Circulating calprotectin as a potential biomarker of persistent olfactory dysfunctions in Post-COVID-19 patients.

BACKGROUND: This longitudinal prospective study aims to investigate the potential of circulating calprotectin (cCLP) as a biomarker in persistent olfactory dysfunctions following COVID-19 infection. METHODS: Thirty-six patients with persistent hyposmia or anosmia post COVID-19 were enrolled (HT0) and re-evaluated after three months of olfactory training (HT1). Two control groups included 18 subjects without olfactory defects post COVID-19 (CG1) and 18 healthy individuals (CG2). Nasal brushing of the olfactory cleft and blood collection were performed to assess circulating calprotectin levels. RESULTS: Higher calprotectin levels were observed in serum and nasal supernatant of hyposmic patients (HT0) compared to control groups (CG1 and CG2). Post-olfactory training (HT1), olfactory function improved significantly, paralleled by decreased calprotectin levels in serum and nasal samples. Circulating calprotectin holds potential as a biomarker in persistent olfactory dysfunctions after COVID-19. The decrease in calprotectin levels post-olfactory training implies a role in monitoring and evaluating treatment responses. DISCUSSION AND CONCLUSIONS: These findings contribute to the growing literature on potential biomarkers in post-COVID-19 olfactory dysfunctions and underscore the importance of investigating novel biomarkers for personalized patient management. Nevertheless, further studies are needed to validate the application of calprotectin assay in nasal diseases and its correlation with nasal cytology.

Constitutive NOS Production Is Modulated by Alzheimer's Disease Pathology Depending on APOE Genotype.

Both the endothelial (eNOS) and the neuronal (nNOS) isoforms of constitutive Nitric Oxide Synthase have been implicated in vascular dysfunctions in Alzheimer's disease (AD). We aimed to explore the relationship between amyloid pathology and NO dynamics by comparing the cerebrospinal fluid (CSF) levels of nNOS and eNOS of 8 healthy controls (HC) and 27 patients with a clinical diagnosis of Alzheimer's disease and isolated CSF amyloid changes, stratified according to APOE ε genotype (APOE ε3 = 13, APOE ε4 = 14). Moreover, we explored the associations between NOS isoforms, CSF AD biomarkers, age, sex, cognitive decline, and blood-brain barrier permeability. In our cohort, both eNOS and nNOS levels were increased in APOE ε3 with respect to HC and APOE ε4. CSF eNOS inversely correlated with CSF Amyloid-ß42 selectively in carriers of APOE ε3; CSF nNOS was negatively associated with age and CSF p-tau only in the APOE ε4 subgroup. Increased eNOS could represent compensative vasodilation to face progressive Aß-induced vasoconstriction in APOE ε3, while nNOS could represent the activation of NO-mediated plasticity strategies in the same group. Our results confirm previous findings that the APOE genotype is linked with different vascular responses to AD pathology.

Interplay between the catecholaminergic enzymatic axis and neurodegeneration/neuroinflammation processes in the Alzheimer's disease continuum.

BACKGROUND AND PURPOSE: The locus coeruleus (LC) provides dopamine/noradrenaline (DA/NA) innervation throughout the brain and undergoes early degeneration in Alzheimer's disease (AD). We evaluated catecholaminergic enzyme levels in the cerebrospinal fluid (CSF) of a group of patients biologically defined as within the AD continuum (ADc) and explored their relationship with AD biomarkers and cytokine/growth factor levels to investigate their interplay with neurodegenerative and neuroinflammatory processes. METHODS: The CSF concentration of DA transporter (DAT), tyrosine-hydroxylase (TH), DOPA-decarboxylase (DDC), and dopamine-ß-hydroxylase (DßH), as well as cytokine/growth factor levels, were analyzed in 41 ADc patients stratified according to CSF beta-amyloid (Aß)1-42 (A) and p-tau (T) in AD pathological changes (A+ T-) and AD (A+ T+) subgroups, as well as in 15 control subjects (A- T-). RESULTS: The ADc group had lower CSF levels of DAT and TH but increased DßH levels to compensate for NA synthesis. DDC levels were higher in the A+ T+ subgroup but comparable with controls in the A+ T- subgroup, probably because the DA system is resilient to the degeneration of LC neurons in the absence of tau pathology. Adjusting for age, sex, APOE genotype, and cognitive status, a significant association was found between TH and Aß1-42 (R2  = 0.25) and between DDC and p-tau (R2  = 0.33). Finally, TH correlated with interleukin (IL)-10 levels (p = 0.0008) and DßH with IL-1ß (p = 0.03), IL-4 (p = 0.02), granulocyte colony-stimulating factor (p = 0.007), and IL-17 (p = 0.01). CONCLUSIONS: Taken together, these findings suggest that catecholaminergic enzymes, functional markers of the catecholaminergic system, are closely linked to the neurodegenerative and neuroinflammatory processes in AD pathology.

