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Gelsolin Amyloidogenesis Is Effectively Modulated by Curcumin and Emetine Conjugated PLGA Nanoparticles.

Srivastava A, Arya P, Goel S, Kundu B, Mishra P, Fnu A - PLoS ONE (2015)

Bottom Line: These two types of aggregates differed in their morphologies, surface hydrophobicity and secondary structural signatures, confirming that they followed distinct pathways.In spite of differences, both these aggregates displayed reduced toxicity against SH-SY5Y human neuroblastoma cells as compared to control gelsolin amyloids.We conclude that the cytotoxicity of gelsolin amyloids can be reduced by either stalling or accelerating its fibrillation process.

View Article: PubMed Central - PubMed

Affiliation: Kusuma School of Biological Sciences, IIT Delhi, New Delhi, India.

ABSTRACT
Small molecule based therapeutic intervention of amyloids has been limited by their low solubility and poor pharmacokinetic characteristics. We report here, the use of water soluble poly lactic-co-glycolic acid (PLGA)-encapsulated curcumin and emetine nanoparticles (Cm-NPs and Em-NPs, respectively), as potential modulators of gelsolin amyloidogenesis. Using the amyloid-specific dye Thioflavin T (ThT) as an indicator along with electron microscopic imaging we show that the presence of Cm-NPs augmented amyloid formation in gelsolin by skipping the pre-fibrillar assemblies, while Em-NPs induced non-fibrillar aggregates. These two types of aggregates differed in their morphologies, surface hydrophobicity and secondary structural signatures, confirming that they followed distinct pathways. In spite of differences, both these aggregates displayed reduced toxicity against SH-SY5Y human neuroblastoma cells as compared to control gelsolin amyloids. We conclude that the cytotoxicity of gelsolin amyloids can be reduced by either stalling or accelerating its fibrillation process. In addition, Cm-NPs increased the fibrillar bulk while Em-NPs defibrillated the pre-formed gelsolin amyloids. Moreover, amyloid modulation happened at a much lower concentration and at a faster rate by the PLGA encapsulated compounds as compared to their free forms. Thus, besides improving pharmacokinetic and biocompatible properties of curcumin and emetine, PLGA conjugation elevates the therapeutic potential of both small molecules against amyloid fibrillation and toxicity.

No MeSH data available.


Related in: MedlinePlus

Hydrophobicity and secondary structure assessment of the aggregates.(A) Nile Red fluorescence of fAGel alone (black squares), with Cm-NPs (red circles) and Em-NPs (blue triangles). The fluorescence spectra of controls are also shown in colour. (B) ATR-FTIR spectra of aggregating samples of fAGel alone (black), with Cm-NPs (red) and with Em-NPs (blue) are compared. In each case the samples were taken after 24 h of incubation with NPs at 0.1 mg/ml concentration. A characteristic 1644 cm-1 peak for Em-NP sample corresponds to majorly unstructured aggregates.
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pone.0127011.g006: Hydrophobicity and secondary structure assessment of the aggregates.(A) Nile Red fluorescence of fAGel alone (black squares), with Cm-NPs (red circles) and Em-NPs (blue triangles). The fluorescence spectra of controls are also shown in colour. (B) ATR-FTIR spectra of aggregating samples of fAGel alone (black), with Cm-NPs (red) and with Em-NPs (blue) are compared. In each case the samples were taken after 24 h of incubation with NPs at 0.1 mg/ml concentration. A characteristic 1644 cm-1 peak for Em-NP sample corresponds to majorly unstructured aggregates.

Mentions: The amyloid assembly progresses through interaction of hydrophobic surfaces often associated with secondary structural changes. Since, the extent of hydrophobic exposure is associated with the toxicity of the amyloid aggregates, we were interested in evaluating the same under the influence of NPs [47, 48]. For this, we employed Nile Red (NR) fluorescence assay (previously used for assessing hydrophobicity) on the 24 h incubated fAGel samples (both with and without NPs), since they exhibited highest degree of morphological differences in TEM and AFM images [49]. Evidently, Cm-NP treatment resulted in reduced NR binding that indicates reduction in surface/volume ratio in Cm-NP samples containing mature fibrils as compared to control that correspond to early/premature aggregates (Fig 6A). On the other hand, Em-NPs caused dramatically reduced NR fluorescence as compared to control fAGel aggregates confirming the unstructured and random aggregate species seen in TEM and AFM images. To further associate these alterations in the hydrophobic surfaces with any secondary structural changes under the influence of NPs, we performed ATR-FTIR analysis of these aggregates.


