A Gut Microbial Mimic that Hijacks Diabetogenic Autoreactivity to Suppress Colitis.

The gut microbiota contributes to the development of normal immunity but, when dysregulated, can promote autoimmunity through various non-antigen-specific effects on pathogenic and regulatory lymphocytes. Here, we show that an integrase expressed by several species of the gut microbial genus Bacteroides encodes a low-avidity mimotope of the pancreatic ß cell autoantigen islet-specific glucose-6-phosphatase-catalytic-subunit-related protein (IGRP206-214). Studies in germ-free mice monocolonized with integrase-competent, integrase-deficient, and integrase-transgenic Bacteroides demonstrate that the microbial epitope promotes the recruitment of diabetogenic CD8+ T cells to the gut. There, these effectors suppress colitis by targeting microbial antigen-loaded, antigen-presenting cells in an integrin ß7-, perforin-, and major histocompatibility complex class I-dependent manner. Like their murine counterparts, human peripheral blood T cells also recognize Bacteroides integrase. These data suggest that gut microbial antigen-specific cytotoxic T cells may have therapeutic value in inflammatory bowel disease and unearth molecular mimicry as a novel mechanism by which the gut microbiota can regulate normal immune homeostasis. PAPERCLIP.

Expanding antigen-specific regulatory networks to treat autoimmunity.

Regulatory T cells hold promise as targets for therapeutic intervention in autoimmunity, but approaches capable of expanding antigen-specific regulatory T cells in vivo are currently not available. Here we show that systemic delivery of nanoparticles coated with autoimmune-disease-relevant peptides bound to major histocompatibility complex class II (pMHCII) molecules triggers the generation and expansion of antigen-specific regulatory CD4(+) T cell type 1 (TR1)-like cells in different mouse models, including mice humanized with lymphocytes from patients, leading to resolution of established autoimmune phenomena. Ten pMHCII-based nanomedicines show similar biological effects, regardless of genetic background, prevalence of the cognate T-cell population or MHC restriction. These nanomedicines promote the differentiation of disease-primed autoreactive T cells into TR1-like cells, which in turn suppress autoantigen-loaded antigen-presenting cells and drive the differentiation of cognate B cells into disease-suppressing regulatory B cells, without compromising systemic immunity. pMHCII-based nanomedicines thus represent a new class of drugs, potentially useful for treating a broad spectrum of autoimmune conditions in a disease-specific manner.

The Iowa Gambling Task on HIV-infected subjects.

HIV-associated neurocognitive disorders (HAND) are characterized by cognitive, behavioral, and motor dysfunctions, which impact daily functioning and are predictive of poor survival among patients. The diagnosis of HAND is marked by clinically significant declines in multiple domains of neurocognitive functioning. Some patients diagnosed with HAND have social problem; however, higher brain dysfunction is not detected in general neuropsychological assessments and the intelligence quotient may remain unchanged. Impaired decision-making may reduce social and occupational qualities of life. The Iowa Gambling Task (IGT) has been developed as a task to evaluate risk predictions at the time of decision-making. In the present study, 38 HIV-infected patients enrolled in our hospital performed IGT and we investigated whether the results obtained are associated with HAND. The median net IGT score of all HIV-infected subjects was significantly lower than that of healthy controls. Patients diagnosed with HAND accounted for 43.8% of the negative net score group. We elucidated the relationship between the net IGT score and HAND for the first time. We think that IGT is a good tool to detect decision-making impairment for ANI and MND. Careful follow-ups of the progression of HAND and increased awareness among HIV-infected patients and medical care workers of the risk of social behavioral disorders, which negatively impact daily life before they are detected, are needed in order to prevent deteriorations in the quality of life of these patients.

Reversal of autoimmunity by boosting memory-like autoregulatory T cells.

