Differences in CD80 and CD86 transendocytosis reveal CD86 as a key target for CTLA-4 immune regulation.

CD28 and CTLA-4 (CD152) play essential roles in regulating T cell immunity, balancing the activation and inhibition of T cell responses, respectively. Although both receptors share the same ligands, CD80 and CD86, the specific requirement for two distinct ligands remains obscure. In the present study, we demonstrate that, although CTLA-4 targets both CD80 and CD86 for destruction via transendocytosis, this process results in separate fates for CTLA-4 itself. In the presence of CD80, CTLA-4 remained ligand bound, and was ubiquitylated and trafficked via late endosomes and lysosomes. In contrast, in the presence of CD86, CTLA-4 detached in a pH-dependent manner and recycled back to the cell surface to permit further transendocytosis. Furthermore, we identified clinically relevant mutations that cause autoimmune disease, which selectively disrupted CD86 transendocytosis, by affecting either CTLA-4 recycling or CD86 binding. These observations provide a rationale for two distinct ligands and show that defects in CTLA-4-mediated transendocytosis of CD86 are associated with autoimmunity.

Allogeneic stem cell transplantation compared to conservative management in adults with inborn errors of immunity.

Allogeneic hematopoietic stem cell transplantation (alloSCT) is curative for severe inborn errors of immunity (IEIs), with recent data suggesting alloSCT in adulthood is safe and effective in selected patients. However, questions remain regarding the indications for and optimal timing of transplant. We retrospectively compared outcomes of transplanted vs matched nontransplanted adults with severe IEIs. Seventy-nine patients (aged ≥ 15 years) underwent alloSCT between 2008 and 2018 for IEIs such as chronic granulomatous disease (n = 20) and various combined immune deficiencies (n = 59). A cohort of nontransplanted patients from the French Centre de Référence Déficits Immunitaires Héréditaires registry was identified blindly for case-control analysis, with ≤3 matched controls per index patient, without replacement. The nontransplanted patients were matched for birth decade, age at last review greater than index patient age at alloSCT, chronic granulomatous disease or combined immune deficiencies, and autoimmune/lymphoproliferative complications. A total of 281 patients were included (79 transplanted, 202 nontransplanted). Median age at transplant was 21 years. Transplant indications were mainly lymphoproliferative disease (n = 23) or colitis (n = 15). Median follow-up was 4.8 years (interquartile range, 2.5-7.2). One-year transplant-related mortality rate was 13%. Estimated disease-free survival at 5 years was higher in transplanted patients (58% vs 33%; P = .007). Nontransplanted patients had an ongoing risk of severe events, with an increased mean cumulative number of recurrent events compared with transplanted patients. Sensitivity analyses removing patients with common variable immune deficiency and their matched transplanted patients confirm these results. AlloSCT prevents progressive morbidity associated with IEIs in adults, which may outweigh the negative impact of transplant-related mortality.

Humoral and cellular responses to SARS-CoV-2 in patients with B-cell haematological malignancies improve with successive vaccination.

Patients with haematological malignancies are more likely to have poor responses to vaccination. Here we provide detailed analysis of the humoral and cellular responses to COVID-19 vaccination in 69 patients with B-cell malignancies. Measurement of anti-spike IgG in serum demonstrated a low seroconversion rate with 27.1% and 46.8% of patients seroconverting after the first and second doses of vaccine, respectively. In vitro pseudoneutralisation assays demonstrated a poor neutralising response, with 12.5% and 29.5% of patients producing a measurable neutralising titre after the first and second doses, respectively. A third dose increased seropositivity to 54.3% and neutralisation to 51.5%, while a fourth dose further increased both seropositivity and neutralisation to 87.9%. Neutralisation titres post-fourth dose showed a positive correlation with the size of the B-cell population measured by flow cytometry, suggesting an improved response correlating with recovery of the B-cell compartment after B-cell depletion treatments. In contrast, interferon gamma ELISpot analysis showed a largely intact T-cell response, with the percentage of patients producing a measurable response boosted by the second dose to 75.5%. This response was maintained thereafter, with only a small increase following the third and fourth doses, irrespective of the serological response at these timepoints.

