Ratio of lymphocyte to monocyte area under the curve as a novel predictive factor for severe infection in multiple sclerosis

Background

Individuals with multiple sclerosis (MS) are vulnerable to all types of infection, because MS itself involves immunodeficiency, in addition to involving treatment with immunosuppressants. Simple predictive variables for infection that are easily assessed in daily examinations are warranted. Lymphocyte area under the curve (L_AUC), defined as the sum of serial absolute lymphocyte counts under the lymphocyte count-time curve, has been established as a predictive factor for several infections after allogenic hematopoietic stem cell transplantation. We assessed whether L_AUC could also be a useful factor for predicting severe infection in MS patients.

Methods

From October 2010 to January 2022, MS patients, diagnosed based on the 2017 McDonald criteria, were retrospectively reviewed. We extracted patients with infection requiring hospitalization (IRH) from medical records and matched with controls in a 1:2 ratio. Variables including clinical severity and laboratory data were compared between the infection group and controls. L_AUC was calculated along with the AUC of total white blood cells (W_AUC), neutrophils (N_AUC), lymphocytes (L_AUC), and monocytes (M_AUC). To correct for different times of blood examination and extract mean values of AUC per time point, we divided the AUC by follow-up duration. For example, in evaluating lymphocyte counts, we defined the ratio of [L_AUC] to [follow-up duration] as [L_AUC/t]. Multivariate regression analysis was conducted to extract predictive factors associated with IRH. Also, discriminative analysis was conducted using candidate variables from multivariate analysis.

Results

The total case-control sample included 177 patients of MS with IRH (n=59) and non-IRH (controls) (n=118). Adjusted odds ratios (OR) for the risk of serious infection in patients with MS with higher baseline expanded disability status scale (EDSS) (OR 1.340, 95% confidence interval [CI] 1.070-1.670, p = 0.010) and lower ratio of L_AUC/t to M_AUC/t (OR 0.766, 95%CI 0.591-0.993, p = 0.046) were significant. Notably, the kind of treatment, including glucocorticoids (GCs), disease-modifying drugs (DMDs) and other immunosuppressants agents, and dose of GCs were not significantly associated with serious infection after correlated with EDSS and ratio of L_AUC/t to M_AUC/t. In discriminative analysis, sensitivity was 88.1% (95%CI 76.5-94.7%) and specificity was 35.6% (95%CI 27.1-45.0%), using EDSS ≥ 6.0 or ratio of L_AUC/t to M_AUC/t ≤ 3.699, while sensitivity was 55.9% (95%CI 42.5-68.6%) and specificity was 83.9% (95%CI 75.7-89.8%), using both EDSS ≥ 6.0 and ratio of L_AUC/t to M_AUC/t ≤ 3.699.

Conclusion

Our study revealed the impact of the ratio L_AUC/t to M_AUC/t as a novel prognostic factor for IRH. Clinicians should pay more attention to laboratory data such as lymphocyte or monocyte counts itself, directly presenting individual immunodeficiency, rather than the kind of drug to prevent infection as a clinical manifestation.

Triggering receptor expressed on myeloid cells 2 deficiency exacerbates injury-induced inflammation in a mouse model of tauopathy

Traumatic brain injury (TBI) promotes several Alzheimer's disease-like pathological features, including microtubule-associated protein tau (MAPT) accumulation within neurons. Macrophage activation in the injured hTau mouse model of tauopathy raises the question whether there is a relationship between MAPT pathology and alterations in macrophage activation following TBI. Triggering receptor expressed on myeloid cells 2 (TREM2) is a critical regulator of microglia and macrophage phenotype, but its mechanisms on TBI remain unclear. To address the association with TREM2 in TBI and MAPT pathology, we studied TREM2 deficiency in hTau mice (hTau;Trem2^-/- ) 3 (acute phase) and 120 (chronic phase) days after experimental TBI. At three days following injury, hTau;Trem2^-/- mice exhibited reduced macrophage activation both in the cortex and hippocampus. However, to our surprise, hTau;Trem2^-/- mice exposed to TBI augments macrophage accumulation in the corpus callosum and white matter near the site of tissue damage in a chronic phase, which results in exacerbated axonal injury, tau aggregation, and impaired neurogenesis. We further demonstrate that TREM2 deficiency in hTau injured mice promotes neuronal dystrophy in the white matter due to impaired phagocytosis of apoptotic cells. Remarkably, hTau;Trem2^-/- exposed to TBI failed to restore blood-brain barrier integrity. These findings imply that TREM2 deficiency accelerates inflammation and neurodegeneration, accompanied by attenuated microglial phagocytosis and continuous blood-brain barrier (BBB) leakage, thus exacerbating tauopathy in hTau TBI mice.

