Search Results (80)

(1) Background: The extracellular matrix (ECM) is a natural scaffold for cells, creating a three-dimensional architecture composed of fibrous proteins (mainly collagen) and proteoglycans, which are synthesized by resident cells. In this study, a physiological hypoxic environment was utilized to enhance ECM production by human mesenchymal stem cells (hMSCs), a process relevant to tissue engineering and regenerative medicine. (2) Methods: hMSCs were treated with deferoxamine (DFO), a pharmaceutical hypoxia-mimetic agent that induces cellular responses similar to low-oxygen conditions through stabilization of hypoxia inducible factor-1α (HIF-1α). The time points 0 h 24 h, 3 h 24 h, and 24 h 24 h refer to DFO being added immediately after cell seeding (before cells adhesion), 3 h after cell seeding (during initial cells attachment), and 24 h after cell seeding (after focal adhesions formation and actin organization), respectively, to evaluate the influence of cell adhesion on ECM deposition. hMSCs incubated in culture media were subsequently exposed to DFO for 24 h. Samples were then subjected to cell viability tests, scanning electron microscopy (SEM), atomic force microscopy (AFM) and laser scanning confocal microscopy (CLSM) assessments. (3) Results: Viability tests indicated that DFO concentrations in the range of 0–300 µM were non-toxic over 24 h. The presence of collagen fibers in the DFO-derived ECM was confirmed with anti-collagen antibodies under CLSM. Increased ECM secretion was observed under the following conditions: 3 μM DFO (24 h 24 h), 100 μM DFO (0 h 24 h) and 300 μM DFO (3 h 24 h). SEM and AFM images revealed the morphology of various stages of collagen formation with both collagen fibrils and fibers identified. (4) Conclusions: Our preliminary study demonstrated enhanced ECM secretion by hMSC treated with DFO at concentrations of 3, 100, and 300 µM within a short cultivation period of 24–48 h without significant affecting cell viability. By mimicking physiological processes, it may be possible to stimulate endogenous tissue regeneration, for example, at an injury site. Full article

Aging is associated with aortic stiffening (AoSt), a condition characterized by diminished aortic elasticity that predisposes individuals to cognitive decline, including Alzheimer’s disease (AD). Emerging evidence implicates medin, which is derived from milk fat globule-EGF factor 8 protein (MFG-E8), as a key link between AoSt and AD. Medin aggregates into aortic medial amyloid (AMA), which is found in approximately 97% of Caucasian individuals aged 50 and above, contributing to vascular inflammation, calcification, and loss of arterial elasticity. These changes may promote hyperpulsatile cerebral blood flow and impair glymphatic clearance, resulting in increased deposition of neurotoxic proteins, such as amyloid-β (Aβ) and possibly medin, which colocalizes with vascular Aβ in the brain. Medin enhances Aβ aggregation, generating heterologous fibrils, and thereby contributes to cerebrovascular dysfunction and neuroinflammation. This interaction (cross-seeding) may deteriorate amyloid pathology in both the vasculature and the parenchyma in AD. Furthermore, medin per se causes endothelial dysfunction, increases oxidative stress, and activates glial cells, promoting the development of a pro-inflammatory environment that enhances cognitive decline. In this manuscript, we contend that medin might act as a bridge connecting the age-related increase in aortic stiffness to AD, and therefore, medin might present a novel therapeutic target within this context. This hypothesis deserves experimental and clinical validation. Full article

