Preservation of memory B cell homeostasis in an individual producing broadly neutralising antibodies against HIV-1

Immunological determinants favouring emergence of broadly neutralising antibodies are crucial to the development of HIV-1 vaccination strategies. Here, we combined RNAseq and B cell cloning approaches to isolate a broadly neutralising antibody (bnAb) ELC07 from an individual living with untreated HIV-1. Using single particle cryogenic electron microscopy (cryo-EM), we show that the antibody recognises a conformational epitope at the gp120-gp41 interface. ELC07 binds the closed state of the viral glycoprotein causing considerable perturbations to the gp41 trimer core structure. Phenotypic analysis of memory B cell subsets from the ELC07 bnAb donor revealed a lack of expected HIV-1-associated dysfunction, specifically no increase in CD21-/CD27- cells was observed whilst the resting memory (CD21+/CD27+) population appeared preserved despite uncontrolled HIV-1 viraemia. Moreover, single cell transcriptomes of memory B cells from this bnAb donor showed a resting memory phenotype irrespective of the epitope they targeted or their ability to neutralise diverse strains of HIV-1. Strikingly, single memory B cells from the ELC07 bnAb donor were transcriptionally similar to memory B cells from HIV-negative individuals. Our results demonstrate that potent bnAbs can arise without the HIV-1-induced dysregulation of the memory B cell compartment and suggest that sufficient levels of antigenic stimulation with a strategically designed immunogen could be effective in HIV-negative vaccine recipients.

Incidence, Risk Factors, and Effect on Allograft Survival of Glomerulonephritis Post-transplantation in a United Kingdom Population: Cohort Study

Background

Post-transplant glomerulonephritis (PTGN) has been associated with inferior long-term allograft survival, and its incidence varies widely in the literature.

Methods

This is a cohort study of 7,623 patients transplanted between 2005 and 2016 at four major transplant UK centres. The diagnosis of glomerulonephritis (GN) in the allograft was extracted from histology reports aided by the use of text-mining software. The incidence of the four most common GN post-transplantation was calculated, and the risk factors for disease and allograft outcomes were analyzed.

Results

In total, 214 patients (2.8%) presented with PTGN. IgA nephropathy (IgAN), focal segmental glomerulosclerosis (FSGS), membranous nephropathy (MN), and membranoproliferative/mesangiocapillary GN (MPGN/MCGN) were the four most common forms of post-transplant GN. Living donation, HLA DR match, mixed race, and other ethnic minority groups were associated with an increased risk of developing a PTGN. Patients with PTGN showed a similar allograft survival to those without in the first 8 years of post-transplantation, but the results suggest that they do less well after that timepoint. IgAN was associated with the best allograft survival and FSGS with the worst allograft survival.

Conclusions

PTGN has an important impact on long-term allograft survival. Significant challenges can be encountered when attempting to analyze large-scale data involving unstructured or complex data points, and the use of computational analysis can assist.

A pilot study evaluating GSK1070806 inhibition of interleukin-18 in renal transplant delayed graft function

INTRODUCTION

Delayed graft function (DGF) following renal transplantation is a manifestation of acute kidney injury (AKI) leading to poor long-term outcome. Current treatments have limited effectiveness in preventing DGF. Interleukin-18 (IL18), a biomarker of AKI, induces interferon-γ expression and immune activation. GSK1070806, an anti-IL18 monoclonal antibody, neutralizes activated (mature) IL18 released from damaged cells following inflammasome activation. This phase IIa, single-arm trial assessed the effect of a single dose of GSK1070806 on DGF occurrence post donation after circulatory death (DCD) kidney transplantation.

METHODS

The 3 mg/kg intravenous dose was selected based on prior studies and physiologically based pharmacokinetic (PBPK) modeling, indicating the high likelihood of a rapid and high level of IL18 target engagement when administered prior to kidney allograft reperfusion. Utilization of a Bayesian sequential design with a background standard-of-care DGF rate of 50% based on literature, and confirmed via extensive registry data analyses, enabled a statistical efficacy assessment with a minimal sample size. The primary endpoint was DGF frequency, defined as dialysis requirement ≤7 days post transplantation (except for hyperkalemia). Secondary endpoints included safety, pharmacokinetics and pharmacodynamic biomarkers.