Correlation analysis between auto-immunological and mutational profiles in myelodysplastic syndromes.

OBJECTIVE AND DESIGN: Systemic-Inflammatory-Autoimmune-Diseases (SIAD) is increasingly considered in Myelodysplastic-Syndromes (MDS). In this line, we evaluated the MDS auto-immunological profile, correlating it to the mutational landscape, trying to identify a molecular-genetic trigger agent related to SIAD. METHODS AND MATERIALS: Eighty-one MDS were enrolled and t-NGS was performed. Anti-Nuclear-Antibodies (ANA) were tested, and ANA-antigenic-specificity was characterized by ANA-profile, ENA-screen, anti-dsDNA. Non-Hematological-Patients (NHP) and Healthy-Donors (HD) were used as controls. RESULTS: At clinically relevant cut-off (≥ 1:160), ANA was significantly more frequent in MDS, while ANA-antigenic-specificity showed a low association rate. ANA ≥ 1:160-positive MDS showed a mutational landscape similar to ANA-negative/ANA < 1:160 MDS. No significant correlations between mutational and immunological profiles were found and UBA1 mutations, related to VEXAS, were absent. CONCLUSIONS: Although ANA-positivity was found to be increased in MDS, the low ANA-antigenic-specificity suggests that autoantibodies didn't recognize autoimmune-pathognomonic antigens. The lack of relationship between genetic profile and ANA-positivity, suggests that MDS genetic variants may not be the direct cause of SIAD.

Evaluation of serological anti-SARS-CoV-2 chemiluminescent immunoassays correlated to live virus neutralization test, for the detection of anti-RBD antibodies as a relevant alternative in COVID-19 large-scale neutralizing activity monitoring.

The Spike-Receptor Binding Domain (S-RBD) is considered the most antigenic protein in SARS-CoV-2 and probably the key player in SARS-CoV-2 immune response. Quantitative immunoassays may help establish an anti-RBD Abs threshold as an indication of protective immunity. Since different immunoassays are commercial, the standard reference method for the neutralizing activity is the live Virus Neutralization Test (VNT). In this study, anti-RBD IgG levels were detected with two chemiluminescent immunoassays in paucisymptomatic, symptomatic and vaccinated subjects, and their neutralizing activity was correlated to VNT titer, using SARS-CoV-2 original and British variant strains. Both immunoassays confirmed higher anti-RBD Abs levels in vaccinated subjects. Furthermore, despite different anti-RBD Abs median concentrations between the immunoassays, a strong positive correlation with VNT was observed. In conclusion, although the SARS-CoV-2 immune response heterogeneity, the use of immunoassays can help in large-scale monitoring of COVID-19 samples, becoming a valid alternative to VNT test for diagnostic routine laboratories.

Validation of a quantitative lateral flow immunoassay (LFIA)-based point-of-care (POC) rapid test for SARS-CoV-2 neutralizing antibodies.

