Inhibition of RIP1 improves immune reconstitution and reduces GVHD mortality while preserving graft-versus-leukemia effects

Graft-versus-host disease (GVHD) remains the major cause of morbidity and nonrelapse mortality (NRM) after hematopoietic cell transplantation (HCT). Inflammatory cytokines mediate damage to key GVHD targets such as intestinal stem cells (ISCs) and also activate receptor interacting protein kinase 1 (RIP1; RIPK1), a critical regulator of apoptosis and necroptosis. We therefore investigated the role of RIP1 in acute GVHD using samples from HCT patients, modeling GVHD damage in vitro with both human and mouse gastrointestinal (GI) organoids, and blocking RIP1 activation in vivo using several well-characterized mouse HCT models. Increased phospho-RIP1 expression in GI biopsies from patients with acute GVHD correlated with tissue damage and predicted NRM. Both the genetic inactivation of RIP1 and the RIP1 inhibitor GNE684 prevented GVHD-induced apoptosis of ISCs in vivo and in vitro. Daily administration of GNE684 for 14 days reduced inflammatory infiltrates in three GVHD target organs (intestine, liver, and spleen) in mice. Unexpectedly, GNE684 administration also reversed the marked loss of regulatory T cells in the intestines and liver during GVHD and reduced splenic T cell exhaustion, thus improving immune reconstitution. Pharmacological and genetic inhibition of RIP1 improved long-term survival without compromising the graft-versus-leukemia (GVL) effect in lymphocytic and myeloid leukemia mouse models. Thus, RIP1inhibition may represent a nonimmunosuppressive treatment for GVHD.

Lactate dehydrogenase contribution to symptom persistence in long COVID: A pooled analysis

There's critical need for risk predictors in long COVID. This meta-analysis evaluates the evidence for an association between plasma lactate dehydrogenase (LDH) and long COVID and explores the contribution of LDH to symptoms persistent across the distinct post-acute sequelae of COVID-19 (PASC) domains. PubMed, EMBASE, Web of Science, and Google Scholar were searched for articles published up to 20 March 2023 for studies that reported data on LDH levels in COVID-19 survivors with and without PASC. Random-effect meta-analysis was employed to estimate the standardized mean difference (SMD) with corresponding 95% confidence interval of each outcome. There were a total of 8289 study participants (3338 PASC vs. 4951 controls) from 46 studies. Our meta-analysis compared to the controls showed a significant association between LDH elevation and Resp-PASC [SMD = 1.07, 95%CI = 0.72, 1.41, p = 0.01] but not Cardio-PASC [SMD = 1.79, 95%CI = -0.02, 3.61, p = 0.05], Neuro-PASC [SMD = 0.19, 95%CI = -0.24, 0.61, p = 0.40], and Gastrointestinal-PASC [SMD = 0.45, 95%CI = -1.08, 1.98, p = 0.56]. This meta-analysis suggests elevated LDH can be used for predicting Resp-PASC, but not Cardio-PASC, Neuro-PASC or gastrointestinal-PASC. Thus, elevated plasma LDH following COVID infection may be considered as a disease biomarker.

Determinants of poor clinical outcome in patients with influenza pneumonia: a systematic review and meta-analysis

BACKGROUND

The clinical burden of influenza is increasing globally. Aging, immunosuppression, and underlying respiratory illness are determinants of poor clinical outcomes, including greater mortality. Bacterial infections seem to be the main reason. Updated information on the role of bacterial infection as the cause of complications would be of value in improving the prognosis of influenza patients.

METHODS

A systematic review and meta-analysis were performed by using the Pubmed repository using keywords like: Influenza, H1N1, Streptococcus pneumoniae, bacterial coinfection, secondary coinfection, bacterial complications in pneumonia, and seasonal influenza. Only articles written in English were only included on publications from 2010 to 2020. Analyses were conducted following PRISMA guidelines. The results were independently validated using a TrinetX database cohort of roughly 4 million patients.

RESULTS

We included 136 studies that contained data from 48,259 influenza-hospitalized patients of any age. Bacterial infections were diagnosed in 5,391 (11.2%). Streptococcus pneumoniae (30.7%) and Staphylococcus aureus (30.4%) were the most frequent microorganisms, followed by Haemophilus influenzae (7.1%) and Pseudomonas aeruginosa (5.9%). The random effects model of the meta-analysis indicated that bacterial infections posed a 3.4-fold increased risk of death compared to influenza infection alone. Unexpectedly, asthma was protective (odds ratio 0.8).