RESULTS

GSK1070806 administration was associated with IL18-GSK1070806 complex detection and increased total serum IL18 levels due to IL18 half-life prolongation induced by GSK1070806 binding. Interferon-γ-induced chemokine levels declined or remained unchanged in most patients. Although the study was concluded prior to the Bayesian-defined stopping point, 4/7 enrolled patients (57%) had DGF, exceeding the 50% standard-of-care rate, and an additional two patients, although not reaching the protocol-defined DGF definition, demonstrated poor graft function. Six of seven patients experienced serious adverse events (SAEs), including two treatment-related SAEs.

CONCLUSION

Overall, using a Bayesian design and extensive PBPK dose modeling with only a small sample size, it was deemed unlikely that GSK1070806 would be efficacious in preventing DGF in the enrolled DCD transplant population.

TRIAL REGISTRATION

NCT02723786.

MO064TISSUE-RESIDENT B CELLS DETERMINE SUSCEPTIBILITY TO URINARY TRACT INFECTION BY ORCHESTRATING MACROPHAGE POLARISATION

Background

Urinary tract infection (UTI) is an important clinical problem. More than half of women and 1 in 10 men will be affected during their lifetime. Many of these affect the lower urinary tract but recurrent pyelonephritis can lead to scarring and chronic kidney disease. There is an increasing appreciation that tissue-resident immune cells, such as macrophages, play an important role in defence against infection, but only little is known about B lymphocytes in this context. Here we sought to address the question of whether B cells reside in the kidney and bladder in homeostasis and to determine their phenotype and contribution to local organ immunity.

Methods and Results

Using intravenous labelling and parabiosis, we identified a population of bona-fide self-renewing, tissue-resident B cells that included non-naïve and innate-like CD5+ B-1 cells, in murine kidneys and urinary bladder (but also in liver and lung). The size and phenotype of this B cell subset was influenced by genetic background, age, and microbiome, with an expanded population evident after co-housing with pet-store mice. Although kidney B cells had less diverse Igh repertoire compared to blood, their seeding was largely independent of their B-cell receptor specificity. In human kidneys we found a similar enrichment for non-naïve B cells compared to blood and spleen.

Using two strains of genetically modified mice with higher (PI3KδE1020K-B) or lower (μMT-) numbers of tissue-resident B cells, we tested the function of these cells during UTI. Surprisingly, the number of tissue-resident B cells inversely correlated with bacterial clearance. We found that these B cells were spatially co-localised with kidney macrophages and skewed their polarization towards an anti-inflammatory M2 phenotype, leading to reduced anti-microbial responses. This effect was, at least in part, driven via IL-10.

Conclusion

In conclusion, our data identify a critical role for tissue-resident B cells in modulating local immunity in the urinary tract, determining the inflammatory ‘set-point’ of resident and recruited myeloid cells, with important clinical implications for the use of B-cell depleting therapies and conditions such as infection, transplant rejection, fibrosis or autoimmunity.

Graphical Abstract

Allograft rejection is associated with development of functional IgE specific for donor MHC antigens

BACKGROUND

Donor-specific antibodies of the IgG isotype are measured routinely for diagnostic purposes in renal transplant recipients and are associated with antibody-mediated rejection and long-term graft loss.

OBJECTIVE

This study aimed to investigate whether MHC-specific antibodies of the IgE isotype are induced during allograft rejection.

METHODS

Anti-MHC/HLA IgE levels were measured in sera of mice grafted with skin or heart transplants from various donor strains and in sera of kidney transplant patients with high levels of HLA IgG. Mediator release was triggered in vitro by stimulating basophils that were coated with murine or human IgE-positive serum, respectively, with specific recombinant MHC/HLA antigens. Kidney tissue samples obtained from organ donors were analyzed by using flow cytometry for cells expressing the high-affinity receptor for IgE (FcεRI).

