High-affinity autoreactive plasma cells disseminate through multiple organs in patients with immune thrombocytopenic purpura

The major therapeutic goal for immune thrombocytopenic purpura (ITP) is to restore normal platelet counts using drugs to promote platelet production or by interfering with mechanisms responsible for platelet destruction. Eighty percent of patients with ITP possess anti–integrin αIIbβ3 IgG autoantibodies that cause platelet opsonization and phagocytosis. The spleen is considered the primary site of autoantibody production by autoreactive B cells and platelet destruction. The immediate failure in approximately 50% of patients to recover a normal platelet count after anti-CD20 rituximab-mediated B cell depletion and splenectomy suggests that autoreactive, rituximab-resistant, IgG-secreting B cells (IgG-SCs) reside in other anatomical compartments. We analyzed more than 3,300 single IgG-SCs from spleen, bone marrow, and/or blood of 27 patients with ITP, revealing high interindividual variability in affinity for αIIbβ3, with variations over 3 logs. IgG-SC dissemination and range of affinities were, however, similar for each patient. Longitudinal analysis of autoreactive IgG-SCs upon treatment with the anti-CD38 mAb daratumumab demonstrated variable outcomes, from complete remission to failure with persistence of high-affinity anti–αIIbβ3 IgG-SCs in the bone marrow. This study demonstrates the existence and dissemination of high-affinity autoreactive plasma cells in multiple anatomical compartments of patients with ITP that may cause the failure of current therapies.     

SARS-CoV-2 Accessory Protein ORF8 Decreases Antibody-Dependent Cellular Cytotoxicity

Viruses use many different strategies to evade host immune responses. In the case of SARS-CoV-2, its Spike mutates rapidly to escape from neutralizing antibodies. In addition to this strategy, ORF8, a small accessory protein encoded by SARS-CoV-2, helps immune evasion by reducing the susceptibility of SARS-CoV-2-infected cells to the cytotoxic CD8+ T cell response. Interestingly, among all accessory proteins, ORF8 is rapidly evolving and a deletion in this protein has been linked to milder disease. Here, we studied the effect of ORF8 on peripheral blood mononuclear cells (PBMC). Specifically, we found that ORF8 can bind monocytes as well as NK cells. Strikingly, ORF8 binds CD16a (FcγRIIIA) with nanomolar affinity and decreases the overall level of CD16 at the surface of monocytes and, to a lesser extent, NK cells. This decrease significantly reduces the capacity of PBMCs and particularly monocytes to mediate antibody-dependent cellular cytotoxicity (ADCC). Overall, our data identifies a new immune-evasion activity used by SARS-CoV-2 to escape humoral responses.     

Quantitative glycoproteomics of high-density lipoproteins

In this work, we developed a targeted glycoproteomic method to monitor the site-specific glycoprofiles and quantities of the most abundant HDL-associated proteins using Orbitrap LC-MS for (glyco)peptide target discovery and QqQ LC-MS for quantitative analysis. We conducted a pilot study using the workflow to determine whether HDL protein glycoprofiles are altered in healthy human participants in response to dietary glycan supplementation.

The optimized HDL glycoproteomics method was sensitive enough to detect the effects of dietary supplements on HDL protein glycoprofiles even in a small sample size.     

Performance and cardiovascular measures in normal adults with extreme MSLT scores and subjective sleepiness levels

STUDY OBJECTIVES: The purpose of this study was to determine the relationship of subjective and objective sleepiness across several nights. Extreme groups were chosen based upon both Multiple Sleep Latency Test (MSLT) findings and report of characteristic subjective sleepiness, and groups were compared across sleep, demographic, performance, and physiologic variables. DESIGN AND SETTING: Subjects spent 3 baseline nights and the following days in the laboratory. Standard polysomnographic recordings were made on each night. On each day, subjects had an MSLT, performance testing, and metabolic and heart rate observation periods. PARTICIPANTS: Participants were 50 adult normal sleepers. INTERVENTIONS: None. MEASUREMENT AND RESULTS: Those subjects with sleep latencies on the MSLT of more than 10 minutes following the adaptation night (Alert) were compared with 2 groups of subjects with sleep latencies on the MSLT of less than 7 minutes following the adaptation night. Subjects with MSLT < 7 were divided into those who reported subjective sleepiness during the day (subjective sleepiness > 1 SD above the mean for the entire group-Sleepy-Sleepy) and those who did not report subjective sleepiness (subjective sleepiness < 1 SD above the mean for the entire group--Sleepy-Alert). The Alert group maintained longer sleep latencies than the other groups and had improved performance on vigilance compared to the Sleepy-Sleepy group on all days and on some days compared to the Sleepy-Alert group. Vigilance was improved in the Sleepy-Alert group compared with the Sleepy-Sleepy group on all days. The Alert group had higher heart rate and increased low/high spectral heart rate power compared to both sleepy groups, and the Sleepy-Alert group had higher heart rate and increased low/high spectral heart rate power compared to the Sleepy-Sleepy group at some points. CONCLUSIONS: It was concluded that normal adults with short MSLT latencies differ from those with longer latencies on both cardiac and performance variables. Also, those individuals with short latencies can be divided into subgroups claiming subjective sleepiness or denying sleepiness. Those denying sleepiness have improved vigilance performance and greater heart rate and low/high spectral heart rate power compared to those with subjective sleepiness. Both the MSLT group differences and the subjective group differences imply that ability to maintain wakefulness and performance in sedentary situations may be related to innate ability to maintain physiologic arousal.     

MOLECULAR BIOLOGY OF AUTOSOMAL DOMINANT POLYCYSTIC KIDNEY DISEASE

Among the prevalent human genetic disorders, human autosomal dominant polycystic kidney disease is certainly one of the most challenging, both from a clinical and a fundamental perspective. In the recent years, important progress opened novel research avenues to elucidate the genetic basis, the cellular pathophysiologic mechanisms and the molecular function of genes and proteins involved in autosomal dominant polycystic kidney disease.     

Expanded polytetrafluoroethylene membranes to wrap surfaces of circulatory support devices in patients undergoing bridge to heart transplantation.

OBJECTIVE: Because of a lack of donor hearts, an increasing number of patients with heart failure must now undergo bridge to cardiac transplantation with a mechanical circulatory support device. Moreover, support periods have become longer. As a result, pericardial adhesions may develop while the support device is implanted, increasing the risk of injury at resternotomy and bleeding after transplantation. Use of expanded polytetrafluoroethylene (ePTFE) pericardial substitutes (membranes) may prevent such adhesions. PATIENTS AND METHODS: From January 1997 to December 1999, ePTFE membranes were used in 23 patients to wrap portions of an implanted left ventricular assist device (LVAD) or total artificial heart (TAH). Any complications during mechanical support or at cardiac transplantation were recorded. Six ePTFE membranes removed at transplantation were studied histologically. RESULTS AND CONCLUSIONS: At resternotomy for transplantation, the plane of dissection between tissues, ePTFE membranes, and surfaces of the mechanical support device were easily discerned. No adhesions were observed between tissues and membranes. There were no injuries during resternotomy and no patient had to undergo reoperation because of bleeding. One patient given a TAH had an infection during circulatory support that was controlled by antibiotic therapy. In another patient, clots developed between the device and an ePTFE membrane; these were removed successfully. Histologic studies of removed ePTFE membranes showed no infiltration of the membranes interstices by collagen or cellular components. Use of ePTFE membranes in patients undergoing bridge to transplantation with either an LVAD or a TAH limited adhesions between tissues and device surfaces without increasing the risk of infection.