Presented here is a protocol for sampling of human placental villous tissue followed by isolation of cytotrophoblasts for primary cell culture. Treatment of trophoblasts with TNFα recapitulates inflammation in the obese intrauterine environment and facilitates the discovery of molecular targets regulated by inflammation in placentas with maternal obesity.
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Method Article
A Primary Human Trophoblast Model to Study the Effect of Inflammation Associated with Maternal Obesity on Regulation of Autophagy in the Placenta
* These authors contributed equally
In This Article
Summary
Abstract
Maternal obesity is associated with an increased risk of adverse perinatal outcomes that are likely mediated by compromised placental function that can be attributed to, in part, the dysregulation of autophagy. Aberrant changes in the expression of autophagy regulators in the placentas from obese pregnancies may be regulated by inflammatory processes associated with both obesity and pregnancy. Described here is a protocol for sampling of villous tissue and isolation of villous cytotrophoblasts from the term human placenta for primary cell culture. This is followed by a method for simulating the inflammatory milieu in the obese intrauterine environment by treating primary trophoblasts from lean pregnancies with tumor necrosis factor alpha (TNFα), a proinflammatory cytokine that is elevated in obesity and in pregnancy. Through the implementation of the protocol described here, it is found that exposure to exogenous TNFα regulates the expression of Rubicon, a negative regulator of autophagy, in trophoblasts from lean pregnancies with female fetuses. While a variety of biological factors in the obese intrauterine environment maintain the potential to modulate critical pathways in trophoblasts, this ex vivo system is especially useful for determining if expression patterns observed in vivo in human placentas with maternal obesity are a direct result of TNFα signaling. Ultimately, this approach affords the opportunity to parse out the regulatory and molecular implications of inflammation associated with maternal obesity on autophagy and other critical cellular pathways in trophoblasts that have the potential to impact placental function.
Introduction
Obesity is an inflammatory state characterized by chronic low-grade inflammation, stemming from excess adipose tissue and nutrient availability. In obesity, proinflammatory cytokines are elevated in metabolic tissues as well as systemically in circulation. A robust body of evidence has shown that TNFα is significantly elevated in the setting of obesity with implications in insulin resistance and metabolic dysfunction1. Activation of TNFα also contributes to disease pathogenesis in conditions such as cancer and autoimmunity, making it an attractive therapeutic target2.
Inflammation in....
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Protocol
Placentae were collected from the Labor and Delivery Unit at University Hospital under a protocol approved by the Institutional Review Board of Oregon Health and Science University in Portland, Oregon, with informed consent from the patients.
1. Collection of Placental Tissue
- Preparation
NOTE: All equipment that encounters tissue must be sterile.- Sterilize the dissecting equipment by autoclaving for 60 min at 121 °C.
- Use personal protective equipment (PPE): lab coats/gowns/scrubs, gloves, and mask with a face shield or goggles.
- Turn on water bath and set to 37 °....
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Results
Term human placentas from lean (pre-pregnancy body mass index (BMI) <25) mothers with uncomplicated pregnancies carrying female offspring were collected and sampled within 15 minutes of delivery by cesarean section (no labor). The placentas were examined for the absence of calcifications and typical development: weighing between 300-600 g with the umbilical cord and membranes removed, round in shape, between 15 - 25 cm in diameter, and umbilical cord inserted into the middle of the pla.......
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Discussion
The placenta, responsible for regulating the growth of the fetus, exhibits compromised function in the obese environment6. Despite the high metabolic demands of trophoblasts, placentas with maternal obesity exhibit dysfunctional mitochondrial respiration6,19. Changes in placental metabolism may contribute to the increased incidence of complications and adverse fetal outcomes observed in obese pregnancies3,
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Disclosures
The authors have nothing to disclose.
Acknowledgements
The authors thank women who donated their placentas for this study. We also thank the Labor and Delivery Department at OHSU and the Maternal and Fetal Research Team for coordinating the collection of placentas. We are grateful to Eric Wang, Ph.D., and Kelly Kuo, MD for support and help with experimental methods and optimization.
