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Objective: The DRB1 locus is strongly associated with both susceptibility and resistance to rheumatoid arthritis (RA). DRB1 alleles encoding the VKA or VRA epitope in positions 11, 71 and 74 confer the highest risk of developing RA, while the allele encoding VEA is protective. We therefore investigated the feasibility of creating antigen-specific tolerance without inducing alloreactivity by replacing lysine with glutamic acid at position 71 in DRβ1*04:01., Materials and Methods: Individual DRB1 alleles and the DRB1*04:01 K71E allele were cloned into T2 cell lines to measure binding of biotinylated peptides. Transgenic animals expressing DRB1*04:01, DRB1*01:01 or DRB1*04:01 K71E were injected with collagen to measure T cell proliferation. Skin and bone marrow transplants between DRB1*04:01 K71E and DRB1*04:01 mice were performed to determine if the single amino acid change at position 71 would be recognized as foreign. DRB1*04:01 mice transplanted with DRB1*04:01 K71E bone marrow were injected with collagen to test if resistance to collagen sensitization could be transferred., Results: Replacing lysine (K) at position 71 in DRβ1*04:01 with glutamic acid (E) blocked collagen peptide binding and rendered the DRB1*04:01 K71E mice resistant to collagen sensitization. Skin and bone marrow transplants from DRB1*04:01 K71E mice were not rejected by DRB1*04:01 mice, suggesting the single E 71 difference was not recognized as allogeneic. Bone marrow from DRB1*04:01 K71E mice adoptively transferred antigen-specific tolerance to collagen to DRB1*04:01 mice., Conclusion: These studies demonstrate that editing a single amino acid in DRβ1*04:01 blocks collagen peptide binding without inducing alloreactivity and could therefore represent a gene therapy approach to induce antigen-specific passive tolerance., (This article is protected by copyright. All rights reserved.)

Graft versus tumor relies on tumor-associated antigens (TAAs) that are presented to donor T cells via human leukocyte antigens (HLAs). The HLA evolutionary divergence (HED) between alleles of a single individual can dictate the ability to present TAAs. The impact of HED in haploidentical donor transplantation (HIDT) has not been studied. We studied the effect of HED on transplant outcomes following HIDT. We analyzed 322 consecutive recipient/donor pairs with a median follow-up of 57.2 months. Pairwise divergence of HLA class I and II showed that HLA-B, -DRB1, and -DQB1 contributing most to mean HED. The mean HED was class I 6.85 (HLA-A 7.08, -B 8.24, and -C 5.07), class II 8.58 (HLA-DRB1 10.97, -DQB1 10.06 and -DPB1 4.06). A high HED in class I mismatched recipient/donor haplotype (RD MM) was significant for worse DFS (HR 1.11, p = 0.020), and relapse (HR 1.11, p = 0.02). Also, a high HED in RD MM HLA-B haplotype had worse OS (HR 1.07, p = 0.02), DFS (HR 1.09, p = 0.002), higher relapse (HR 1.10, p = 0.003), and similar NRM to low HED. The multivariate analysis showed that high HED in RD MM HLA-B (≥7.8 vs <7.8) had worse DFS (HR 1.53, p = 0.01), higher relapse (HR 1.61, p = 0.024), and similar NRM and OS., (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)

Background: Mesenchymal stromal/stem cells (MSCs) play a critical role in wound healing. Corlicyte ® is an MSC product derived from allogeneic umbilical cord tissue donated under an institutional review board-approved protocol and processed in accordance with section 501(a)(2)(B) of the Federal Food, Drug, and Cosmetic Act. This open-label phase 1 trial was performed under a United States Food and Drug Administration Investigational New Drug Application to establish the safety and tolerability of Corlicyte ® in patients with diabetes and chronic diabetic foot ulcer (DFU)., Methods: Escalating doses were applied topically twice a week for up to 8 weeks after ulcer debridement, wound photography, and measurement. Subjects were followed for 4 weeks after the treatment phase. Adverse events were assessed at every visit., Results: Nine subjects in 2 dosing cohorts completed the trial. No subjects experienced a serious adverse reaction to Corlicyte ® or the development of anti-human leukocyte antigen (HLA) antibodies. Sixty percentage of subjects in the lower dose cohort experienced ulcer closure by Day 70 of follow-up, while the mean ulcer size was reduced by 54-67% in the other subjects., Conclusions: Topical administration of Corlicyte ® , a novel biologic therapy consisting of allogeneic umbilical cord lining MSCs, appeared safe and tolerable and resulted in a significant decrease in ulcer area, demonstrating its potential as a therapy for healing of chronic DFU.

