Notch signaling drives intestinal graft-versus-host disease in mice and nonhuman primates

Notch signaling promotes T cell pathogenicity and graft-versus-host disease (GVHD) after allogeneic hematopoietic cell transplantation (allo-HCT) in mice, with a dominant role for the Delta-like Notch ligand DLL4. To assess whether Notch's effects are evolutionarily conserved and to identify the mechanisms of Notch signaling inhibition, we studied antibody-mediated DLL4 blockade in a nonhuman primate (NHP) model similar to human allo-HCT. Short-term DLL4 blockade improved posttransplant survival with durable protection from gastrointestinal GVHD in particular. Unlike prior immunosuppressive strategies tested in the NHP GVHD model, anti-DLL4 interfered with a T cell transcriptional program associated with intestinal infiltration. In cross-species investigations, Notch inhibition decreased surface abundance of the gut-homing integrin α4β7 in conventional T cells while preserving α4β7 in regulatory T cells, with findings suggesting increased β1 competition for α4 binding in conventional T cells. Secondary lymphoid organ fibroblastic reticular cells emerged as the critical cellular source of Delta-like Notch ligands for Notch-mediated up-regulation of α4β7 integrin in T cells after allo-HCT. Together, DLL4-Notch blockade decreased effector T cell infiltration into the gut, with increased regulatory to conventional T cell ratios early after allo-HCT. Our results identify a conserved, biologically unique, and targetable role of DLL4-Notch signaling in intestinal GVHD.

Anatomical and molecular characterization of some rhigonematid parasites of millipedes in Nigeria, with new insights into their phylogeny

Parasitic nematodes of millipedes from Nigeria are molecularly characterized for the first time. During nematode surveys on live giant African millipedes from several localities in Nigeria, 4 species of rhigonematids were identified by application of integrative taxonomical approaches (morpho-anatomy and molecular markers), including Brumptaemilius sp., Gilsonema gabonensis, Obainia pachnephorus, and Rhigonema disparovis. The results of morphometric and molecular analyses of D2-D3 28S, ITS, partial 18S rRNA, and cytochrome oxidase c subunit 1 (COI) gene sequences further characterized the rhigonematid species, and clearly separated them from other related species. Phylogenetic relationships based on 28S and 18S rRNA genes suggest that genera within Ransomnematoidea (Ransomnema, Heth, Carnoya, Brumptaemilius, Cattiena, Insulanema, Gilsonema) and Rhigonematoidea (Rhigonema, Obainia, Xystrognathus, Trachyglossoides, Ichthyocephaloides) clustered rather closer than could be expected in view of their morphological differences. Phylogenetic relationships based on ITS and COI are congruent with those of other ribosomal genes; however, they are not conclusive due to the scarcity of available sequences of these genes for these genera in NCBI.

Spatiotemporal single-cell profiling reveals that invasive and tissue-resident memory donor CD8+ T cells drive gastrointestinal acute graft-versus-host disease

Organ infiltration by donor T cells is critical to the development of acute graft-versus-host disease (aGVHD) in recipients after allogeneic hematopoietic stem cell transplant (allo-HCT). However, deconvoluting the transcriptional programs of newly recruited donor T cells from those of tissue-resident T cells in aGVHD target organs remains a challenge. Here, we combined the serial intravascular staining technique with single-cell RNA sequencing to dissect the tightly connected processes by which donor T cells initially infiltrate tissues and then establish a pathogenic tissue residency program in a rhesus macaque allo-HCT model that develops aGVHD. Our results enabled creation of a spatiotemporal map of the transcriptional programs controlling donor CD8⁺ T cell infiltration into the primary aGVHD target organ, the gastrointestinal (GI) tract. We identified the large and small intestines as the only two sites demonstrating allo-specific, rather than lymphodepletion-driven, T cell infiltration. GI-infiltrating donor CD8⁺ T cells demonstrated a highly activated, cytotoxic phenotype while simultaneously developing a canonical tissue-resident memory T cell (T_RM) transcriptional signature driven by interleukin-15 (IL-15)/IL-21 signaling. We found expression of a cluster of genes directly associated with tissue invasiveness, including those encoding adhesion molecules (ITGB2), specific chemokines (CCL3 and CCL4L1) and chemokine receptors (CD74), as well as multiple cytoskeletal proteins. This tissue invasion transcriptional signature was validated by its ability to discriminate the CD8⁺ T cell transcriptome of patients with GI aGVHD from those of GVHD-free patients. These results provide insights into the mechanisms controlling tissue occupancy of target organs by pathogenic donor CD8⁺ T_RM cells during aGVHD in primate transplant recipients.

