Using Multiphoton Intravital Microscopy to Study Neutrophil Transmigration and Blood-Brain Barrier Permeability in a Mouse Model of Herpes Simplex Virus Encephalitis.

Multiphoton intravital microscopy (MP-IVM) is an imaging technique used for the observation of living organisms at a microscopic resolution. The tissue of interest is exposed through a window allowing imaging of cells in real time. Using MP-IVM, the temporospatial kinetics of leukocyte transendothelial migration can be visualized and quantitated using reporter mice and cell-specific fluorophore-conjugated monoclonal antibodies to track the leukocytes within and outside of vascular beds. Here we describe a method used to study neutrophil transendothelial migration and blood-brain barrier permeability in a mouse model of herpes simplex virus I (HSV) encephalitis.

Diagnostic markers of acute encephalitis syndrome and COVID-associated multisystem inflammatory syndrome in children from Southern India.

Acute encephalitis syndrome (AES) in children poses a significant public health challenge in India. This study aims to explore the utility of host inflammatory mediators and neurofilament (NfL) levels in distinguishing etiologies, assessing disease severity, and predicting outcomes in AES. We assessed 12 mediators in serum (n = 58) and 11 in cerebrospinal fluid (CSF) (n = 42) from 62 children with AES due to scrub typhus, viral etiologies, and COVID-associated multisystem inflammatory syndrome (MIS-C) in Southern India. Additionally, NfL levels in serum (n = 20) and CSF (n = 18) were examined. Clinical data, including Glasgow coma scale (GCS) and Liverpool outcome scores, were recorded. Examining serum and CSF markers in the three AES etiology groups revealed notable distinctions, with scrub typhus differing significantly from viral and MIS-C causes. Viral causes had elevated serum CCL11 and CCL2 compared with scrub typhus, while MIS-C cases showed higher HGF levels than scrub typhus. However, CSF analysis showed a distinct pattern with the scrub typhus group exhibiting elevated levels of IL-1RA, IL-1ß, and TNF compared with MIS-C, and lower CCL2 levels compared with the viral group. Modeling the characteristic features, we identified that age ≥3 years with serum CCL11 < 180 pg/mL effectively distinguished scrub typhus from other AES causes. Elevated serum CCL11, HGF, and IL-6:IL-10 ratio were associated with poor outcomes (p = 0.038, 0.005, 0.02). Positive CSF and serum NfL correlation, and negative GCS and serum NfL correlation were observed. Median NfL levels were higher in children with abnormal admission GCS and poor outcomes. Measuring immune mediators and brain injury markers in AES provides valuable diagnostic insights, with the potential to facilitate rapid diagnosis and prognosis. The correlation between CSF and serum NfL, along with distinctive serum cytokine profiles across various etiologies, indicates the adequacy of blood samples alone for assessment and monitoring. The association of elevated levels of CCL11, HGF, and an increased IL-6:IL-10 ratio with adverse outcomes suggests promising avenues for therapeutic exploration, warranting further investigation.

Cognitive domains affected post-COVID-19; a systematic review and meta-analysis.

BACKGROUND AND PURPOSE: This review aims to characterize the pattern of post-COVID-19 cognitive impairment, allowing better prediction of impact on daily function to inform clinical management and rehabilitation. METHODS: A systematic review and meta-analysis of neurocognitive sequelae following COVID-19 was conducted, following PRISMA-S guidelines. Studies were included if they reported domain-specific cognitive assessment in patients with COVID-19 at >4 weeks post-infection. Studies were deemed high-quality if they had >40 participants, utilized healthy controls, had low attrition rates and mitigated for confounders. RESULTS: Five of the seven primary Diagnostic and Statistical Manual of Mental Disorders (DSM-5) cognitive domains were assessed by enough high-quality studies to facilitate meta-analysis. Medium effect sizes indicating impairment in patients post-COVID-19 versus controls were seen across executive function (standardised mean difference (SMD) -0.45), learning and memory (SMD -0.55), complex attention (SMD -0.54) and language (SMD -0.54), with perceptual motor function appearing to be impacted to a greater degree (SMD -0.70). A narrative synthesis of the 56 low-quality studies also suggested no obvious pattern of impairment. CONCLUSIONS: This review found moderate impairments across multiple domains of cognition in patients post-COVID-19, with no specific pattern. The reported literature was significantly heterogeneous, with a wide variety of cognitive tasks, small sample sizes and disparate initial disease severities limiting interpretability. The finding of consistent impairment across a range of cognitive tasks suggests broad, as opposed to domain-specific, brain dysfunction. Future studies should utilize a harmonized test battery to facilitate inter-study comparisons, whilst also accounting for the interactions between COVID-19, neurological sequelae and mental health, the interplay between which might explain cognitive impairment.