Blunting autoreactivity without compromising immunity remains an elusive goal in the treatment of autoimmunity. We show that progression to autoimmune diabetes results in the conversion of naive low-avidity autoreactive CD8(+) T cells into memory-like autoregulatory cells that can be expanded in vivo with nanoparticles coated with disease-relevant peptide-major histocompatibility complexes (pMHC-NP). Treatment of NOD mice with monospecific pMHC-NPs expanded cognate autoregulatory T cells, suppressed the recruitment of noncognate specificities, prevented disease in prediabetic mice, and restored normoglycemia in diabetic animals. pMHC-NP therapy was inconsequential in mice engineered to bear an immune system unresponsive to the corresponding epitope, owing to absence of epitope-experienced autoregulatory T cells. pMHC-NP-expanded autoregulatory T cells suppressed local presentation of autoantigens in an interferon-gamma-, indoleamine 2,3-dioxygenase-, and perforin-dependent manner. Nanoparticles coated with human diabetes-relevant pHLA complexes restored normoglycemia in a humanized model of diabetes. These observations expose a paradigm in the pathogenesis of autoimmunity amenable for therapeutic intervention.

The cross-priming capacity and direct presentation potential of an autoantigen are separable and inversely related properties.

We investigated whether a prevalent epitope of the ß-cell-specific autoantigen islet-specific glucose-6-phosphatase catalytic subunit-related protein (IGRP206-214) reaches regional Ag-presentation pathways via unprocessed polypeptide chains, as free IGRP206-214 peptide or via preformed IGRP206-214/K(d) complexes. This was accomplished by expressing bacterial artificial chromosome transgenes encoding wild-type (stable) or ubiquitinated (unstable) forms of IGRP in IGRP-deficient NOD mice carrying MHC class I-deficient ß-cells, dendritic cells, or B cells. We investigated the ability of the pancreatic lymph nodes of these mice to prime naive IGRP206-214-reactive CD8(+) T cells in vivo, either in response to spontaneous Ag shedding, or to synchronized forms of ß-cell necrosis or apoptosis. When IGRP was made unstable by targeting it for proteasomal degradation within ß-cells, the cross-priming, autoimmune-initiating potential of this autoantigen (designated autoantigenicity) was impaired. Yet at the same time, the direct presentation, CTL-targeting potential of IGRP (designated pathogenicity) was enhanced. The appearance of IGRP206-214 in regional Ag-presentation pathways was dissociated from transfer of IGRP206-214 or IGRP206-214/K(d) from ß cells to dendritic cells. These results indicate that autoantigenicity and pathogenicity are separable and inversely related properties and suggest that pathogenic autoantigens, capable of efficiently priming CTLs while marking target cells for CTL-induced killing, may have a critical balance of these two properties.

Antidiabetogenic MHC class II promotes the differentiation of MHC-promiscuous autoreactive T cells into FOXP3+ regulatory T cells.

Polymorphisms in MHC class II molecules, in particular around ß-chain position-57 (ß57), afford susceptibility/resistance to multiple autoimmune diseases, including type 1 diabetes, through obscure mechanisms. Here, we show that the antidiabetogenic MHC class II molecule I-A(b) affords diabetes resistance by promoting the differentiation of MHC-promiscuous autoreactive CD4(+) T cells into disease-suppressing natural regulatory T cells, in a ß56-67-regulated manner. We compared the tolerogenic and antidiabetogenic properties of CD11c promoter-driven transgenes encoding I-A(b) or a form of I-A(b) carrying residues 56-67 of I-Aß(g7) (I-A(b-g7)) in wild-type nonobese diabetic (NOD) mice, as well as NOD mice coexpressing a diabetogenic and I-A(g7)-restricted, but MHC-promiscuous T-cell receptor (4.1). Both I-A transgenes protected NOD and 4.1-NOD mice from diabetes. However, whereas I-A(b) induced 4.1-CD4(+) thymocyte deletion and 4.1-CD4(+)Foxp3(+) regulatory T-cell development, I-A(b-g7) promoted 4.1-CD4(+)Foxp3(+) Treg development without inducing clonal deletion. Furthermore, non-T-cell receptor transgenic NOD.CD11cP-I-A(b) and NOD.CD11cP-IA(b-g7) mice both exported regulatory T cells with superior antidiabetogenic properties than wild-type NOD mice. We propose that I-A(b), and possibly other protective MHC class II molecules, afford disease resistance by engaging a naturally occurring constellation of MHC-promiscuous autoreactive T-cell clonotypes, promoting their deviation into autoregulatory T cells.