Introduction: A strong epidemiologic link exists between cigarette smoke (CS) exposure and susceptibility to tuberculosis (TB). Macrophage and murine studies showed that CS and nicotine impair host-protective immune cells against Mycobacterium tuberculosis (MTB) infection. While CS and nicotine may activate T regulatory cells (Tregs), little is known about how CS may affect these immunosuppressive cells with MTB infection., Methods: We investigated whether CS-exposed Tregs could exacerbate MTB infection in co-culture with human macrophages and in recipient mice that underwent adoptive transfer of Tregs from donor CS-exposed mice., Results: We found that exposure of primary human Tregs to CS extract impaired the ability of unexposed human macrophages to control an MTB infection by inhibiting phagosome-lysosome fusion and autophagosome formation. Neutralizing CTLA-4 on the CS extract-exposed Tregs abrogated the impaired control of MTB infection in the macrophage and Treg co-cultures. In Foxp3 + GFP + DTR + (Thy1.2) mice depleted of endogenous Tregs, adoptive transfer of Tregs from donor CS-exposed B6.PL(Thy1.1) mice with subsequent MTB infection of the Thy1.2 mice resulted in a greater burden of MTB in the lungs and spleens than those that received Tregs from air-exposed mice. Mice that received Tregs from donor CS-exposed mice and infected with MTB had modest but significantly reduced numbers of interleukin-12-positive dendritic cells and interferon-gamma-positive CD4 + T cells in the lungs, and an increased number of total programmed cell death protein-1 (PD-1) positive CD4 + T cells in both the lungs and spleens., Discussion: Previous studies demonstrated that CS impairs macrophages and host-protective T effector cells in controlling MTB infection. We now show that CS-exposed Tregs can also impair control of MTB in co-culture with macrophages and in a murine model., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Bai, Verma, Garcia, Musheyev, Kim, Fornis, Griffith, Li, Whittel, Gadwa, Ohanjanyan, Eggleston, Galvan, Freed, Ordway and Chan.)

Immune checkpoint inhibitors have been found to be effective in metastatic MSI-high colorectal cancers (CRC), however, have no efficacy in microsatellite stable (MSS) cancers, which comprise the majority of mCRC cases. Cabozantinib is a small molecule multi-tyrosine kinase inhibitor that is FDA approved in advanced renal cell, medullary thyroid, and hepatocellular carcinoma. Using Human Immune System (HIS) mice, we tested the ability of cabozantinib to prime MSS-CRC tumors to enhance the potency of immune checkpoint inhibitor nivolumab. In four independent experiments, we implanted distinct MSS-CRC patient-derived xenografts (PDXs) into the flanks of humanized BALB/c-Rag2 null Il2rγ null Sirpα NOD (BRGS) mice that had been engrafted with human hematopoietic stem cells at birth. For each PDX, HIS-mice cohorts were treated with vehicle, nivolumab, cabozantinib, or the combination. In three out of the four models, the combination had a lower tumor growth rate compared to vehicle or nivolumab-treated groups. Furthermore, interrogation of the HIS in immune organs and tumors by flow cytometry revealed increased Granzyme B+, TNFα+ and IFNγ+ CD4+ T cells among the human tumor infiltrating leukocytes (TIL) that correlated with reduced tumor growth in the combination-treated HIS-mice. Notably, slower growth correlated with increased expression of the CD4+ T cell ligand, HLA-DR, on the tumor cells themselves. Finally, the cabozantinib/nivolumab combination was tested in comparison to cobimetinib/atezolizumab. Although both combinations showed tumor growth inhibition, cabozantinib/nivolumab had enhanced cytotoxic IFNγ and TNFα+ T cells. This pre-clinical in vivo data warrants testing the combination in clinical trials for patients with MSS-CRC., Competing Interests: Exelixis supplied cabozantinib and funded this study, with TP as Principal Investigator, but had no role in study design, data collection, data analysis, data interpretation, or writing of the report. WM is the principal investigator of a phase II clinical trial of cabozantinib in patients with refractory metastatic colorectal cancer that is sponsored by Exelixis NCT03542877. AL is the principal investigator of a phase II clinical trial of cabozantinib in combination with nivolumab in metastatic colorectal cancer which is co-sponsored by Bristol Myers Squibb and Exelixis NCT04963283. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Lang, Leal, Marín-Jiménez, Hartman, Shulman, Navarro, Lewis, Capasso, Bagby, Yacob, MacBeth, Freed, Eckhardt, Jordan, Blatchford, Pelanda, Lieu, Messersmith and Pitts.)

The "heterozygote advantage" hypothesis has been postulated regarding the role of human leukocyte antigen (HLA) in non-Hodgkin lymphoma (NHL), where homozygous loci are associated with an increased risk of disease. In this retrospective study, we analyzed the HLA homozygosity of 3789 patients with aplastic anemia (AA), acute lymphocytic leukemia (ALL), acute myeloblastic leukemia (AML), chronic lymphocytic leukemia (CLL), chronic myeloid leukemia (CML), myelodysplastic syndrome (MDS), multiple myeloma (MM), and non-Hodgkin lymphoma (NHL) at HLA-A, B, C, DRB1 and DQB1 loci compared to 169,964 normal controls. HLA homozygosity at one or more loci was only associated with an increased risk in NHL patients (OR = 1.28, 95% CI [1.09, 1.50], p = 0.002). This association was not seen in any of the other hematologic diseases. Homozygosity at HLA-A alone, HLA-B + C only, and HLA-DRB1 + DQB1 only was also significantly associated with NHL. Finally, we observed a 17% increased risk of NHL with each additional homozygous locus (OR per locus = 1.17, 95% CI [1.08, 1.25], p trend = 2.4 × 10 -5 ). These results suggest that reduction of HLA diversity could predispose individuals to an increased risk of developing NHL., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 American Society for Histocompatibility and Immunogenetics. Published by Elsevier Inc. All rights reserved.)

