Biomarkers of inflammation and epithelial barrier function in multiple sclerosis

Neurofilament light in serum: Reference values and effect of risk factors for multiple sclerosis

BACKGROUND

The measurement of neurofilament light (NFL) in blood samples has been established as a sensitive measure of neuroaxonal damage in a wide range of diseases in the peripheral and central nervous system, including multiple sclerosis (MS). Previous studies have identified confounding factors that may influence the serum concentration of NFL.

AIM

We aimed at investigating the relationship between known confounders (age, body mass index, blood volume) and risk factors for MS (smoking and human leukocyte antigen (HLA)) on serum concentrations of NFL in control subjects. In addition, we compared different methods for correction for confounders when applied to newly diagnosed patients with MS.

METHODS

We measured serum concentrations of NFL by single molecule array analysis in 1.101 control subjects without neurological disease from 4 different cohorts (including 906 healthy blood donors) and 72 patients with newly diagnosed relapsing-remitting MS. A questionnaire on smoking habits was distributed to the 906 healthy blood donors, and the HLA risk alleles HLA-DRB1*15:01 and HLA-A*02:01 were genotyped by TaqMan allelic-discrimination PCR analysis in these subjects.

RESULTS

We confirmed that serum concentrations of NFL increase with age, but we also found that sample storage conditions for the different cohorts of control subjects had a substantial effect. Prolonged storage time and storage at -20° were independently associated with lower serum concentrations of NFL than shorter storage time and storage at -80° In samples from the large cohort of blood donors, we confirmed an association between high BMI and high blood volume with lower serum concentrations of NFL and found that this association was marginally stronger for BMI than for blood volume. We found no association between smoking and HLA risk factors for MS with serum concentrations of NFL in the blood donor cohort. Finally, we found that a simple method for correcting for the effect of age on NFL performed as well as Z-scores, which consider the effect of both age and BMI. This was shown when discriminating between patients with MS and control subjects and between MS patients with and without Gd-enhancing MRI lesions.

CONCLUSIONS

We confirm an association between serum concentrations of NFL, age, and BMI, but we also find that it may often be sufficient to correct for the effect of age alone. The effect of BMI should, however, be considered along with the effect of other confounding factors, including various comorbidities.

Neutrophils in Inflammatory Diseases: Unraveling the Impact of Their Derived Molecules and Heterogeneity

Inflammatory diseases involve numerous disorders and medical conditions defined by an insufficient level of self-tolerance. These diseases evolve over the course of a multi-step process through which environmental variables play a crucial role in the emergence of aberrant innate and adaptive immunological responses. According to experimental data accumulated over the past decade, neutrophils play a significant role as effector cells in innate immunity. However, neutrophils are also involved in the progression of numerous diseases through participation in the onset and maintenance of immune-mediated dysregulation by releasing neutrophil-derived molecules and forming neutrophil extracellular traps, ultimately causing destruction of tissues. Additionally, neutrophils have a wide variety of functional heterogeneity with adverse effects on inflammatory diseases. However, the complicated role of neutrophil biology and its heterogeneity in inflammatory diseases remains unclear. Moreover, neutrophils are considered an intriguing target of interventional therapies due to their multifaceted role in a number of diseases. Several approaches have been developed to therapeutically target neutrophils, involving strategies to improve neutrophil function, with various compounds and inhibitors currently undergoing clinical trials, although challenges and contradictions in the field persist. This review outlines the current literature on roles of neutrophils, neutrophil-derived molecules, and neutrophil heterogeneity in the pathogenesis of autoimmune and inflammatory diseases with potential future therapeutic strategies.

Elevated Fecal Calprotectin Accompanied by Intestinal Neutrophil Infiltration and Goblet Cell Hyperplasia in a Murine Model of Multiple Sclerosis

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system caused by myelin-specific autoreactive T cells. We previously demonstrated intestinal barrier disruption and signs of inflammation in experimental autoimmune encephalomyelitis (EAE), a model of MS. Fecal calprotectin is a disease activity biomarker in inflammatory bowel diseases, released by neutrophils in response to inflammation. We aimed to further investigate EAE manifestations in the gastrointestinal tract and to determine whether calprotectin is a useful biomarker of intestinal inflammation in EAE. Calprotectin was analyzed in feces, cecal contents, and plasma of EAE mice. Infiltrating neutrophils and goblet cells were investigated in different parts of the gastrointestinal tract before the onset of neurological symptoms and during established disease. We found increased calprotectin levels in feces, cecal content, and plasma preceding EAE onset that further escalated during disease progression. Increased neutrophil infiltration in the intestinal tissue concomitant with IL-17 expression and myeloperoxidase activity was found to correlate well with clinical activity. Increased goblet cells in the intestine, similar to irritable bowel syndrome (IBS), were also observed. The results suggest calprotectin as a good biomarker of gastrointestinal inflammation in EAE and the potential of this model as a useful animal model for IBS.

