Polyvinylidene Fluoride Alters Inflammatory Responses by Activation-induced Cell Death in Macrophages

Our plain-English summary of Polyvinylidene Fluoride Alters Inflammatory Responses by Activation-induced Cell Death in Macrophages, by H.G. Kim, S.H. Kim, T.S. Kim, et al (Immune Network, 2017).

The study

• Authors: H.G. Kim, S.H. Kim, T.S. Kim, T.W. Park, R. Won, H.D. Park, S.A. Choi, Y.W. Jung
• Journal: Immune Network
• Published: 2017;17(6):402-409
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Carbon nanotubes (CNTs) are nanomaterials that have been employed in generating diverse materials. We previously reported that CNTs induce cell death in macrophages, possibly via asbestosis. Therefore, we generated CNT-attached polyvinylidene fluoride (PVDF), which is an established polymer in membrane technology, and then examined whether CNT-attached PVDF is immunologically safe for medical purposes compared to CNT alone. To test this, we treated RAW 264.7 murine macrophages (RAW cells) with CNT-attached PVDF and analyzed the production of nitric oxide (NO), a potent proinflammatory mediator, in these cells. RAW cells treated with CNT-attached PVDF showed reduced NO production in response to lipopolysaccharide. However, the same treatment also decreased the cell number suggesting that this treatment can alter the homeostasis of RAW cells. Although cell cycle of RAW cells was increased by PVDF treatment with or without CNTs, apoptosis was enhanced in these cells. Taken together, these results indicate that PVDF with or without CNTs modulates inflammatory responses possibly due to activation-induced cell death in macrophages.

In plain English

This laboratory study from Korea did not test asbestos. It used a mouse macrophage cell line (RAW 264.7) grown in culture. The authors' earlier work had found that carbon nanotubes can kill macrophages, which they described as probably due to "asbestosis caused by frustrated macrophages." Here they tested whether nanotubes attached to a polyvinylidene fluoride (PVDF) filter membrane would avoid this. Cells were treated with plain PVDF, PVDF with single-walled nanotubes, or PVDF with multi-walled nanotubes, with or without the bacterial substance LPS. All three materials reduced the nitric oxide made by LPS-stimulated cells and reduced cell numbers. Plain PVDF raised the share of cells in the S and G2 phases of the cell cycle. It also raised the share of apoptotic (dying) cells from 5.83 to 19.2 percent without LPS and from 17.4 to 35.3 percent with LPS. Nanotube-bearing PVDF doubled this share without LPS but left it unchanged with LPS. The authors concluded that PVDF itself altered macrophage survival and needs to be investigated for medical applications. They said the cause of the cell death was not clear.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: laboratory (in vitro) cell-culture experiment
• Who was studied: RAW 264.7 mouse macrophage cell line grown in culture; no humans or animals studied
• Exposure: PVDF filter membrane alone, PVDF with single-walled carbon nanotubes (SWCNT), or PVDF with multi-walled carbon nanotubes (MWCNT), for 24 h, with or without LPS stimulation; nanotubes averaged 18 nm wide and 0.1 μm long. No asbestos was tested.
• Main results:
  • LPS-stimulated cells treated with any of the three membranes produced less nitric oxide than negative controls
  • Cell numbers fell with PVDF alone and with SWCNT- or MWCNT-bound PVDF
  • PVDF alone increased the frequency of cells in the S/G2 phase of the cell cycle, with or without LPS
  • Nanotube-bearing PVDF increased the ratio of cells in the S/G2 phase in LPS-stimulated cells
  • The ratio of apoptotic cells in the LPS-stimulated group was 3 times that of negative controls
  • PVDF alone raised the share of apoptotic cells from 5.83 to 19.2 percent without LPS and from 17.4 to 35.3 percent with LPS (Figure 4 plots these as Ratio (%))
  • In LPS-treated cells, the percentage of apoptotic cells with nanotube-bound PVDF was unchanged
  • Without LPS, nanotube-bound PVDF increased annexin V-positive (apoptotic) cells 2-fold compared with the DMEM control
• The authors' conclusion: The authors concluded that PVDF itself altered macrophage survival, probably through activation-induced cell death, and that PVDF needs to be investigated for medical applications. They also concluded that other mesh materials should be explored for carrying carbon nanotubes.
• Limitations the authors state:
  • The authors stated that the cause of the cell death seen with PVDF is not clear

Topics

Medical terms in this study, explained in our Lexicon: Macrophage, Apoptosis.

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