matching constraint variables include sex, age, ethnicity, highest qualification, and labour force status. Outcome variables include personal and national well-being scores from 0 to 10 (extremely dissatisfied-extremely satisfied). Spatial microsimulation is used to create a synthetic population based on the above data. Results show lower mean national well-being scores than personal well-being scores, with spatial variations that broadly reflect patterns of socioeconomic deprivation. Low mean values for both personal and national well-being scores are seen in rural areas of high socioeconomic deprivation, particularly those with large Māori populations. High mean values are associated with areas of low deprivation. Additionally, high national well-being scores are associated with areas of agricultural activity, particularly in the South Island. Consideration should be given to factors that influence responses in such topics however, including demographic profiles as well as economic and social conditions of individuals and their surrounding communities. This study demonstrates that spatial microsimulation can be used as a powerful tool to understand population well-being. It can help support future planning and resource allocation, aiding in achieving health equity.

FC 040INTERIM RESULTS OF PHASE 1 AND 2 TRIALS TO INVESTIGATE THE SAFETY, TOLERABILITY, PHARMACOKINETICS, PHARMACODYNAMICS, AND CLINICAL ACTIVITY OF BION-1301 IN PATIENTS WITH IGA NEPHROPATHY

Background and Aims

IgA nephropathy (IgAN), the leading cause of primary glomerulonephritis, is an autoimmune disease with no approved treatments.1 Progression to end-stage-renal disease occurs in up to 45% of IgAN patients, requiring dialysis or kidney transplant to manage.2-4 A critical step in IgAN pathogenesis is the production of galactose-deficient IgA1 (Gd-IgA1) leading to the generation of anti-Gd-IgA1 autoantibodies and the formation of immune complexes that result in kidney inflammation and damage.5 A Proliferation-Inducing Ligand (APRIL), a soluble factor that regulates B cell differentiation, proliferation and survival of plasma cells, and IgA class-switching is elevated in patients with IgAN6, 7. IgAN patients with high plasma APRIL levels are reported as having higher levels of Gd-IgA1 and proteinuria and lower estimated glomerular filtration rates compared to those with lower plasma APRIL levels.7 BION-1301 is a novel humanized blocking antibody targeting APRIL that has been evaluated in a Phase 1 study of healthy volunteers (HV). In Parts 1 and 2 of the Phase 1 study in HV, we previously reported that BION-1301 was well-tolerated with no serious adverse events (SAEs), a pharmacokinetic (PK) half life >30 days and demonstrated dose-dependent pharmacodynamic (PD) effects characterized by durable reductions in serum levels of free April (fAPRIL), IgA and Gd-IgA1, IgM, and to a lesser extent IgG8. Here we present interim results from Part 3 of the Phase 1 and the Phase 2 Open-Label Extension (OLE) trials that characterize the safety, PK and PD profile, and preliminary efficacy of BION-1301 in patients with IgAN.

Method

The Phase 1 study (NCT03945318) comprises 3 parts. Parts 1 and 2 assessed single- and multiple ascending doses of BION-1301 in HV from 10mg to 1350mg and 50mg to 450mg once every 2 weeks for one month, respectively. Part 3 is an ongoing, open-label, two cohort design in approximately 20 IgAN patients with BION-1301 at a starting dose and regimen of 450mg once every 2 weeks for a total of 3 months. Key eligibility criteria for Part 3 include: (1) urine protein ≥0.5 g/24h or baseline UPCR ≥0.5 g/g, (2) stable/optimized dose of ACE-I/ARB or be intolerant to ACE-I/ARB, and (3) biopsy-verified diagnosis of IgAN within the past 10 years. Patients completing Part 3 are eligible to enroll in the Phase 2 OLE study (NCT04684745) to receive BION-1301 for up to an additional 2 years. To evaluate PK and PD effects of BION-1301, serum levels of BION-1301, free APRIL (fAPRIL), anti-drug antibodies (ADA), neutralizing antibodies (NAbs), and Gd-IgA1 were quantitated using ELISA-based immunoassays. Serum levels of IgA, IgG, and IgM were measured by immunoturbidimetry. UPCR was assessed from 24-hour urine collections.

