Background: Hyaluronan accumulates in chronic demyelinated multiple sclerosis (MS) lesions. Results: 4-Methylumbelliferone (4MU) inhibits HA synthesis, is protective in active and passive MS models, modulates T-cell responses, and prevents CXCL12 suppression within inflamed and non-inflamed CNS tissue. Conclusion: Inhibition of hyaluronan synthesis protects against CNS inflammation. Significance: Study data substantiate a link between hyaluronan and CNS inflammation.

Hepatitis D virus (HDV) infection is highly prevalent in patients with chronic hepatitis B (CHB). AASLD guidelines recommend a risk-based screening approach. Our aim was to ascertain if the risk-based approach leads to appropriate HDV screening, identify targets to improve screening rates, and study HDV clinical burden. CHB patients screened for HDV from 01/2016 to 12/2021 were identified. Level of training and specialty of providers ordering HDV screening tests were determined. HDV seropositive (HDV+) patient charts were reviewed for the presence of individual risk factors per the AASLD guidelines to determine if they met screening criteria. The severity of liver disease at the time of HDV screening was compared between the HDV+ group and a matched (based on age, hepatitis B e antigen status, BMI and sex) HDV seronegative (HDV−) group. During the study period, 1444/11,190 CHB patients were screened for HDV. Most screening tests were ordered by gastroenterology (90.2%) specialists and attending physicians (80.5%). HDV+ rate was 88/1444 (6%), and 72 HDV+ patients had complete information for analysis. 18% of HDV+ patients would be missed by a risk-based screening approach due to unreported or negative risk factors (see Table ). A significantly higher number of HDV+ patients had developed significant fibrosis (p = 0.001) and cirrhosis (p < 0.01) by the time of screening than HDV− (n = 67) patients. In conclusion, targeted interventions are needed towards trainees and primary care clinics to improve screening rates. Current risk-based criteria do not appropriately screen for HDV. It is time for universal screening of HDV in CHB patients.

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We previously showed that intrathecal administration of methotrexate slowed disability progression in multiple sclerosis (MS) patients with progressive disease. In general MS patients with progressive disease respond poorly to anti-inflammatory therapies. In order to better understand the mechanism by which methotrexate is protective in progressive MS, we analyzed its impact on the non-inflammatory cuprizone-induced demyelination model. When low-dose methotrexate was administered intracerebroventricularly it reduced demyelination and accumulation of GFAP+ reactive astrocytes in the corpus callosum. Administration of methotrexate after the withdrawal of cuprizone neither delayed remyelination nor influenced the number of astrocytes in the corpus callosum suggesting that methotrexate does not interfere with repair processes in the CNS. Moreover, methotrexate increased the expression of IGF1 in vitro and in vivo, a factor known to protect oligodendrocytes and limit the activation of astrocytes. Our studies show that methotrexate has an impact on pathogenic process in a demyelination model whose pathophysiological basis is not primarily related to inflammatory mechanisms, similar to neurodegenerative mechanisms associated with progressive MS. The pronounced inhibitory influence of methotrexate on the accumulation of astrocytes in the corpus callosum suggests that intrathecal methotrexate modulates astroglial activation in progressive MS possibly by promoting CNS production of IGF1.