Tonsillectomy Improved Therapeutic Response in Anti-SRP Myopathy With Chronic Tonsillitis

Chronic tonsillitis has been attracted attention as a source of abnormal immune responses and a possible trigger of autoimmune diseases such as IgA nephritis, IgA vasculitis, palmoplantar pustulosis, psoriasis, rheumatoid arthritis, Behçet’s disease, and myositis. Here we present the first report of anti–signal recognition particle antibody–associated necrotizing myopathy (anti-SRP myopathy) with IgA nephropathy and chronic tonsillitis in which the therapeutic response to intravenous immunoglobulin (IVIG) treatment was dramatically improved after tonsillectomy and accompanied by a rapid increase in ΔIgG, defined as the change in serum IgG levels 2 weeks after the start of IVIG treatment relative to pre-treatment levels. Moreover, serum anti-SRP antibody titers became undetectable after tonsillectomy even though the resected tonsils did not produce anti-SRP antibodies. Tonsillectomy should be considered when chronic tonsillitis is observed in patients with autoimmune diseases showing poor response to treatment, including anti-SRP myopathy.

Proteomic analysis of exosome-enriched fractions derived from cerebrospinal fluid of amyotrophic lateral sclerosis patients

Exosomes contain many proteins associated with neurodegenerative diseases. To identify new candidate biomarkers and proteins associated with amyotrophic lateral sclerosis (ALS), we performed liquid chromatography-tandem mass spectrometry proteomic analysis of exosome-enriched fractions isolated from cerebrospinal fluid (CSF) of sporadic ALS patients using gel filtration chromatography. Proteomic data revealed that three proteins were increased and 11 proteins were decreased in ALS patients. The protein with the greatest increase in exosome-enriched fractions of CSF derived from ALS was novel INHAT repressor (NIR), which is closely associated with nucleolar function. By immunohistochemical analysis, we found that NIR was reduced in the nucleus of motor neurons in ALS patients. Our results demonstrate the potential utility of our methodology for proteomic analysis of CSF exosomes and suggest that nucleolar stress might play a role in sporadic ALS pathogenesis through the dysfunction of NIR.

GGC Repeat Expansion of NOTCH2NLC in Adult Patients with Leukoencephalopathy

Leukoencephalopathies comprise a broad spectrum of disorders, but the genetic background of adult leukoencephalopathies has rarely been assessed. In this study, we analyzed 101 Japanese patients with genetically unresolved adult leukoencephalopathy using whole-exome sequencing and repeat-primed polymerase chain reaction for detecting GGC expansion in NOTCH2NLC. NOTCH2NLC was recently identified as the cause of neuronal intranuclear inclusion disease. We found 12 patients with GGC expansion in NOTCH2NLC as the most frequent cause of adult leukoencephalopathy followed by NOTCH3 variants in our cohort. Furthermore, we found 1 case with de novo GGC expansion, which might explain the underlying pathogenesis of sporadic cases. ANN NEUROL 2019;86:962-968.

