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Streptococcus mutans Extracellular Vesicles Regulate Early Streptococcus sanguinis Nanoadhesion
(SAGE Publications, 2026-02-24)
C. Leiva-Sabadini
;
C.M. Lévesque
;
L. Bozec
;
SCHUH, CHRISTINA
;
S. Aguayo
<jats:p> Dental caries remains a globally prevalent disease, driven by microbial dysbiosis and competitive ecological shifts within the oral biofilm. A key interaction in this context is the antagonism between <jats:italic toggle="yes">Streptococcus mutans</jats:italic> and <jats:italic toggle="yes">Streptococcus sanguinis</jats:italic> , two early colonizers of the dentin surfaces. While bacterial extracellular vesicles (bEVs) have emerged as important mediators of microbial communication, their role in interspecies adhesion and early biofilm dynamics remains poorly understood. This study explored how <jats:italic toggle="yes">S. mutans</jats:italic> –derived bEVs, isolated from planktonic cultures and biofilms grown on native or glycated type I collagen substrates, modulate <jats:italic toggle="yes">S. sanguinis</jats:italic> nanoadhesion and initial biofilm formation. Bacterial EVs were characterized using nanoparticle tracking analysis and transmission electron microscopy, and their functional effects were assessed via atomic force microscopy–based single-cell force spectroscopy. This approach enabled direct quantification of bacterial adhesion forces and single-molecule unbinding events under different vesicle-exposure conditions. Our results demonstrated that planktonic-derived bEVs enhanced <jats:italic toggle="yes">S. sanguinis</jats:italic> adhesion at 5-s contact times, while bEVs from collagen-bound <jats:italic toggle="yes">S. mutans</jats:italic> biofilms, particularly those grown on glycated matrices, consistently reduced adhesion forces, rupture lengths, and unbinding events. Optical coherence tomography imaging confirmed that these nanoscale effects translated into altered early biofilm architecture, with planktonic bEVs promoting thicker, denser biofilms and biofilm-derived bEVs leading to sparser colonization. Our findings suggest that <jats:italic toggle="yes">S. mutans</jats:italic> bEVs exhibit a context-dependent modulatory effect on <jats:italic toggle="yes">S. sanguinis</jats:italic> , enhancing adhesion under planktonic conditions and suppressing it upon biofilm establishment. This biphasic behavior may represent a strategic mechanism for niche domination during caries initiation. Moreover, collagen glycation—mimicking aged or hyperglycemic dentin—further influenced bEV function, underscoring the importance of the host matrix state in microbial interactions. Overall, this study highlights a previously unrecognized role for bEVs in shaping early oral dysbiosis at the single-cell level. </jats:p>
1Scopus© Citations 1
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Nanoscale Dynamics of Streptococcal Adhesion to AGE-Modified Collagen
(2023)
C. Leiva-Sabadini
;
P. Tiozzo-Lyon
;
L. Hidalgo-Galleguillos
;
L. Rivas
;
A.I. Robles
<jats:p> The adhesion of initial colonizers such as Streptococcus mutans to collagen is critical for dentinal and root caries progression. One of the most described pathological and aging-associated changes in collagen—including dentinal collagen—is the generation of advanced glycation end-products (AGEs) such as methylglyoxal (MGO)–derived AGEs. Despite previous reports suggesting that AGEs alter bacterial adhesion to collagen, the biophysics driving oral streptococcal attachment to MGO-modified collagen remains largely understudied. Thus, the aim of this work was to unravel the dynamics of the initial adhesion of S. mutans to type I collagen in the presence and absence of MGO-derived AGEs by employing bacterial cell force spectroscopy with atomic force microscopy (AFM). Type I collagen gels were treated with 10 mM MGO to induce AGE formation, which was characterized with microscopy and enzyme-linked immunosorbent assay. Subsequently, AFM cantilevers were functionalized with living S. mutans UA 159 or Streptococcus sanguinis SK 36 cells and probed against collagen surfaces to obtain force curves displaying bacterial attachment in real time, from which the adhesion force, number of events, Poisson analysis, and contour and rupture lengths for each individual detachment event were computed. Furthermore, in silico computer simulation docking studies between the relevant S. mutans UA 159 collagen-binding protein SpaP and collagen were computed, in the presence and absence of MGO. Overall, results showed that MGO modification increased both the number and adhesion force of single-unbinding events between S. mutans and collagen, without altering the contour or rupture lengths. Both experimental and in silico simulations suggest that this effect is due to increased specific and nonspecific forces and interactions between S. mutans UA 159 and MGO-modified collagen substrates. In summary, these results suggest that collagen alterations due to aging and glycation may play a role in early bacterial adherence to oral tissues, associated with conditions such as aging or chronic hyperglycemia, among others. </jats:p>
1Scopus© Citations 13
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Nanomechanical and Molecular Characterization of Aging in Dentinal Collagen
(2022)
C.M.A.P. Schuh
;
C. Leiva-Sabadini
;
S. Huang
;
N.P. Barrera
;
L. Bozec
<jats:p> Methylglyoxal (MGO) is an important molecule derived from glucose metabolism with the capacity of attaching to collagen and generating advanced glycation end products (AGEs), which accumulate in tissues over time and are associated with aging and diseases. However, the accumulation of MGO-derived AGEs in dentin and their effect on the nanomechanical properties of dentinal collagen remain unknown. Thus, the aim of the present study was to quantify MGO-based AGEs in the organic matrix of human dentin as a function of age and associate these changes with alterations in the nanomechanical and ultrastructural properties of dentinal collagen. For this, 12 healthy teeth from <26-y-old and >50-y-old patients were collected and prepared to obtain crown and root dentin discs. Following demineralization, MGO-derived AGEs were quantified with a competitive ELISA. In addition, atomic force microscopy nanoindentation was utilized to measure changes in elastic modulus in peritubular and intertubular collagen fibrils. Finally, principal component analysis was carried out to determine aging profiles for crown and root dentin. Results showed an increased presence of MGO AGEs in the organic matrix of dentin in the >50-y-old specimens as compared with the <26-y-old specimens in crown and root. Furthermore, an increase in peritubular and intertubular collagen elasticity was observed in the >50-y-old group associated with ultrastructural changes in the organic matrix as determined by atomic force microscopy analysis. Furthermore, principal component analysis loading plots suggested different “aging profiles” in crown and root dentin, which could have important therapeutic implications in restorative and adhesive dentistry approaches. Overall, these results demonstrate that the organic matrix of human dentin undergoes aging-related changes due to MGO-derived AGEs with important changes in the nanomechanical behavior of collagen that may affect diagnostic and restorative procedures in older people. </jats:p>
5Scopus© Citations 7

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