Encephalitis in Previously Healthy Children

TLR3/TRIF pathway confers protection against herpes simplex encephalitis through NK cell activation mediated by a loop of type I IFN and IL-15 from epithelial and dendritic cells

Autosomal recessive (AR) and dominant (AD) deficiencies of TLR3 and TRIF are believed to be crucial genetic causes of herpes simplex encephalitis (HSE), which is a fatal disease causing focal or global cerebral dysfunction following infection with herpes simplex virus type 1 (HSV-1). However, few studies have been conducted on the immunopathological networks of HSE in the context of TLR3 and TRIF defects at the cellular and molecular levels. In this work, we deciphered the crosstalk between type I IFN (IFN-I)-producing epithelial layer and IL-15-producing dendritic cells (DC) to activate NK cells for the protective role of TLR3/TRIF pathway in HSE progression after vaginal HSV-1 infection. TLR3- and TRIF-ablated mice showed enhanced susceptibility to HSE progression, along with high HSV-1 burden in vaginal tract, lymphoid tissues and CNS. The increased HSV-1 burden in TLR3- and TRIF-ablated mice did not correlate with increased infiltration of Ly-6C+ monocytes, but it was closely associated with impaired NK cell activation in vaginal tract. Furthermore, using delicate ex vivo experiments and bone marrow transplantation, TRIF deficiency in tissue-resident cells, such as epithelial cells in vaginal tract, was found to cause impaired NK cell activation by means of low IFN-I production, whereas IFN-I receptor in DC was required for NK cell activation via IL-15 production in response to IFN-I produced from epithelial layer. These results provide new information about IFN-I- and IL-15-mediated crosstalk between epithelial cells and DC at the primary infection site, which suppresses HSE progression in a TLR3- and TRIF-dependent manner.

Addressing vaccine-preventable encephalitis in vulnerable populations

PURPOSE OF REVIEW

Vaccinations have been pivotal in lowering the global disease burden of vaccine-preventable encephalitides, including Japanese encephalitis, tick-borne encephalitis, measles encephalitis, and rabies encephalitis, among others.

RECENT FINDINGS

Populations vulnerable to vaccine-preventable infections that may lead to encephalitis include those living in endemic and rural areas, military members, migrants, refugees, international travelers, younger and older persons, pregnant women, the immunocompromised, outdoor, healthcare and laboratory workers, and the homeless. There is scope for improving the availability and distribution of vaccinations, vaccine equity, surveillance of vaccine-preventable encephalitides, and public education and information.

SUMMARY

Addressing these gaps in vaccination strategies will allow for improved vaccination coverage and lead to better health outcomes for those most at risk for vaccine-preventable encephalitis.

Pediatric Autoimmune Encephalitis Following COVID-19 Infection

Similar to the pathogenesis of autoimmune disease, SARS-CoV-2 (COVID-19) infection has been shown to be associated with dysregulated and persistent inflammatory reactions and production of some antibodies. We report 3 pediatric patients found to have serum SARS-CoV-2 antibodies who presented with neurologic findings suggestive of postinfectious autoimmune-mediated encephalitis. All 3 cases showed lymphocytic pleocytosis on cerebrospinal fluid studies and marked improvement in neurologic symptoms after high-dose intravenous corticosteroids. The manifestations of SARS-CoV-2 infection in the pediatric population are still an evolving area of study, and these cases suggest autoimmune-mediated encephalitis as yet another SARS-CoV-2 related complication.

In-depth analysis reveals complex molecular aetiology in a cohort of idiopathic cerebral palsy

Cerebral palsy is the most prevalent physical disability in children; however, its inherent molecular mechanisms remain unclear. In the present study, we performed in-depth clinical and molecular analysis on 120 idiopathic cerebral palsy families, and identified underlying detrimental genetic variants in 45% of these patients. In addition to germline variants, we found disease-related postzygotic mutations in ∼6.7% of cerebral palsy patients. We found that patients with more severe motor impairments or a comorbidity of intellectual disability had a significantly higher chance of harbouring disease-related variants. By a compilation of 114 known cerebral-palsy-related genes, we identified characteristic features in terms of inheritance and function, from which we proposed a dichotomous classification system according to the expression patterns of these genes and associated cognitive impairments. In two patients with both cerebral palsy and intellectual disability, we revealed that the defective TYW1, a tRNA hypermodification enzyme, caused primary microcephaly and problems in motion and cognition by hindering neuronal proliferation and migration. Furthermore, we developed an algorithm and demonstrated in mouse brains that this malfunctioning hypermodification specifically perturbed the translation of a subset of proteins involved in cell cycling. This finding provided a novel and interesting mechanism for congenital microcephaly. In another cerebral palsy patient with normal intelligence, we identified a mitochondrial enzyme GPAM, the hypomorphic form of which led to hypomyelination of the corticospinal tract in both human and mouse models. In addition, we confirmed that the aberrant Gpam in mice perturbed the lipid metabolism in astrocytes, resulting in suppressed astrocytic proliferation and a shortage of lipid contents supplied for oligodendrocytic myelination. Taken together, our findings elucidate novel aspects of the aetiology of cerebral palsy and provide insights for future therapeutic strategies.

Management of Japanese Encephalitis: A Current Update

Japanese encephalitis (JE) continues to be one of the world’s most serious infections with no definitive treatment or guidelines. The high morbidity and mortality rate among symptomatic patients warrant the need for further investigation in this regard. Our review focuses on the recent updates on Japanese encephalitis treatment. For that reason, we used an advanced PubMed search with JE and drugs like minocycline, interferon, ribavirin, immunoglobulin, dexamethasone, and acyclovir. All research was done in full papers written in the English language and conducted in humans. This review aims to compare and analyze recent papers regarding JE treatment to guide healthcare providers with the latest information and make evidence-based decisions when presented with this infection. Overall, only minocycline had promising results because one of the two studies showed statistically significant results. The second study showed positive trends in children over 12 years and patients who survived on the first day of hospitalization. The study with intravenous immunoglobulin (IVIG) did not improve the outcomes; however, it increased the levels of neutralizing antibodies. Further study with higher doses may change the outcomes in patients with JE. The other drugs failed to show promising results.