The peripheral endocannabinoid system and its association with biomarkers of inflammation in untreated patients with multiple sclerosis

BACKGROUND AND PURPOSE

The endocannabinoid system (ECS) has been found altered in patients with multiple sclerosis (MS). However, whether the ECS alteration is present in the early stage of MS remains unknown. First, we aimed to compare the ECS profile between newly diagnosed MS patients and healthy controls (HCs). Next, we explored the association of the ECS, biomarkers of inflammation, and clinical parameters in newly diagnosed MS patients.

METHODS

Whole blood gene expression of ECS components and levels of endocannabinoids in plasma were measured by real-time quantitative polymerase chain reaction and ultra-high-pressure liquid chromatography-mass spectrometry, respectively, in 66 untreated MS patients and 46 HCs.

RESULTS

No differences were found in the gene expression or plasma levels of the selected ECS components between newly diagnosed MS patients and HCs. Interferon-γ, encoded by the gene IFNG, correlated positively (ρ = 0.60) with the expression of G protein-coupled receptor 55 (GPR55), and interleukin1β (IL1B) correlated negatively (ρ = -0.50) with cannabinoid receptor 2 (CNR2) in HCs.

CONCLUSIONS

We found no alteration in the peripheral ECS between untreated patients with MS and HC. Furthermore, our results indicate that the ECS has a minor overall involvement in the early stage of MS on inflammatory markers and clinical parameters when compared with HCs.

Impaired intestinal permeability in patients with multiple sclerosis

BACKGROUND

A number of recent studies have shown that the intestinal microbiome, part of the brain-gut axis, is implicated in the pathophysiology of multiple sclerosis. An essential part of this axis, is the intestinal barrier and gastrointestinal disorders with intestinal barrier dysregulation appear to be linked to CNS demyelination, and hence involved in the etiopathogenesis of multiple sclerosis (MS).

OBJECTIVE

The aim of this study was to evaluate the integrity of the intestinal barrier in patients with clinically definite multiple sclerosis (CDMS) and clinically isolated syndrome (CIS) using two serum biomarkers, claudin-3 (CLDN3), a component of tight epithelial junctions, and intestinal fatty acid binding protein (I-FABP), a cytosolic protein in enterocytes.

METHODS

Serum levels of CLDN3 in 37 MS patients and 22 controls, and serum levels of I-FABP in 46 MS patients and 51 controls were measured using commercial ELISA kits. Complete laboratory tests excluded the presence of gluten-related disorders in all subjects. Thirty MS patients received either disease-modifying drugs (DMD), immunosuppression (IS) or corticosteroid treatment.

RESULTS

CLDN3 levels were only significantly higher in the MS patients treated with DMD or IS compared to the control group (P=0.006). There were no differences in I-FABP serum levels between the groups. Serum CLDN3 levels did not correlate with serum I-FABP levels in CDMS, in CIS patients or controls.

CONCLUSIONS

In multiple sclerosis patients, the intestinal epithelium may be impaired with increased permeability, but without significant enterocyte damage characterized by intracellular protein leakage. Based on our data, CLDN3 serum levels appear to assess intestinal dysfunction in MS patients but mainly in treated ones.

Evaluation of plasma soluble urokinase plasminogen activator receptor (SuPAR) levels in ulcerative colitis

BACKGROUND AND STUDY AIM

Soluble urokinase plasminogen activator receptor (SuPAR), a soluble form of the urokinase-type plasminogen activator receptor, is a biomarker produced by macrophages, monocytes, neutrophils, active T cells, endothelial cells, and circulating tumor cells. SuPAR is a novel biomarker showing altered inflammation in many inflammatory diseases. This study aims to investigate the SuPAR level in ulcerative colitis (UC) patients, and to evaluate the SuPAR level in active, and remission patients.