Tau Pathology in Chronic Traumatic Encephalopathy and Alzheimer's Disease: Similarities and Differences

Traumatic brain injury (TBI) has been associated with the development of Alzheimer's disease (AD) because these conditions share common pathological hallmarks: amyloid-β and hyperphosphorylated tau accumulation. However, given recent data it is uncertain if a history of TBI leads to the development of AD. Moreover, chronic traumatic encephalopathy (CTE), caused by repetitive mild TBI and characterized by progressive neurodegeneration with hyperphosphorylated tau, has come to be recognized as distinct from AD. Therefore, it is important to elucidate the clinical outcomes and molecular mechanisms underlying tau pathology following TBI. We summarize the histopathological features and clinical course of TBI in CTE, comparing the tau pathology with that in AD. Following brain injury, diffuse axonal injury, and hyperphosphorylated tau aggregates are observed within a shorter period than in AD. Hyperphosphorylated tau deposition usually begins in the perivascular area of the sulci in the cerebral cortex, then spreads unevenly in the cortex in CTE, while AD shows diffuse distribution of hyperphosphorylated tau in the cortical areas. We also highlight the molecular profile of tau and the implications of tau progression throughout the brain in both diseases. Tau contains phosphorylation sites common to both conditions. In particular, phosphorylation at Thr²³¹ triggers a conformational change to the toxic cis form of tau, which is suggested to drive neurodegeneration. Although the mechanism of rapid tau accumulation remains unknown, the structural diversity of tau might result in these different outcomes. Finally, future perspectives on CTE in terms of tau reduction are discussed.

Ataxic phenotype with altered CaV3.1 channel property in a mouse model for spinocerebellar ataxia 42

Spinocerebellar ataxia 42 (SCA42) is a neurodegenerative disorder recently shown to be caused by c.5144G > A (p.Arg1715His) mutation in CACNA1G, which encodes the T-type voltage-gated calcium channel Ca_V3.1. Here, we describe a large Japanese family with SCA42. Postmortem pathological examination revealed severe cerebellar degeneration with prominent Purkinje cell loss without ubiquitin accumulation in an SCA42 patient. To determine whether this mutation causes ataxic symptoms and neurodegeneration, we generated knock-in mice harboring c.5168G > A (p.Arg1723His) mutation in Cacna1g, corresponding to the mutation identified in the SCA42 family. Both heterozygous and homozygous mutants developed an ataxic phenotype from the age of 11-20 weeks and showed Purkinje cell loss at 50 weeks old. Degenerative change of Purkinje cells and atrophic thinning of the molecular layer were conspicuous in homozygous knock-in mice. Electrophysiological analysis of Purkinje cells using acute cerebellar slices from young mice showed that the point mutation altered the voltage dependence of Ca_V3.1 channel activation and reduced the rebound action potentials after hyperpolarization, although it did not significantly affect the basic properties of synaptic transmission onto Purkinje cells. Finally, we revealed that the resonance of membrane potential of neurons in the inferior olivary nucleus was decreased in knock-in mice, which indicates that p.Arg1723His Ca_V3.1 mutation affects climbing fiber signaling to Purkinje cells. Altogether, our study shows not only that a point mutation in CACNA1G causes an ataxic phenotype and Purkinje cell degeneration in a mouse model, but also that the electrophysiological abnormalities at an early stage of SCA42 precede Purkinje cell loss.

Microglia in Alzheimer's Disease: Risk Factors and Inflammation

Microglia are resident immune cells in the central nervous system (CNS) that originate from myeloid progenitor cells in the embryonic yolk sac and are maintained independently of circulating monocytes throughout life. In the healthy state, microglia are highly dynamic and control the environment by rapidly extending and retracting their processes. When the CNS is inflamed, microglia can give rise to macrophages, but the regulatory mechanisms underlying this process have not been fully elucidated. Recent genetic studies have suggested that microglial function is compromised in Alzheimer's disease (AD), and that environmental factors such as diet and brain injury also affect microglial activation. In addition, studies of triggering receptor expressed on myeloid cells 2-deficiency in AD mice revealed heterogeneous microglial reactions at different disease stages, complicating the therapeutic strategy for AD. In this paper, we describe the relationship between genetic and environmental risk factors and the roles of microglia in AD pathogenesis, based on studies performed in human patients and animal models. We also discuss the mechanisms of inflammasomes and neurotransmitters in microglia, which accelerate the development of amyloid-β and tau pathology.