The role of NK cell alloreactivity on outcomes after T cell-replete haploidentical donor transplantation (HIDT) remains uncertain. After transplantation, newly formed NK cells are licensed through interactions of donor inhibitory KIR (iKIR) and NKG2A receptors with their cognate ligands on recipient cells. Donor NKG2A recognizes HLA-E bound by recipient HLA class I leader peptides, a process requiring methionine (M) at position -21 of the leader sequence. An rs1050458C/T dimorphism results in approximately 40% of individuals expressing at least one copy of -21M HLA-B (M/M or M/T [M+]), allowing ligand expression. We assessed the impact of recipient HLA-B-leader genotype (M+ versus M- [T/T]) and HLA-C-group iKIR missing ligand (ML, C1C1/C2C2 versus C1C2) on relapse and disease-free survival (DFS) in recipients of post-transplantation cyclophosphamide (PTCy)-based HIDT. Based on preclinical data, we hypothesized that the relative impact of each variable may depend on disease lineage (lymphoid versus myeloid). To this end, we analyzed outcomes of 322 consecutive PTCy-based HIDT recipients with hematologic malignancy who underwent transplantation at a single institution using standardized supportive care measures with mature follow-up (median 45 months). Primary endpoints were relapse and DFS of patients based on HLA-B-leader genotype and HLA-C-group iKIR ML. Planned subgroup analysis included patient with lymphoid versus myeloid malignancy. M+ HLA-B-leader genotype and HLA-C-group iKIR ML were seen in 42% and 49% of recipients, respectively. The presence of a recipient M+ B-leader (versus M-) improved overall survival (OS) and DFS and lowered cumulative incidence of relapse (CIR), an effect primarily seen in lymphoid malignancies (80% versus 51%, 72% versus 41%, 16% versus 42%, respectively). In contrast, myeloid malignancy patients benefited most from HLA-C-group iKIR ML with better OS and DFS and lower CIR (67% versus 51%, 64% versus 44%, 25% versus 45%, respectively). Multivariate analysis confirmed the disease-specific associations of improved relapse/DFS with M+ HLA-B-leader in lymphoid malignancy (hazard ratio [HR] 0.20, P < .001/HR 0.34, P <.001) and HLA-C-group iKIR ML in myeloid malignancy (HR 0.44, P = .004/HR 0.54, P = .009). Neither HLA-B-leader nor iKIR ML was associated with the incidence of non-relapse mortality or acute or chronic graft-versus-host disease. Two distinct NK cell education pathways predict relapse and DFS after HIDT-PTCy in a disease-specific manner: the presence of recipient M+ HLA-B-leader genotype improves outcome in patients with lymphoid malignancies, whereas HLA-C-group iKIR ML improves outcome in patients with myeloid malignancies. These findings strengthen the essential role of NK cells for optimal GVL in the context of HIDT-PTCy and may suggest different approaches to improving transplant outcome depending on disease type., Competing Interests: Conflict of interest statement There are no conflicts of interest to report., (Copyright © 2022 The American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc. All rights reserved.)

The cell surface serine protease Transmembrane Protease 2 (TMPRSS2) is required to cleave the spike protein of SARS-CoV-2 for viral entry into cells. We determined whether negatively-charged heparin enhanced TMPRSS2 inhibition by alpha-1-antitrypsin (AAT). TMPRSS2 activity was determined in HEK293T cells overexpressing TMPRSS2. We quantified infection of primary human airway epithelial cells (hAEc) with human coronavirus 229E (HCoV-229E) by immunostaining for the nucleocapsid protein and by the plaque assay. Detailed molecular modeling was undertaken with the heparin-TMPRSS2-AAT ternary complex. Enoxaparin enhanced AAT inhibition of both TMPRSS2 activity and infection of hAEc with HCoV-229E. Underlying these findings, detailed molecular modeling revealed that: (i) the reactive center loop of AAT adopts an inhibitory-competent conformation compared with the crystal structure of TMPRSS2 bound to an exogenous (nafamostat) or endogenous (HAI-2) TMPRSS2 inhibitor and (ii) negatively-charged heparin bridges adjacent electropositive patches at the TMPRSS2-AAT interface, neutralizing otherwise repulsive forces. In conclusion, enoxaparin enhances AAT inhibition of both TMPRSS2 and coronavirus infection. Such host-directed therapy is less likely to be affected by SARS-CoV-2 mutations. Furthermore, given the known anti-inflammatory activities of both AAT and heparin, this form of treatment may target both the virus and the excessive inflammatory consequences of severe COVID-19., (© 2022. The Author(s).)