Objectives: The compound 3-(4-Hydroxy-3-methoxyphenyl) propionic acid (HMPA) is a terminal metabolite derived from polyphenol compounds. It has been studied for its potential to support brain health indirectly through its anti-oxidant effects and ability to enhance the gut environment; however, its role in dementia pathogenesis is unclear. Therefore, the aim of this study was to evaluate how HMPA inhibits Aβ42 aggregation in vitro. Methods: We examined the inhibitory effects of HMPA on amyloid-β protein (Aβ) aggregation using a thioflavin T (ThT) assay and electron microscopy (EM). Results: ThT assays demonstrated that HMPA inhibited both the nucleation and elongation phases of Aβ aggregation. Additionally, EM of low-molecular-weight (LMW) Aβ42 in the presence of HMPA demonstrated shorter fibrils compared to those formed without HMPA. The EC₅₀ of HMPA in LMW Aβ42 was 5–6 mM. Conclusions: These findings indicate that, similar to several polyphenol compounds such as myricetin and rosmarinic acid, HMPA may inhibit Aβ pathogenesis, although it requires a fairly high concentration in vitro. These findings suggest the potential of HMPA as a lead compound for modulating Aβ-related neurodegeneration. Full article

We aimed to simulate tau abnormalities—specifically hyperphosphorylation and aggregation—that are hallmarks of tauopathies, including Alzheimer’s disease, to evaluate tau-targeting therapies. To model pathological p-tau accumulation at early disease stages, we exposed mouse cortical cultures to redox-active iron from hemin (Hm), a breakdown product of hemoglobin, or challenged them with the excitatory neurotransmitter glutamate. Using the AT8 phospho-specific antibody, we demonstrate that a subtoxic concentration of Hm (3 µM) promotes pathological p-tau accumulation in a subpopulation of cultured cortical neurons and their proximal neurites. Uric acid (UA; 0.1–200 µM), the metabolic end-product of purines in humans, prevented p-tau build-up. Neither xanthine, the immediate precursor of UA, nor allantoin, its oxidized product, reproduced this effect. Live cell imaging studies revealed that UA operates by repressing iron-driven lipid peroxidation. DOT (3 µM), a brain-permeant tetracycline (TC) without antibiotic activity, mimicked UA’s anti-tau and antioxidant effects. Interestingly, both UA and DOT remained effective in preventing p-tau accumulation induced by glutamate (10 µM). To simulate tau aggregation at more advanced disease stages, we conducted a Thioflavin-T aggregation assay. Our findings revealed that UA and DOT prevented tau aggregation seeded by heparin. However, only DOT remained effective when heparin-assembled tau fibrils were used as the seeding material. In summary, our results indicate that UA-elevating agents may hold therapeutic utility for tauopathies. The non-purine compound DOT could serve as an effective alternative to UA-related therapies. Full article

Pathological aggregation of α-synuclein (αS) is implicated in the pathogenesis of Parkinson’s disease (PD) and other α-synucleinopathies. The current view is that neuron-to-neuron spreading of αS pathology contributes to the progression of α-synucleinopathy. We used an A53T mutant human αS transgenic mouse model (TgA53T) to examine whether the site of pathogenic αS inoculation affects the pattern of neuropathology and whether soluble and insoluble fractions derived from crude pathogenic tissue lysates exhibit differential capacities to initiate αS pathology. To test whether the inoculation site impacts the ultimate spatial/temporal patterns of αS pathology, αS preformed fibrils (PFFs), or brain homogenates from TgA53T mice with α-synucleinopathy, were injected into the cortex/striatum, brainstem, or skeletal muscle. In all cases, inoculation of pathogenic αS induced end-stage motor dysfunction within ~100 days post-inoculation (dpi). Significantly, irrespective of the inoculation sites, the ultimate distribution of the αS pathology was like that seen in normally aged TgA53T mice at end-stage, indicating that the intrinsic neuronal vulnerability is a significant determinant in the induction of αS pathology, even when initiated by inoculation of pathogenic αS. Temporal analysis of brainstem-injected TgA53T mice show that initial αS pathology was seen by 30 days post-inoculation and inflammatory changes occur at later stages. In addition, we show that both highly soluble (S150) and insoluble (P150) fractions from end-stage TgA53T mice can seed de novo αS pathology in vivo. Moreover, the endoplasmic reticulum (ER)-enriched fraction from the TgA53T mice were highly pathogenic as the ER fraction induced αS pathology faster than other fractions when injected unilaterally into TgA53T mice. Our results suggest that multiple αS species from the brain can initiate the development of progressive αS pathology. Full article