CD28 blockade controls T cell activation to prevent graft-versus-host disease in primates

Controlling graft-versus-host disease (GVHD) remains a major unmet need in stem cell transplantation, and new, targeted therapies are being actively developed. CD28-CD80/86 costimulation blockade represents a promising strategy, but targeting CD80/CD86 with CTLA4-Ig may be associated with undesired blockade of coinhibitory pathways. In contrast, targeted blockade of CD28 exclusively inhibits T cell costimulation and may more potently prevent GVHD. Here, we investigated FR104, an antagonistic CD28-specific pegylated-Fab', in the nonhuman primate (NHP) GVHD model and completed a multiparameter interrogation comparing it with CTLA4-Ig, with and without sirolimus, including clinical, histopathologic, flow cytometric, and transcriptomic analyses. We document that FR104 monoprophylaxis and combined prophylaxis with FR104/sirolimus led to enhanced control of effector T cell proliferation and activation compared with the use of CTLA4-Ig or CTLA4-Ig/sirolimus. Importantly, FR104/sirolimus did not lead to a beneficial impact on Treg reconstitution or homeostasis, consistent with control of conventional T cell activation and IL-2 production needed to support Tregs. While FR104/sirolimus had a salutary effect on GVHD-free survival, overall survival was not improved, due to death in the absence of GVHD in several FR104/sirolimus recipients in the setting of sepsis and a paralyzed INF-γ response. These results therefore suggest that effectively deploying CD28 in the clinic will require close scrutiny of both the benefits and risks of extensively abrogating conventional T cell activation after transplant.

Chimeric Antigen Receptor T Cell-Mediated Neurotoxicity in Nonhuman Primates

Chimeric antigen receptor (CAR) T-cell immunotherapy has revolutionized the treatment of refractory leukemias and lymphomas, but is associated with significant toxicities, namely cytokine release syndrome (CRS) and neurotoxicity. A major barrier to developing therapeutics to prevent CAR T cell-mediated neurotoxicity is the lack of clinically relevant models. Accordingly, we developed a rhesus macaque (RM) model of neurotoxicity via adoptive transfer of autologous CD20-specific CAR T cells. Following cyclophosphamide lymphodepletion, CD20 CAR T cells expand to 272 to 4,450 cells/μL after 7 to 8 days and elicit CRS and neurotoxicity. Toxicities are associated with elevated serum IL6, IL8, IL1RA, MIG, and I-TAC levels, and disproportionately high cerebrospinal fluid (CSF) IL6, IL2, GM-CSF, and VEGF levels. During neurotoxicity, both CD20 CAR and non-CAR T cells accumulate in the CSF and in the brain parenchyma. This RM model demonstrates that CAR T cell-mediated neurotoxicity is associated with proinflammatory CSF cytokines and a pan-T cell encephalitis.Significance: We provide the first immunologically relevant, nonhuman primate model of B cell-directed CAR T-cell therapy-mediated CRS and neurotoxicity. We demonstrate CAR and non-CAR T-cell infiltration in the CSF and in the brain during neurotoxicity resulting in pan-encephalitis, accompanied by increased levels of proinflammatory cytokines in the CSF. Cancer Discov; 8(6); 750-63. ©2018 AACR.This article is highlighted in the In This Issue feature, p. 663.

Combined OX40L and mTOR blockade controls effector T cell activation while preserving Treg reconstitution after transplant

A critical question facing the field of transplantation is how to control effector T cell (T_eff) activation while preserving regulatory T cell (T_reg) function. Standard calcineurin inhibitor-based strategies can partially control T_effs, but breakthrough activation still occurs, and these agents are antagonistic to T_reg function. Conversely, mechanistic target of rapamycin (mTOR) inhibition with sirolimus is more T_reg-compatible but is inadequate to fully control T_eff activation. In contrast, blockade of OX40L signaling has the capacity to partially control T_eff activation despite maintaining T_reg function. We used the nonhuman primate graft-versus-host disease (GVHD) model to probe the efficacy of combinatorial immunomodulation with sirolimus and the OX40L-blocking antibody KY1005. Our results demonstrate significant biologic activity of KY1005 alone (prolonging median GVHD-free survival from 8 to 19.5 days), as well as marked, synergistic control of GVHD with KY1005 + sirolimus (median survival time, >100 days; P < 0.01 compared to all other regimens), which was associated with potent control of both T_H/T_C1 (T helper cell 1/cytotoxic T cell 1) and T_H/T_C17 activation. Combined administration also maintained T_reg reconstitution [resulting in an enhanced T_reg/T_eff ratio (40% over baseline) in the KY1005/sirolimus cohort compared to a 2.9-fold decrease in the unprophylaxed GVHD cohort]. This unique immunologic signature resulted in transplant recipients that were able to control GVHD for the length of analysis and to down-regulate donor/recipient alloreactivity despite maintaining anti-third-party responses. These data indicate that combined OX40L blockade and sirolimus represents a promising strategy to induce immune balance after transplant and is an important candidate regimen for clinical translation.