With the widespread use of coronavirus disease 2019 (COVID-19) vaccines, a rapid and reliable method to detect SARS-CoV-2 neutralizing antibodies (NAbs) is extremely important for monitoring vaccine effectiveness and immunity in the population. The purpose of this study was to evaluate the performance of the RapiRead™ reader and the TestNOW™ COVID-19 NAb rapid point-of-care (POC) test for quantitative measurement of antibodies against the spike protein receptor-binding domain of severe respiratory syndrome coronavirus 2 (SARS-CoV-2) in different biological matrices compared to chemiluminescence immunoassay (CLIA) methods. Ninety-four samples were collected and analyzed using a RapiRead™ reader and TestNOW™ COVID-19 NAb kits for detecting neutralizing antibodies, and then using two CLIAs. The data were compared statistically using the Kruskal-Wallis test for more than two groups or the Mann-Whitney test for two groups. Specificity and sensitivity were evaluated using a receiver operating characteristic (ROC) curve. Good correlation was observed between the rapid lateral flow immunoassay (LFIA) test system and both CLIA methods. RapiRead™ reader/TestNOW™ COVID-19 NAb vs. Maglumi: correlation coefficient (r) = 0.728 for all patients; r = 0.841 for vaccinated patients. RapiRead™ reader/TestNOW™ COVID-19 NAb vs. Mindray: r = 0.6394 in all patients; r = 0.8724 in vaccinated patients. The time stability of the POC serological test was also assessed considering two times of reading, 12 and 14 minutes. The data revealed no significant differences. The use of a RapiRead™ reader and TestNOW™ COVID-19 NAb assay is a quantitative, rapid, and valid method for detecting SARS-CoV-2 neutralizing antibodies and could be a useful tool for screening studies of SARS-CoV-2 infection and assessing the efficacy of vaccines in a non-laboratory context.

Combined anti-SARS-CoV-2 IgA, IgG, and IgM Detection as a Better Strategy to Prevent Second Infection Spreading Waves.

Coronavirus disease (COVID-19) is challenging many health, economic, and social systems. RT-PCR assays are diagnosis gold standard; however, they can lead to false-negative results. Therefore, anti-SARS-CoV-2 IgG, IgM, and IgA investigation can play a complementary role in assessing the individuals immune status. Majority of serological tests focus on IgM and IgG although IgA are the main immunoglobulins involved in mucosal immunity. It has been reported that digestive symptoms may occur in the absence of any typical respiratory symptom. Thus, a complete screening, comprising IgA, IgM, and IgG detection could be more consistent and useful in patients with atypical symptoms or in paucisymptomatic cases. Current literature describes over 200 immunoassays available worldwide, pointing out a great results variability, depending on methodology or antigens' nature. In our study we evaluated anti-SARS-CoV-2 IgA, IgM, and IgG trend on a control group and on two COVID-19 patient groups (early and late infection time) with a lateral-flow combined immunoassay (LFIA) and an enzyme-linked immunosorbent assay (ELISA). Dissimilar antibodies time kinetics have been described in COVID-19 (decreasing IgM concentration with IgA/IgG persistence for a longer time; as well as persistent IgA, IgG, and IgM concentration); our results confirmed both of them depending on the methodology; therefore, it is difficult to compare different studies outcomes, suggesting the importance of a serological tests international standardization. Nevertheless, we propose a flowchart with combined anti-SARS-CoV-2 IgG/IgM/IgA detection as a screening on general population, where serological positivity should be considered as an "alert," to avoid and contain possible new outbreaks.

Performance evaluation of the new Chemiluminescence Immunoassay CL-1200i Thyroid Panel.

Aim of this work was to verify the analytical performance of thyroid panel tests measured by chemiluminescence immunoassay (CLIA) CL-1200i and to validate its efficacy as laboratory test for thyroid disorder.Serum samples were obtained by standard centrifugation, thawed and assayed in a blinded fashion, and in a single batch. This study compares the values of thyroid panel tests measured by Mindray CL-1200i chemiluminescent system to the Abbott platforms for TSH, FT3, FT4, and Beckman Coulter for Tg, TgAb, and TPOAb on patient serum samples. A total of 180 randomly selected patients including both hospitalized and ambulatory patients from the Policlinico Tor Vergata (PTV) of the University of Rome Tor Vergata were used. In all analyses performed, the thyroid panel tests of the Mindray platform showed discriminative ability to quantitatively assess the analyte involved in thyroid disease and disorder. This study verified that Mindray CL-1200i chemiluminescent system thyroid panel tests is a valid method for obtaining a quantitative analysis of thyroid disorders. It showed high diagnostic efficiency and could represent a valid tool with a potential reduction in time and workload for the diagnosis.