Amyloid deposition has been reported to localize within thrombi; however, its pathological characteristics, particularly its precursor proteins, remain poorly understood. This study aimed to elucidate the pathological features of thrombus-associated amyloid deposition by immunohistochemistry combined with proteomic analyses using liquid chromatography–tandem mass spectrometry with laser microdissection. Our findings revealed that thrombus-associated amyloid deposits within the thrombus and vessel wall primarily comprised apolipoprotein A-I, with a mixture of amyloid fibrils derived from amyloidogenic proteins, including transthyretin and lactoferrin. Given that these proteins are present in the blood, our results support a previous hypothesis that proteins denatured during thrombus aging are a source of amyloid. Furthermore, phagocytes were infiltrated around the intramural and extravascular deposits rather than around the amyloid deposits within the thrombus. Therefore, amyloid deposits generated within the thrombus may be transported from regions with limited blood flow to the vessel wall and surrounding tissues, where blood flow is present, during thrombus processing. These deposits were primarily removed by phagocytic cells. Our results suggest that a facilitative effect on deposition occurs via a cross-seeding mechanism between amyloid fibrils and that phagocytes can remove amyloid deposits. These findings help elucidate the pathogenesis of localized amyloidosis. Full article

Intrinsically disordered proteins (IDPs), such as tau, beta-amyloid (Aβ), and alpha-synuclein (αSyn), are prone to misfolding, resulting in pathological aggregation and propagation that drive neurodegenerative diseases, including Alzheimer’s disease (AD), frontotemporal dementia (FTD), and Parkinson’s disease (PD). Misfolded IDPs are prone to aggregate into oligomers and fibrils, exacerbating disease progression by disrupting cellular functions in the central nervous system, triggering neuroinflammation and neurodegeneration. Furthermore, aggregated IDPs exhibit prion-like behavior, acting as seeds that are released into the extracellular space, taken up by neighboring cells, and have a propagating pathology across different regions of the brain. Conventional inhibitors, such as small molecules, peptides, and antibodies, face challenges in stability and blood–brain barrier penetration, limiting their efficacy. In recent years, nanotechnology-based strategies, such as multifunctional nanoplatforms or nanoparticles, have emerged as promising tools to address these challenges. These nanoplatforms leverage tailored designs to prevent or remodel the aggregation of IDPs and reduce associated neurotoxicity. This review discusses recent advances in nanoplatforms designed to target tau, Aβ, and αSyn aggregation, with a focus on their roles in reducing neuroinflammation and neurodegeneration. We examine critical aspects of nanoplatform design, including the choice of material backbone and targeting moieties, which influence interactions with IDPs. We also highlight key mechanisms including the interaction between nanoplatforms and IDPs to inhibit their aggregation, redirect aggregation cascade towards nontoxic, off-pathway species, and disrupt fibrillar structures into soluble forms. We further outline future directions for enhancing IDP clearance, achieving spatiotemporal control, and improving cell-specific targeting. These nanomedicine strategies offer compelling paths forward for developing more effective and targeted therapies for neurodegenerative diseases. Full article

Biofilm-associated amyloid proteins have emerged as significant contributors to the progression of neurodegenerative diseases, representing a complex intersection of microorganisms and human health. The cross-beta sheet structure characteristic of amyloids produced by gut-colonizing bacteria remains intact, crucial for the resilience of biofilms. These amyloids exacerbate neurodegenerative disorders such as Alzheimer’s and Parkinson’s by cross-seeding human amyloidogenic proteins like amyloid-beta and α-synuclein, accelerating their misfolding and aggregation. Despite molecular chaperones and heat shock proteins maintaining protein homeostasis, bacterial amyloids can overwhelm them, worsening neuronal damage. Genetic variations in chaperone genes further influence amyloidogenesis and neurodegeneration. Persistent bacterial infections and inflammation compromise the blood-brain barrier, allowing inflammatory molecules and amyloids to enter the brain, perpetuating the cycle of neurodegeneration. The gut-brain axis underscores the impact of dysbiosis and gut microbiota on brain function, potentially contributing to neurodegeneration. The enhancement of biofilm resilience and antibiotic resistance by functional amyloid fibrils complicates the treatment landscape. The interplay among chaperone systems, microbial amyloids, and neurodegenerative diseases underscores the urgent need for advanced treatment strategies targeting these pathways to attenuate disease progression. Understanding the processes that relate biofilm-associated amyloids to the onset of neurological disorders is critical for diagnosing and developing novel treatment strategies. Full article

