IL-22 hinders antiviral T cell responses and exacerbates ZIKV encephalitis in immunocompetent neonatal mice.

BACKGROUND: The Zika virus (ZIKV) outbreak that occurred in multiple countries was linked to increased risk of nervous system injuries and congenital defects. However, host immunity- and immune-mediated pathogenesis in ZIKV infection are not well understood. Interleukin-22 (IL-22) is a crucial cytokine for regulating host immunity in infectious diseases. Whether IL-22 plays, a role in ZIKV infection is unknown. METHODS: The cellular source of IL-22 was identified in IFNAR-/- mice and wild-type (WT) neonatal mice during ZIKV infection. To determine the role of IL-22, we challenged 1-day-old WT and IL-22-/- mice with ZIKV and monitored clinical manifestations. Glial cell activation in the brain was assessed by confocal imaging. ZIKV-specific CD8+ T cell responses in both the spleen and brain were analyzed by flow cytometry. In addition, glial cells were cultured in vitro and infected with ZIKV in the presence of IL-22, followed by the evaluation of cell proliferation, cytokine expression, and viral loads. RESULTS: We found that γδ T cells were the main source of IL-22 during ZIKV infection in both the spleen and brain. WT mice began to exhibit weight loss, staggered steps, bilateral hind limb paralysis, and weakness at 10 days post-infection (dpi) and ultimately succumbed to infection at 16-19 dpi. IL-22 deficiency lessened weight loss, moderated the systemic inflammatory response, and greatly improved clinical signs of neurological disease and mortality. ZIKV infection also induced the activation of microglia and astrocytes in vitro. Additional analysis demonstrated that the absence of IL-22 resulted in reduced activation of microglia and astrocytes in the cortex. Although IL-22 displayed a negligible effect on glial cells in vitro, IL-22-/- mice mounted more vigorous ZIKV-specific CD8+ T cell responses, which led to a more effective control of ZIKV in the brain. CONCLUSIONS: Our data revealed a pathogenic role of IL-22 in ZIKV encephalitis.

EEG Characteristics in COVID-19 Survivors and Non-survivors With Seizures and Encephalopathy.

The objective of this study is to report EEG findings in both COVID-19 survivors and non-survivors who underwent EEG either due to seizure or encephalopathy. Out of total 1468 COVID-19-positive patients, 19 patients underwent EEG. Eight out of 19 patients had a history of seizure disorder and in the remaining 11 with no prior history of seizures, four had a clinical seizure during their hospital stay. Only one had new-onset complex focal status epilepticus on EEG. Amongst the survivors (13/19), the most common EEG findings were normal followed by mild diffuse slowing. Amongst the non-survivors (6/19), the most common EEG finding was moderate to severe slowing in 50% of the patients. It can be deduced that COVID-19 infection does not increase the propensity of epileptiform discharges on EEG. There is perhaps a trend towards increased risk of new-onset status epilepticus in patients with encephalopathy and focal lesions.

Impact of Acute Confusional State in Patients With COVID-19 and a Predictive Score.

BACKGROUND: Acute confusional state (ACS) in COVID-19 is shown to be associated with poor clinical outcomes. METHODS: We assessed the impact of ACS - defined as a documented deterioration of mental status from baseline on the alertness and orientation to time, place, and person - on inpatient mortality and the need for intensive care unit (ICU) transfer in inpatient admissions with active COVID-19 infection in a single-center retrospective cohort of inpatient admissions from a designated COVID-19 tertiary care center using an electronic health record system. Furthermore, we developed and validated a neurological history and symptom-based predictive score of developing ACS. RESULTS: Thirty seven out of 245 (15%) patients demonstrated ACS. Nineteen (51%) patients had multifactorial ACS, followed by 11 (30%) patients because of hypoxemia. ACS patients were significantly older (80 [70-85] years vs 50.5 [38-69] years, p < 0.001) and demonstrated more frequent history of dementia (43% vs 9%, p < 0.001) and epilepsy (16% vs 2%, p = 0.001). ACS patients observed significantly higher in-hospital mortality (45.9% vs 1.9%, aOR [adjusted odds ratio]: 15.7, 95% CI = 3.6-68.0, p < 0.001) and need for ICU transfer (64.9% vs 35.1%, aOR: 2.7, 95% CI = 1.2-6.1, p = 0.015). In patients who survived hospitalization, ACS was associated with longer hospital stay (6 [3.5-10.5] days vs 3 [2-7] day, p = 0.012) and numerically longer ICU stay (6 [4-10] days vs 3 [2-6] days, p = 0.078). A score to predict ACS demonstrated 75.68% sensitivity and 81.73% specificity at a cutoff of ≥3. CONCLUSION: A high prevalence of ACS was found in patients with COVID-19 in our study cohort. Patients with ACS demonstrated increased mortality and need for ICU care. An internally validated score to predict ACS demonstrated high sensitivity and specificity in our cohort.