RESULTS

Donor MHC class I- and MHC class II-specific IgE was found on acute rejection of skin and heart grafts in several murine strain combinations, as well as during chronic antibody-mediated heart graft rejection. Anti-HLA IgE, including donor HLA class I and II specificities, was identified in a group of sensitized transplant recipients. Murine and human anti-MHC/HLA IgE triggered mediator release in coated basophils on stimulation with specific MHC/HLA antigens. HLA-specific IgE was not linked to atopy, and allergen-specific IgE present in allergic patients did not cross-react with HLA antigens. FcεRI+ cells were found in the human renal cortex and medulla and provide targets for HLA-specific IgE.

CONCLUSION

These results demonstrate that MHC/HLA-specific IgE develops during an alloresponse and is functional in mediating effector mechanisms.

Single-cell transcriptomes from human kidneys reveal the cellular identity of renal tumors

Messenger RNA encodes cellular function and phenotype. In the context of human cancer, it defines the identities of malignant cells and the diversity of tumor tissue. We studied 72,501 single-cell transcriptomes of human renal tumors and normal tissue from fetal, pediatric, and adult kidneys. We matched childhood Wilms tumor with specific fetal cell types, thus providing evidence for the hypothesis that Wilms tumor cells are aberrant fetal cells. In adult renal cell carcinoma, we identified a canonical cancer transcriptome that matched a little-known subtype of proximal convoluted tubular cell. Analyses of the tumor composition defined cancer-associated normal cells and delineated a complex vascular endothelial growth factor (VEGF) signaling circuit. Our findings reveal the precise cellular identities and compositions of human kidney tumors.

Long- and short-term outcomes in renal allografts with deceased donors: A large recipient and donor genome-wide association study

Improvements in immunosuppression have modified short-term survival of deceased-donor allografts, but not their rate of long-term failure. Mismatches between donor and recipient HLA play an important role in the acute and chronic allogeneic immune response against the graft. Perfect matching at clinically relevant HLA loci does not obviate the need for immunosuppression, suggesting that additional genetic variation plays a critical role in both short- and long-term graft outcomes. By combining patient data and samples from supranational cohorts across the United Kingdom and European Union, we performed the first large-scale genome-wide association study analyzing both donor and recipient DNA in 2094 complete renal transplant-pairs with replication in 5866 complete pairs. We studied deceased-donor grafts allocated on the basis of preferential HLA matching, which provided some control for HLA genetic effects. No strong donor or recipient genetic effects contributing to long- or short-term allograft survival were found outside the HLA region. We discuss the implications for future research and clinical application.

The Human Cell Atlas

The recent advent of methods for high-throughput single-cell molecular profiling has catalyzed a growing sense in the scientific community that the time is ripe to complete the 150-year-old effort to identify all cell types in the human body. The Human Cell Atlas Project is an international collaborative effort that aims to define all human cell types in terms of distinctive molecular profiles (such as gene expression profiles) and to connect this information with classical cellular descriptions (such as location and morphology). An open comprehensive reference map of the molecular state of cells in healthy human tissues would propel the systematic study of physiological states, developmental trajectories, regulatory circuitry and interactions of cells, and also provide a framework for understanding cellular dysregulation in human disease. Here we describe the idea, its potential utility, early proofs-of-concept, and some design considerations for the Human Cell Atlas, including a commitment to open data, code, and community.

The Human Cell Atlas

The recent advent of methods for high-throughput single-cell molecular profiling has catalyzed a growing sense in the scientific community that the time is ripe to complete the 150-year-old effort to identify all cell types in the human body. The Human Cell Atlas Project is an international collaborative effort that aims to define all human cell types in terms of distinctive molecular profiles (such as gene expression profiles) and to connect this information with classical cellular descriptions (such as location and morphology). An open comprehensive reference map of the molecular state of cells in healthy human tissues would propel the systematic study of physiological states, developmental trajectories, regulatory circuitry and interactions of cells, and also provide a framework for understanding cellular dysregulation in human disease. Here we describe the idea, its potential utility, early proofs-of-concept, and some design considerations for the Human Cell Atlas, including a commitment to open data, code, and community.

Donors With Immune Thrombocytopenia: Do They Pose a Risk to Transplant Recipients?