Delineating tissue-specific alloimmunity during acute GVHD

After allogeneic hematopoietic cell transplantation (allo-HCT), donor T cells undergo priming in secondary lymphoid tissues followed by migration to different target organs, where they mediate inflammation and cause acute Graft-versus-Host Disease (aGVHD). Here, we characterized T cells infiltrating GVHD-target organs using a model of aGVHD in non-human primates in order to delineate tissue-specific patterns of the alloimmune response. We found that aGVHD profoundly shifted the T cell phenotype from the naïve state toward an effector-memory state in both the blood and secondary lymphoid organs, with an attenuated shift in non-lymphoid organs. However, in all compartments, tissue-infiltrating T cells demonstrated an aGVHD-specific activated phenotype characterized by a high rate of proliferation and elevated effector functions. In addition, transcriptomic profiles of aGVHD- and tissue-residency developed in T cells residing the colon, liver and lungs as well as in the blood. To further delineate the patterns of T cell trafficking and activation during aGVHD, we directly labeled leukocytes in vivo using fluorescent anti-CD45 antibodies. Using this approach, we detected notable changes in T cell trafficking patterns which included increased T cell trafficking to lymph nodes, lungs and kidneys after allo-HCT, with rates of T cell migration to the GI tract unchanged even during aGVHD. These data provides novel insights into the spatial organization of systemic alloimmunity during aGVHD and the organ-specific impact of this disease on T cell trafficking, activation and functional maturation.

Redescription of Steinernema longicaudum Shen & Wang (Nematoda: Steinernematidae); geographic distribution and phenotypic variation between allopatric populations

Steinernema longicaudum Shen & Wang is redescribed based on a comparative morphological study of specimens from the type isolate from China, and two other isolates recovered from Korea and the USA. For the first and second generation female, the location of the vulva, shape of the vulval lips, and shape and length of the tail were newly observed diagnostic characters. A more detailed description of the morphology of the male spicules and gubernaculum, and the arrangement of the genital papillae is included. A description, based on scanning electron microscopy observations, of the lateral field pattern of the third-stage infective juveniles is also provided. Additionally, restriction fragment length polymorphism profiles based on the internal transcribed spacer region, and cross-breeding tests supplement the description of this species.

Use of heme compounds as iron sources by pathogenic neisseriae requires the product of the hemO gene

Heme compounds are an important source of iron for neisseriae. We have identified a neisserial gene, hemO, that is essential for heme, hemoglobin (Hb), and haptoglobin-Hb utilization. The hemO gene is located 178 bp upstream of the hmbR Hb receptor gene in Neisseria meningitidis isolates. The product of the hemO gene is homologous to enzymes that degrade heme; 21% of its amino acid residues are identical, and 44% are similar, to those of the human heme oxygenase-1. DNA sequences homologous to hemO were ubiquitous in commensal and pathogenic neisseriae. HemO genetic knockout strains of Neisseria gonorrhoeae and N. meningitidis were unable to use any heme source, while the assimilation of transferrin-iron and iron-citrate complexes was unaffected. A phenotypic characterization of a conditional hemO mutant, constructed by inserting an isopropyl-beta-D-thiogalactopyranoside (IPTG)-regulated promoter upstream of the ribosomal binding site of hemO, confirmed the indispensability of the HemO protein in heme utilization. The expression of HemO also protected N. meningitidis cells against heme toxicity. hemO mutants were still able to transport heme into the cell, since both heme and Hb could complement an N. meningitidis hemA hemO double mutant for growth. The expression of the HmbR receptor was reduced significantly by the inactivation of the hemO gene, suggesting that hemO and hmbR are transcriptionally linked. The expression of the unlinked Hb receptor, HpuAB, was not altered. Comparison of the polypeptide patterns of the wild type and the hemO mutant led to detection of six protein spots with an altered expression pattern, suggesting a more general role of HemO in the regulation of gene expression in Neisseriae.

Uptake and retention in suckling rats of 51chromium fed with human milk or infant formulas

Optimum concentration of Cr for infant formulas has not been established. Such components as soy protein or supplemental Fe could influence absorption and retention. Suckling rat pups were used to evaluate the influence of three commercial formulas and human milk, all of which had been incubated with 51CrCl3 for 1 h, on the uptake and retention of the added 51Cr. After fasting 3 h, the pups were intubated with a single dose of 25 microCi 51CrCl3 in either a cow's milk-based formula, an Fe-supplemented cow's milk-based formula, a soy-based formula, or human milk. Six hours later, 51Cr was counted in five organs, thymus, blood, and total urine. Absorption of 51Cr was low. At 6 h, percent 51Cr in blood was < 0.2% of the dose, and total 51Cr excretion in urine was < 1.8%. The uptake and retention of 51Cr and its concentration in any of the organs, thymus, blood, and urine were not influenced by different types of formula or by human milk.

Incorporating fuzzy membership functions into the perceptron algorithm

The perceptron algorithm, one of the class of gradient descent techniques, has been widely used in pattern recognition to determine linear decision boundaries. While this algorithm is guaranteed to converge to a separating hyperplane if the data are linearly separable, it exhibits erratic behavior if the data are not linearly separable. Fuzzy set theory is introduced into the perceptron algorithm to produce a ``fuzzy algorithm'' which ameliorates the convergence problem in the nonseparable case. It is shown that the fuzzy perceptron, like its crisp counterpart, converges in the separable case. A method of generating membership functions is developed, and experimental results comparing the crisp to the fuzzy perceptron are presented.