PATIENTS AND METHODS

Patient and healthy control SuPAR levels were analyzed by immunoassay method. SuPAR levels between UC patients and control group were compared. The difference between SuPAR levels in patients with active UC and UC in remission was analyzed. The relationship between C-reactive protein level, Total Mayo score, Mayo Endoscopic score used to predict disease activity, and amount of SuPAR were evaluated.

RESULTS

SuPAR levels were determined in the UC patient group (2170,3 ± 121,0 pg/ml), and healthy controls (2130,7 ± 164,8 pg/ml) (p = 0. 805). Median SuPAR levels were determined in moderate UC (2479 pg/ml), mild UC (1944 pg/ml), and patients in remission (1774 pg/ml) (p = 0,207). There were no significant relationships between SuPAR levels and CRP levels, Total Mayo score, disease duration in the UC group (r = 0.177, r = 0.267, and r = 0,007; respectively p > 0.05). A slightly positive correlation was found between Mayo Endoscopic Score and SuPAR level (r = 0.303; p = 0.031).

CONCLUSION

SuPAR is of limited value in the diagnosis of ulcerative colitis and in the assessment of disease activation.

Neurofilament light chain in blood as a diagnostic and predictive biomarker for multiple sclerosis: A systematic review and meta-analysis

Background

Neurofilament light chain (NfL) in cerebrospinal fluid (CSF) is a biomarker of multiple sclerosis (MS). However, CSF sampling is invasive and has limited the clinical application. With the development of highly sensitive single-molecule assay, the accurate quantification of the very low NfL levels in blood become feasible. As evidence being accumulated, we performed a meta-analysis to evaluate the diagnostic and predictive value of blood NfL in MS patients.

Methods

We performed literature search on PubMed, EMBASE, Web of Science and Cochrane Library from inception to May 31, 2022. The blood NfL differences between MS vs. controls, MS vs. clinically isolated syndrome (CIS), progressive MS (PMS) vs. relapsing-remitting MS (RRMS), and MS in relapse vs. MS in remission were estimated by standard mean difference (SMD) and corresponding 95% confidence interval (CI). Pooled hazard ratio (HR) and 95%CI were calculated to predict time to reach Expanded Disability Status Scale (EDSS) score≥4.0 and to relapse.

Results

A total of 28 studies comprising 6545 MS patients and 2477 controls were eligible for meta-analysis of diagnosis value, and 5 studies with 4444 patients were synthesized in analysis of predictive value. Blood NfL levels were significantly higher in MS patients vs. age-matched controls (SMD = 0.64, 95%CI 0.44–0.85, P<0.001), vs. non-matched controls (SMD = 0.76, 95%CI 0.56–0.96, P<0.001) and vs. CIS patients (SMD = 0.30, 95%CI 0.18–0.42, P<0.001), in PMS vs. RRMS (SMD = 0.56, 95%CI 0.27–0.85, P<0.001), and in relapsed patients vs. remitted patients (SMD = 0.54, 95%CI 0.16–0.92, P = 0.005). Patients with high blood NfL levels had shorter time to reach EDSS score≥4.0 (HR = 2.36, 95%CI 1.32–4.21, P = 0.004) but similar time to relapse (HR = 1.32, 95%CI 0.90–1.93, P = 0.155) compared to those with low NfL levels.

Conclusion

As far as we know, this is the first meta-analysis evaluating the diagnosis and predictive value of blood NfL in MS. The present study indicates blood NfL may be a useful biomarker in diagnosing MS, distinguishing MS subtypes and predicting disease worsening in the future.

MRI of the Entire Spinal Cord-Worth the While or Waste of Time? A Retrospective Study of 74 Patients with Multiple Sclerosis

Spinal cord lesions are included in the diagnosis of multiple sclerosis (MS), yet spinal cord MRI is not mandatory for diagnosis according to the latest revisions of the McDonald Criteria. We investigated the distribution of spinal cord lesions in MS patients and examined how it influences the fulfillment of the 2017 McDonald Criteria. Seventy-four patients with relapsing-remitting MS were examined with brain and entire spinal cord MRI. Sixty-five patients received contrast. The number and anatomical location of MS lesions were assessed along with the Expanded Disability Status Scale (EDSS). A Chi-square test, Fischer’s exact test, and one-sided McNemar’s test were used to test distributions. MS lesions were distributed throughout the spinal cord. Diagnosis of dissemination in space (DIS) was increased from 58/74 (78.4%) to 67/74 (90.5%) when adding cervical spinal cord MRI to brain MRI alone (p = 0.004). Diagnosis of dissemination in time (DIT) was not significantly increased when adding entire spinal cord MRI to brain MRI alone (p = 0.04). There was no association between the number of spinal cord lesions and the EDSS score (p = 0.71). MS lesions are present throughout the spinal cord, and spinal cord MRI may play an important role in the diagnosis and follow-up of MS patients.

