Studying serum neurofilament light chain levels as a potential new biomarker for small fiber neuropathy.

BACKGROUND AND PURPOSE: Diagnosing small fiber neuropathies can be challenging. To address this issue, whether serum neurofilament light chain (sNfL) could serve as a potential biomarker of damage to epidermal Aδ- and C-fibers was tested. METHODS: Serum NfL levels were assessed in 30 patients diagnosed with small fiber neuropathy and were compared to a control group of 19 healthy individuals. Electrophysiological studies, quantitative sensory testing and quantification of intraepidermal nerve fiber density after skin biopsy were performed in both the proximal and distal leg. RESULTS: Serum NfL levels were not increased in patients with small fiber neuropathy compared to healthy controls (9.1 ± 3.9 and 9.4 ± 3.8, p = 0.83) and did not correlate with intraepidermal nerve fiber density at the lateral calf or lateral thigh or with other parameters of small fiber impairment. CONCLUSION: Serum NfL levels cannot serve as a biomarker for small fiber damage.

Case Report: Balancing immune responses - multiple sclerosis disease exacerbation under BRAF/MEK treatment for malignant melanoma.

Background: Combination treatment with BRAF/MEK inhibitors favorably impact progression-free survival in malignant melanoma. However, it may cause paradoxical activation of the MAPK/ERK pathway in immune cells without BRAF mutation, which may lead to over activation of the immune system, especially in patients with pre-existing autoimmune conditions. In this case report, treatment of malignant melanoma with BRAF/MEK inhibitors was associated with radiological disease exacerbation of pre-existing multiple sclerosis (MS). Case presentation: A 47-year-old patient with pre-existing MS was diagnosed with malignant melanoma in June 2020. Anti-tumor treatment was initiated with a combination therapy of BRAF inhibitor dabrafenib and MEK inhibitor trametinib. In February 2022, the patient presented at our neurological clinic after routine MRI revealed exacerbation of radiological MS disease activity with ten new and gadolinium-enhancing lesions, and concomitant high levels of neurofilament light chain (NfL) in serum, a marker for axonal damage. In-depth analysis of immune cells in both peripheral blood and cerebrospinal fluid was performed by multi-color flow cytometry. After treatment with the B cell-depleting antibody ocrelizumab, MS disease stability was obtained and anti-tumor medication could be continued. Conclusions: Immunomodulatory treatment in cancer patients is highly effective from an oncological point of view, but may be associated with autoimmune side effects. This is of special importance in patients with pre-existing autoimmune diseases, as reflected by our case of MS disease reactivation under treatment with BRAF/MEK inhibitors. In our case, sequential modulation of immune cell subsets by B cell depletion, associated with marked shifts in B and T cell subsets, allowed for stabilization of disease and continuation of anti-tumor treatment.

Elevated neurofilament light chain CSF/serum ratio indicates impaired CSF outflow in idiopathic intracranial hypertension.

BACKGROUND: Impaired cerebrospinal fluid (CSF) homeostasis is central to the pathogenesis of idiopathic intracranial hypertension (IIH), although the precise mechanisms involved are still not completely understood. The aim of the current study was to assess the CSF/serum ratio of neurofilament light chain levels (QNfL) as a potential indicator of functional CSF outflow obstruction in IIH patients. METHODS: NfL levels were measured by single molecule array in CSF and serum samples of 87 IIH patients and in three control groups, consisting of 52 multiple sclerosis (MS) patients with an acute relapse, 21 patients with an axonal polyneuropathy (PNP), and 41 neurologically healthy controls (HC). QNfL was calculated as the ratio of CSF and serum NfL levels. Similarly, we also assessed the CSF/serum ratio of glial fibrillary acidic protein (QGFAP) levels to validate the QNfL data. Routine CSF parameters including the CSF/serum albumin ratio (QAlb) were determined in all groups. Lumbar puncture opening pressure of IIH patients was measured by manometry. RESULTS: CSF-NfL levels (r = 0.29, p = 0.008) and QNfL (0.40, p = 0.0009), but not serum NfL (S-NfL) levels, were associated with lumbar puncture opening pressure in IIH patients. CSF-NfL levels were increased in IIH patients, MS patients, and PNP patients, whereas sNfL levels were normal in IIH, but elevated in MS and PNP. Remarkably, QNfL (p < 0.0001) as well as QGFAP (p < 0.01) were only increased in IIH patients. QNfL was positively correlated with CSF-NfL levels (r = 0.51, p = 0.0012) and negatively correlated with S-NfL levels (r = - 0.51, p = 0.0012) in HC, while it was only positively associated with CSF-NfL levels in IIH patients (r = 0.71, p < 0.0001). An increase in blood-CSF barrier permeability assessed by QAlb did not lead to a decrease in QNfL in any cohort. CONCLUSIONS: The observed elevation of QNfL in IIH patients, which was associated with lumbar puncture opening pressure, indicates a reduced NfL transition from the CSF to serum compartment. This supports the hypothesis of a pressure-dependent CSF outflow obstruction to be critically involved in IIH pathogenesis.

