COVID-19 and plasma cells: Is there long-lived protection?

Infection with SARS-CoV-2, the etiology of the ongoing COVID-19 pandemic, has resulted in over 450 million cases with more than 6 million deaths worldwide, causing global disruptions since early 2020. Memory B cells and durable antibody protection from long-lived plasma cells (LLPC) are the mainstay of most effective vaccines. However, ending the pandemic has been hampered by the lack of long-lived immunity after infection or vaccination. Although immunizations offer protection from severe disease and hospitalization, breakthrough infections still occur, most likely due to new mutant viruses and the overall decline of neutralizing antibodies after 6 months. Here, we review the current knowledge of B cells, from extrafollicular to memory populations, with a focus on distinct plasma cell subsets, such as early-minted blood antibody-secreting cells and the bone marrow LLPC, and how these humoral compartments contribute to protection after SARS-CoV-2 infection and immunization.

Association between travel distance and overall survival among patients with adrenocortical carcinoma.

BACKGROUND AND OBJECTIVES: Regionalization of care is associated with improved perioperative outcomes after adrenalectomy. However, the relationship between travel distance and treatment of adrenocortical carcinoma (ACC) is unknown. We investigated the association between travel distance, treatment, and overall survival (OS) among patients with ACC. METHODS: Patients diagnosed with ACC between 2004 and 2017 were identified with the National Cancer Database. Long distance was defined as the highest quintile of travel (≥42.2 miles). The likelihood of surgical management and adjuvant chemotherapy (AC) were determined. The association between travel distance, treatment, and OS was evaluated. RESULTS: Of 3492 patients with ACC included, 2337 (66.9%) received surgery. Rural residents were more likely to travel long distances for surgery than metropolitan residents (65.8% vs. 15.5%, p < 0.001), and surgery was associated with improved OS (HR 0.43, 95% CI 0.34-0.54). Overall, 807 (23.1%) patients received AC with rates decreasing approximately 1% per 4-mile travel distance increase. Also, long distance travel was associated with worse OS among surgically treated patients (HR 1.21, 95% CI 1.05-1.40). CONCLUSIONS: Surgery was associated with improved overall survival for patients with ACC. However, increased travel distance was associated with lower likelihood to receive adjuvant chemotherapy and decreased overall survival.

Adolescent exposure to a solid high-fat, high-sugar 'cafeteria' diet leads to more pronounced changes in metabolic measures and gut microbiome composition than liquid sugar in female rats.

Adolescence is a dynamic developmental period where unhealthy solid foods and sugar-sweetened beverages are routinely consumed. Regular consumption of solid 'junk' foods rich in fat and refined carbohydrate and sugar-sweetened beverages are independently associated with an increased risk of metabolic disease and altered gut microbiome composition. Here we used a validated rat model to determine the effects of a solid 'cafeteria' diet high in fat and sugar (Caf) and 10% liquid sucrose solution (Suc) on food intake, metabolic measures and gut microbiome composition. Sixty adolescent female Sprague-Dawley rats were fed standard chow with or without continuous access to Caf diet and/or Suc for 13 weeks (n = 15). Exposure to cafeteria diet and liquid sucrose each increased body weight gain and adiposity, with no synergistic effects. Gut microbiome alpha and beta diversity parameters were more strongly affected by exposure to Caf diet than access to liquid Suc. Nonetheless, providing liquid sucrose to rats fed chow altered gut microbiome beta diversity and significantly enriched the abundance of five taxa from order Clostridiales. By contrast, in the two groups fed Caf, Suc did not alter beta diversity, with few differentially abundant taxa between Caf and Caf + Suc groups. In sum, liquid sucrose and solid cafeteria diet exerted largely independent effects on metabolic and gut microbiome measures. Interventions targeting either solid junk foods or sugary beverages are likely to reduce diet-related disease burden.

Telesimulation to Improve Critical Decision-Making in Prehospital Airway Management: A Feasibility Study.

