Disease mechanisms as subtypes: Inflammation in Parkinson disease and related disorders

Distinct subcellular localization of tau and alpha-synuclein in lewy body disease

Lewy bodies and neurofibrillary tangles, composed of α-synuclein (α-syn) and tau, respectively, often are found together in the same brain and correlate with worsening cognition. Human postmortem studies show colocalization of α-syn and tau occurs in Lewy bodies, but with limited effort to quantify colocalization. In this study, postmortem middle temporal gyrus tissue from decedents (n = 9) without temporal lobe disease (control) or with Lewy body disease (LBD) was immunofluorescently labeled with antibodies to phosphorylated α-syn (p-α-syn), tau phosphorylated at Ser202/Thr205 (p-tau), or exposure of tau's phosphatase-activating domain (PAD-tau) as a marker of early tau aggregates. Immunofluorescence for major-histocompatibility complex class 2 (MHCII) and ionized calcium binding adaptor molecule 1 (Iba1) also was performed because inflammation is an additional pathological hallmark of LBDs, and they were a positive control for two markers known to colocalize. The abundance of p-α-syn, p-tau, and MHCII was significantly associated with diagnosis of LBD. Quantification of colocalization showed that MHCII and Iba1 colocalized, demonstrating activated immune cells are mostly microglia. However, p-α-syn rarely colocalized with p-tau or PAD-tau, although the overlap of p-α-syn with PAD-tau was significantly associated with LBD. In the rare cases pathologic α-syn and pathologic tau were found in the same Lewy body or Lewy neurite, tau appeared to surround α-syn but did not colocalize within the same structure. The relationship between tau and α-syn copathology is important for explaining clinical symptoms, severity, and progression, but there is no evidence for frequent, direct protein-protein interactions in the middle temporal gyrus.

Exceeding the Limits with Nutraceuticals: Looking Towards Parkinson's Disease and Frailty

One of the most pressing challenges facing society today is the rising prevalence of physical and cognitive frailty. This geriatric condition makes older adults more vulnerable to disability, illness, and a heightened risk of mortality. In this scenario, Parkinson's disease (PD) and geriatric frailty, which share several common characteristics, are becoming increasingly prevalent worldwide, underscoring the urgent need for innovative strategies. Nutraceuticals are naturally occurring bioactive compounds contained in foods, offering health benefits over and above essential nutrition. By examining the literature from the past decade, this review highlights how nutraceuticals can act as complementary therapies, addressing key processes, such as oxidative stress, inflammation, and neuroprotection. Notably, the antioxidant action of nutraceuticals appears particularly beneficial in regard to PD and geriatric frailty. For instance, antioxidant-rich nutraceuticals may mitigate the oxidative damage linked to levodopa therapy in PD, potentially reducing the side effects and enhancing treatment sustainability. Similarly, the antioxidant effects of nutraceuticals may amplify the benefits of physical activity, enhancing muscle function, cognitive health, and resilience, thereby reducing the risk of frailty. This review proposes a holistic approach integrating nutraceuticals with exercise, pharmacotherapy, and lifestyle adjustments. It promises to transform the management of ARD, prolong life, and improve the quality of life and well-being of older people.

Microglia signaling in health and disease - Implications in sex-specific brain development and plasticity

Microglia, the intrinsic neuroimmune cells residing in the central nervous system (CNS), exert a pivotal influence on brain development, homeostasis, and functionality, encompassing critical roles during both aging and pathological states. Recent advancements in comprehending brain plasticity and functions have spotlighted conspicuous variances between male and female brains, notably in neurogenesis, neuronal myelination, axon fasciculation, and synaptogenesis. Nevertheless, the precise impact of microglia on sex-specific brain cell plasticity, sculpting diverse neural network architectures and circuits, remains largely unexplored. This article seeks to unravel the present understanding of microglial involvement in brain development, plasticity, and function, with a specific emphasis on microglial signaling in brain sex polymorphism. Commencing with an overview of microglia in the CNS and their associated signaling cascades, we subsequently probe recent revelations regarding molecular signaling by microglia in sex-dependent brain developmental plasticity, functions, and diseases. Notably, C-X3-C motif chemokine receptor 1 (CX3CR1), triggering receptors expressed on myeloid cells 2 (TREM2), calcium (Ca2+), and apolipoprotein E (APOE) emerge as molecular candidates significantly contributing to sex-dependent brain development and plasticity. In conclusion, we address burgeoning inquiries surrounding microglia's pivotal role in the functional diversity of developing and aging brains, contemplating their potential implications for gender-tailored therapeutic strategies in neurodegenerative diseases.