A recent analysis compared the proteome of (i) blood clots seen in two diseases—sepsis and long COVID—when blood was known to have clotted into an amyloid microclot form (as judged by staining with the fluorogenic amyloid stain thioflavin T) with (ii) that of those non-amyloid clots considered to have formed normally. Such fibrinaloid microclots are also relatively resistant to fibrinolysis. The proteins that the amyloid microclots contained differed markedly both from the soluble proteome of typical plasma and that of normal clots, and also between the diseases studied (an acute syndrome in the form of sepsis in an ITU and a chronic disease represented by Long COVID). Many proteins in the amyloid microclots were low in concentration in plasma and were effectively accumulated into the fibres, whereas many other abundant plasma proteins were excluded. The proteins found in the microclots associated with the diseases also tended to be themselves amyloidogenic. We here ask effectively the inverse question. This is: can the clot proteome tell us whether the clots associated with a particular disease contained proteins that are observed uniquely (or are highly over-represented) in known amyloid clots relative to normal clots, and thus were in fact amyloid in nature? The answer is in the affirmative in a variety of major coagulopathies, viz., venous thromboembolism, pulmonary embolism, deep vein thrombosis, various cardiac issues, and ischaemic stroke. Galectin-3-binding protein and thrombospondin-1 seem to be especially widely associated with amyloid-type clots, and the latter has indeed been shown to be incorporated into growing fibrin fibres. These may consequently provide useful biomarkers with a mechanistic basis. Full article

Corneal fibroblasts are central to normal and abnormal wound healing in the cornea. During the wound healing process, several biochemical and biophysical signals that are present in the extracellular matrix (ECM) play critical roles in regulating corneal fibroblast behavior. The translocation and activation of Yes-associated protein (YAP)—a main transcriptional factor in the Hippo signaling pathway—is one example of mechanotransduction involving these signals. However, how corneal fibroblasts integrate these simultaneous cues is unknown. In this study, we utilized well-defined micropatterns of aligned collagen fibrils and other ECM proteins to explore the effects of cell density, topography, geometric confinement, and ECM composition on the translocation of YAP in corneal fibroblasts. We observed that when human corneal fibroblasts (HTKs) were confined to narrow micropatterns (50 μm and 100 μm) of proteins, there was a high degree of cell alignment irrespective of cell seeding density. However, the location of YAP was dependent upon the cell seeding density, ECM composition, and topography. YAP was more nuclear-localized on substrates coated with aligned collagen fibrils or fibronectin as compared to substrates coated with monomeric collagen, random collagen fibrils, or poly-L-Lysine. In addition, we also observed that YAP nuclear localization was significantly reduced when HTKs were cultured on aligned collagen fibrils, monomeric collagen, or fibronectin in the presence of monoclonal blocking antibodies against α₅ or β₁ integrin subunits. Finally, we observed that HTK cells formed fibrillar fibronectin on both monomeric collagen and aligned collagen fibrils. These findings provide new insights into how simultaneous biochemical and biophysical cues affect YAP localization in corneal fibroblasts. Full article