OBJECTIVES: Telesimulation, in which learners and evaluators use technology to connect remotely to simulation-based learning activities, is effective for skills and decision-making review. Historical models in which learners are colocated with the simulation equipment have inherent issues, especially for emergency medical services (EMS) providers. This feasibility study placed the evaluators in the simulation center, whereas the learners were at a distance steering the scenario evolution through telehealth technologies. METHODS: Volunteer EMS providers across South Carolina with varying levels of training and experience completed difficult airway management scenarios focused on clinical decision making. The program consisted of pre- and postexperience examinations, a lecture, and increasingly complicated simulations using high-fidelity mannequins that were facilitated by local trainers under the direction of remote trainees. Audio and video content, including vital signs and cardiac monitoring, were live streamed. Participants worked in two-person teams with lead providers on each scenario clinically assessing and managing cases of anaphylaxis. Data were collected from the simulations using Laerdal software, as well as examination and survey results. RESULTS: A total of 24 participants completed all of the elements of the training. Trends toward improvement in times to bag-mask ventilation and initial epinephrine administration were noted. Average cognitive test scores increased by 9.6%, and learners reported improved comfort with simulation (75%, P ≥ 0.0001) and videoconferencing (83%, P ≥ 0.0001). They also reported high degrees of comfort with intubation (73.3%) following the training. CONCLUSIONS: This method of telesimulation appears to be a viable addition to continuing EMS education and may address access issues for some providers.

Immediate Reactions After the First Dose of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Messenger RNA Vaccines Do Not Preclude Second-Dose Administration.

Addressing coronavirus disease 2019 (COVID-19) vaccine hesitancy and minimizing potential vaccine contraindications are critical to combatting the pandemic. We describe a practical approach to immediate adverse events after the first dose of messenger RNA vaccines for severe acute respiratory syndrome coronavirus 2, focusing on diagnosis and management of allergic reactions.

Murine cytomegalovirus dissemination but not reactivation in donor-positive/recipient-negative allogeneic kidney transplantation can be effectively prevented by transplant immune tolerance.

Cytomegalovirus (CMV) reactivation from latently infected donor organs post-transplantation and its dissemination cause significant comorbidities in transplant recipients. Transplant-induced inflammation combined with chronic immunosuppression has been thought to provoke CMV reactivation and dissemination, although sequential events in this process have not been studied. Here, we investigated this process in a high-risk donor CMV-positive to recipient CMV-negative allogeneic murine kidney transplantation model. Recipients were either treated with indefinite immunosuppression or tolerized in a donor-specific manner. Untreated recipients served as controls. Kidney allografts from both immunosuppressed and tolerized recipients showed minimal alloimmunity-mediated graft inflammation and normal function for up to day 60 post-transplantation. However, despite the absence of such inflammation in the immunosuppressed and tolerized groups, CMV reactivation in the donor positive kidney allograft was readily observed. Interestingly, subsequent CMV replication and dissemination to distant organs only occurred in immunosuppressed recipients in which CMV-specific CD8 T cells were functionally impaired; whereas in tolerized recipients, host anti-viral immunity was well-preserved and CMV dissemination was effectively prevented. Thus, our studies uncoupled CMV reactivation from its dissemination, and underscore the potential role of robust transplantation tolerance in preventing CMV diseases following allogeneic kidney transplantation.

Donor apoptotic cell-based therapy for effective inhibition of donor-specific memory T and B cells to promote long-term allograft survival in allosensitized recipients.

Allosensitization constitutes a major barrier in transplantation. Preexisting donor-reactive memory T and B cells and preformed donor-specific antibodies (DSAs) have all been implicated in accelerated allograft rejection in sensitized recipients. Here, we employ a sensitized murine model of islet transplantation to test strategies that promote long-term immunosuppression-free allograft survival. We demonstrate that donor-specific memory T and B cells can be effectively inhibited by peritransplant infusions of donor apoptotic cells in combination with anti-CD40L and rapamycin, and this treatment leads to significant prolongation of islet allograft survival in allosensitized recipients. We further demonstrate that late graft rejection in recipients treated with this regimen is associated with a breakthrough of B cells and their aggressive graft infiltration. Consequently, additional posttransplant B cell depletion effectively prevents late rejection and promotes permanent acceptance of islet allografts. In contrast, persistent low levels of DSAs do not seem to impair graft outcome in these recipients. We propose that B cells contribute to late rejection as antigen-presenting cells for intragraft memory T cell expansion but not to alloantibody production and that a therapeutic strategy combining donor apoptotic cells, anti-CD40L, and rapamycin effectively inhibits proinflammatory B cells and promotes long-term islet allograft survival in such recipients.