Interleukin-2 gene variation impairs regulatory T cell function and causes autoimmunity.

Autoimmune diseases are thought to result from imbalances in normal immune physiology and regulation. Here, we show that autoimmune disease susceptibility and resistance alleles on mouse chromosome 3 (Idd3) correlate with differential expression of the key immunoregulatory cytokine interleukin-2 (IL-2). In order to test directly that an approximately twofold reduction in IL-2 underpins the Idd3-linked destabilization of immune homeostasis, we show that engineered haplodeficiency of Il2 gene expression not only reduces T cell IL-2 production by twofold but also mimics the autoimmune dysregulatory effects of the naturally occurring susceptibility alleles of Il2. Reduced IL-2 production achieved by either genetic mechanism correlates with reduced function of CD4(+) CD25(+) regulatory T cells, which are critical for maintaining immune homeostasis.

Successful rituximab treatment in an elderly patient with recurrent thrombotic thrombocytopenic purpura.

An 81-year-old man presenting with fever, neurological symptoms, thrombocytopenia, and hemolytic anemia was diagnosed with acquired idiopathic thrombotic thrombocytopenic purpura (TTP). His disintegrin-like and metalloproteinase with thrombospondin type 1 motifs 13 (ADAMTS13) activity was <1% and the ADAMTS13 inhibitor titer was 3.2 BU/ml. He received plasma exchange and steroid administration until remission was achieved. Seven months later, he suffered from paralysis of the right hand, hemolytic anemia, and thrombocytopenia. We confirmed TTP recurrence based on ADAMTS13 activity <1% and an ADAMTS13 inhibitor titer of 19.4 BU/ml. Four infusions of rituximab were administered in addition to plasma exchange and steroid pulse therapy. Platelet count recovery was observed within 5 days. No severe side effects related to rituximab occurred. Although rituximab has not been approved for TTP in Japan, we report the efficacy and safety of rituximab in an elderly patient with recurrent TTP. We suggest that rituximab therapy should be started as soon as possible for recurrent TTP in patients with high titers of ADAMTS13 inhibitor.

IL-2 promotes the function of memory-like autoregulatory CD8+ T cells but suppresses their development via FoxP3+ Treg cells.

IL-2 plays a critical role in both effector T-cell development and FoxP3(+) CD4(+) Treg-cell homeostasis. A reduction in Il2 transcription results in impaired FoxP3(+) CD4(+) Treg-cell recruitment and function, and accounts for the association between murine Il2 and type 1 diabetes (T1D). The progression of T1D elicits a disease-countering negative feedback regulatory loop that involves the differentiation of low-avidity autoreactive CD8(+) T cells into memory-like autoregulatory T cells in a CD4(+) Th-dependent manner. Since these auto-regulatory T cells express IL-2Rß (CD122), we hypothesized that their development might also be regulated by IL-2. Here, we investigate the effects of differences in IL-2 expression on this autoregulatory subset. We show that decreased IL-2 production impairs the regulatory capacity of memory-like autoregulatory CD8(+) CD122(+) T cells. Surprisingly, we also find that a reduction in IL-2 production capacity increases memory autoregulatory CD8(+) T-cell formation indirectly, by decreasing the development and function of FoxP3(+) Treg cells in nonobese diabetic mice. These results illustrate a complex homeostatic interplay between IL-2, CD4(+) Th cells, FoxP3(+) CD4(+) Treg cells and autoregulatory CD8(+) T-cell memory whereby IL-2 controls the function of both Treg-cell subsets, but IL-2-potentiation of FoxP3(+) CD4(+) Treg-cell function results in the suppression of CD4(+) Th-cell activation and autoregulatory memory CD8(+) T-cell formation.