Retrospective, Landmark Analysis of Long-term Adult Morbidity Following Allogeneic HSCT for Inborn Errors of Immunity in Infancy and Childhood.

PURPOSE: Allogeneic hematopoietic stem cell transplant (HSCT) remains the treatment of choice for patients with inborn errors of immunity (IEI). There is little published medical outcome data assessing late medical complications following transition to adult care. We sought to document event-free survival (EFS) in transplanted IEI patients reaching adulthood and describe common late-onset medical complications and factors influencing EFS. METHODS: In this landmark analysis, 83 adults surviving 5 years or more following prior HSCT in childhood for IEI were recruited. The primary endpoint was event-free survival, defined as time post-first HSCT to graft failure, graft rejection, chronic infection, life-threatening or recurrent infections, malignancy, significant autoimmune disease, moderate to severe GVHD or major organ dysfunction. All events occurring less than 5 years post-HSCT were excluded. RESULTS: EFS was 51% for the whole cohort at a median of 20 years post HSCT. Multivariable analysis identified age at transplant and whole blood chimerism as independent predictors of long-term EFS. Year of HSCT, donor, conditioning intensity and underlying diagnosis had no significant impact on EFS. 59 events occurring beyond 5 years post-HSCT were documented in 37 patients (45% cohort). A total of 25 patients (30% cohort) experienced ongoing significant complications requiring active medical intervention at last follow-up. CONCLUSION: Although most patients achieved excellent, durable immune reconstitution with infrequent transplant-related complications, very late complications are common and associated with mixed chimerism post-HSCT. Early intervention to correct mixed chimerism may improve long-term outcomes and adult health following HSCT for IEI in childhood.

Outcomes of patients with hematologic malignancies and COVID-19: a systematic review and meta-analysis of 3377 patients.

Outcomes for patients with hematologic malignancy infected with COVID-19 have not been aggregated. The objective of this study was to perform a systematic review and meta-analysis to estimate the risk of death and other important outcomes for these patients. We searched PubMed and EMBASE up to 20 August 2020 to identify reports of patients with hematologic malignancy and COVID-19. The primary outcome was a pooled mortality estimate, considering all patients and only hospitalized patients. Secondary outcomes included risk of intensive care unit admission and ventilation in hospitalized patients. Subgroup analyses included mortality stratified by age, treatment status, and malignancy subtype. Pooled prevalence, risk ratios (RRs), and 95% confidence intervals (CIs) were calculated using a random-effects model. Thirty-four adult and 5 pediatric studies (3377 patients) from Asia, Europe, and North America were included (14 of 34 adult studies included only hospitalized patients). Risk of death among adult patients was 34% (95% CI, 28-39; N = 3240) in this sample of predominantly hospitalized patients. Patients aged ≥60 years had a significantly higher risk of death than patients <60 years (RR, 1.82; 95% CI, 1.45-2.27; N = 1169). The risk of death in pediatric patients was 4% (95% CI, 1-9; N = 102). RR of death comparing patients with recent systemic anticancer therapy to no treatment was 1.17 (95% CI, 0.83-1.64; N = 736). Adult patients with hematologic malignancy and COVID-19, especially hospitalized patients, have a high risk of dying. Patients ≥60 years have significantly higher mortality; pediatric patients appear to be relatively spared. Recent cancer treatment does not appear to significantly increase the risk of death.

Gene therapy for primary immunodeficiencies.