Rejection of xenogeneic porcine islets in humanized mice is characterized by graft-infiltrating Th17 cells and activated B cells.

Xenogeneic porcine islet transplantation is a promising potential therapy for type 1 diabetes (T1D). Understanding human immune responses against porcine islets is crucial for the design of optimal immunomodulatory regimens for effective control of xenogeneic rejection of porcine islets in humans. Humanized mice are a valuable tool for studying human immune responses and therefore present an attractive alternative to human subject research. Here, by using a pig-to-humanized mouse model of xenogeneic islet transplantation, we described the human immune response to transplanted porcine islets, a process characterized by dense islet xenograft infiltration of human CD45+ cells comprising activated human B cells, CD4+ CD44+ IL-17+ Th17 cells, and CD68+ macrophages. In addition, we tested an experimental immunomodulatory regimen in promoting long-term islet xenograft survival, a triple therapy consisting of donor splenocytes treated with ethylcarbodiimide (ECDI-SP), and peri-transplant rituximab and rapamycin. We observed that the triple therapy effectively inhibited graft infiltration of T and B cells as well as macrophages, promoted transitional B cells both in the periphery and in the islet xenografts, and provided a superior islet xenograft protection. Our study therefore indicates an advantage of donor ECDI-SP treatment in controlling human immune cells in promoting long-term islet xenograft survival.

The impact of belatacept on third-party HLA alloantibodies in highly sensitized kidney transplant recipients.

Recent evidence suggests that belatacept reduces the durability of preexisting antibodies to class I and class II human leukocyte antigens (HLAs). In this case series of 163 highly sensitized kidney transplant candidates whose calculated panel-reactive antibody (cPRA) activity was ≥98% to 100%, the impact of belatacept on preexisting HLA antibodies was assessed. Of the 163 candidates, 72 underwent transplantation between December 4, 2014 and April 15, 2017; 60 of these transplanted patients remained on belatacept consecutively for at least 6 months. We observed a decrease in the breadth and/or strength of HLA class I antibodies as assessed by FlowPRA in belatacept-treated patients compared to controls who did not receive belatacept. Specifically, significant HLA antibody reduction was evident for class I (P < .0009). Posttransplant belatacept-treated patients also had a clinically significant reduction in their cPRA compared to controls (P < .01). Collectively, these findings suggest belatacept can reduce HLA class I antibodies in a significant proportion of highly sensitized recipients and could be an option to improve pretransplant compatibility with organ donors.

Infrequently expressed miRNAs in colorectal cancer tissue and tumor molecular phenotype.

This corrects the article DOI: 10.1038/modpathol.2017.38.

PDGFRß-P2A-CreERT2 mice: a genetic tool to target pericytes in angiogenesis.

Pericytes are essential mural cells distinguished by their association with small caliber blood vessels and the presence of a basement membrane shared with endothelial cells. Pericyte interaction with the endothelium plays an important role in angiogenesis; however, very few tools are currently available that allow for the targeting of pericytes in mouse models, limiting our ability to understand their biology. We have generated a novel mouse line expressing tamoxifen-inducible Cre-recombinase under the control of the platelet-derived growth factor receptor ß promoter: PDGFRß-P2A-CreER T2 . We evaluated the expression of the PDGFRß-P2A-CreER T2 line by crossing it with fluorescent reporter lines and analyzed reporter signal in the angiogenic retina and brain at different time points after tamoxifen administration. Reporter lines showed labeling of NG2+, desmin+, PDGFRß+ perivascular cells in the retina and the brain, indicating successful targeting of pericytes; however, signal from reporter lines was also observed in a small subset of glial cells both in the retina and the brain. We also evaluated recombination in tumors and found efficient recombination in perivascular cells associated with tumor vasculature. As a proof of principle, we used our newly generated driver to delete Notch signaling in perivascular cells and observed a loss of smooth muscle cells in retinal arteries, consistent with previously published studies evaluating Notch3 null mice. We conclude that the PDGFRß-P2A-CreER T2 line is a powerful new tool to target pericytes and will aid the field in gaining a deeper understanding of the role of these cells in physiological and pathological settings.