Analysis of chemotherapy-induced neutropenia and optimal timing for prophylactic use of G-CSF in B-cell non-Hodgkin lymphoma patients treated with R-CHOP.

BACKGROUND: Febrile neutropenia (FN) is one of the serious complications of chemotherapy. However, the hematological nadir after chemotherapy and the timing of prophylaxis for FN remain unclear, especially for outpatients. METHODS: We prospectively analyzed laboratory data from outpatients treated with a single chemotherapy regimen, rituximab (R)-CHOP, on three consultation days (days 8, 10, and 15) after chemotherapy to identify any factors that might predict the onset of the hematological nadir and the optimal timing of G-CSF prophylaxis. RESULTS: A total of 100 courses of chemotherapy (total 33 patients) were analyzed. Onset of the hematological nadir was not predictable in any of the patients who had a white blood cell count (WBC) of >5,500 × 10(6)/L and/or monocyte count of >80 × 10(6)/L on day 8, and thus there was little opportunity for G-CSF prophylaxis in each treatment course. Among patients who had a WBC count of 1,500-5,500 × 10(6)/L on day 8, the monocyte count on day 8 was significantly associated with the hematological nadir. Patients who had a monocyte count of <5 × 10(6)/L on day 8, were identified as a high-risk group for neutropenia for whom G-CSF administration during the current treatment course should be considered. CONCLUSION: Our results indicate that, in outpatients receiving R-CHOP chemotherapy, the monocyte count on day 8 is a useful marker of the hematological nadir, allowing an opportunity for G-CSF prophylaxis.

A Novel Splice Donor Site Mutation Leading to Inherited Type I Protein S Deficiency.

Inherited Protein S (PS) deficiency is an autosomal dominant thrombotic disorder. We encountered a case of inherited type I PS deficiency following a close examination for recurrent pregnancy loss and identified the mutation responsible; a novel splice donor site mutation in intron 13 of the PROS1 gene appeared to have caused a frameshift with premature termination at amino acid +551. These results will contribute to the creation of an accurate database and define the molecular basis for PS deficiency.

Reference guide for the diagnosis of adult primary immune thrombocytopenia, 2023 edition.

Primary immune thrombocytopenia (ITP) is an autoimmune disorder characterized by isolated thrombocytopenia due to accelerated platelet destruction and impaired platelet production. Diagnosis of ITP is still challenging because ITP has been diagnosed by exclusion. Exclusion of thrombocytopenia due to bone marrow failure is especially important in Japan because of high prevalence of aplastic anemia compared to Western countries. Hence, we propose a new diagnostic criteria involving the measurement of plasma thrombopoietin (TPO) levels and percentage of immature platelet fraction (RP% or IPF%); 1) isolated thrombocytopenia with no morphological evidence of dysplasia in any blood cell type in a blood smear, 2) normal or slightly increased plasma TPO level (< cutoff), 3) elevated RP% or IPF% (> upper limit of normal), and 4) absence of other conditions that potentially cause thrombocytopenia including secondary ITP. A diagnosis of ITP is made if conditions 1-4 are all met. Cases in which criterion 2 or 3 is not met or unavailable are defined as "possible ITP," and diagnosis of ITP can be made mainly by typical clinical course. These new criteria enable us to clearly differentiate ITP from aplastic anemia and other forms of hypoplastic thrombocytopenia and can be highly useful in clinical practice for avoiding unnecessary bone marrow examination as well as for appropriate selection of treatments.

Antiplatelet effects of hydroxychloroquine in patients with systemic lupus erythematosus evaluated by the total thrombus-formation analysis system (T-TAS).