Spontaneous cleavage reactions normally occur in vivo on amino acid peptide backbones, leading to fragmentation products that can have different physiological roles and toxicity, particularly when the substrate of the hydrolytic processes are neuronal peptides and proteins highly related to neurodegeneration. We report a hydrolytic study performed with the HPLC-MS technique at different temperatures (4 °C and 37 °C) on peptide fragments of different neuronal proteins (amyloid-β, tau, and α-synuclein) in physiological conditions in the presence of Cu²⁺ and Zn²⁺ ions, two metal ions found at millimolar concentrations in amyloid plaques. The coordination of these metal ions with these peptides significantly protects their backbones toward hydrolytic degradation, preserving the entire sequences over two weeks in solution, while the free peptides in the same buffer are fully fragmented after the same or even shorter incubation period. Our data show that peptide cleavage is not only ruled by the chemical sensitivity of amino acids, but the peptide conformation changes induced by metal coordination influence hydrolytic reactions. The enhanced stability of neuronal peptides provided by metal coordination can increase local levels of amyloidogenic species capable of seeding fibril growth, resulting in aberrant protein depositions and deficits in neuronal activity. Full article

Background: Elettaria cardamomum (Cardamom) and Foeniculum vulgare (Fennel) are well-known spices and are also used as natural mouth fresheners. This study was performed to evaluate their neuroprotective ability based on certain acellular and cellular assays. Methods: Hexane and ethyl acetate extracts were prepared using cardamom and fennel seeds. GC/MS was performed for the identification of important bioactive compounds. Cell-based assays were performed using SH-SY5Y cells. Hydrogen peroxide was used for the induction of oxidative stress, and evaluation was done based on neuroprotection, reduced reactive oxygen species, and restoration of mitochondrial membrane potential (MMP). Additionally, anti-Aβ fibrillization/oligomerization activities were also analyzed along with anti-acetylcholinesterase activity. Results: α-Terpinyl acetate and anethol were identified as major phytocompounds in cardamom and fennel, respectively. Cardamom extracts and α-terpinyl acetate were more potent acetylcholinesterase (AChE) inhibitors than fennel extracts and anethol [IC₅₀ cardamom extracts, 130–150 μg/mL; α-terpinyl acetate, 61.87 μg/mL; anethol, 374.2 μg/mL; fennel extracts, >1 mg/mL] and showed mixed-type inhibition. Only the extracts displayed potent anti-Aβ fibrilization activity (>50%). Anethol showed potent anti-Aβ oligomerization activity (>50%), followed by α-terpinyl acetate and fennel-H (~36%). The neuroprotective potential of the spice extracts/phytochemicals was evaluated in SH-SY5Y cells by using H₂O₂-induced oxidative stress. Cardamom-EA displayed the best neuroprotection (0.01 to 30 μg/mL). No neuroprotection was observed by α-terpinyl acetate and anethol. Cardamom extracts and fennel-H restored the normal reactive oxygen species (ROS) levels at 30 µg/mL and 1 µg/mL, respectively. Conclusion: Overall, the extracts provided better neuroprotection than the pure compounds in cellular assays and displayed strong anti-Aβ fibrilization activity. Full article

In classical amyloidoses, amyloid fibres form through the nucleation and accretion of protein monomers, with protofibrils and fibrils exhibiting a cross-β motif of parallel or antiparallel β-sheets oriented perpendicular to the fibre direction. These protofibrils and fibrils can intertwine to form mature amyloid fibres. Similar phenomena can occur in blood from individuals with circulating inflammatory molecules (and also some originating from viruses and bacteria). Such pathological clotting can result in an anomalous amyloid form termed fibrinaloid microclots. Previous proteomic analyses of these microclots have shown the presence of non-fibrin(ogen) proteins, suggesting a more complex mechanism than simple entrapment. We thus provide evidence against such a simple entrapment model, noting that clot pores are too large and centrifugation would have removed weakly bound proteins. Instead, we explore whether co-aggregation into amyloid fibres may involve axial (multiple proteins within the same fibril), lateral (single-protein fibrils contributing to a fibre), or both types of integration. Our analysis of proteomic data from fibrinaloid microclots in different diseases shows no significant quantitative overlap with the normal plasma proteome and no correlation between plasma protein abundance and their presence in fibrinaloid microclots. Notably, abundant plasma proteins like α-2-macroglobulin, fibronectin, and transthyretin are absent from microclots, while less abundant proteins such as adiponectin, periostin, and von Willebrand factor are well represented. Using bioinformatic tools, including AmyloGram and AnuPP, we found that proteins entrapped in fibrinaloid microclots exhibit high amyloidogenic tendencies, suggesting their integration as cross-β elements into amyloid structures. This integration likely contributes to the microclots’ resistance to proteolysis. Our findings underscore the role of cross-seeding in fibrinaloid microclot formation and highlight the need for further investigation into their structural properties and implications in thrombotic and amyloid diseases. These insights provide a foundation for developing novel diagnostic and therapeutic strategies targeting amyloidogenic cross-seeding in blood clotting disorders. Full article