Laquinimod attenuates inflammation by modulating macrophage functions in traumatic brain injury mouse model

Background

Traumatic brain injury (TBI) is a critical public health and socio-economic problem worldwide. A growing body of evidence supports the involvement of inflammatory events in TBI. It has been reported that resident microglia and infiltrating monocytes promote an inflammatory reaction that leads to neuronal death and eventually behavioral and cognitive impairment. Currently, there is no effective treatment for TBI and the development of new therapeutic strategies is a scientific goal of highest priority. Laquinimod, an orally administered neuroimmunomodulator initially developed for the treatment of multiple sclerosis, might be a promising neuroprotective therapy for TBI. Herein, we aim to investigate the hypothesis that laquinimod will reduce the central nervous system (CNS) damage caused by TBI.

Methods

To test our hypothesis, Ccr2^rfp/+Cx3cr1^gfp/+ mice were submitted to a moderate TBI induced by fluid percussion. Sham controls were submitted only to craniotomy. Mice were treated daily by oral gavage with laquinimod (25 mg/kg) 7 days before and 3 days after TBI. The brains of mice treated or not treated with laquinimod were collected at 3 and 120 days post injury, and brain morphological changes, axonal injury, and neurogenesis were evaluated by microscopy analysis. We also isolated microglia from infiltrating monocytes, and the expression of immune gene mRNAs were analyzed by employing a quantitative NanoString nCounter technique.

Results

Laquinimod prevented ventricle enlargement caused by TBI in the long term. Immunohistochemical analyses revealed decreased axonal damage and restored neurogenesis in the laquinimod-treated TBI group at early stage (3 days post injury). Notably, laquinimod inhibited the monocytes infiltration to the brain. Hierarchial clustering demonstrated that the microglial gene expression from the TBI group treated with laquinimod resembles the sham group more than the TBI-water control group.

Conclusions

Administration of laquinimod reduced lesion volume and axonal damage and restored neurogenesis after TBI. Laquinimod might be a potential therapy strategy to improve TBI long-term prognosis.

Electronic supplementary material

The online version of this article (10.1186/s12974-018-1075-y) contains supplementary material, which is available to authorized users.

Traumatic Brain Injury in hTau Model Mice: Enhanced Acute Macrophage Response and Altered Long-Term Recovery

Traumatic brain injury (TBI) induces widespread neuroinflammation and accumulation of microtubule associated protein tau (MAPT): two key pathological features of tauopathies. This study sought to characterize the microglial/macrophage response to TBI in genomic-based MAPT transgenic mice in a Mapt knockout background (called hTau). Two-month-old hTau and age-matched control male and female mice received a single lateral fluid percussion TBI or sham injury. Separate groups of mice were aged to an acute (3 days post-injury [DPI]) or chronic (135 DPI) post-injury time point. As judged by tissue immunostaining for macrophage markers, microglial/macrophage response to TBI was enhanced at 3 DPI in hTau mice compared with control TBI and sham mice. However, MAPT phosphorylation increased in hTau mice regardless of injury group. Flow cytometric analysis revealed distinct populations of microglia and macrophages within all groups at 135 DPI. Unexpectedly, microglial reactivity was significantly reduced in hTau TBI mice compared with all other groups. Instead, hTau TBI mice showed a persistent macrophage response. In addition, TBI enhanced MAPT pathology in the temporal cortex and hippocampus of hTau TBI mice compared with controls 135 DPI. A battery of behavioral tests revealed that TBI in hTau mice resulted in compromised use of spatial search strategies to complete a water maze task, despite lack of motor or visual deficits. Collectively, these data indicate that the presence of wild-type human tau alters the microglial/macrophage response to a single TBI, induces delayed, region-specific MAPT pathology, and alters cognitive recovery; however, the causal relationship between these events remains unclear. These results highlight the potential significance of communication between MAPT and microglia/macrophages following TBI, and emphasize the role of neuroinflammation in post-injury recovery.

Hippocampal adult neurogenesis: Does the immune system matter?