OBJECTIVES: Hydroxychloroquine (HCQ) has been shown to reduce thrombotic events in patients with SLE. However, the antiplatelet effects of HCQ are only supported by the platelet aggregation assay, which is a non-physiological test. The total thrombus-formation analysis system (T-TAS) is a microchip-based flow chamber system that mimics physiological conditions and allows for the quantitative analysis of thrombogenicity. The present study investigated the antiplatelet effects of HCQ using T-TAS. METHODS: This was a single-centre cross-sectional study on 57 patients with SLE. We measured the area under the pressure curve for 10 min (PL-AUC10) and the time to 10 kPa (T10) in patients with SLE using T-TAS and examined their relationships with the use of HCQ. PL-AUC10 and platelet aggregation were also measured at several HCQ concentrations using blood samples from healthy donors. RESULTS: PL-AUC10 was significantly lower in the HCQ/real body weight (RBW) ≥5 mg/kg group than in the <5 mg/kg group, while T10 was similar, indicating that HCQ inhibited overall thrombus formation rather than the initiation of thrombus formation. The antiplatelet effects of HCQ were initially detected at HCQ/RBW of approximately 4 mg/kg and reached a plateau at around 5.5 mg/kg. The administration of HCQ/RBW >4.6 mg/kg clearly exerted antiplatelet effects. Additionally, HCQ inhibited thrombus formation in T-TAS and the platelet aggregation response to epinephrine in a dose-dependent manner. CONCLUSIONS: We demonstrated the antiplatelet effects of HCQ under conditions simulating the physiological environment by using T-TAS and identified the range of doses at which HCQ exerted antiplatelet effects.

Empirical voriconazole therapy for febrile neutropenic patients with hematological disorders: a prospective multicenter trial in Japan.

An open-label, prospective, multicenter study was conducted between October 2006 and March 2010 to assess the efficacy and safety of intravenous voriconazole (VRCZ) as empirical therapy for antibiotic-refractory febrile neutropenia in Japanese patients with hematological disorders. In addition, to find the patient groups that may benefit from antifungal therapy, the definition of invasive fungal infection proposed by EORTC/MSG (2002) was assessed in this study. Plasma (1-3)-ß-D-glucan and Aspergillus PCR in blood were also measured to improve the diagnostic accuracy. A total of 103 patients (median age, 59 years), including 25 undergoing induction chemotherapies and 19 allogeneic hematopoietic cell transplants, were evaluable. Sixty-nine percent of the patients achieved resolution of clinical symptoms and 31% achieved treatment success, defined as fulfilling the previously described five-part composite endpoint. Although VRCZ was discontinued in 9.7% of the patients because of adverse effects, all the patients recovered soon after discontinuation of VRCZ. The treatment success rate of VRCZ appeared to be higher in patients categorized as "not classified" compared with "possible invasive fungal disease" according to the EORTC/MSG criteria. Moreover, six "not classified" patients were positive for either plasma (1-3)-ß-D-glucan (n = 5) or Aspergillus PCR in blood (n = 2). The present study demonstrates that empirical VRCZ therapy is safe and effective in Japanese patients. Additionally, (1-3)-ß-D-glucan and Aspergillus PCR tests were expected to provide additional information on the diagnosis of invasive fungal infections.

In situ recognition of autoantigen as an essential gatekeeper in autoimmune CD8+ T cell inflammation.

A current paradigm states that non-antigen-specific inflammatory cues attract noncognate, bystander T cell specificities to sites of infection and autoimmune inflammation. Here we show that cues emanating from a tissue undergoing spontaneous autoimmune inflammation cannot recruit naive or activated bystander T cell specificities in the absence of local expression of cognate antigen. We monitored the recruitment of CD8(+) T cells specific for the prevalent diabetogenic epitope islet-specific glucose-6-phosphatase catalytic subunit-related protein (IGRP)(206-214) in gene-targeted nonobese diabetic (NOD) mice expressing a T cell "invisible" IGRP(206-214) sequence. These mice developed islet inflammation and diabetes with normal incidence and kinetics, but their inflammatory lesions could recruit neither naive (endogenous or exogenous) nor ex vivo-activated IGRP(206-214)-reactive CD8(+) T cells. Conversely, IGRP(206-214)-reactive, but not nonautoreactive CD8(+) T cells rapidly homed to and accumulated in the inflamed islets of wild-type NOD mice. Our results indicate that CD8(+) T cell recruitment to a site of autoimmune inflammation results from an active process that is strictly dependent on local display of cognate pMHC and suggest that CD8(+) T cells contained in extralymphoid autoimmune lesions are largely autoreactive.