Primary immunodeficiencies (PIDs) are a group of rare inherited disorders of the immune system. Many PIDs are devastating and require a definitive therapy to prevent progressive morbidity and premature mortality. Allogeneic haematopoietic stem cell transplantation (alloHSCT) is curative for many PIDs, and while advances have resulted in improved outcomes, the procedure still carries a risk of mortality and morbidity from graft failure or graft-versus-host disease (GvHD). Autologous haematopoietic stem cell gene therapy (HSC GT) has the potential to correct genetic defects across haematopoietic lineages without the complications of an allogeneic approach. HSC GT for PID has been in development for the last two decades and the first licensed HSC-GT product for adenosine deaminase-deficient severe combined immunodeficiency (ADA-SCID) is now available. New gene editing technologies have the potential to circumvent some of the problems associated with viral gene-addition. HSC GT for PID shows great promise, but requires a unique approach for each disease and carries risks, notably insertional mutagenesis from gamma-retroviral gene addition approaches and possible off-target toxicities from gene-editing techniques. In this review, we discuss the development of HSC GT for PID and outline the current state of clinical development before discussing future developments in the field.

Clinical outcomes and risk factors for severe COVID-19 in patients with haematological disorders receiving chemo- or immunotherapy.

Haematology patients receiving chemo- or immunotherapy are considered to be at greater risk of COVID-19-related morbidity and mortality. We aimed to identify risk factors for COVID-19 severity and assess outcomes in patients where COVID-19 complicated the treatment of their haematological disorder. A retrospective cohort study was conducted in 55 patients with haematological disorders and COVID-19, including 52 with malignancy, two with bone marrow failure and one immune-mediated thrombotic thrombocytopenic purpura (TTP). COVID-19 diagnosis coincided with a new diagnosis of a haematological malignancy in four patients. Among patients, 82% were on systemic anti-cancer therapy (SACT) at the time of COVID-19 diagnosis. Of hospitalised patients, 37% (19/51) died while all four outpatients recovered. Risk factors for severe disease or mortality were similar to those in other published cohorts. Raised C-reactive protein at diagnosis predicted an aggressive clinical course. The majority of patients recovered from COVID-19, despite receiving recent SACT. This suggests that SACT, where urgent, should be administered despite intercurrent COVID-19 infection, which should be managed according to standard pathways. Delay or modification of therapy should be considered on an individual basis. Long-term follow-up studies in larger patient cohorts are required to assess the efficacy of treatment strategies employed during the pandemic.

Successful outcome following allogeneic hematopoietic stem cell transplantation in adults with primary immunodeficiency.

The primary immunodeficiencies (PIDs), rare inherited diseases characterized by severe dysfunction of immunity, have been successfully treated by allogeneic hematopoietic stem cell transplantation (Allo-HSCT) in childhood. Controversy exists regarding optimal timing and use of Allo-HSCT in adults, due to lack of experience and previous poor outcomes. Twenty-nine consecutive adult patients, with a mean age at transplant of 24 years (range, 17-50 years), underwent Allo-HSCT. Reduced-intensity conditioning (RIC) included fludarabine (Flu)/melphalan/alemtuzumab (n = 20), Flu/busulfan (Bu)/alemtuzumab (n = 8), and Flu/Bu/antithymocyte globulin (n = 1). Stem cell donors were matched unrelated donors or mismatched unrelated donors (n = 18) and matched related donors (n = 11). Overall survival (OS), event-free survival, transplant-related mortality (TRM), acute and chronic graft-versus-host disease incidence and severity, time to engraftment, lineage-specific chimerism, immune reconstitution, and discontinuation of immunoglobulin replacement therapy were recorded. OS at 3 years for the whole cohort was 85.2%. The rarer PID patients without chronic granulomatous disease (CGD) achieved an OS at 3 years of 88.9% (n = 18), compared with 81.8% for CGD patients (n = 11). TRM was low with only 4 deaths observed at a median follow-up of 3.5 years. There were no cases of early or late rejection. In all surviving patients, either stable mixed chimerism or full donor chimerism were observed. At last follow-up, 87% of the surviving patients had no evidence of persistent or recurrent infections. Allo-HSCT is safe and effective in young adult patients with severe PID and should be considered the treatment of choice where an appropriate donor is available.

Wild hummingbirds rely on landmarks not geometry when learning an array of flowers.

