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Published on: May 21, 2018
Human breast milk-derived exosomes attenuate lipopolysaccharide-induced activation in microglia
Oluwatomi Akinduro1, Sanjay Kumar1, Yuechuan Chen2
1Department of Pediatrics/Division of Neonatology and Center of Glial Biology in Medicine at the University of Alabama School of Medicine, UAB Women and Infant Center, University of Alabama at Birmingham, 1700 6th Ave South, Birmingham, AL, 35294, USA.
Abstract:
Microglia mediate the immune response in the central nervous system to many insults, including lipopolysaccharide (LPS), a bacterial endotoxin that initiates neuroinflammation in the neonatal population, especially preterm infants. The synthesis of the proinflammatory proteins CD40 and NLRP3 depends on the canonical NF-κB cascade as the genes encoding CD40 and NLRP3 are transcribed by the phosphorylated NF-κB p50/p65 heterodimer in LPS-induced microglia. Exosomes, which are nanosized vesicles (40-150 nm) involved in intercellular communication, are implicated in many pathophysiological processes. Human breast milk, which is rich in exosomes, plays a vital role in neonatal immune system maturation and adaptation. Activated microglia may cause brain-associated injuries or disorders; therefore, we hypothesize that human breast milk-derived exosomes (HBME) attenuate LPS-induced activation of CD40 and NLRP3 by decreasing p38 MAPK and NF-κB p50/p65 activation/phosphorylation downstream of TLR4 in murine microglia (BV2). Human microglia (HMC3) showed a significant decrease in p65 phosphorylation. We isolated purified HBME and characterized them using nanoparticle tracking analysis, transmission electron microscopy, fluorescence-activated cell sorting, and western blots. Analysis of microglia exposed to LPS and HBME indicated that HBME modulated the expression of signaling molecules in the canonical NF-κB pathway, including MyD88, IκBα, p38 MAPK, NF-κB p65, and their products CD40, NLRP3, and cytokines IL-1β and IL-10. Thus, HBMEs have great potential for attenuating the microglial response to LPS.
Insights
Human breast milk-derived exosomes (HBME) can reduce neuroinflammation in neonatal brain injury. HBME attenuate lipopolysaccharide (LPS)-induced microglial activation by inhibiting key inflammatory pathways, offering a potential therapeutic approach.
Area of Science:
- Neuroscience
- Immunology
- Cell Biology
Background:
- Microglia are key immune cells in the central nervous system, responding to insults like lipopolysaccharide (LPS).
- LPS triggers neuroinflammation via the NF-κB pathway, increasing CD40 and NLRP3, which is detrimental in neonates.
- Human breast milk-derived exosomes (HBME) are crucial for neonatal immune development and may modulate microglial responses.
Purpose of the Study:
- To investigate if HBME can attenuate LPS-induced activation of CD40 and NLRP3 in microglia.
- To determine if HBME reduce p38 MAPK and NF-κB p50/p65 activation downstream of TLR4.
- To explore HBME's potential in mitigating LPS-induced neuroinflammation in neonatal settings.
Main Methods:
- Purification and characterization of HBME using nanoparticle tracking analysis, TEM, FACS, and Western blots.
- Exposure of murine microglia (BV2) and human microglia (HMC3) to LPS and HBME.
- Analysis of signaling molecules (MyD88, IκBα, p38 MAPK, NF-κB p65) and inflammatory products (CD40, NLRP3, IL-1β, IL-10) via Western blot.
Main Results:
- HBME significantly decreased p65 phosphorylation in human microglia (HMC3).
- HBME modulated key signaling molecules in the canonical NF-κB pathway, including MyD88, IκBα, and p38 MAPK.
- HBME reduced the expression of pro-inflammatory proteins CD40 and NLRP3, and cytokines IL-1β and IL-10 in LPS-treated microglia.
Conclusions:
- Human breast milk-derived exosomes (HBME) effectively attenuate LPS-induced microglial activation.
- HBME reduce neuroinflammation by inhibiting the p38 MAPK and NF-κB signaling pathways.
- HBME show significant potential as a therapeutic strategy for neonatal neuroinflammation and brain injury.