Transplant-mediated alloimmune thrombocytopenia (TMAT) from donors with immune thrombocytopenia (ITP) can result in significant bleeding complications in the recipient. The risk to a recipient of TMAT if they receive an organ from a donor with ITP is unknown. The outcomes of recipients of organs from deceased donors with ITP recorded in the UK Transplant Registry between 2000 and 2015 were reviewed. Twenty-one deceased organ donors had a predonation diagnosis of ITP. These donors were significantly more likely to have died from intracranial hemorrhage than were all other deceased organ donors (85% vs. 57%, p < 0.001). Organs from donors with ITP resulted in 49 organ transplants (31 kidney, 14 liver, four heart), with only one case of TMAT, which occurred in a liver transplant recipient and resulted in death from bleeding complications 18 days posttransplantation. The recipient of a kidney from the same organ donor was not affected. Unadjusted 5-year patient and graft survival was significantly worse for liver transplant recipients from donors with ITP compared with liver transplant recipients from donors without ITP (64% vs. 85%, p = 0.012). Organs from donors with ITP may be considered for transplantation, but livers should be used with caution.

Phosphoinositide 3-kinase δ gene mutation predisposes to respiratory infection and airway damage

Genetic mutations cause primary immunodeficiencies (PIDs) that predispose to infections. Here, we describe activated PI3K-δ syndrome (APDS), a PID associated with a dominant gain-of-function mutation in which lysine replaced glutamic acid at residue 1021 (E1021K) in the p110δ protein, the catalytic subunit of phosphoinositide 3-kinase δ (PI3Kδ), encoded by the PIK3CD gene. We found E1021K in 17 patients from seven unrelated families, but not among 3346 healthy subjects. APDS was characterized by recurrent respiratory infections, progressive airway damage, lymphopenia, increased circulating transitional B cells, increased immunoglobulin M, and reduced immunoglobulin G2 levels in serum and impaired vaccine responses. The E1021K mutation enhanced membrane association and kinase activity of p110δ. Patient-derived lymphocytes had increased levels of phosphatidylinositol 3,4,5-trisphosphate and phosphorylated AKT protein and were prone to activation-induced cell death. Selective p110δ inhibitors IC87114 and GS-1101 reduced the activity of the mutant enzyme in vitro, which suggested a therapeutic approach for patients with APDS.

Guided imagery to improve functional outcomes post-anterior cruciate ligament repair: randomized-controlled pilot trial

Imagery can improve functional outcomes post-anterior cruciate ligament repair (ACLR). Research is needed to investigate potential mechanisms for this effect. The aim of this study was to (a) evaluate the effectiveness of an imagery intervention to improve functional outcomes post-ACLR, and (b) explore potential mechanisms. A randomized-controlled pilot trial was conducted. Participants were randomized to guided imagery and standard rehabilitation or standard rehabilitation alone (control). The primary outcome was knee strength 6-month post-operatively. Secondary outcomes were knee laxity at 6-months, and change in psychological (self-efficacy) and neurohormonal (adrenaline, noradrenaline, dopamine) variables. Participants (n=21; 62% male) were 34.86 (SD 8.84) years. Following the intervention, no statistical differences between groups for knee strength extension at 180°/s (t=-0.43, P=0.67), or at 60°/s (t=-0.72, P=0.48) were found. A statistically significant effect was found for knee laxity, F=4.67, P<0.05, mean difference of -3.02 (95% CI -4.44 to -1.60), favoring the intervention. No differences were found for self-efficacy; however, an overall effect was found for noradrenaline, F(1, 19) 19.65, P<0.001, η(2) =0.52, and dopamine, F(1, 19) 6.23, P=0.02, η(2) =0.29, favoring the intervention. This imagery intervention improved knee laxity and healing-related neurobiological factors.

