This review analyzes the role of TNF-α and its increase in biological fluids in mild cognitive impairment, and Alzheimer’s disease (AD). The potential inhibition of TNF-α with pharmacological strategies paves the way for preventing AD and improving cognitive function in people at risk for dementia. We conducted a narrative review to characterize the evidence in relation to the involvement of TNF-α in AD and its possible therapeutic inhibition. Several studies report that patients with RA and systemic inflammatory diseases treated with TNF-α blocking agents reduce the probability of emerging dementia compared with the general population. Animal model studies also showed interesting results and are discussed. An increasing amount of basic scientific data and clinical studies underscore the importance of inflammatory processes and subsequent glial activation in the pathogenesis of AD. TNF-α targeted therapy is a biologically plausible approach for cognition preservation and further trials are necessary to investigate the potential benefits of therapy in populations at risk of developing AD.

Vitamin D may have multiple effects on the nervous system and its deficiency can represent a possible risk factor for the development of many neurological diseases. Recent studies are also trying to clarify the different effects of vitamin D supplementation over the course of progressive neurological diseases. In this narrative review, we summarise vitamin D chemistry, metabolism, mechanisms of action, and the recommended daily intake. The role of vitamin D on gene transcription and the immune response is also reviewed. Finally, we discuss the scientific evidence that links low 25-hydroxyvitamin D concentrations to the onset and progression of severe neurological diseases, such as multiple sclerosis, Parkinson’s disease, Alzheimer’s disease, migraine, diabetic neuropathy and amyotrophic lateral sclerosis. Completed and ongoing clinical trials on vitamin D supplementation in neurological diseases are listed.

Several studies indicate that the development of Alzheimer's disease (AD) has strong interactions with immune mechanisms within the brain, indicating a close association between inflammation in the central nervous system and the progression of neurodegeneration. Despite considerable progress in understanding the inflammatory aspects of AD, several of them remain unresolved. Pro-inflammatory cytokines and microglia are pivotal components in the inflammatory cascade. Among these, the role of interleukin-8 (IL-8) in neurodegeneration seems complex and multifaceted, involving inflammation, neurotoxicity, blood-brain barrier disruption, and oxidative stress, and is still poorly characterized. We conducted a review to describe the evidence of IL-8 involvement in AD. IL-8 is a cytokine known for its proinflammatory properties and typically produced by macrophages, predominantly functions as a chemotactic signal for attracting neutrophils to inflamed sites in the bloodstream. Interestingly, IL-8 is also present in the brain, where it is primarily released by microglia in response to inflammatory signals. This review aims to provide a comprehensive overview of the structure, function, and regulatory mechanisms of IL-8 relevant to AD pathology.

Peripherin is a class III intermediate filament protein that has recently gained attention as a potential biomarker for axonal damage in the peripheral nervous system. This review examines peripherin gene expression, protein structure, and its functions in both healthy and diseased states. Peripherin is predominantly expressed in the peripheral nervous system, especially in motor and sensory neurons, and plays a critical role in neurite growth, stability, and axonal transport during myelination. Its expression is regulated by various cytokines and undergoes several post‐transcriptional modifications. Peripherin interacts with multiple proteins, including neurofilaments and kinases, influencing cytoskeletal dynamics and neuronal functions. The review also explores peripherin involvement in several neurological disorders, such as Amyotrophic Lateral Sclerosis, where its abnormal expression and aggregation contribute to disease pathology. Additionally, peripherin has been linked to polyneuropathies, traumatic axonal injury, and diabetic neuropathy, suggesting its broader relevance as a biomarker in these conditions. The potential of peripherin as a biomarker is further supported by recent studies using ultrasensitive detection methods, which have identified elevated peripherin levels in the serum of patients with neurological diseases. Despite the promising findings, the application of peripherin as a biomarker in clinical settings remains limited, primarily due to challenges in its detection and the need for further validation in diverse patient populations. Future research directions include the development of more sensitive assays and the exploration of peripherin's role in non‐neuronal tissues, which may expand its diagnostic and therapeutic potential.