Results

In Part 3 of Phase 1 and the Phase 2 OLE trial to date, BION-1301 has been well tolerated in IgAN patients receiving a 450mg dose every two weeks for 12+ weeks with no SAEs observed. Consistent with PD responses previously reported in HVs, durable reductions in serum levels of fAPRIL and immunoglobulins were also observed in IgAN patients. Clinically meaningful reductions in proteinuria were observed as early as 12 weeks and were associated with the reduction in IgA. Additional data from patients receiving long-term treatment will be updated.

Conclusion

BION-1301 is a novel humanized anti-APRIL monoclonal antibody being developed as a potential treatment for patients with IgAN. BION-1301 offers disease modifying potential by directly targeting the underlying multi-hit immune pathogenesis of IgAN, which is not addressed with the current standard of care treatment. Promising early biomarker and clinical activity responses support the continued development of BION-1301 in IgAN.

MO286DESIGN OF A PH1, MULTICENTER TRIAL TO INVESTIGATE THE SAFETY, TOLERABILITY, PK/PD OF BION-1301 IN HEALTHY VOLUNTEERS AND ADULTS WITH IGAN AND A MULTICENTER, OPEN-LABEL EXTENSION STUDY FOR IGAN PATIENTS WHO PARTICIPATED IN A PRIOR TRIAL OF BION-1301

Background and Aims

IgA nephropathy (IgAN), the leading cause of primary glomerulonephritis, is an autoimmune disease with no approved treatments.1 Progression to end-stage-renal disease occurs in up to 45% of IgAN patients, requiring dialysis or kidney transplant to manage.2-4 A critical step in IgAN pathogenesis is the production of galactose-deficient IgA1 (Gd-IgA1) leading to the generation of anti-Gd-IgA autoantibodies and the formation of immune complexes that result in kidney inflammation and damage.5 A Proliferation-Inducing Ligand (APRIL), a soluble factor that regulates B cell differentiation, proliferation and survival of plasma cells, and IgA class-switching is elevated in patients with IgAN6, 7. IgAN patients with high plasma APRIL levels are reported as having higher levels of Gd-IgA1 and proteinuria and lower estimated glomerular filtration rates compared to those with lower plasma APRIL levels.7 BION-1301 is a novel humanized blocking antibody targeting APRIL.

The primary objective of Study ADU-CL-19 is to assess the short-term safety and tolerability of BION-1301 in Healthy Volunteers (HV) and IgAN patients and to secondarily assess the short-term pharmacokinetics (PK), pharmacodynamics (PD), immunogenicity, and preliminary clinical activity of BION-1301. The primary objective of Study ADU-CL-24 is to characterize the long-term safety of BION-1301 in IgAN patients who completed treatment in ADU-CL-19 while secondarily assessing the long-term PK, PD, immunogenicity, and preliminary clinical activity of BION-1301.

Method

The Phase 1 study (ADU-CL-19; NCT03945318) comprises 3 parts. Parts 1 and 2 are double-blind, randomized, placebo-controlled single and multiple ascending dose designs in HV; both parts have been completed.

Part 3 is an ongoing multicenter (US and UK), multiple-dose, two cohort design in approximately 20 patients with IgAN (10/cohort). Key eligibility criteria for Part 3 includes: (1) urine protein ≥0.5 g/24h or baseline UPCR ≥0.5 g/g, (2) stable/optimized dose of ACE-I/ARB or intolerant to ACE-I/ARB, and (3) biopsy-verified diagnosis of IgAN within the past 10 years. In Part 3, patients in Cohort 1 are receiving BION-1301 at 450mg every 2 weeks for 3 months. The dose and schedule for Cohort 2 will be determined by the Safety Review Team (SRT) based on data from the first 5 patients. After 3 months of treatment, patients continue safety follow-up for approximately 6 months unless deciding to enroll in the open-label extension (OLE) study, withdraw from the study, or are lost to follow up.

Study ADU-CL-24 (NCT04684745) is a Phase 2 Open-Label Extension (OLE) of Study ADU-CL-19. Eligibility for the OLE study is restricted to those patients who completed at least 75% of their intended doses as well as the End of Treatment (EOT) visit in Study ADU-CL-19. Patients who enroll directly from the ADU-CL-19 EOT visit are not required to attend an additional screening visit. This is encouraged to maintain un-interrupted dosing. Once enrolled in the OLE, patients receive BION-1301 at the same dose and regimen as assigned in the parent study for up to 2 years. The dose, route, and regimen of BION-1301 may change after review of emergent safety, PK, PD and efficacy data by the SRT.