Clinical validation of a second generation anti-SARS-CoV-2 IgG and IgM automated chemiluminescent immunoassay.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has proven to be extremely contagious and has spread rapidly all over the world. A key aspect in limiting the virus diffusion is to ensure early and accurate diagnosis. Serological assays could be an alternative in increasing testing capabilities, particularly when used as part of an algorithmic approach combined with molecular analysis. The aim of this study was to evaluate the diagnostic accuracy of a second generation chemiluminescent automated immunoassay able to detect anti-SARS-CoV-2 immunoglobulin G (IgG) and immunoglobulin M (IgM) antibodies. Data are carried out on healthy subjects and other infectious diseases pre-pandemic sera, as controls, and on two different coronavirus disease 2019 hospitalized patient groups (early and late infection time). Data obtained have been analyzed in terms of precision, linearity, sensitivity and specificity. Specificities are: 100% for anti-SARS-CoV-2 IgG and 98% for anti-SARS-CoV-2 IgM, in all patient groups. Sensitivities are: 97%, 100%, and 98% for anti-SARS-CoV-2 IgG and 87%, 83%, and 86% for anti-SARS-CoV-2 IgM in the early infection, in the late infection and in the total patient group, respectively. The Mindray anti-SARS-CoV-2 IgG and IgM assays demonstrated higher sensitivity and specificity, indicating that IgG and IgM simultaneous detection is useful even in the early phases of infection.

Circulating calprotectin as a supporting inflammatory marker in discriminating SARS-CoV-2 infection: an observational study.

OBJECTIVE AND DESIGN: Fecal calprotectin (CLP) is widely known for its detection in stools of patients with inflammatory bowel diseases (IBDs), to investigate the intestinal inflammatory status. Current research is promoting the circulating protein role as a systemic inflammatory marker. However, most studies report serum calprotectin analysis although plasma assay prevents its massive release by granulocytes. In this perspective, the ongoing SARS-CoV-2 pandemic deserves deployment of convenient and easy-to-dose markers that could reliably address the state of infection. METHODS: We analyzed serum circulating calprotectin (cCLP) levels in hospitalized COVID-19 patients and plasma cCLP levels from patients with suspected SARS-CoV-2 infection, then assessed negative or positive on molecular tests. RESULTS: Our results confirm a significant circulating calprotectin increase in infected subjects respect to controls, in serum and plasma. Moreover, plasma calprotectin has higher levels in suspected patients with positive SARS-CoV-2-RT-PCR, compared to suspected patients with negative SARS-CoV-2-RT-PCR. Furthermore, ROC curves results showed the circulating plasma calprotectin discriminatory ability to differentiate infected SARS-CoV-2 patients at a cutoff value greater than 131.3 ng/ml. CONCLUSIONS: Our data propose circulating calprotectin as a new, quantitative and predictive marker, which in addition to being an interesting generic inflammatory marker may provide important indications in SARS-CoV-2 infection.

MCAM/MUC18/CD146 as a Multifaceted Warning Marker of Melanoma Progression in Liquid Biopsy.

Human malignant melanoma shows a high rate of mortality after metastasization, and its incidence is continuously rising worldwide. Several studies have suggested that MCAM/MUC18/CD146 plays an important role in the progression of this malignant disease. MCAM/MUC18/CD146 is a typical single-spanning transmembrane glycoprotein, existing as two membrane isoforms, long and short, and an additional soluble form, sCD146. We previously documented that molecular MCAM/MUC18/CD146 expression is strongly associated with disease progression. Recently, we showed that MCAM/MUC18/CD146 and ABCB5 can serve as melanoma-specific-targets in the selection of highly primitive circulating melanoma cells, and constitute putative proteins associated with disease spreading progression. Here, we analyzed CD146 molecular expression at onset or at disease recurrence in an enlarged melanoma case series. For some patients, we also performed the time courses of molecular monitoring. Moreover, we explored the role of soluble CD146 in different cohorts of melanoma patients at onset or disease progression, rather than in clinical remission, undergoing immune therapy or free from any clinical treatment. We showed that MCAM/MUC18/CD146 can be considered as: (1) a membrane antigen suitable for identification and enrichment in melanoma liquid biopsy; (2) a highly effective molecular "warning" marker for minimal residual disease monitoring; and (3) a soluble protein index of inflammation and putative response to therapeutic treatments.