Migraine in multiple sclerosis and other chronic inflammatory diseases

Migraine is a very prevalent disease worldwide and is a major cause of disability. As known for a long time, migraine is associated with neurogenic inflammation. Epidemiological studies have shown that migraine is comorbid with several chronic inflammatory diseases, including multiple sclerosis (MS), chronic inflammatory rheumatic diseases (CIRDs) and inflammatory bowel diseases (IBDs). This brief narrative review highlights some recent data supporting a link between migraine and these three chronic inflammatory diseases. Studies found that migraine prevalence is approximately two-fold higher in these diseases compared to the general population. The causal link between migraine and these chronic inflammatory diseases has not been identified yet. Here, we suggest that systemic mediators (such as cytokines) and gut microbiome make migraine worse or add significant risks. Systemic inflammation biomarkers and gut microbiome modification are certainly avenues worth exploring.

Circulating levels of tight junction proteins in multiple sclerosis: Association with inflammation and disease activity before and after disease modifying therapy

BACKGROUND

Tight junction proteins contribute to maintenance of epithelial and endothelial barriers such as the intestinal barrier and the blood brain barrier (BBB). Increased permeability of these barriers has been linked to disease activity in MS and there is currently a lack of easily accessible biomarkers predicting disease activity in MS.

AIM

To investigate whether levels of circulating tight junction proteins occludin and zonula occludens-1 (ZO-1) are associated with biomarkers of inflammation and disease activity; and to determine whether they could serve as clinical biomarkers.

METHODS

We prospectively included 72 newly diagnosed patients with relapsing remitting MS or clinically isolated syndrome with no prior disease modifying therapy (DMT) use and 50 healthy controls (HCs). Patients were followed with blood samples, 3 tesla MRI, and clinical evaluation for 12 months. Occludin, ZO-1, calprotectin and soluble urokinase-type plasminogen activator receptor (suPAR) were measured by ELISA; serum neurofilament light (NfL) and IL-6 by single-molecule array (SIMOA). The mRNA expression of IFNG, IL1R1, IL10, IL1B, ARG1 and TNF was measured by quantitative real time polymerase chain reaction (qPCR) in whole blood.

RESULTS

Plasma occludin levels were higher in MS patients compared with HCs. After 12 months on DMT, occludin levels were reduced by approximately 25% irrespective of 1st or 2nd line DMT (p<0.001). Furthermore, NfL and calprotectin levels were significantly reduced by 31% and 29%, respectively. Occludin and ZO-1 did not correlate with biomarkers of inflammation and did not predict disease activity at baseline or after 12 months.

CONCLUSIONS

Higher levels of occludin suggest an increased permeability of the BBB and/or the intestinal barrier in MS patients. The reduction of occludin after 12 months on DMTs might reflect repair of these barriers upon treatment. However, plasma levels of ZO-1 and occludin could not predict clinical or MRI disease activity as determined by regression and ROC-curve analysis. Our results do not indicate a clear clinically relevant role for circulating tight junction proteins as biomarkers of disease activity in MS and further investigations in larger cohorts are needed to clarify this issue.

Oxysterols and multiple sclerosis: Physiopathology, evolutive biomarkers and therapeutic strategy

Multiple sclerosis is an autoimmune disease that affects the central nervous system. Dysfunction of the immune system leads to lesions that cause motor, sensory, cognitive, visual and/or sphincter disturbances. In the long term, these disorders can progress towards an irreversible handicap. The diagnosis takes time because there are no specific criteria to diagnose multiple sclerosis. To realize the diagnosis, a combination of clinical, biological, and radiological arguments is therefore required. Hence, there is a need to identify multiple sclerosis biomarkers. Some biomarkers target immunity through the detection of oligoclonal bands, the measurement of the IgG index and cytokines. During the physiopathological process, the blood-brain barrier can be broken, and this event can be identified by measuring metalloproteinase activity and diffusion of gadolinium in the brain by magnetic resonance imaging. Markers of demyelination and of astrocyte and microglial activity may also be of interest as well as markers of neuronal damage and mitochondrial status. The measurement of different lipids in the plasma and cerebrospinal fluid can also provide suitable information. These different lipids include fatty acids, fatty acid peroxidation products, phospholipids as well as oxidized derivatives of cholesterol (oxysterols). Oxysterols could constitute new biomarkers providing information on the form of multiple sclerosis, the outcome of the disease and the answer to treatment.