Results

Parts 1 and 2 of the Phase 1 study in HV are complete and the data were presented at ASN in 20208 Part 3 of the Phase 1 and the Phase 2 OLE study are ongoing, and interim results from the first dose cohort in IgAN patients are being presented in a separate poster at this meeting.

Conclusion

The design of the Phase 1 and Phase 2 OLE studies described in HVs and IgAN patients have enabled the generation of short- and long-term safety, PK, PD, immunogenicity and preliminary efficacy data for BION-1301. The Phase 1 short-term data will guide the design of future later-stage trials of BION-1301, while the long-term data from OLE will enable a greater understanding of the potential long-term risk/benefit profile of BION-1301 in IgAN patients.

Subglottic stenosis and endobronchial disease in granulomatosis with polyangiitis

OBJECTIVES

To describe tracheobronchial disease in patients with granulomatosis with polyangiitis (GPA) and evaluate the utility of dynamic expiratory CT to detect large-airway disease.

METHODS

Demographic and clinical features associated with the presence of subglottic stenosis (SGS) or endobronchial involvement were assessed in a multicentre, observational cohort of patients with GPA. A subset of patients with GPA from a single-centre cohort underwent dynamic chest CT to evaluate the airways.

RESULTS

Among 962 patients with GPA, SGS and endobronchial disease were identified in 95 (10%) and 59 (6%) patients, respectively. Patients with SGS were more likely to be female (72% vs 53%, P < 0.01), younger at time of diagnosis (36 vs 49 years, P < 0.01), and have saddle-nose deformities (28% vs 10%, P < 0.01), but were less likely to have renal involvement (39% vs 62%, P < 0.01). Patients with endobronchial disease were more likely to be PR3-ANCA positive (85% vs 66%, P < 0.01), with more ENT involvement (97% vs 77%, P < 0.01) and less renal involvement (42% vs 62%, P < 0.01). Disease activity in patients with large-airway disease was commonly isolated to the subglottis/upper airway (57%) or bronchi (32%). Seven of 23 patients screened by dynamic chest CT had large-airway pathology, including four patients with chronic, unexplained cough, discovered to have tracheobronchomalacia.

CONCLUSION

SGS and endobronchial disease occur in 10% and 6% of patients with GPA, respectively, and may occur without disease activity in other organs. Dynamic expiratory chest CT is a potential non-invasive screening test for large-airway involvement in GPA.

Loss-of-function mutations in TNFAIP3 leading to A20 haploinsufficiency cause an early-onset autoinflammatory disease

Systemic autoinflammatory diseases are driven by abnormal activation of innate immunity. Herein we describe a new disease caused by high-penetrance heterozygous germline mutations in TNFAIP3, which encodes the NF-κB regulatory protein A20, in six unrelated families with early-onset systemic inflammation. The disorder resembles Behçet's disease, which is typically considered a polygenic disorder with onset in early adulthood. A20 is a potent inhibitor of the NF-κB signaling pathway. Mutant, truncated A20 proteins are likely to act through haploinsufficiency because they do not exert a dominant-negative effect in overexpression experiments. Patient-derived cells show increased degradation of IκBα and nuclear translocation of the NF-κB p65 subunit together with increased expression of NF-κB-mediated proinflammatory cytokines. A20 restricts NF-κB signals via its deubiquitinase activity. In cells expressing mutant A20 protein, there is defective removal of Lys63-linked ubiquitin from TRAF6, NEMO and RIP1 after stimulation with tumor necrosis factor (TNF). NF-κB-dependent proinflammatory cytokines are potential therapeutic targets for the patients with this disease.

Loss-of-function mutations in TNFAIP3 leading to A20 haploinsufficiency cause an early-onset autoinflammatory disease

Systemic autoinflammatory diseases are driven by abnormal activation of innate immunity. Herein we describe a new disease caused by high-penetrance heterozygous germline mutations in TNFAIP3, which encodes the NF-κB regulatory protein A20, in six unrelated families with early-onset systemic inflammation. The disorder resembles Behçet's disease, which is typically considered a polygenic disorder with onset in early adulthood. A20 is a potent inhibitor of the NF-κB signaling pathway. Mutant, truncated A20 proteins are likely to act through haploinsufficiency because they do not exert a dominant-negative effect in overexpression experiments. Patient-derived cells show increased degradation of IκBα and nuclear translocation of the NF-κB p65 subunit together with increased expression of NF-κB-mediated proinflammatory cytokines. A20 restricts NF-κB signals via its deubiquitinase activity. In cells expressing mutant A20 protein, there is defective removal of Lys63-linked ubiquitin from TRAF6, NEMO and RIP1 after stimulation with tumor necrosis factor (TNF). NF-κB-dependent proinflammatory cytokines are potential therapeutic targets for the patients with this disease.