CONCLUSION

Bacterial infections diagnosed in 11.2% of influenza patients increase 3.4-fold the mortality risk. S. pneumoniae, S. aureus, H. influenzae and P. aeruginosa account for nearly 75% of cases. Earlier diagnosis and use of antibiotics should improve outcomes in this population.

Hemodialysis-Associated Immune Dysregulation in SARS-CoV-2-Infected End-Stage Renal Disease Patients

Patients on hemodialysis show dysregulated immunity, basal hyperinflammation and a marked vulnerability to COVID-19. We evaluated the immune profile in COVID-19 hemodialysis patients and the changes associated with clinical deterioration after the hemodialysis session. Recruited patients included eight hemodialysis subjects with active, PCR-confirmed SARS-CoV-2 infection, five uninfected hemodialysis patients and five healthy controls. In SARS-CoV-2-infected hemodialysis patients TNF-α, IL-6 and IL-8 were particularly increased. Lymphopenia was mostly due to reduction in CD4+ T, B and central memory CD8+ T cells. There was a predominance of classical and intermediate monocytes with reduced HLA-DR expression and enhanced production of pro-inflammatory molecules. Immune parameters were analysed pre- and post-hemodialysis in three patients with COVID-19 symptoms worsening after the hemodialysis session. There was a higher than 2.5-fold increase in GM-CSF, IFN-γ, IL-1β, IL-2, IL-6, IL-17A and IL-21 in serum, and augmentation of monocytes-derived TNF-α, IL-1β and IL-8 and CXCL10 (p < 0.05). In conclusion, COVID-19 in hemodialysis patients associates with alteration of lymphocyte subsets, increasing of pro-inflammatory cytokines and monocyte activation. The observed worsening during the hemodialysis session in some patients was accompanied by augmentation of particular inflammatory cytokines, which might suggest biomarkers and therapeutic targets to prevent or mitigate the hemodialysis-related deterioration during SARS-CoV-2 infection.

Cellular and humoral immune responses and breakthrough infections after three SARS-CoV-2 mRNA vaccine doses

Background

SARS-CoV-2 vaccination has proven the most effective measure to control the COVID-19 pandemic. Booster doses are being administered with limited knowledge on their need and effect on immunity.

Objective

To determine the duration of specific T cells, antibodies and neutralization after 2-dose vaccination, to assess the effect of a third dose on adaptive immunity and to explore correlates of protection against breakthrough infection.

Methods

12-month longitudinal assessment of SARS-CoV-2-specific T cells, IgG and neutralizing antibodies triggered by 2 BNT162b2 doses followed by a third mRNA-1273 dose in a cohort of 77 healthcare workers: 17 with SARS-CoV-2 infection prior to vaccination (recovered) and 60 naïve.

Results

Peak levels of cellular and humoral response were achieved 2 weeks after the second dose. Antibodies declined thereafter while T cells reached a plateau 3 months after vaccination. The decline in neutralization was specially marked in naïve individuals and it was this group who benefited most from the third dose, which resulted in a 20.9-fold increase in neutralization. Overall, recovered individuals maintained higher levels of T cells, antibodies and neutralization 1 to 6 months post-vaccination than naïve. Seventeen asymptomatic or mild SARS-CoV-2 breakthrough infections were reported during follow-up, only in naïve individuals. This viral exposure boosted adaptive immunity. High peak levels of T cells and neutralizing antibodies 15 days post-vaccination associated with protection from breakthrough infections.

Conclusion

Booster vaccination in naïve individuals and the inclusion of viral antigens other than spike in future vaccine formulations could be useful strategies to prevent SARS-CoV-2 breakthrough infections.

Development of Potent Cellular and Humoral Immune Responses in Long-Term Hemodialysis Patients After 1273-mRNA SARS-CoV-2 Vaccination

Long-term hemodialysis (HD) patients are considered vulnerable and at high-risk of developing severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) infection due to their immunocompromised condition. Since COVID-19 associated mortality rates are higher in HD patients, vaccination is critical to protect them. The response towards vaccination against COVID-19 in HD patients is still uncertain and, in particular the cellular immune response is not fully understood. We monitored the humoral and cellular immune responses by analysis of the serological responses and Spike-specific cellular immunity in COVID-19-recovered and naïve HD patients in a longitudinal study shortly after vaccination to determine the protective effects of 1273-mRNA vaccination against SARS-CoV-2 in these high-risk patients. In naïve HD patients, the cellular immune response measured by IL-2 and IFN-ɣ secretion needed a second vaccine dose to significantly increase, with a similar pattern for the humoral response. In contrast, COVID-19 recovered HD patients developed a potent and rapid cellular and humoral immune response after the first vaccine dose. Interestingly, when comparing COVID-19 recovered healthy volunteers (HV), previously vaccinated with BNT162b2 vaccine to HD patients vaccinated with 1273-mRNA, these exhibited a more robust immune response that is maintained longitudinally. Our results indicate that HD patients develop strong cellular and humoral immune responses to 1273-mRNA vaccination and argue in favor of personalized immune monitoring studies in HD patients, especially if COVID-19 pre-exposed, to adapt COVID-19 vaccination protocols for this immunocompromised population.