Infrequently expressed miRNAs in colorectal cancer tissue and tumor molecular phenotype.

We have previously shown that commonly expressed miRNAs influenced tumor molecular phenotype in colorectal cancer. We hypothesize that infrequently expressed miRNAs, when showing higher levels of expression, help to define tumor molecular phenotype. In this study, we examine 304 miRNAs expressed in at least 30 individuals, but in <50% of the population and with a mean level of expression above 1.0 relative florescent unit. We examine associations in 1893 individuals who have the tumor molecular phenotype data as well as miRNA expression levels for both carcinoma and normal colorectal tissue. We compare miRNAs uniquely associated with tumor molecular phenotype to the RNAseq data to identify genes associated with these miRNAs. This information is used to further identify unique pathways associated with tumor molecular phenotypes of TP53-mutated, KRAS-mutated, CpG island methylator phenotype and microsatellite instability tumors. Thirty-seven miRNAs were uniquely associated with TP53-mutated tumors; 30 of these miRNAs had higher level of expression in TP53-mutated tumors, while seven had lower levels of expression. Of the 34 miRNAs associated with CpG island methylator phenotype-high tumors, 16 were more likely to have a CpG island methylator phenotype-high tumor and 19 were less likely to be CpG island methylator phenotype-high. For microsatellite instability, 13 of the 22 infrequently expressed miRNAs were significantly less likely to be expressed in microsatellite unstable tumors. KRAS-mutated tumors were not associated with any miRNAs after adjustment for multiple comparisons. Of the dysregulated miRNAs, 17 were more likely to be TP53-mutated tumors while simultaneously being less likely to be CpG island methylator phenotype-high and/or microsatellite instability tumors. Genes regulated by these miRNAs were involved in numerous functions and pathways that influence cancer risk and progression. In summary, some infrequently expressed miRNAs, when expressed at higher levels, appear to have significant biological meaning in terms of tumor molecular phenotype and gene expression profiles.

Predictors and outcomes of delayed plastic biliary stent removal following endoscopic retrograde cholangiopancreatography.

OBJECTIVE: Plastic biliary stents are commonly placed during endoscopic retrograde cholangiopancreatography (ERCP) and should be removed or replaced within 3 months to reduce the risk of stent obstruction. The aim of the study was to identify predictors and outcomes of patients who had delayed plastic biliary stent removal following ERCP. MATERIALS AND METHODS: Consecutive patients who received ERCP with plastic biliary stent placement at Loma Linda University Medical Center (10/2004-6/2013) were identified. Delayed removal was defined as presence of stent >3 months after index ERCP. Multivariable regression analysis to identify baseline characteristics associated with delayed removal was performed. Clinical outcomes of stent obstruction (e.g., cholangitis, hospitalization, intensive care) were also collected for those with delayed removal. RESULTS: Among 374 patients undergoing ERCP with plastic biliary stent, 71 (19%) had delayed stent removal. Patients who had anesthesia assistance (AOR = 3.8, 95%CI 1.2-11.4), non-English primary language (AOR = 3.0, 95%CI 1.5-6.2), and outpatient ERCP (AOR = 2.0, 95%CI 1.1-3.4) had increased while choledocholithiasis (AOR = 0.5, 95%CI 0.3-0.99) had lower odds of delayed stent removal. Among those with delayed removal, 13 (18%) were hospitalized for stent obstruction (5 (7%) had cholangitis, 8 (11%) were hospitalized for more than a week, and 3 (4%) required intensive care). CONCLUSIONS: Almost one-fifth of patients who underwent ERCP with plastic biliary stent placement had delayed removal with nearly one-fifth of these patients requiring hospitalization for stent obstruction. Targeting patients at risk by improving communication and ease of scheduling an ERCP may reduce preventable adverse events associated with delayed biliary stent removal.