Gelsolin Amyloidogenesis Is Effectively Modulated by Curcumin and Emetine Conjugated PLGA Nanoparticles.

Srivastava A, Arya P, Goel S, Kundu B, Mishra P, Fnu A - PLoS ONE (2015)

Hydrophobicity and secondary structure assessment of the aggregates.(A) Nile Red fluorescence of fAGel alone (black squares), with Cm-NPs (red circles) and Em-NPs (blue triangles). The fluorescence spectra of controls are also shown in colour. (B) ATR-FTIR spectra of aggregating samples of fAGel alone (black), with Cm-NPs (red) and with Em-NPs (blue) are compared. In each case the samples were taken after 24 h of incubation with NPs at 0.1 mg/ml concentration. A characteristic 1644 cm-1 peak for Em-NP sample corresponds to majorly unstructured aggregates.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4440822&req=5

pone.0127011.g006: Hydrophobicity and secondary structure assessment of the aggregates.(A) Nile Red fluorescence of fAGel alone (black squares), with Cm-NPs (red circles) and Em-NPs (blue triangles). The fluorescence spectra of controls are also shown in colour. (B) ATR-FTIR spectra of aggregating samples of fAGel alone (black), with Cm-NPs (red) and with Em-NPs (blue) are compared. In each case the samples were taken after 24 h of incubation with NPs at 0.1 mg/ml concentration. A characteristic 1644 cm-1 peak for Em-NP sample corresponds to majorly unstructured aggregates.
Mentions: The amyloid assembly progresses through interaction of hydrophobic surfaces often associated with secondary structural changes. Since, the extent of hydrophobic exposure is associated with the toxicity of the amyloid aggregates, we were interested in evaluating the same under the influence of NPs [47, 48]. For this, we employed Nile Red (NR) fluorescence assay (previously used for assessing hydrophobicity) on the 24 h incubated fAGel samples (both with and without NPs), since they exhibited highest degree of morphological differences in TEM and AFM images [49]. Evidently, Cm-NP treatment resulted in reduced NR binding that indicates reduction in surface/volume ratio in Cm-NP samples containing mature fibrils as compared to control that correspond to early/premature aggregates (Fig 6A). On the other hand, Em-NPs caused dramatically reduced NR fluorescence as compared to control fAGel aggregates confirming the unstructured and random aggregate species seen in TEM and AFM images. To further associate these alterations in the hydrophobic surfaces with any secondary structural changes under the influence of NPs, we performed ATR-FTIR analysis of these aggregates.

Bottom Line: These two types of aggregates differed in their morphologies, surface hydrophobicity and secondary structural signatures, confirming that they followed distinct pathways.In spite of differences, both these aggregates displayed reduced toxicity against SH-SY5Y human neuroblastoma cells as compared to control gelsolin amyloids.We conclude that the cytotoxicity of gelsolin amyloids can be reduced by either stalling or accelerating its fibrillation process.

View Article: PubMed Central - PubMed

Affiliation: Kusuma School of Biological Sciences, IIT Delhi, New Delhi, India.

ABSTRACT
Small molecule based therapeutic intervention of amyloids has been limited by their low solubility and poor pharmacokinetic characteristics. We report here, the use of water soluble poly lactic-co-glycolic acid (PLGA)-encapsulated curcumin and emetine nanoparticles (Cm-NPs and Em-NPs, respectively), as potential modulators of gelsolin amyloidogenesis. Using the amyloid-specific dye Thioflavin T (ThT) as an indicator along with electron microscopic imaging we show that the presence of Cm-NPs augmented amyloid formation in gelsolin by skipping the pre-fibrillar assemblies, while Em-NPs induced non-fibrillar aggregates. These two types of aggregates differed in their morphologies, surface hydrophobicity and secondary structural signatures, confirming that they followed distinct pathways. In spite of differences, both these aggregates displayed reduced toxicity against SH-SY5Y human neuroblastoma cells as compared to control gelsolin amyloids. We conclude that the cytotoxicity of gelsolin amyloids can be reduced by either stalling or accelerating its fibrillation process. In addition, Cm-NPs increased the fibrillar bulk while Em-NPs defibrillated the pre-formed gelsolin amyloids. Moreover, amyloid modulation happened at a much lower concentration and at a faster rate by the PLGA encapsulated compounds as compared to their free forms. Thus, besides improving pharmacokinetic and biocompatible properties of curcumin and emetine, PLGA conjugation elevates the therapeutic potential of both small molecules against amyloid fibrillation and toxicity.

No MeSH data available.


Related in: MedlinePlus