IFPA meeting 2015 workshop report I: placental mitochondrial function, transport systems and epigenetics

Workshops are an important part of the IFPA annual meeting as they allow for discussion of specialized topics. At IFPA meeting 2015 there were twelve themed workshops, three of which are summarized in this report. These workshops covered areas of placental regulation and nutrient handling: 1) placental epigenetics; 2) placental mitochondrial function; 3) placental transport systems.

Behçet syndrome manifestations and activity in the United States versus Turkey -- a cross-sectional cohort comparison

OBJECTIVE

To compare clinical manifestations and activity of Behçet syndrome (BS) in the United States versus Turkey using validated outcome measures.

METHODS

Consecutive patients with BS from the US National Institutes of Health (NIH), New York University, and the University of Istanbul were evaluated. Disease activity was measured using the Behçet's Syndrome Activity Scale (BSAS) and the Behçet's Disease Current Activity Form (BDCAF) with quality of life measured by the Behçet Disease Quality of Life (BDQOL) form. One-way ANOVA, t-tests, and multivariate regression analyses were performed.

RESULTS

Mean age did not differ between sites; however, more women were seen in the United States versus in Turkey (p < 0.001), and disease duration was longer in the United States (p = 0.02). Organ manifestations were similar for oral and genital ulcers, skin disease, arthralgia, eye disease, and thrombosis. However, more gastrointestinal (p < 0.001) and neurologic disease (p = 0.003) was seen in the United States. BSAS and BDCAF scores were worse in the United States compared to Turkey (p = 0.013 and < 0.001, respectively). Worse mean BDQOL scores were observed at the NIH compared to Istanbul (not significant). Multivariable regression models showed worse scores in ethnically atypical patients for BSAS and BDCAF (p = 0.04 and p = 0.001), American patients for BDCAF (p = 0.01), older age for BDCAF (p = 0.005), and women for BDQOL (p = 0.01).

CONCLUSION

Demographic and clinical manifestations of BS differ between sites with higher disease activity in the United States compared to Turkey. Referral patterns, age, sex, ethnicity, and country of origin may be important in these differences. These observations raise the question of whether pathogenic mechanisms differ in Turkish and American patients.

IFPA Meeting 2011 workshop report I: Placenta: Predicting future health; roles of lipids in the growth and development of feto-placental unit; placental nutrient sensing; placental research to solve clinical problems--a translational approach

Workshops are an important part of the IFPA annual meeting as they allow for discussion of specialized topics. At IFPA meeting 2011 there were twelve themed workshops, four of which are summarized in this report. These workshops related to both basic science and clinical research into placental growth and nutrient sensing and were divided into 1) placenta: predicting future health; 2) roles of lipids in the growth and development of feto-placental unit; 3) placental nutrient sensing; 4) placental research to solve clinical problems: a translational approach.

IFPA Meeting 2010 Workshops Report II: Placental pathology; trophoblast invasion; fetal sex; parasites and the placenta; decidua and embryonic or fetal loss; trophoblast differentiation and syncytialisation

Workshops are an important part of the IFPA annual meeting. At IFPA Meeting 2010 diverse topics were discussed in twelve themed workshops, six of which are summarized in this report. 1. The placental pathology workshop focused on clinical correlates of placenta accreta/percreta. 2. Mechanisms of regulation of trophoblast invasion and spiral artery remodeling were discussed in the trophoblast invasion workshop. 3. The fetal sex and intrauterine stress workshop explored recent work on placental sex differences and discussed them in the context of whether boys live dangerously in the womb.4. The workshop on parasites addressed inflammatory responses as a sign of interaction between placental tissue and parasites. 5. The decidua and embryonic/fetal loss workshop focused on key regulatory mediators in the decidua, embryo and fetus and how alterations in expression may contribute to different diseases and adverse conditions of pregnancy. 6. The trophoblast differentiation and syncytialisation workshop addressed the regulation of villous cytotrophoblast differentiation and how variations may lead to placental dysfunction and pregnancy complications.

