Objective: Our aim was to assess the real-world effectiveness of immune checkpoint inhibitors for treatment of patients with progressive multifocal leukoencephalopathy (PML). Methods: We conducted a multicenter survey compiling retrospective data from 79 PML patients, including 38 published cases and 41 unpublished cases, who received immune checkpoint inhibitors as add-on to standard of care. Oneyear follow-up data were analyzed to determine clinical outcomes and safety profile. Logistic regression was used to identify variables associated with 1-year survival. Results: Predisposing conditions included hematological malignancy (n = 38, 48.1%), primary immunodeficiency (n = 14, 17.7%), human immunodeficiency virus/acquired immunodeficiency syndrome (n = 12, 15.2%), inflammatory disease (n = 8, 10.1%), neoplasm (n = 5, 6.3%), and transplantation (n = 2, 2.5%). Pembrolizumab was most commonly used (n = 53, 67.1%). One-year survival was 51.9% (41/79). PML-immune reconstitution inflammatory syndrome (IRIS)

Restoring anti-JC virus (JCV) immunity is the only treatment of progressive multifocal leukoencephalopathy (PML). Interleukin-7 is a cytokine that increases number and function of T cells. We analyzed a population of PML patients who received recombinant human IL-7 (rhIL-7) to estimate survival and its determinants. Methods: After exclusion of patients with missing data or receiving other immunotherapies, findings from 64 patients with proven PML who received rhIL-7 between 2007 and 2020 were retrospectively analyzed. Logistic regression was used to analyze variables associated with one-year survival. Results: Underlying conditions were HIV/AIDS (n = 27, 42%), hematological malignancies (n = 16, 25%), primary immunodeficiencies (n = 13, 20%), solid organ transplantation (n = 4, 6%) and chronic inflammatory diseases (n = 4, 6%). One-year survival was 54.7% and did not differ by underlying condition. Survival was not associated with baseline characteristics, but with a >50% increase in blood lymphocytes (OR 4.1, 95%CI 1.2-14.9) and CD4 + T cells (OR 5.9, 95%CI 1.7-23.3), and a > 1 log copies/mL decrease in cerebrospinal fluid JCV DNA (OR 7.6, 95%CI 1.6-56.1) during the first month after rhIL-7 initiation. Side effects were mainly local and flu-like symptoms (n = 8, 12.5%) and PML-immune reconstitution inflammatory syndrome (IRIS) (n = 5, 8%). Interpretation: In this non-controlled retrospective study, survival did not differ from that expected in HIV/AIDS patients, but might have been improved in those with hematological malignancies, primary immunodeficiencies and transplant recipients. RhIL-7 might have contributed to the increase in blood lymphocytes and decrease in CSF JCV replication that were associated with better survival.

Cerebellar Purkinje neurons integrate information transmitted at excitatory synapses formed by granule cells. Although these synapses are considered essential sites for learning, most of them appear not to transmit any detectable electrical information and have been defined as silent. It has been proposed that silent synapses are required to maximize information storage capacity and ensure its reliability, and hence to optimize cerebellar operation. Such optimization is expected to occur once the cerebellar circuitry is in place, during its maturation and the natural and steady improvement of animal agility. We therefore investigated whether the proportion of silent synapses varies over this period, from the third to the sixth postnatal week in mice. Selective expression of a calcium indicator in granule cells enabled quantitative mapping of presynaptic activity, while postsynaptic responses were recorded by patch clamp in acute slices. Through this approach and the assessment of two anatomical features (the distance that separates adjacent planar Purkinje dendritic trees and the synapse density), we determined the average excitatory postsynaptic potential per synapse. Its value was four to eight times smaller than responses from paired recorded detectable connections, consistent with over 70% of synapses being silent. These figures remained remarkably stable across maturation stages. According to the proposed role for silent synapses, our results suggest that information storage capacity and reliability are optimized early during cerebellar maturation. Alternatively, silent synapses may have roles other than adjusting the information storage capacity and reliability.

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The members of the 'And The Dat'AIDS study group' are given in the Appendix.