Background: Hypertension is a major risk factor for ischemic stroke. An important strategy in controlling hypertension is dietary modification. The present study evaluates the effect of Dietary Approaches to Stop Hypertension (DASH) diet on the risk of ischemic stroke. Methods: A case–control study was carried out, including 214 ischemic stroke cases recruited within the first 48 h of diagnosis and 214 controls, divided equally into hospitalized and non-hospitalized participants. Controls were matched to cases based on age and gender. Socio-demographic characteristics were assessed, in addition to adherence to the DASH diet, which was measured using a preconstructed DASH diet index (ranging from 0 (lowest) to 11 (highest)). For stroke patients, Modified Rankin Score (mRS) was measured to assess disability. Results: Smoking, hypertension, hyperlipidemia, atrial fibrillation, and myocardial infarction were significantly associated with ischemic stroke (p < 0.001). Higher adherence to the DASH diet was correlated to lower rates of stroke, where cases scored 5.042 ± 1.486 compared to 6.654 ± 1.471 for controls (p < 0.001). Eating more grains, vegetables, fruits, dairy products, nuts, seeds, and beans, and lower levels of fat, fewer sweets, and less sodium were associated with lower rates of ischemic stroke (p = 0.038 for sweets and p < 0.001 for all the remaining), while meat, poultry, and fish did not have any significant effect (p = 0.46). A multivariate analysis showed that lower adherence to the DASH diet (p < 0.001, OR: 0.526, CI95% 0.428–0.645) was associated with a higher incidence of ischemic stroke and an increased likelihood of having high disability levels (mRS 5–6) (p = 0.041, OR: 2.49 × 10⁻⁸, CI95% 0–2.49 × 10⁻⁸). Conclusions: The relation between the DASH diet and risk of stroke highlights the necessity for strict adherence to dietary restrictions, suggesting a protective role for the DASH diet in stroke pathogenesis and prognosis. Full article

Tau is an intrinsically disordered protein involved in several neurodegenerative diseases where a common hallmark is the appearance of tau aggregates in the brain. One common approach to elucidate the mechanisms behind the aggregation of tau has been to recapitulate in vitro the self-assembly process in a fast and reproducible manner. While the seeding of tau aggregation is prompted by negatively charged cofactors, the obtained fibrils are morphologically distinct from those found in vivo. The Tau AD core fragment (TADC, tau 306–378) has emerged as a new model and potential solution for the cofactor-free in vitro aggregation of tau. Here, we use TADC to further study this process combining multiple amyloid-detecting fluorophores and fibril bioimaging. We confirmed by transmission electron microscopy that this fragment forms fibrils after quiescent incubation at 37 °C. We then employed a panel of eight amyloid-binding fluorophores to query the formed species by acquiring their emission spectra. The results obtained showed that nearly all dyes detect TADC self-assembled species. However, the successful monitoring of TADC aggregation kinetics was limited to three fluorophores (X-34, Bis-ANS, and pFTAA) which yielded sigmoidal curves but different aggregation half-times, hinting to different species being detected. Altogether, this study highlights the potential of using multiple extrinsic fluorescent probes, alone or in combination, as tools to further clarify mechanisms behind the aggregation of amyloidogenic proteins. Full article