[Rituximab for managing refractory thrombotic thrombocytopenic purpura: a report of three cases].

About 20% of TTP are resistant to plasma exchange. As reported in a few case reports and small case series, rituximab has been used in the treatment of TTP with some benefit. However, the optimal dosing, frequency, and timing of rituximab remain to be determined. We treated three cases of refractory TTP with rituximab. Case 1 exhibited brain sequelae probably due to the late administration of rituximab, case 2 died before the expected effect of rituximab could occur, and case 3 recovered completely because of the early administration of rituximab. These results suggest that rituximab should be given as early as possible in TTP, but large clinical studies are required to determine the optimal use of rituximab in TTP.

Transcriptional re-programming of insulin B-chain epitope-specific T-follicular helper cells into anti-diabetogenic T-regulatory type-1 cells.

Systemic delivery of nanoparticles (NPs) coated with mono-specific autoimmune disease-relevant peptide-major histocompatibility complex class II (pMHCII) molecules can resolve organ inflammation in various disease models in a disease-specific manner without impairing normal immunity. These compounds invariably trigger the formation and systemic expansion of cognate pMHCII-specific T-regulatory type 1 (TR1) cells. By focusing on type 1 diabetes (T1D)-relevant pMHCII-NP types that display an epitope from the insulin B-chain bound to the same MHCII molecule (IAg7) on three different registers, we show that pMHCII-NP-induced TR1 cells invariably co-exist with cognate T-Follicular Helper (TFH)-like cells of quasi-identical clonotypic composition and are oligoclonal, yet transcriptionally homogeneous. Furthermore, these three different TR1 specificities have similar diabetes reversal properties in vivo despite being uniquely reactive against the peptide MHCII-binding register displayed on the NPs. Thus, pMHCII-NP treatment using nanomedicines displaying different epitope specificities results in the simultaneous differentiation of multiple antigen-specific TFH-like cell clones into TR1-like cells that inherit the fine antigenic specificity of their precursors while acquiring a defined transcriptional immunoregulatory program.

A T follicular helper cell origin for T regulatory type 1 cells.

Chronic antigenic stimulation can trigger the differentiation of antigen-experienced CD4+ T cells into T regulatory type 1 (TR1) cells, a subset of interleukin-10-producing Treg cells that do not express FOXP3. The identities of the progenitor(s) and transcriptional regulators of this T-cell subset remain unclear. Here, we show that the peptide-major histocompatibility complex class II (pMHCII) monospecific immunoregulatory T-cell pools that arise in vivo in different genetic backgrounds in response to pMHCII-coated nanoparticles (pMHCII-NPs) are invariably comprised of oligoclonal subpools of T follicular helper (TFH) and TR1 cells with a nearly identical clonotypic composition but different functional properties and transcription factor expression profiles. Pseudotime analyses of scRNAseq data and multidimensional mass cytometry revealed progressive downregulation and upregulation of TFH and TR1 markers, respectively. Furthermore, pMHCII-NPs trigger cognate TR1 cell formation in TFH cell-transfused immunodeficient hosts, and T-cell-specific deletion of Bcl6 or Irf4 blunts both the TFH expansion and TR1 formation induced by pMHCII-NPs. In contrast, deletion of Prdm1 selectively abrogates the TFH-to-TR1 conversion. Bcl6 and Prdm1 are also necessary for anti-CD3 mAb-induced TR1 formation. Thus, TFH cells can differentiate into TR1 cells in vivo, and BLIMP1 is a gatekeeper of this cellular reprogramming event.