Alemtuzumab-induced immune phenotype and repertoire changes: implications for secondary autoimmunity.

Alemtuzumab is a monoclonal antibody that causes rapid depletion of CD52-expressing immune cells. It has proven to be highly efficacious in active relapsing-remitting multiple sclerosis; however, the high risk of secondary autoimmune disorders has greatly complicated its use. Thus, deeper insight into the pathophysiology of secondary autoimmunity and potential biomarkers is urgently needed. The most critical time points in the decision-making process for alemtuzumab therapy are before or at Month 12, where the ability to identify secondary autoimmunity risk would be instrumental. Therefore, we investigated components of blood and CSF of up to 106 multiple sclerosis patients before and after alemtuzumab treatment focusing on those critical time points. Consistent with previous reports, deep flow cytometric immune-cell profiling (n = 30) demonstrated major effects on adaptive rather than innate immunity, which favoured regulatory immune cell subsets within the repopulation. The longitudinally studied CSF compartment (n = 18) mainly mirrored the immunological effects observed in the periphery. Alemtuzumab-induced changes including increased numbers of naïve CD4+ T cells and B cells as well as a clonal renewal of CD4+ T- and B-cell repertoires were partly reminiscent of haematopoietic stem cell transplantation; in contrast, thymopoiesis was reduced and clonal renewal of T-cell repertoires after alemtuzumab was incomplete. Stratification for secondary autoimmunity did not show clear immununological cellular or proteomic traits or signatures associated with secondary autoimmunity. However, a restricted T-cell repertoire with hyperexpanded T-cell clones at baseline, which persisted and demonstrated further expansion at Month 12 by homeostatic proliferation, identified patients developing secondary autoimmune disorders (n = 7 without secondary autoimmunity versus n = 5 with secondary autoimmunity). Those processes were followed by an expansion of memory B-cell clones irrespective of persistence, which we detected shortly after the diagnosis of secondary autoimmune disease. In conclusion, our data demonstrate that (i) peripheral immunological alterations following alemtuzumab are mirrored by longitudinal changes in the CSF; (ii) incomplete T-cell repertoire renewal and reduced thymopoiesis contribute to a proautoimmune state after alemtuzumab; (iii) proteomics and surface immunological phenotyping do not identify patients at risk for secondary autoimmune disorders; (iv) homeostatic proliferation with disparate dynamics of clonal T- and B-cell expansions are associated with secondary autoimmunity; and (v) hyperexpanded T-cell clones at baseline and Month 12 may be used as a biomarker for the risk of alemtuzumab-induced autoimmunity.

Neurofilament light chain levels reflect outcome in a patient with glutamic acid decarboxylase 65 antibody-positive autoimmune encephalitis under immune checkpoint inhibitor therapy.

Neurological immune-mediated side effects are rare but often severe complications of immune checkpoint inhibitor (ICI) treatment. This report describes a severe case of nivolumab/ipilimumab-associated glutamic acid decarboxylase 65-positive autoimmune encephalitis. It proposes neurofilament light chain levels, a biomarker indicating axonal damage, in the cerebrospinal fluid and serum as a putative novel biomarker for this diagnostically and therapeutically challenging entity with an often unfavorable outcome. Additionally, we provide an overview of previous reports of patients developing autoimmune encephalitis under ICI treatment.

Increased frequency of proinflammatory CD4 T cells and pathological levels of serum neurofilament light chain in adult drug-resistant epilepsy.