Imprinted genes, placental development and fetal growth

In mammals, imprinted genes have an important role in feto-placental development. They affect the growth, morphology and nutrient transfer capacity of the placenta and, thereby, control the nutrient supply for fetal growth. In particular, the reciprocally imprinted Igf2-H19 gene complex has a central role in these processes and matches the placental nutrient supply to the fetal nutrient demands for growth. Comparison of Igf2P0 and complete Igf2 null mice has shown that interplay between placental and fetal Igf2 regulates both placental growth and nutrient transporter abundance. In turn, epigenetic modification of imprinted genes via changes in DNA methylation may provide a mechanism linking environmental cues to placental phenotype, with consequences for development both before and after birth. Changes in expression of imprinted genes, therefore, have major implications for developmental programming and may explain the poor prognosis of the infant born small for gestational age and the wide spectrum of adult-onset diseases that originate in utero.

Regulation of Placental Efficiency for Nutrient Transport by Imprinted Genes

Intrauterine growth and development can impact upon the long-term health of an individual. The fetus is dependent upon the placenta for its supply of nutrients and oxygen from the mother. In turn, the functional capacity of the placenta to supply that demand is under the control of the fetal and maternal genomes. Recent evidence suggests that imprinted genes, a class of genes found in placental mammals whose expression depends on their parental origin, have multiple roles in the placenta. The imprinted genes regulate the growth and transport capacity of the placenta, thereby controlling the supply of nutrients. They may also regulate the growth rate of fetal tissues directly, thereby controlling nutrient demand by the fetus. Recent studies using mice with deletions or disruption of imprinted genes with an altered balance between placental and fetal growth and changes in placental efficiency are indicative of feto-placental signalling of fetal nutrient demand. We propose that signalling mechanisms involving growth demand signals and nutrient transporters are likely to occur and are important for fine tuning normal fetal growth.

System A amino acid transporter activity in human placental microvillous membrane vesicles in relation to various anthropometric measurements in appropriate and small for gestational age babies

Fetal growth and development is dependent on the transfer of amino acids from maternal to fetal blood across the microvillous plasma membrane (MVM) and basal plasma membrane of placental syncytiotrophoblast. The aim of this study was to determine the relationship of system A amino acid transporter (SysA) activity in MVM to a variety of measurements of size at birth in a group of term small for gestational age (SGA) babies and in a group of appropriate for gestational age (AGA) babies. Mean SysA activities (nmol/mg vesicle protein/30 s +/- SEM) were: SGA, 0.027 +/- 0.004 (n = 25) and AGA, 0.045 +/- 0.005 (n = 24); p = 0.006. Spearman rank correlations were calculated for SGA (n = 19-25) and AGA (n = 21-24) groups for SysA activity against the following anthropometric measurements: abdominal circumference, birth weight, length, midarm circumference (MAC), head circumference, midarm circumference:head circumference ratio, placental weight (PW), placental ratio (placental weight:birth weight), birth weight:length ratio, Ponderal index (birth weight/length3) and triceps and subscapular skin-fold thicknesses (tsft and ssft). In SGA babies, SysA activity was positively correlated (p < 0.05) with subscapular skin-fold thicknesses (r = 0.48), triceps skin-fold thicknesses (r = 0.42), PW (r = 0.42), and placental ratio (r = 0.46). In AGA babies, the only significant correlation was an inverse one with placental ratio (r = -0.50). These data suggest there are differences in the relationship between placental SysA activity and fetal proportion in term AGA compared with SGA babies.

Electrical potential difference between exocelomic fluid and maternal blood in early pregnancy

The forces that drive transfer of solutes between maternal blood and embryo in early human pregnancy are poorly understood. The aim of this study was to determine whether there is an electrical potential difference (PD) between maternal blood and the exocelomic cavity and between maternal blood and the amniotic cavity in the normal human conceptus at or before 10 wk of pregnancy. We measured PD between a saline-filled catheter in a forearm vein of women undergoing termination of pregnancy for psychological reasons in the first trimester and a second saline-filled catheter in the exocelomic cavity or amniotic cavity of their conceptus. The mean (+/- SE) maternal blood/exocelomic cavity PD in eight women was 8.7 +/- 1.0 mV and the mean maternal blood/amniotic cavity PD in four of the women was 6.7 +/- 1.3 mV, embryo side negative for both sets of measurement. These data show that there is a PD between maternal and embryonic extracellular fluid in the first trimester that will directly influence exchange of ions between the two compartments.