Rats, birds or fish trained to find a reward in one corner of a small enclosure tend to learn the location of the reward using both nearby visual features and the geometric relationships of corners and walls. Because these studies are conducted under laboratory and thereby unnatural conditions, we sought to determine whether wild, free-living rufous hummingbirds (Selasphorus rufus) learning a single reward location within a rectangular array of flowers would similarly employ both nearby visual landmarks and the geometric relationships of the array. Once subjects had learned the location of the reward, we used test probes in which one or two experimental landmarks were moved or removed in order to reveal how the birds remembered the reward location. The hummingbirds showed no evidence that they used the geometry of the rectangular array of flowers to remember the reward. Rather, they used our experimental landmarks, and possibly nearby, natural landmarks, to orient and navigate to the reward. We believe this to be the first test of the use of rectangular geometry by wild animals, and we recommend further studies be conducted in ecologically relevant conditions in order to help determine how and when animals form complex geometric representations of their local environments.

Improving access to gene therapy for rare diseases.

Effective gene therapy approaches have been developed for many rare diseases, including inborn errors of immunity and metabolism, haemoglobinopathies and inherited blindness. Despite successful pre-clinical and clinical results, these gene therapies are not widely available, primarily for non-medical reasons. Lack of commercial interest in therapies for ultra-rare diseases, costs of development and complex manufacturing processes required for advanced therapy medicinal products (ATMPs) are some of the main problems that are restricting access. The complexities and costs of navigating the regulatory environments in different jurisdictions for treatments that affect small numbers of patients is a problem unique to ATMPS for rare and ultra-rare diseases. In this Perspective, we outline some of the challenges and potential solutions that, we hope, will improve access to gene therapy for rare diseases.

Natural killer cell responses during SARS-CoV-2 infection and vaccination in people living with HIV-1.

Natural killer (NK) cell subsets with adaptive properties are emerging as regulators of vaccine-induced T and B cell responses and are specialized towards antibody-dependent functions contributing to SARS-CoV-2 control. Although HIV-1 infection is known to affect the NK cell pool, the additional impact of SARS-CoV-2 infection and/or vaccination on NK cell responses in people living with HIV (PLWH) has remained unexplored. Our data show that SARS-CoV-2 infection skews NK cells towards a more differentiated/adaptive CD57+FcεRIγ- phenotype in PLWH. A similar subset was induced following vaccination in SARS-CoV-2 naïve PLWH in addition to a CD56bright population with cytotoxic potential. Antibody-dependent NK cell function showed robust and durable responses to Spike up to 148 days post-infection, with responses enriched in adaptive NK cells. NK cell responses were further boosted by the first vaccine dose in SARS-CoV-2 exposed individuals and peaked after the second dose in SARS-CoV-2 naïve PLWH. The presence of adaptive NK cells associated with the magnitude of cellular and humoral responses. These data suggest that features of adaptive NK cells can be effectively engaged to complement and boost vaccine-induced adaptive immunity in potentially more vulnerable groups such as PLWH.

Attenuated humoral responses in HIV after SARS-CoV-2 vaccination linked to B cell defects and altered immune profiles.

We assessed a cohort of people living with human immunodeficiency virus (PLWH) (n = 110) and HIV negative controls (n = 64) after 1, 2 or 3 SARS-CoV-2 vaccine doses. At all timepoints, PLWH had significantly lower neutralizing antibody (nAb) titers than HIV-negative controls. We also observed a delayed development of neutralization in PLWH that was underpinned by a reduced frequency of spike-specific memory B cells (MBCs). Improved neutralization breadth was seen against the Omicron variant (BA.1) after the third vaccine dose in PLWH but lower nAb responses persisted and were associated with global MBC dysfunction. In contrast, SARS-CoV-2 vaccination induced robust T cell responses that cross-recognized variants in PLWH. Strikingly, individuals with low or absent neutralization had detectable functional T cell responses. These PLWH had reduced numbers of circulating T follicular helper cells and an enriched population of CXCR3+CD127+CD8+T cells after two doses of SARS-CoV-2 vaccination.