Daystay hamstring ACL reconstruction performed under regional anaesthesia

Daycase ACL reconstruction is commonly performed under general anaesthesia with a patella tendon graft. We report our experience with hamstring reconstruction under regional anaesthesia. Over a 14-month period, 104 daycase arthroscopic ACL reconstructions were performed by one surgeon and one anaesthetist. All operations were performed under spinal anaesthesia with a femoral nerve block. Patients were discharged with oral analgesia, brace and a cryocuff. One hundred and two patients were prospectively evaluated with a visual analogue pain score (0-10) and a patient satisfaction questionnaire. Of these 102 patients, 101 (99%) were happy to be discharged on the same day. One patient was admitted from the daycase unit, and one patient was re-admitted. Patients were very satisfied with the pain relief provided. The mean visual analogue pain score was 1.0 at discharge, 1.8 in the middle of the first night, and 2.1 on the first post-op day. Patients experienced significantly more pain the day after surgery than the evening of surgery (p=0.04). We conclude that hamstring ACL reconstruction under regional anaesthesia is well tolerated by patients as a daycase procedure.

The effect of fixation technique on graft position in anterior cruciate ligament reconstruction

The purpose of this paper was to determine the extent to which the technique used in ACL reconstruction and fixation influences graft placement. This is a Comparative Radiographic cohort study. Precise graft placement is one of the most crucial components of a successful anterior cruciate ligament (ACL) reconstruction. Two commonly used techniques of ACL reconstruction are arthroscopic bone-patellar tendon-bone (B-PT-B) autograft with interference screw fixation and semi-tendinosus and gracilis (ST + G) tendon autograft with endobutton femoral and multiple staple belt buckle tibial fixation. Using radiographic measurements of bone tunnel position following ACL reconstruction this study quantified the extent to which these techniques influenced graft placement. Femoral and tibial tunnel position in ACL reconstruction was determined using the post-operative radiographs of 40 male patients who had undergone ACL reconstruction (20 B-PT-B and 20 ST + G). The primary outcome measure was location of bone tunnel position following ACL reconstruction. Measurements were based on the guidelines of Amis et al. Femoral tunnel position of B-PT-B grafts was an average of 9.36% more anterior in the sagittal plane than with ST + G grafts. The mean position of B-PT-B grafts was at 31.11% (SD = 5.45%). The mean position of the ST + G grafts was 21.76% (SD = 6.62%). This difference between the two was found to be significant (p < .001). As demonstrated by this study, placement and orientation may vary to accommodate technique and fixation. Clinical outcomes measured were similar in both groups.

Posterior cruciate ligament injuries of the knee joint

Posterior cruciate ligament (PCL) injuries have a reported incidence of between 3 and 37%, depending on the clinical setting. The most common mechanism of injury in motor vehicle accidents is a dashboard injury or direct force to the proximal anterior tibia. Sports related injuries result from hyperflexion of the knee with the foot typically plantarflexed. The latter mechanism is the most common cause of isolated PCL injuries, while in the trauma population as many as 95% of patients with knee injuries have combined ligamentous damage. Improved knowledge at an anatomical, biomechanical and clinical level has provided the orthopaedist with a more defined treatment algorithm. Isolated, partial PCL injuries (grades I and II) can best be treated nonoperatively while complete injuries (grade III) may require operative treatment based on clinical symptoms. All combined ligamentous injuries usually respond best with surgical management.

The anterior cruciate ligament and arthritis

In this article, the authors assess the natural history of osteoarthritis in the anterior cruciate ligament deficient knee, and examine the factors which may influence its progression: meniscal resection, osteochondral lesions, malalignment, concomitant ligamentous pathology, biological factors, and surgery. The role of anterior cruciate reconstruction, high tibial osteotomy in the coronal and sagittal plane, meniscal allografts, and combined procedures will be reviewed. Finally, the authors' approach to this increasingly common problem is presented.

Results of the Souter-Strathclyde total elbow arthroplasty in patients with rheumatoid arthritis. A preliminary report

The results of 19 consecutive Souter-Strathclyde total elbow arthroplasties (Zimmer, London) in 17 patients with a mean follow-up time of 41 months are reported. Pain relief was achieved in all cases, with 13 elbows becoming entirely pain-free. The mean range of flexion increased 24 degrees and extension improved 8 degrees, with upper limb function greatly improved. The complication rate was 32%, including three nerve palsies, of which two resolved completely, and three early postoperative dislocations. There were two cases of prosthetic loosening, one following revision surgery for a traumatic humeral fracture in the early postoperative period. The authors consider the overall functional results with the Souter-Strathclyde prosthesis to be satisfactory in this group of patients.