This work was funded by NIH HD076259A (AM) and AHA GRNT29960007 (AM).
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Materials
| Name | Company | Catalog Number | Comments |
|---|---|---|---|
| 10X HBSS | Gibco | 14185-052 | |
| CaCl2 (anhyd.) | Sigma-Aldrich | C1016-100G | |
| MgSO4 (anhyd.) | Sigma-Aldrich | M7506-500G | |
| Hepes | Fisher Scientific | BP310-500 | |
| Trypsin | Gibco | 15090-046 | |
| DNAse | Worthington Biochemical Corp. | LS002139 | |
| Protease/Phosphatase inhibitors | Thermofisher Scientific | 88668 | |
| Tris HCl | Invitrogen | 15506-017 | |
| EDTA | Invitrogen | 15576-028 | |
| NaCl | Sigma-Aldrich | S7653-1KG | |
| SDS | Fisher Scientific | BP166-600 | |
| Sodium deoxycholate. | Fisher Scientific | AAJ6228822 | |
| Triton X-100 | Sigma-Aldrich | X100-500ML | |
| Iscove’s Modified Dulbecco’s Medium (IMDM) | Gibco | 12440-046 | |
| Fetal Bovine Serum (FBS) | Corning | 35-010-CV | |
| Neonatal Calf Serum (NCS) | Gibco | 26010-074 | |
| Penicillin/Streptomycin (Pen/Strep) | Gibco | 15140-122 | |
| 10% Formalin | Fisher Scientific | 23-427-098 | |
| DMSO | Sigma-Aldrich | D2650-100ML | |
| TNFα | Sigma-Aldrich | SRP3177-50UG | |
| Phosphate Buffered Saline (PBS) | Gibco | 70013-032 | |
| K2EDTA vacutainer blood collection tubes | BD | 366450 | |
| Percoll (Density Gradient Media, DGM) | GE Healthcare | 17-0891-01 | |
| 6 well plates | Corning | 353046 | |
| Cell strainers | Fisher Scientific | 22363549 | |
| Eppendorf Safe-Lock Tubes 2.0 mL, natural | Fisher Scientific | 22363352 | |
| Trypan Blue | Corning | 25-900-Cl | |
| Bio-Rad Mini-PROTEAN Tetra System | Bio-Rad | 1658001FC | |
| Bio-Rad Mini Trans-Blot Cell | Bio-Rad | 1658033 | |
| TGX FastCast Acrylamide Kit, 12% | Bio-Rad | 1610175 | |
| Mini-Protean 3 Multi-Casting Chamber | Bio-Rad | 1654112 | |
| 4X Laemmli Sample Buffer | Bio-Rad | 1610747 | |
| 2-Mercaptoethanol | Sigma-Aldrich | M3148-100ML | |
| Glycine | Bio-Rad | 1610718 | |
| Tween-20 | Sigma-Aldrich | P7949-500ML | |
| Instant Nonfat Dry Milk | Carnation | ||
| Rubicon (D9F7) Rabbit mAb | Cell Signalling Technology | 8465S | |
| Monoclonal Anti-β-Actin antibody produced in mouse | Sigma-Aldrich | A2228-100UL | |
| Anti-rabbit IgG, HRP-linked Antibody | Cell Signalling Technology | 7074S | |
| Anti-mouse IgG, HRP-linked Antibody | Cell Signalling Technology | 7076S | |
| SuperSignal West Pico PLUS Chemiluminescent Substrate | Thermo Scientific | 34578 |
References
- Gregor, M. F., Hotamisligil, G. S. Inflammatory mechanisms in obesity. Annu. Rev. Immunol. 29, 415-445 (2011).
- van Horssen, R., Ten Hagen, T. L. M., Eggermont, A. M. M. TNF-alpha in cancer treatment: molecular insights, antitumor effects, and clinical utility. Oncologist. 11 (4), 397-408 (2006).
- Yogev, Y., Catalano, P. M.
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