Placental transporter activity and expression in relation to fetal growth

The question of whether there are causative or compensatory changes in placental transport physiology affecting fetal growth is considered. Reductions in uterine and umbilical blood flow in growth retardation will reduce maternofetal exchange of lipophilic solutes, such as O2 and CO2, but will not have a major effect on the transfer of hydrophilic solutes. These solutes are transferred across the placenta by paracellular diffusion, transporter protein-mediated transport and endocytosis-exocytosis. Neither paracellular diffusion nor endocytosis-exocytosis has been investigated in relation to fetal growth. The weight of evidence is that there is no change in the activity and expression of the syncytiotrophoblast GI UTI glucose transporter in fetal growth retardation. However, there is strong evidence that the activity of the system A amino acid transporter, per milligram of placental membrane protein, is altered in relation to fetal growth, but in a complex manner. There is also some weaker evidence that the activity of the Na(+)-H+ exchanger, per milligram of placental membrane protein, is directly related to birth-weight. There are no data for other solute transporters; a considerable amount of work still remains to be done in order to understand the relationship between placental function and fetal growth rate.

Mechanisms of alphafetoprotein transfer in the perfused human placental cotyledon from uncomplicated pregnancy

We investigated the mechanisms of alphafetoprotein (AFP) transfer across the human placenta by correlating measurements of AFP transfer with cytochemical localization of AFP. Placental cotyledons were dually perfused in vitro with either the fetal or maternal perfusate containing umbilical cord plasma as a source of AFP. Steady state AFP clearance, corrected for release of endogenous AFP, was 0.973 +/- 0.292 microliter/min per gram in the fetal to maternal direction (n = 10), significantly higher (P < 0.02) than that in the maternal to fetal direction (n = 5; 0.022 +/- 0.013 microliter/min per gram). Clearance of a similarly sized protein, horseradish peroxidase was also asymmetric but clearance of the small tracer creatinine was not. Using a monoclonal antibody, we localized AFP to fibrinoid deposits in regions of villi with discontinuities of the syncytiotrophoblast, to cytotrophoblast cells in these deposits, to syncytiotrophoblast on some villi, and to trophoblast cells in the decidua. We conclude that AFP transfer in the placenta is asymmetric and that there are two available pathways for AFP transfer: (a) from the fetal circulation into the villous core and across fibrinoid deposits at discontinuities in the villous syncytiotrophoblast to enter the maternal circulation; and (b) AFP present in the decidua could enter vessels that traverse the basal plate.

Choriocarcinoma cells increase the number of differentiating human cytotrophoblasts through an in vitro interaction

The human placenta arises from the zygote through single cell intermediates called cytotrophoblasts that in turn give rise to a syncytium. In culture, mononucleated cytotrophoblasts exhibit little, if any, cell division but are converted to multinucleated cells. Choriocarcinoma, the malignant tumor of placenta trophoblast, comprises a mixed population of dividing cellular intermediates that resemble cytotrophoblasts but are less differentiated. Because the choriocarcinoma intermediates arise from dividing cells, the tumor may contain one or more cell types in abundance not present in the population of isolated placental cells. To study placental differentiation through cell-cell interaction, choriocarcinoma cell lines were co-cultured with placenta-derived cytotrophoblasts, and placental hormone biosynthesis, as a marker of differentiation was examined. We reasoned that intermediates formed by the tumor might interact with and complement those intermediates in the placenta-derived cytotrophoblast population. Co-culturing either the JAr or JEG choriocarcinoma cell lines with cytotrophoblasts elevated the synthesis of the chorionic gonadotropin alpha and beta subunits 10-20 fold, and human placental lactogen 5-fold. The effect was specific for these trophoblast-derived cells, since comparable quantities of Chinese hamster ovary or HeLa cells did not affect the placental cytotrophoblast culture. Further experiments suggested that the source of enhanced synthesis was the cytotrophoblasts. We propose that an interaction between cytotrophoblasts and choriocarcinoma cells occurs, which results in an increased number of differentiating cytotrophoblasts. Such co-cultures may represent a model system for examining choriocarcinoma cell interaction with normal cells, a process known to occur in vivo. The data are also consistent with the hypothesis that the regulated chorionic gonadotropin production in the placenta is determined by interaction among trophoblast cells at different stages of differentiation.