Mental health outcomes of encephalitis: An international web-based study.

BACKGROUND AND PURPOSE: Acute encephalitis is associated with psychiatric symptoms. Despite this, the extent of mental health problems following encephalitis has not been systematically reported. METHODS: We recruited adults who had been diagnosed with encephalitis of any aetiology to complete a web-based questionnaire. RESULTS: In total, 445 respondents from 31 countries (55.1% UK, 23.1% USA) responded. Infectious encephalitis constituted 65.4% of cases, autoimmune 29.7%. Mean age was 50.1 years, 65.8% were female, and median time since encephalitis diagnosis was 7 years. The most common self-reported psychiatric symptoms were anxiety (75.2%), sleep problems (64.4%), mood problems (62.2%), and unexpected crying (35.2%). Self-reported psychiatric diagnoses were common: anxiety (44.0%), depression (38.6%), panic disorder (15.7%), and posttraumatic stress disorder (PTSD; 21.3%). Severe mental illnesses such as psychosis (3.3%) and bipolar affective disorder (3.1%) were reported. Self-reported diagnosis rates were broadly consistent with results from the Psychiatric Diagnostic Screening Questionnaire. Many respondents also reported they had symptoms of anxiety (37.5%), depression (28.1%), PTSD (26.8%), or panic disorder (20.9%) that had not been diagnosed. Rates of psychiatric symptoms did not differ between autoimmune and infectious encephalitis. In total, 37.5% respondents had thought about suicide, and 4.4% had attempted suicide, since their encephalitis diagnosis. More than half of respondents (53.5%) reported they had no, or substandard, access to appropriate mental health care. High rates of sensory hypersensitivities (>75%) suggest a previously unreported association. CONCLUSIONS: This large international survey indicates that psychiatric symptoms following encephalitis are common and that mental health care provision may be inadequate. We highlight a need for proactive psychiatric input.

Para-infectious brain injury in COVID-19 persists at follow-up despite attenuated cytokine and autoantibody responses.

To understand neurological complications of COVID-19 better both acutely and for recovery, we measured markers of brain injury, inflammatory mediators, and autoantibodies in 203 hospitalised participants; 111 with acute sera (1-11 days post-admission) and 92 convalescent sera (56 with COVID-19-associated neurological diagnoses). Here we show that compared to 60 uninfected controls, tTau, GFAP, NfL, and UCH-L1 are increased with COVID-19 infection at acute timepoints and NfL and GFAP are significantly higher in participants with neurological complications. Inflammatory mediators (IL-6, IL-12p40, HGF, M-CSF, CCL2, and IL-1RA) are associated with both altered consciousness and markers of brain injury. Autoantibodies are more common in COVID-19 than controls and some (including against MYL7, UCH-L1, and GRIN3B) are more frequent with altered consciousness. Additionally, convalescent participants with neurological complications show elevated GFAP and NfL, unrelated to attenuated systemic inflammatory mediators and to autoantibody responses. Overall, neurological complications of COVID-19 are associated with evidence of neuroglial injury in both acute and late disease and these correlate with dysregulated innate and adaptive immune responses acutely.