Serum Short-Chain Fatty Acids and Associations With Inflammation in Newly Diagnosed Patients With Multiple Sclerosis and Healthy Controls

Multiple sclerosis (MS) is a chronic immune-mediated disease characterized by demyelination and neuroaxonal damage in the central nervous system. The etiology is complex and is still not fully understood. Accumulating evidence suggests that our gut microbiota and its metabolites influence the MS pathogenesis. Short-chain fatty acids (SCFAs), such as acetate, propionate and butyrate, are metabolites produced by gut microbiota through fermentation of indigestible carbohydrates. SCFAs and kynurenine metabolites have been shown to have important immunomodulatory properties, and propionate supplementation in MS patients has been associated with long-term clinical improvement. However, the underlying mechanisms of action and its importance in MS remain incompletely understood. We analyzed serum levels of SCFAs and performed targeted metabolomics in relation to biomarkers of inflammation, and clinical and MRI measures in newly diagnosed patients with relapsing-remitting MS before their first disease modifying therapy and healthy controls (HCs). We demonstrated that serum acetate levels were nominally reduced in MS patients compared with HCs. The ratios of acetate/butyrate and acetate/(propionate + butyrate) were significantly lower in MS patients in a multivariate analysis (orthogonal partial least squares discriminant analysis; OPLS-DA). The mentioned ratios and acetate levels correlated negatively with the pro-inflammatory biomarker IFNG, indicating an inverse relation between acetate and inflammation. In contrast, the proportion of butyrate was found higher in MS patients in the multivariate analysis, and both butyrate and valerate correlated positively with proinflammatory cytokines (IFNG and TNF), suggesting complex bidirectional regulatory properties of SCFAs. Branched SCFAs were inversely correlated with clinical disability, at a nominal significance level. Otherwise SCFAs did not correlate with clinical variables or MRI measures. There were signs of an alteration of the kynurenine pathway in MS, and butyrate was positively correlated with the immunomodulatory metabolite 3-hydroxyanthranilic acid. Other variables that influenced the separation between MS and HCs were NfL, ARG1 and IL1R1, D-ribose 5-phosphate, pantothenic acid and D-glucuronic acid. In conclusion, we provide novel results in this rapidly evolving field, emphasizing the complexity of the interactions between SCFAs and inflammation; therefore, further studies are required to clarify these issues before supplementation of SCFAs can be widely recommended.

Detection of Dysbiosis and Increased Intestinal Permeability in Brazilian Patients with Relapsing-Remitting Multiple Sclerosis

Dysbiosis, associated with barrier disruption and altered gut–brain communications, has been associated with multiple sclerosis (MS). In this study, we evaluated the gut microbiota in relapsing–remitting patients (RRMS) receiving disease-modifying therapies (DMTs) and correlated these data with diet, cytokines levels, and zonulin concentrations. Stool samples were used for 16S sequencing and real-time PCR. Serum was used for cytokine determination by flow cytometry, and zonulin quantification by ELISA. Pearson’s chi-square, Mann–Whitney, and Spearman’s correlation were used for statistical analyses. We detected differences in dietary habits, as well as in the gut microbiota in RRMS patients, with predominance of Akkermansia muciniphila and Bacteroides vulgatus and decreased Bifidobacterium. Interleukin-6 concentrations were decreased in treated patients, and we detected an increased intestinal permeability in RRMS patients when compared with controls. We conclude that diet plays an important role in the composition of the gut microbiota, and intestinal dysbiosis, detected in RRMS patients could be involved in increased intestinal permeability and affect the clinical response to DTMs. The future goal is to predict therapeutic responses based on individual microbiome analyses (personalized medicine) and propose dietary interventions and the use of probiotics or other microbiota modulators as adjuvant therapy to enhance the therapeutic efficacy of DMTs.