Uterine and placental blood flow indexes and antinuclear autoantibodies in unexplained recurrent pregnancy loss: should they be investigated in pregnancy as correlated potential factors? A retrospective study.

BACKGROUND: The potential role of antinuclear antibodies (ANA) in recurrent pregnancy loss (RPL) pathogenesis is still debated, although some evidences suggest that they could affect pregnancy outcome, leading to a higher miscarriage rate in these patients. A hypothesized mechanism is through changes in uterine flow in pre-conceptional stage, by modifying endometrial receptivity in RPL. However, scant data are available, in pregnancy, about their role in RPL placental perfusion, also in relation to its potential treatments, such as low molecular weight heparin (LMWH). The aim of this study is to retrospectively further investigate the correlation between two-dimensional (2D) and three-dimensional (3D) uterine and placental flow indexes and the presence or the absence of ANA in women with unexplained RPL (uRPL), treated or not treated with LMWH. METHODS: 2D Doppler measurement of pulsatility index (PI) of the uterine arteries and 3D ultrasonography determination of vascularization index (VI), flow index (FI) and vascularization flow index (VFI) was carried out with the aid of the virtual organ computer-aided analysis (VOCAL) technique in LMWH treated (n 24) and not treated-uRPL patients (n 20) and in the relative control group (n 27), each group divided in ANA+ and ANA- subgroups. Serum assay for the presence of ANA was performed in all women. RESULTS: No differences were found in PI, VFI and VI values, by comparing the different groups. A difference in VI values was found for ANA- patients between RPL women not treated with LMWH and the treated ones (p = 0,01), which have lower VI values and similar to controls. By considering only ANA- treated and not treated RPL patients, the ROC curve shows an area of 0,80 and at the VI cut-off of 11,08 a sensitivity of 85% and a specificity of 67%. CONCLUSIONS: LMWH could exert a potential beneficial effect in restoring the physiological blood flow supply in terms of VI in uRPL ANA- status, suggesting to include ANA and VI investigations in the RPL diagnostic algorithm in a research context, since further studies are needed to clarify this challenging hypothesis in order to try to ameliorate ANA and abnormal placental vascularization negative influence on RPL pregnancy outcome .

Amniotic fluid antiphospholipid antibodies: potential role in antiphospholipid syndrome-independent aberrant implantation process.

BACKGROUND: The direct role of antiphospholipid antibodies (aPL) at maternal-fetal interface has not been fully investigated, especially whether they are involved in physiological and pathological implantation conditions, in an antiphospholipid syndrome (APS)-independent manner. In fact, trophoblast cells and placental endothelial cells at the implantation site express potential aPL targeted-phospholipid antigens (PL Ags); thus, the local production and presence of their specific antibodies, not related to APS (characterized by aPL presence in the peripheral blood), could be a potential marker of aberrant invasion, implantation and fetal-maternal immune tolerance processes. METHODS: Anti-Beta2glycoprotein I (anti-ß2GPI) and anticardiolipin (aCL Ab) antibodies (the most clinically relevant aPL) were detected by immunoenzymatic assay (ELISA), in the amniotic fluid (AF) of 167 women with physiological and complicated common pregnancy conditions, sharing an aberrant implantation process, such as recurrent pregnancy loss (RPL), autoimmune hypothyroidism (ahT) and smoking. All women included in the study were negative to peripheral blood aPL. RESULTS: aCL and anti-ß2GPI antibodies were detectable in all the AF samples. RPL, ahT and smoking patients had higher level of anti-ß2GPI Abs (IgM) compared to women with physiological pregnancies (p < 0.0001). Since IgM cannot cross the placenta, their local production in response to maternal-fetal interface stimuli, could be hypothesized. CONCLUSIONS: The presence of aPL in the AF (not related to APS) could reveal a potential clinical significance at maternal-fetal interface in selected pregnancy complications, in which an aberrant implantation process, and in turn an impaired fetal-maternal immune tolerance cross-talk, could occur.

Beta-amyloid and phosphorylated tau metabolism changes in narcolepsy over time.