Silymarin and Inflammation: Food for Thoughts

Inflammation is a vital defense mechanism, creating hostile conditions for pathogens, preventing the spread of tissue infection and repairing damaged tissues in humans and animals. However, when inflammation resolution is delayed or compromised as a result of its misregulation, the process proceeds from the acute phase to chronic inflammation, leading to the development of various chronic illnesses. It is proven that redox balance disturbances and oxidative stress are among major factors inducing NF-κB and leading to over-inflammation. Therefore, the anti-inflammatory properties of various natural antioxidants have been widely tested in various in vitro and in vivo systems. Accumulating evidence indicates that silymarin (SM) and its main constituent silibinin/silybin (SB) have great potential as an anti-inflammation agent. The main anti-inflammatory mechanism of SM/SB action is attributed to the inhibition of TLR4/NF-κB-mediated signaling pathways and the downregulated expression of pro-inflammatory mediators, including TNF-α, IL-1β, IL-6, IL-12, IL-23, CCL4, CXCL10, etc. Of note, in the same model systems, SM/SB was able to upregulate anti-inflammatory cytokines (IL-4, IL-10, IL-13, TGF-β, etc.) and lipid mediators involved in the resolution of inflammation. The inflammatory properties of SM/SB were clearly demonstrated in model systems based on immune (macrophages and monocytes) and non-immune (epithelial, skin, bone, connective tissue and cancer) cells. At the same time, the anti-inflammatory action of SM/SB was confirmed in a number of in vivo models, including toxicity models, nonalcoholic fatty liver disease, ischemia/reperfusion models, stress-induced injuries, ageing and exercising models, wound healing and many other relevant model systems. It seems likely that the anti-inflammatory activities of SM/SB are key elements on the health-promoting properties of these phytochemicals.

Palmitoylethanolamide shows limited efficacy in controlling cerebral cryptococcosis in vivo

Cryptococcus neoformans (Cn) is an encapsulated neurotropic fungal pathogen and the causative agent of cryptococcal meningoencephalitis (CME) in humans. Recommended treatment for CME is Amphotericin B (AmpB) and 5-fluorocytosine (5-FC). Though effective, AmpB has displayed numerous adverse side effects due to its potency and nephrotoxicity, prompting investigation into alternative treatments. Palmitoylethanolamide (PEA) is an immunomodulatory compound capable of promoting neuroprotection and reducing inflammation. To investigate the efficacy of PEA as a therapeutic alternative for CME, we intracerebrally infected mice with Cn and treated them with PEA or AmpB alone or in combination. Our results demonstrate that PEA alone does not significantly prolong survival nor reduce fungal burden, but when combined with AmpB, PEA exerts an additive effect and promotes both survivability and fungal clearance. However, we compared this combination to traditional AmpB and 5-FC treatment in a survivability study and observed lower efficacy. Overall, our study revealed that PEA alone is not effective as an antifungal agent in the treatment of CME. Importantly, we describe the therapeutic capability of PEA in the context of Cn infection and show that its immunomodulatory properties may confer limited protection when combined with an effective fungicidal agent.

Palmitoylethanolamide shows limited efficacy in controlling cerebral cryptococcosis in vivo

Cryptococcus neoformans ( Cn ) is an encapsulated neurotropic fungal pathogen and the causative agent of cryptococcal meningoencephalitis (CME) in humans. Recommended treatment for CME is Amphotericin B (AmpB) and 5-fluorocytosine (5-FC). Though effective, AmpB has displayed numerous adverse side effects due to its potency and nephrotoxicity, prompting investigation into alternative treatments. Palmitoylethanolamide (PEA) is an immunomodulatory compound capable of promoting neuroprotection and reducing inflammation. To investigate the efficacy of PEA as a therapeutic alternative for CME, we intracerebrally infected mice with Cn and treated them with PEA or AmpB alone or in combination. Our results demonstrate that PEA alone does not significantly prolong survival nor reduce fungal burden, but when combined with AmpB, PEA exerts an additive effect and promotes both survivability and fungal clearance. However, we compared this combination to traditional AmpB and 5-FC treatment in a survivability study and observed lower efficacy. Overall, our study revealed that PEA alone is not effective as an antifungal agent in the treatment of CME. Importantly, we describe the therapeutic capability of PEA in the context of Cn infection and show that its immunomodulatory properties may confer limited protection when combined with an effective fungicidal agent.