How breast implants affect the immune system?

Implant surface topography can influence the development of scarring, inflammation, and other complications.

Silicone breast implants are a highly preferred choice among women seeking breast augmentation procedures. These implants come in different sizes and shapes, ranging from low profile to high profile breast implants.

According to the U.S. Food and Drug Administration data, these implants need to be replaced within ten years due to the buildup of scar tissue and other complications.

Now, MIT scientists analyzed how the varying surface architecture found in these implants affect the immune system. Sometimes, it leads to the development of adverse effects, including an unusual type of lymphoma.

Breast implants are often made of silicon. Sometimes, patients experience a complication called capsular contracture, in which scar tissue forms around the implant and squeezes it, creating pain or discomfort and visible deformation of the implant.

These implants could also flip after implantation, requiring them to be surgically adjusted or removed.

In 2019, the U.S. Food and Drug Administration today took significant action to protect women from breast implant-associated anaplastic large cell lymphoma (BIA-ALCL) by requesting the manufacturer recall all highly textured breast implants (about 80 microns).

In 2015, scientists explored how the unique surface of implants interacts with the surrounding tissue and the immune system. The same experiment was performed with other commonly used implants. They began by testing five commercially available implants with different topographies, including the degree of roughness. These included the highly textured one previously recalled, one that is completely smooth, and three that are somewhere in between.

In the rabbit-modeled study, scientists found that surrounding tissues show increased activity when exposed to roughest implant surfaces. All implants were found to stimulate T cells in different ways. More specifically, implants with rough surfaces stimulated more pro-inflammatory T-cell responses.

This implies that rough implants rub against the surrounding tissue and cause more irritation. Also, this explains why rougher implants can lead to lymphoma: some of the texture sloughs off and gets trapped in nearby tissue, where it provokes chronic inflammation that can eventually lead to cancer.

Scientists performed the same study on mice by using miniaturized versions of these implants. They found that highly textured implants provoked more macrophage activity, scar tissue formation, and higher inflammatory T cells.

After performing single-cell RNA sequencing of immune cells, they confirmed that the cells were expressing pro-inflammatory genes.

Joshua Dolloff, a former MIT postdoc who is now an assistant professor at Johns Hopkins University, said, “While completely smooth surface implants also had higher levels of macrophage response and fibrosis, it was very clear in mice that individual cells were more stressed and were expressing more of a pro-inflammatory phenotype in response to the highest surface roughness.”

“We believe that this is due to such surface architecture existing on the scale of individual cells of the body, allowing the cells to perceive them differently.”

Rachel Brem, director of breast imaging and intervention and a professor of radiology at George Washington University Medical Center, noted, “The study investigates one of the most timely and increasingly perplexing problems in breast reconstruction — how to identify silicone breast implants with the least immunologic response to minimize the risk of implant-induced lymphoma.”

“The finding of a complex inflammatory and anti-inflammatory response is critically important, as is the finding that the 4-micron textured implant results in a thinner, translucent capsule than that found with smooth implants, and is the optimal formulation of a silicone breast implant to result in the least thick, least overall immunogenic response. This is a critically important finding which will allow for the development of the optimal implant for patients.”

After an animal-model study, scientists determined how human patients respond to different types of silicone breast implants. They were surprised to found the same kinds of immune responses that they had seen in the animal studies. They observed that tissue samples exposed to highly textured implants for many years showed signs of a chronic, long-term immune response. They also found that scar tissue was thicker in patients who had more highly textured implants.

Omid Veiseh, a former MIT postdoc, said“Doing across-the-board comparisons in mice, rabbits, and then in human [tissue samples] provides a much more robust and substantial body of evidence about how these compare to one another.”

Other authors of the paper include Marcos Sforza, Tracy Ann Perry, Jennifer Haupt, Morgan Jamiel, Courtney Chambers, Amanda Nash, Samira Aghlara-Fotovat, Jessica Stelzel, Stuart Bauer, Sarah Neshat, John Hancock, Natalia Araujo Romero, Yessica Elizondo Hidalgo, Isaac Mora Leiva, Alexandre Mendonca Munhoz, Ardeshir Bayat, Brian Kinney, H. Courtney Hodges, Roberto Miranda, and Mark Clemens.

Journal Reference:
  1. Dolloff, J.C., Veiseh, O., de Mezerville, R. et al. The surface topography of silicone breast implants mediates the foreign body response in mice, rabbits, and humans. Nat Biomed Eng (2021). DOI: 10.1038/s41551-021-00739-4

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