Background: Despite their potential usefulness as biomarkers, no study has investigated the interactions between cerebrospinal fluid (CSF) changes of neurofilament light chain (NfL), glial fibrillary acidic protein (GFAP), growth differentiation factor 15 (GDF-15), transactive response DNA binding protein (TDP-43) and interleukin-6 (IL-6) and the core AD CSF biomarkers in the same cohort of AD patients. Objectives: The aim of this pilot study is to evaluate the CSF levels of these analytes in patients with AD and assess their clinical relevance in this neurological condition. Design: Cross-sectional study. Methods: We assessed the levels of NfL, GFAP, GDF-15, TDP-43 and IL-6 in the CSF samples of 52 early AD patients and evaluated their partial reciprocal correlations and those with Abeta42, p-Tau, t-Tau and Mini-Mental State Examination (MMSE), always adding age, sex and educational level as covariates. Results: MMSE score showed a positive correlation with the Aβ 1-42 concentrations ( r = 0.485; p < 0.001), and a negative correlation with GDF-15 concentrations ( r = −0.418; p = 0.002). IL-6 concentrations showed a positive correlation with NfL concentrations ( r = 0.312; p = 0.026) and a negative correlation with TDP-43 concentrations ( r = −0.322; p = 0.021). TDP-43 concentrations showed a positive correlation with GFAP ( r = 0.33, p = 0.018). The mediation analysis suggests that the association between GDF-15 and MMSE is primarily mediated by Aβ 1-42. CSF GDF-15 concentrations were higher in AD patients with low Aβ 1-42 concentrations than those with high Aβ 1-42 concentrations ( p < 0.001). Conclusion: Our findings highlight that CSF IL-6 levels correlate positively with markers of neuronal damage. CSF TDP-43 levels significantly correlated with GFAP, suggesting a potential link with reactive gliosis and astrocyte activation. In addition, while CSF GDF-15 levels negatively correlate with MMSE scores, mediation analysis revealed that this association is primarily indirect and mediated through Aβ 1-42 levels.

Background: Neurofilament light chains (NfL) represent reliable serum biomarkers of neuroaxonal injury. Due to their low serum levels, precise detection methods are critical. This study aimed to scrutinize the comparability of two techniques: Single Molecule Array (SiMoA) and Ella automated immunoassay, analyzing serum NfL levels in ATTRv presymptomatic subjects and polyneuropathy patients.Methods: Blood samples were processed and analyzed using commercial Ella and SiMoA kits. Statistical analysis included the Wilcoxon signed‐rank test, Spearman correlation, Bland–Altman, and Passing‐Bablok regression. ANCOVA models were used to compare NfL levels between cohorts.Results: The study measured serum NfL levels in 55 symptomatic and 55 presymptomatic ATTRv subjects. Median NfL concentrations were significantly higher with Ella (median 27.5 pg/mL) than SiMoA (median 15.9 pg/mL). Both methods showed a strong positive correlation (r = 0.8, p < 0.001), but Ella overestimated NfL by 42%. Bland–Altman analysis revealed a mean bias of 15.4 pg/mL, with limits of agreement between −41.1 and 72.0 pg/mL. The slope of the Passing–Bablok regression line was 0.58, and the intercept was 3.48 pg/mL, suggesting that the Ella platform tends to overestimate NfL concentrations compared to the SiMoA platform, especially at higher concentrations. Both methods effectively distinguished presymptomatic from symptomatic patients (p < 0.001 for both).Conclusions: Our findings underscore that both platforms are effective in measuring serum NfL, with Ella consistently overestimating, especially at higher concentrations. The difference between the two platforms must be taken into account when deeming the concentrations as pathological or normal, as well as when conducting longitudinal studies.