Circulatory follicular helper T lymphocytes associate with lower incidence of CMV infection in kidney transplant recipients

Primary infection and/or reactivation of cytomegalovirus (CMV) in kidney transplant recipients (KTR) favor rejection and mortality. T follicular helper cells (TFH) could contribute to protection against CMV. Circulatory TFH (cTFH) were studied pretransplant and early posttransplant in 90 CMV seropositive KTR not receiving antithymocyte globulin or antiviral prophylaxis, followed-up for 1 year. Patients who presented CMV infection had significantly lower cTFH and activated cTFH pretransplant and early posttransplant. Pretransplant activated cTFH were also lower within patients who developed CMV disease. Pre- and 14 days posttransplant activated cTFH were an independent protective factor for CMV infection (HR 0.41, p = .01; and 0.52, p = .02, respectively). KTR with low cTFH 7 days posttransplant (<11.9%) had lower CMV infection-free survival than patients with high cTFH (28.2% vs. 67.6%, p = .002). cTFH were associated with CMV-specific neutralizing antibodies (Nabs). In addition, IL-21 increased interferon-γ secretion by CMV-specific CD8⁺ T cells in healthy controls. Thus, we show an association between cTFH and lower incidence of CMV infection, probably through their cooperation in CMV-specific Nab production and IL-21-mediated enhancement of CD8⁺ T cell activity. Moreover, monitoring cTFH pre- and early posttransplant could improve CMV risk stratification and help select KTR catalogued at low/intermediate risk who could benefit from prophylaxis.

Longitudinal dynamics of SARS-CoV-2-specific cellular and humoral immunity after natural infection or BNT162b2 vaccination

The timing of the development of specific adaptive immunity after natural SARS-CoV-2 infection, and its relevance in clinical outcome, has not been characterized in depth. Description of the long-term maintenance of both cellular and humoral responses elicited by real-world anti-SARS-CoV-2 vaccination is still scarce. Here we aimed to understand the development of optimal protective responses after SARS-CoV-2 infection and vaccination. We performed an early, longitudinal study of S1-, M- and N-specific IFN-γ and IL-2 T cell immunity and anti-S total and neutralizing antibodies in 88 mild, moderate or severe acute COVID-19 patients. Moreover, SARS-CoV-2-specific adaptive immunity was also analysed in 234 COVID-19 recovered subjects, 28 uninfected BNT162b2-vaccinees and 30 uninfected healthy controls. Upon natural infection, cellular and humoral responses were early and coordinated in mild patients, while weak and inconsistent in severe patients. The S1-specific cellular response measured at hospital arrival was an independent predictive factor against severity. In COVID-19 recovered patients, four to seven months post-infection, cellular immunity was maintained but antibodies and neutralization capacity declined. Finally, a robust Th1-driven immune response was developed in uninfected BNT162b2-vaccinees. Three months post-vaccination, the cellular response was comparable, while the humoral response was consistently stronger, to that measured in COVID-19 recovered patients. Thus, measurement of both humoral and cellular responses provides information on prognosis and protection from infection, which may add value for individual and public health recommendations.

Alterations in Circulating Monocytes Predict COVID-19 Severity and Include Chromatin Modifications Still Detectable Six Months after Recovery

An early analysis of circulating monocytes may be critical for predicting COVID-19 course and its sequelae. In 131 untreated, acute COVID-19 patients at emergency room arrival, monocytes showed decreased surface molecule expression, including low HLA-DR, in association with an inflammatory cytokine status and limited anti-SARS-CoV-2-specific T cell response. Most of these alterations had normalized in post-COVID-19 patients 6 months after discharge. Acute COVID-19 monocytes transcriptome showed upregulation of anti-inflammatory tissue repair genes such as BCL6, AREG and IL-10 and increased accessibility of chromatin. Some of these transcriptomic and epigenetic features still remained in post-COVID-19 monocytes. Importantly, a poorer expression of surface molecules and low IRF1 gene transcription in circulating monocytes at admission defined a COVID-19 patient group with impaired SARS-CoV-2-specific T cell response and increased risk of requiring intensive care or dying. An early analysis of monocytes may be useful for COVID-19 patient stratification and for designing innate immunity-focused therapies.