PURPOSE: The aim od this study is to test whether metabolism of beta-amyloid and tau proteins changes in narcolepsy along with the disease course. METHODS: We analyzed a population of narcoleptic drug-naïve patients compared to a sample of healthy controls. Patients and controls underwent lumbar puncture for assessment of cerebrospinal fluid (CSF) beta-amyloid1-42 (Aß42), total tau (t-tau), and phosphorylated tau (p-tau) levels. Moreover, based on the median disease duration of the whole narcolepsy group, the patients were divided into two subgroups: patients with a short disease duration (SdN, <5 years) and patients with a long disease duration (LdN, >5 years). RESULTS: We found significantly lower CSF Aß42 levels in the whole narcolepsy group with respect to controls. Taking into account the patient subgroups, we documented reduced CSF Aß42 levels in SdN compared to both LdN and controls. Even LdN patients showed lower CSF Aß42 levels with respect to controls. Moreover, we documented higher CSF p-tau levels in LdN patients compared to both SdN and controls. Finally, a significant positive correlation between CSF Aß42 levels and disease duration was evident. CONCLUSIONS: We hypothesize that beta-amyloid metabolism and cascade may be impaired in narcolepsy not only at the onset but also along with the disease course, although they show a compensatory profile over time. Concurrently, also CSF biomarkers indicative of neural structure (p-tau) appear to be altered in narcolepsy patients with a long disease duration. However, the mechanism underlying beta-amyloid and tau metabolism impairment in narcolepsy remains still unclear and deserves to be better elucidated.

CSF beta-amyloid levels are altered in narcolepsy: a link with the inflammatory hypothesis?

Narcolepsy is characterized by hypocretin deficiency due to the loss of hypothalamic orexinergic neurons, and is associated with both the human leucocyte antigen DQB1*06:02 and the T cell receptor polymorphism. The above relationship suggests autoimmune/inflammatory processes underlying the loss of orexinergic neurons in narcolepsy. To test the autoimmune/inflammatory hypothesis by means of cerebrospinal fluid (CSF) levels of beta-amyloid1-42 and/or total tau proteins in a sample of narcoleptic patients, we analysed 16 narcoleptic patients and 16 healthy controls. Beta-amyloid1-42 CSF levels were significantly lower in narcoleptic patients compared with healthy controls. We also documented pathologically low levels of CSF beta-amyloid1-42 (<500 pg mL(-1) ) in six of 16 narcoleptic patients (37.5%). We hypothesize that the significant decrease of the CSF beta-amyloid1-42 levels in narcoleptic patients may support both the inflammatory/autoimmune hypothesis as the basis of the pathogenesis of narcolepsy and the prevalence of an 'amyloidogenic' pathway caused by the deficiency of the alpha-secretases enzymes.

Alteration of circadian sleep-wake rhythm and salivary melatonin secretion in idiopathic/isolated REM sleep behavior disorder: Preliminary evidence.

OBJECTIVE/BACKGROUND: Idiopathic/isolated REM sleep behavior disorder (iRBD) is widely regarded as an early sign of neurodegeneration leading to synucleinopathies. While circadian rhythm alterations in iRBD have been preliminarily demonstrated, evidence on melatonin secretion patterns in this clinical condition is limited. To address this knowledge gap, this exploratory study aimed to integrate salivary melatonin measurement with actigraphic monitoring in individuals with iRBD and age-matched healthy controls (HC) under real-life conditions. METHODS: Participants diagnosed with iRBD and HC underwent clinical evaluation and wore an actigraph for seven days and nights. Salivary melatonin concentrations were measured at five time points during the last night of recording. Comparative analyses were conducted on clinical data, actigraphic parameters, and melatonin levels between the two groups. RESULTS: iRBD participants (n = 18) showed greater motor (p < 0.01) and non-motor symptoms (p < 0.001), alongside disruptions in circadian sleep-wake rhythm compared to HC (n = 10). Specifically, actigraphy revealed a delayed central phase measurement (p < 0.05), reduced activity during the most active hours (p < 0.001), and decreased relative amplitude (p < 0.05). Total salivary melatonin concentration was significantly lower in iRBD (p < 0.05), with a slight but non-significant phase delay in dim light melatonin onset. CONCLUSIONS: This exploratory study highlights a dysregulation of circadian sleep-wake rhythm coupled with reduced melatonin secretion in iRBD. Future research could add to these preliminary findings to evaluate novel treatment approaches to regulate the sleep-wake cycle and elucidate the implications of circadian dysregulation in the conversion from iRBD to neurodegeneration.