OBJECTIVE: Adult drug-resistant epilepsy (DRE) is associated with significant morbidity. Infiltration of immune cells is observed in DRE epileptic foci; however, the relation between DRE and the peripheral immune cell compartment remains only partially understood. We aimed to investigate differences in immune cell populations, cytokines, and neurodegenerative biomarkers in the peripheral blood of subjects with epilepsy versus healthy controls, and in DRE compared to well-controlled epilepsy (WCE). METHODS: Peripheral blood mononuclear cells and serum from >120 age- and sex-matched adults suffering from focal onset epilepsy and controls were analyzed by multipanel flow cytometry, multiplex immunoassays, and ultrasensitive single molecule array. RESULTS: Using a data-driven analytical approach, we identified that CD4 T cells in the peripheral blood are present in a higher proportion in DRE patients. Moreover, we observed that the frequency of CD4 T cells expressing proinflammatory cytokines interleukin (IL)-17A, IL-22, tumor necrosis factor, interferon-γ, and granulocyte-macrophage colony-stimulating factor, but not anti-inflammatory cytokines IL-10 and IL-4, is elevated in the peripheral blood of DRE subjects compared to WCE. In parallel, we found that Th17-related circulating proinflammatory cytokines are elevated, but Th2-related cytokine IL-4 is reduced, in the serum of epilepsy and DRE subjects. As Th17 cells can exert neurotoxicity, we measured levels of serum neurofilament light chain (sNfL), a marker of neuronal injury. We found significantly elevated levels of sNfL in DRE compared to controls, especially among older individuals. SIGNIFICANCE: Our data support that DRE is associated with an expansion of the CD4 Tcell subset in the peripheral blood and with a shift toward a proinflammatory Th17/Th1 CD4 Tcell immune profile. Our results further show that pathological levels of sNfL are more frequent in DRE, supporting a potential neurodegenerative component in adult DRE. With this work, we provide evidence for novel potential inflammatory and degenerative biomarkers in DRE.

NfL (Neurofilament Light Chain) Levels as a Predictive Marker for Long-Term Outcome After Ischemic Stroke.

Background and Purpose- Ischemic stroke causes major disability as a consequence of neuronal loss and recurrent ischemic events. Biomarkers predicting tissue damage or stroke recurrence might be useful to guide an individualized stroke therapy. NfL (neurofilament light chain) is a promising biomarker that might be used for this purpose. Methods- We used individual data of patients with an acute ischemic stroke and clinical long term follow-up. Serum NfL (sNfL) was quantified within 24 hours after admission and after 1 year and compared with other biomarkers (GDF15 [growth differentiation factor 15], S100, NT-proBNP [N-terminal pro-B-type natriuretic peptide], ANP [atrial natriuretic peptide], and FABP [fatty acid-binding protein]). The primary end point was functional outcome after 90 days and cerebrovascular events and death (combined cardiovascular end point) within 36 months of follow-up. Results- Two hundred eleven patients (mean age, 68.7 years; SD, ±12.6; 41.2% women) with median clinical severity on the National Institutes of Health Stroke Scale (NIHSS) score of 3 (interquartile range, 1-5) and long-term follow-up with a median of 41.8 months (interquartile range, 40.0-44.5) were prospectively included. We observed a significant correlation between sNfL and NIHSS at hospital admission (r=0.234; P<0.001). sNfL levels increased with the grade of age-related white matter changes (P<0.001) and were able to predict unfavorable clinical outcome (modified Rankin Scale score, ≥2) 90 days after stroke (odds ratio [OR], 1.562; 95% CI, 1.003-2.433; P=0.048) together with NIHSS (OR, 1.303; 95% CI, 1.164-1.458; P<0.001) and age-related white matter change rating (severe; OR, 3.326; 95% CI, 1.186-9.326; P=0.022). Similarly, sNfL was valuable for the prediction of the combined cardiovascular end point (OR, 2.002; 95% CI, 1.213-3.302; P=0.007), besides NIHSS (OR, 1.110; 95% CI, 1.000-1.232; P=0.049), diabetes mellitus (OR, 2.942; 95% CI, 1.306-6.630; P=0.005), and age-related white matter change rating (severe; OR, 4.816; 95% CI, 1.206-19.229; P=0.026) after multivariate regression analysis. Kaplan-Meier analysis revealed significantly more combined cardiovascular end points (18 [14.1%] versus 38 [45.8%], log-rank test P<0.001) during long-term follow-up in patients with elevated sNfL levels. Conclusions- sNFL is a valuable biomarker for functional independence 90 days after ischemic stroke and predicts cardiovascular long-term outcome. Clinical Trial Registration- URL: http://www.isrctn.com. Unique identifier: ISRCTN 46104198.