MO912INMUNE STATUS ON HAEMODIALYSIS PATTIENTS AFFECTED WITH COVID19 INFECTION

Background and Aims

End-stage renal disease patients on haemodialysis (HD) seem more likely to develop severe COVID19 disease. Over the course of COVID disease, we observed a poor tolerance to HD sessions with a marked tendency of clinical deterioration over them.

The objective is to evaluate changes on immunological system over HD session on patients affected with COVID19 compared with patients without COVID19.

Method

Fourteen HD patients were studied including 9 confirmed COVID19 infection and 5 healthy controls. Predialysis and postdialysis blood samples were compared to study alterations on immune status. We identified cytoKines by Luminex (CCL2, CXCL10, IL1Ra, IL10, IL12p70, TNFα, IL17Ra, IL6, IL7) and adaptive lymphocyte subsets (CD4/CD8 naïve, CD4/CD8 MC, CD4/CD8 MP, CD19, CD56). Monocyte subsets (CD14+CD16-, CD14+CD16+, CD14-CD16+) were detected from peripheral blood mononuclear cells (PBMC), as well as immune activation (CD11b, HLA-DR, CD86) and migration factors (CCR2, CCR5). The supernatant of isolated CD14+ cells after 4-hour stimulation with LPS where analysed by Luminex to measure cytokines (CCL2, CXCL10, GM-CSF, IL10, IL12p70, IL17Ra, IL6, IL7, TNFα).

Results

Patients with COVID19 presented predialysis: (1) higher plasmatic levels of IL12p70, TNFα e IL7, (2) lymphopenia and neutrophilia, (3) higher percentage of intermediate monocytes and lower of non-classical, (4) lower membrane expression of CCR2, HLA-DR y CD86 over Cd14+ cells, and (5) higher production of CCL2, GM-CSF, IL10, IL12p70 y IL17Ra by LPS stimulated monocytes compared with patients without COVID19. When analysed the fold-change between pre and postdialysis values, patients with COVID19 infection present a: (a) higher plasmatic levels of IL6, IL1Ra, CCL2 e CXCL10, (b) reductions of total lymphocites, (c) higher membrane expression of CCR2, CD33 y CD86 on CD14+ cells, and (d) higher production of TNFα, GM-CSF, IL10, IL17, IL6 e IL7 by LPS stimulated monocytes compared with patients without COVID19. No differences on lymphocite subset were found.

Conclusion

The clinical deterioration on COVID19 infected patients over HD session could be related with monocyte activation and pro-inflammatory cytokines secretion.

IL-6-based mortality risk model for hospitalized patients with COVID-19

Background

Coronavirus disease 2019 (COVID-19) has rapidly become a global pandemic. Because the severity of the disease is highly variable, predictive models to stratify patients according to their mortality risk are needed.

Objective

Our aim was to develop a model able to predict the risk of fatal outcome in patients with COVID-19 that could be used easily at the time of patients' arrival at the hospital.

Methods

We constructed a prospective cohort with 611 adult patients in whom COVID-19 was diagnosed between March 10 and April 12, 2020, in a tertiary hospital in Madrid, Spain. The analysis included 501 patients who had been discharged or had died by April 20, 2020. The capacity of several biomarkers, measured at the beginning of hospitalization, to predict mortality was assessed individually. Those biomarkers that independently contributed to improve mortality prediction were included in a multivariable risk model.

Results

High IL-6 level, C-reactive protein level, lactate dehydrogenase (LDH) level, ferritin level, d-dimer level, neutrophil count, and neutrophil-to-lymphocyte ratio were all predictive of mortality (area under the curve >0.70), as were low albumin level, lymphocyte count, monocyte count, and ratio of peripheral blood oxygen saturation to fraction of inspired oxygen (SpO₂/FiO₂). A multivariable mortality risk model including the SpO₂/FiO₂ ratio, neutrophil-to-lymphocyte ratio, LDH level, IL-6 level, and age was developed and showed high accuracy for the prediction of fatal outcome (area under the curve 0.94). The optimal cutoff reliably classified patients (including patients with no initial respiratory distress) as survivors and nonsurvivors with 0.88 sensitivity and 0.89 specificity.

Conclusion

This mortality risk model allows early risk stratification of hospitalized patients with COVID-19 before the appearance of obvious signs of clinical deterioration, and it can be used as a tool to guide clinical decision making.