Adult hippocampal neurogenesis involves proliferation, survival, differentiation and integration of newborn neurons into pre-existing neuronal networks. Although its functional significance in the central nervous system (CNS) has not comprehensively elucidated, adult neurogenesis has been attributed a role in cognition, learning and memory. There is a growing body of evidence that CNS resident as well as peripheral immune cells participate in regulating hippocampal adult neurogenesis. Microglial cells are closely associated with neural stem/progenitor cell (NSPC) in the neurogenic niche engaged in a bidirectional communication with neurons, which may be important for adult neurogenesis. Microglial and neuronal crosstalk is mediated in part by CX3CL1/CX3CR1 signaling and a disruption in this pathway has been associated with impaired neurogenesis. It has been also reported that microglial neuroprotective or neurotoxic effects in adult neurogenesis occur in a context-dependent manner. Apart from microglia other brain resident and peripheral immune cells including pericytes, perivascular macrophages, mast cells and T-cells also modulate this phenomenon. It is worth mentioning that under some physiological circumstances such as normal aging there is a significant decrease in hippocampal neurogenesis. A role for innate and adaptive immune system in adult neurogenesis has been also reported during aging. Here, we review the current evidence regarding neuro-immune interactions in the regulation of neurogenesis under distinct conditions, including aging.

Ccr2 deletion dissociates cavity size and tau pathology after mild traumatic brain injury

Background

Millions of people experience traumatic brain injury (TBI) as a result of falls, car accidents, sports injury, and blast. TBI has been associated with the development of neurodegenerative conditions such as Alzheimer’s disease (AD) and chronic traumatic encephalopathy (CTE). In the initial hours and days, the pathology of TBI comprises neuronal injury, breakdown of the blood–brain barrier, and inflammation. At the cellular level, the inflammatory reaction consists of responses by brain-resident microglia, astrocytes, and vascular elements as well as infiltration of peripheral cells. After TBI, signaling by chemokine (C-C motif) ligand 2 (CCL2) to the chemokine (C-C motif) receptor 2 (CCR2) is a key regulator of brain infiltration by monocytes.

Methods

We utilized mice with one or both copies of Ccr2 disrupted by red fluorescent protein (RFP, Ccr2^RFP/+ and Ccr2^RFP/RFP). We subjected these mice to the mild lateral fluid percussion model of TBI and examined several pathological outcomes 3 days later in order to determine the effects of altered monocyte entry into the brain.

Results

Ccr2 deletion reduced monocyte infiltration, diminished lesion cavity volume, and lessened axonal damage after mild TBI, but the microglial reaction to the lesion was not affected. We further examined phosphorylation of the microtubule-associated protein tau, which aggregates in brains of people with TBI, AD, and CTE. Surprisingly, Ccr2 deletion was associated with increased tau mislocalization to the cell body in the cortex and hippocampus by tissue staining and increased levels of phosphorylated tau in the hippocampus by Western blot.

Conclusions

Disruption of CCR2 enhanced tau pathology and reduced cavity volume in the context of TBI. The data reveal a complex role for CCR2⁺ monocytes in TBI, as monitored by cavity volume, axonal damage, and tau phosphorylation.

Ontogeny and functions of central nervous system macrophages

Microglia, the only nonneuroepithelial cells found in the parenchyma of the CNS, originate during embryogenesis from the yolk sac and enter the CNS quite early (embryonic day 9.5-10 in mice). Thereafter, microglia are maintained independently of any input from the blood and, in particular, do not require hematopoietic stem cells as a source of replacement for senescent cells. Monocytes are hematopoietic cells, derived from bone marrow. The ontogeny of microglia and monocytes is important for understanding CNS pathologies. Microglial functions are distinct from those of blood-derived monocytes, which invade the CNS only under pathological conditions. Recent data reveal that microglia play an important role in managing neuronal cell death, neurogenesis, and synaptic interactions. In this article, we discuss the physiology of microglia and the functions of monocytes in CNS pathology. We address the roles of microglia and monocytes in neurodegenerative diseases as an example of CNS pathology.