Autoantibody profiles assessment in individuals with persistent olfactory impairment following SARS-CoV-2 infection.

BACKGROUND: Olfactory impairment, particularly hyposmia and anosmia, has emerged as a distinctive early symptom of SARS-CoV-2. Drawing on the historical association of autoimmune diseases with olfactory function, this study delves into the connections between COVID-19, autoimmunity, and persistent olfactory dysfunctions, focusing on individuals experiencing long-lasting smell disorders (3-18 months post-SARS-CoV-2 infection). METHODS: The study comprised 36 Long Covid patients with persistent olfactory dysfunctions, alongside two control groups. Olfactory functionality was assessed using the Sniffin' Sticks extended test. Non-invasive olfactory mucosa brushing and nasal secretions were processed for nasal samples, while serum samples were obtained through peripheral venous sampling. A panel of autoantibodies, including Immunocirculating Complexes, ANA, ENA, and AECA, was investigated in serum and brush supernatant samples. RESULTS: Contrary to expectations, the absence of traditional autoantibodies challenges the proposed autoimmune etiology of Long Covid-associated olfactory dysfunction. However, the presence and potential pathogenic role of AECA suggest viral cytopathic and inflammatory involvement in specific anatomical districts. One hypothesis explores the impact of inflammation and cytokine release induced by the viral infection, altering neuronal signaling and contributing to persistent hyposmia. CONCLUSION: This research contributes to our understanding of the complex relationships between autoimmunity, olfactory impairment, and COVID-19. The absence of classical autoantibodies challenges prevailing theories, while the prominence of AECA hints at unique viral-induced pathogenic mechanisms. By unraveling these complexities, this study enhances our comprehension of post-acute sequelae, offering valuable perspectives on immune-mediated responses in the aftermath of the pandemic.

Cerebrospinal-fluid biomarkers for predicting phenoconversion in patients with isolated rapid-eye movement sleep behavior disorder.

STUDY OBJECTIVES: Patients with isolated rapid-eye-movement sleep behavior disorder (iRBD) have an increased risk of developing neurodegenerative diseases. This study assessed cerebrospinal-fluid (CSF) biomarkers of neurodegeneration and blood-brain barrier (BBB) alteration in patients with iRBD compared to controls and ascertain whether these biomarkers may predict phenoconversion to alpha-synucleinopathies (Parkinson's Disease (PD), Dementia with Lewy bodies (DLB), Multiple System Atrophy (MSA)). METHODS: Patients and controls underwent between 2012 and 2016 a neurological assessment, a lumbar puncture for CSF biomarker analysis (ß-amyloid42 - Aß42; total-tau, and phosphorylated tau), and BBB alteration (CSF/serum albumin ratio). All patients with iRBD were followed until 2021 and then classified into patients who converted to alpha-synucleinopathies (iRBD converters, cRBD) or not (iRBD non-converters, ncRBD). RESULTS: Thirty-four patients with iRBD (mean age 67.12 ±â€…8.14) and 33 controls (mean age 64.97 ±â€…8.91) were included. At follow-up (7.63 ±â€…3.40 years), eight patients were ncRBD and 33 patients were cRBD: eleven converted to PD, 10 to DLB, and two to MSA. Patients with iRBD showed lower CSF Aß42 levels and higher CSF/serum albumin ratio than controls. Cox regression analysis showed that the phenoconversion rate increases with higher motor impairment (hazard ratio [HR] = 1.23, p = 0.032). CSF Aß42 levels predicted phenoconversion to DLB (HR = 0.67, p = 0.038) and BBB alteration predicted phenoconversion to PD (HR = 1.20, p = 0.038). DISCUSSION: This study showed that low CSF Aß42 levels and high BBB alteration may predict the phenoconversion to DLB and PD in patients with iRBD, respectively. These findings highlight the possibility to discriminate phenoconversion in iRBD patients through CSF biomarkers; however, further studies are needed.