Tolerogenic Role of Myeloid Suppressor Cells in Organ Transplantation

Myeloid-derived suppressor cells (MDSC) are a heterogeneous population of immature cells of myeloid origin with a specific immune inhibitory function that negatively regulates the adaptive immune response. Since MDSC participate in the promotion of tolerance in the context of organ transplantation, therapeutic strategies that regulate the induction and development of MDSC have been the center of scientist attention. Here we review literature regarding induction of MDSC with demonstrated suppressive function among different types of allografts and their mechanism of action. While manipulation of MDSC represents a potential therapeutic approach for the promotion of donor specific tolerance in solid organ transplantation, further characterization of their specific phenotype, which distinguishes MDSC from non-suppressive myeloid cells, and detailed evaluation of the inhibitory mechanism that determines their suppressive function, is necessary for the realistic application of MDSC as biomarkers in health and disease and their potential use as immune cell therapy in organ transplantation.

Longitudinal profile of circulating T follicular helper lymphocytes parallels anti-HLA sensitization in renal transplant recipients

Antibody-mediated rejection is responsible for 30%-50% of renal graft failures. Differentiation of B cells into antibody-producing plasmablasts depends on the collaboration of follicular helper T cells (Tfh). We analyzed circulating Tfh (cTfh) in kidney recipients and studied cTfh relationship with anti-HLA antibody production and graft outcome. cTfh were longitudinally analyzed in a prospective cohort of patients (n = 206), pre- and posttransplantation. Clinical data, HLA sensitization, and cTfh function were recorded. Both pretransplant and 6-month posttransplant cTfh were able to derive IgG-producing plasmablasts. Pretransplant cTfh was decreased in patients, especially in those who received dialysis. However, these cells were increased in patients with previous allograft or transfusions and in HLA-sensitized recipients. After transplantation cTfh expanded, significantly more in patients who developed de novo anti-HLA antibodies than in patients who remained unsensitized. Augmented pretransplant cTfh positively correlated with higher intensity of pretransplant anti-HLA class I and with de novo anti-HLA class I and anti-HLA class II antibodies. Consistently, pretransplantation cTfh were higher in patients who experienced acute rejection (HR = 1.14 [1.04-1.25]). Thus, we show a role for Tfh in anti-HLA sensitization and rejection. Multicenter studies with additional patient cohorts are needed to validate these results. Immunosuppressive drugs targeting Tfh could be useful to improve outcomes.

Isolated De Novo Antiendothelial Cell Antibodies and Kidney Transplant Rejection

BACKGROUND

Studies analyzing the role of antiendothelial cell antibodies (AECAs) in large series of kidney transplant recipients are scarce, and HLA, MHC (major histocompatibility complex) class I-related chain A (MICA), and angiotensin II type 1 receptor have not been formally excluded as targets.

STUDY DESIGN

Retrospective study of a cohort of kidney transplant recipients.

SETTING & PARTICIPANTS

324 kidney transplant recipients who were negative for anti-HLA, anti-MICA, and anti-angiotensin II type 1 receptor antibodies were tested for AECAs in pre- and posttransplantation serum samples.

PREDICTORS

AECA-positive (preformed [pre⁺/post⁺] vs de novo [pre^-/post⁺]) versus AECA-negative (pre^-/post^-) before or after transplantation.

OUTCOMES

Patient mortality, transplant loss, and acute rejection events.

RESULTS

66 (20%) patients were AECA positive (39 [12%] preformed, 27 [8%] de novo) and 258 (80%) were AECA negative. During a follow-up of 10 years, 7 (18%) AECA pre⁺/post⁺ patients had rejections compared with 14 (52%) AECA pre^-/post⁺ and 57 (22%) AECA pre^-/post^- recipients (OR, 3.80; P=0.001). AECA pre^-/post⁺ status emerged as an independent risk factor for transplant rejection compared to the AECA pre^-/post^- group (OR, 5.17; P<0.001). However, AECA pre⁺/post⁺ and AECA pre^-/post⁺ patients did not show higher risk for either patient death (ORs of 1.49 [P=0.7] and 1.06 [P=0.9], respectively) or transplant loss (ORs of 1.22 and 0.86, respectively; P for both = 0.8) compared to the AECA pre^-/post^- population.

LIMITATIONS

Retrospective study. Posttransplantation sera were collected before or after rejection, entailing a nearly cross-sectional relationship between the exposure and outcome. Lack of identification of precise antigens for AECAs.

CONCLUSIONS

De novo AECAs may be associated with rejection. These antibodies might serve as biomarkers of endothelium damage in kidney transplant recipients.