Rh immunization by the partial D antigen of category DVa

Reported here is the first example of a partial D antigen stimulating the production of anti-D: stimulation was of fetal origin. During her second pregnancy, anti-D developed in the serum of a D-negative mother who had received Rh immunoglobulin after the birth of her first D-positive child. Her second baby had moderate neonatal jaundice and was successfully treated by phototherapy. Subsequently the red cells of the father and of the first child were shown to carry a partial D antigen of category DVa type. Six available batches of Rh immunoglobulin reacted with DVa cells.

The immunoglobulin mu chains of membrane-bound and secreted IgM molecules differ in their C-terminal segments

The B lymphocytes synthesizes two forms of IgM molecules during its development from a stem cell to a mature antibody-secreting plasma cell. The monomeric receptor IgM molecule is affixed to the plasma membrane and triggers the later stages of B cell differentiation, whereas the pentameric secreted IgM molecule is an effector of humoral immunity. The structural differences between membrane-bound and secreted IgM molecules are reflected in the differences between their heavy or mu chains. We have previously determined the complete amino acid sequence of a murine secreted mu (microsecond) chain. In this study, we have compared the structures of the secreted and membrane-bound mu (micron) heavy chains by peptide mapping, micro-sequence and carboxypeptidase analyses. These studies demonstrate that the micron and microsecond chains are very similar throughout their VH, C mu 1, C mu 2, C mu 3 and C mu 4 domains. The micron and microsecond chains differ in the amino acid sequence of their C-terminal segments. These studies in conjunction with those carried out on the micron and microsecond mRNAs and the C mu gene suggest that the micron and microsecond chains from a given B cell are identical except for their 41 and 20 residue C-terminal segments, respectively. The amino acid sequence of the 41 residue C membrane terminal segment predicted from the corresponding micron mRNA is in agreement with all the protein studies reported in this paper.

Endotoxemia of cirrhosis: an observation not substantiated

Physiologic similarities between cirrhotic and septic patients have implicated systemic endotoxemia as a possible mediator of the hemodynamic, neurologic, and hematologic complications observed in patients with cirrhosis of the liver. The recently reported high prevalence of endotoxin in ascites, as well as in portal and systemic plasma, has further incriminated endotoxin of gut origin as the responsible agent. Limulus amebocyte lysate tests were performed upon peripheral plasma of 38 cirrhotic patients; portal plasma and ascites were assayed in 14 and 11 of these patients, respectively. No endotoxin was detectable. We believe that the ubiquity of endotoxin, with the attendant opportunities for specimen contamination, is the most likely explanation for the recently reported high prevalence of endotoxin in the plasma and ascites of cirrhotic patients.

Amino acid sequence of a mouse immunoglobulin mu chain

The complete amino acid sequence of the mouse mu chain from the BALB/c myeloma tumor MOPC 104E is reported. The C mu region contains four consecutive homology regions of approximately 110 residues and a COOH-terminal region of 19 residues. A comparison of this mu chain from mouse with a complete mu sequence from human (Ou) and a partial mu chain sequence from dog (Moo) reveals a striking gradient of increasing homology from the NH2-terminal to the COOH-terminal portion of these mu chains, with the former being the least and the latter the most highly conserved. Four of the five sites of carbohydrate attachment appear to be at identical residue positions when the constant regions of the mouse and human mu chains are compared. The mu chain of MOPC 104E has a carbohydrate moiety attached in the second hypervariable region. This is particularly interesting in view of the fact that MOPC 104E binds alpha-(1 leads to 3)-dextran, a simple carbohydrate. The structural and functional constraints imposed by these comparative sequence analyses are discussed.

Laboratory suggestions: Improving the sensitivity of the Fletcher factor assay

The prolonged activated partial thromboplastin times observed with Fletcher factor (prekallikrein)-deficient plasmas become nearly normal after the plasma is incubated with contact surfaces or with an activator. Those shorter times may lead to relatively flat reference curves for Fletcher factor assays under certain conditions. The authors examine in detail the effect of incubation time upon the sensitivity of Fletcher factor assays. Four different surface activators were used in the tests to determine the optimal activation for each type. An incubation time of 1 min produced maximal sensitivity with each surface activator tested. All reagents remained stable for at least an hour at 37.5 C.