Viral shedding and immune responses to respiratory syncytial virus infection in older adults.

BACKGROUND: Comprehensive analyses of host, viral, and immune factors associated with severe respiratory syncytial virus (RSV) infection in adults have not been performed. METHODS: Adults with RSV infection identified in both outpatient and inpatient settings were evaluated. Upper and lower respiratory tract virus load, duration of virus shedding, select mucosal chemokine and cytokine levels, humoral and mucosal immunoglobulin responses, and systemic T-cell responses were measured. RESULTS: A total of 111 RSV-infected adults (61 outpatients and 50 hospitalized patients) were evaluated. Hospitalized subjects shed virus in nasal secretions at higher titers and for longer durations than less ill outpatients, had greater mucosal interleukin 6 (IL-6) levels throughout infection, and had higher macrophage inflammatory protein 1α (MIP-1α) levels early in infection. Persons >64 years old and those with more severe disease had a higher frequency of activated T cells in the blood than younger, less ill subjects at infection. Multivariate analysis found that the presence of underlying medical conditions, female sex, increased mucosal IL-6 level, and longer duration of virus shedding were associated with severe disease. Older age and increased nasal MIP-1α levels were of borderline statistical significance. CONCLUSIONS: Multiple factors, but not older age, are independently associated with severe RSV infection in adults. The presence of underlying medical conditions had the greatest influence on disease severity.

Hepatic Encephalopathy-A Guide to Laboratory Testing.

Hepatic encephalopathy (HE) remains both a clinical diagnosis and one of exclusion. Laboratory testing is largely focused on identifying precipitating factors. Ammonia levels in the blood can be helpful for the diagnosis of HE but are not required for confirmation. More recent literature is lending support to the prognostic capabilities of ammonia in cirrhosis, both in predicting future HE events and in determining outcomes in hospitalized patients. Accurate ammonia testing requires strict protocols to avoid common pitfalls in the measurement of this labile analyte. Future studies investigating the utility of other laboratory testing to diagnose, stage, or predict HE are encouraged.

The Majority of SARS-CoV-2 Plasma Cells are Excluded from the Bone Marrow Long-Lived Compartment 33 Months after mRNA Vaccination.

The goal of any vaccine is to induce long-lived plasma cells (LLPC) to provide life-long protection. Natural infection by influenza, measles, or mumps viruses generates bone marrow (BM) LLPC similar to tetanus vaccination which affords safeguards for decades. Although the SARS-CoV-2 mRNA vaccines protect from severe disease, the serologic half-life is short-lived even though SARS-CoV-2-specific plasma cells can be found in the BM. To better understand this paradox, we enrolled 19 healthy adults at 1.5-33 months after SARS-CoV-2 mRNA vaccine and measured influenza-, tetanus-, or SARS-CoV-2-specific antibody secreting cells (ASC) in LLPC (CD19-) and non-LLPC (CD19+) subsets within the BM. All individuals had IgG ASC specific for influenza, tetanus, and SARS-CoV-2 in at least one BM ASC compartment. However, only influenza- and tetanus-specific ASC were readily detected in the LLPC whereas SARS-CoV-2 specificities were mostly excluded. The ratios of non-LLPC:LLPC for influenza, tetanus, and SARS-CoV-2 were 0.61, 0.44, and 29.07, respectively. Even in five patients with known PCR-proven history of infection and vaccination, SARS-CoV-2-specific ASC were mostly excluded from the LLPC. These specificities were further validated by using multiplex bead binding assays of secreted antibodies in the supernatants of cultured ASC. Similarly, the IgG ratios of non-LLPC:LLPC for influenza, tetanus, and SARS-CoV-2 were 0.66, 0.44, and 23.26, respectively. In all, our studies demonstrate that rapid waning of serum antibodies is accounted for by the inability of mRNA vaccines to induce BM LLPC.