Identification of a public CDR3 motif and a biased utilization of T-cell receptor V beta and J beta chains in HLA-A2/Melan-A-specific T-cell clonotypes of melanoma patients

<p>Abstract</p> <p>Background</p> <p>Assessment of T-cell diversity, besides giving insights about the molecular basis of tumor antigen recognition, has clinical implications since it provides criteria for evaluating antigen-specific T cells clinically relevant for spontaneous and vaccine-induced anti-tumor activity. Melan-A is one of the melanoma antigens most frequently recognized by peripheral and tumor-infiltrating lymphocytes in HLA-A2+ melanoma patients. Many clinical trials involving anti-tumor vaccination have been conducted using modified versions of this peptide.</p> <p>Methods</p> <p>We conducted an in-depth characterization of 210 T-cell receptor beta chain (TRB) clonotypes derived from T cells of HLA-A2+ melanoma patients displaying cytotoxic activity against natural and A27L-modified Melan-A peptides. One hundred and thirteen Melan-A-specific clonotypes from melanoma-free subjects, 199 clonotypes from T-cell clones from melanoma patients specific for melanoma antigens other than Melan-A, and 305 clonotypes derived from T cells of HLA-A2+ individuals showing unrelated specificities, were used as control. After sequence analysis, performed according to the IMGT definitions, TRBV and TRBJ usage, CDR3 length and amino acid composition were compared in the four groups of clonotypes.</p> <p>Results</p> <p>TRB sequences of Melan-A-specific clonotypes obtained from melanoma patients were highly heterogeneous, but displayed a preferential usage of few TRBV and TRBJ segments. Furthermore, they included a recurrent "public" amino acid motif (Glycine-Leucine-Glycine at positions 110-112-113 of the CDR3) rearranged with dominant TRBV and TRBJ segments and, in one case, associated with a full conservation of the entire TRB sequence.</p> <p>Conclusion</p> <p>Contrary to what observed for public anti-Melan-A T-cell receptor alpha motifs, which had been identified in several clonotypes of both melanoma patients and healthy controls, the unexpectedly high contribution of a public TRB motif in the recognition of a dominant melanoma epitope in melanoma patients may provide important information about the biology of anti-tumor T-cell responses and improve monitoring strategies of anti-tumor vaccines.</p

Peripheral accumulation of newly produced T and B lymphocytes in natalizumab-treated multiple sclerosis patients

The anti-α4 monoclonal antibody natalizumab inhibits lymphocyte extravasation into the central nervous system and increases peripheral T and B lymphocytes in multiple sclerosis patients. To investigate whether the lymphocyte accumulation was due to a higher lymphocyte production, an altered homeostasis, or a differential transmigration of lymphocyte subsets through endothelia, T-cell receptor excision circles and kappa-deleting recombination excision circles were quantified before and after treatment, T-cell receptor repertoire was analyzed by spectratyping, and T- and B-lymphocyte subset migration was studied using transwell coated with vascular and lymphatic endothelial cells. We found that the number of newly produced T and B lymphocytes is increased because of a high release and of a low propensity of naïve subsets to migrate across endothelial cells. In some patients this resulted in an enlargement of T-cell heterogeneity. Because new lymphocyte production ensures the integrity of immune surveillance, its quantification could be used to monitor natalizumab therapy safety

Effects of combined antiretroviral therapy on B- and T-cell release from production sites in long-term treated HIV-1+ patients

BACKGROUND: The immune system reconstitution in HIV-1- infected patients undergoing combined antiretroviral therapy is routinely evaluated by T-cell phenotyping, even though the infection also impairs the B-cell mediated immunity. To find new laboratory markers of therapy effectiveness, both B- and T- immune recovery were evaluated by means of a follow-up study of long-term treated HIV-1- infected patients, with a special focus on the measure of new B- and T-lymphocyte production. METHODS: A longitudinal analysis was performed in samples obtained from HIV-1-infected patients before therapy beginning and after 6, 12, and 72 months with a duplex real-time PCR allowing the detection of K-deleting recombination excision circles (KRECs) and T-cell receptor excision circles (TRECs), as measures of bone-marrow and thymic output, respectively. A cross sectional analysis was performed to detect B- and T-cell subsets by flow cytometry in samples obtained at the end of the follow-up, which were compared to those of untreated HIV-1-infected patients and uninfected controls. RESULTS: The kinetics and the timings of B- and T-cell release from the bone marrow and thymus during antiretroviral therapy were substantially different, with a decreased B-cell release and an increased thymic output after the prolonged therapy. The multivariable regression analysis showed that a longer pre-therapy infection duration predicts a minor TREC increase and a major KREC reduction. CONCLUSIONS: The quantification of KRECs and TRECs represents an improved method to monitor the effects of therapies capable of influencing the immune cell pool composition in HIV-1-infected patients

Simultaneous quantification of natural and inducible regulatory T-cell subsets during interferon-\u3b2 therapy of multiple sclerosis patients

The mechanisms underlying the therapeutic activity of interferon-\u3b2 in multiple sclerosis are still not completely understood. In the present study, we evaluated the short and long-term effects of interferon-\u3b2 treatment on different subsets of regulatory T cells in relapsing-remitting multiple sclerosis patients biologically responsive to treatment because of mixovirus resistance&nbsp;protein A inducibility

Sequential monitoring of lymphocyte subsets and of T-and-B cell neogenesis indexes to identify time-varying immunologic profiles in relation to graft-versus-host disease and relapse after allogeneic stem cell transplantation

T and B lymphocyte subsets have been not univocally associated to Graft-versus-host disease (GVHD) and relapse of hematological alignancies after stem cell transplantation (SCT). Their sequential assessment together with B and T cell neogenesis indexes has been not thoroughly analysed in relation to these changing and interrelated immunologic/clinic events yet. Lymphocyte subsets in peripheral blood (PB) and B and T cell neogenesis indexes were analysed together at different time points in a prospective study of 50 patients. Principal component analysis (PCA) was used as first step of multivariate analysis to address issues related to a high number of variables versus a relatively low number of patients. Multivariate analysis was completed by Fine-Gray proportional hazard regression model. PCA identified 3 clusters of variables (PC1-3), which correlated with acute GVHD: PC1 (pre-SCT: KRECs 656608/ml, unswitched memory B 44%, CD8+TCM cells>4%; HR 1.9, p = 0.01), and PC3 (at aGVHD onset: CD4+TEMRA69%, switched memory CD19+ = 0 cells and KRECs<6614/ml at +90; HR 0.1, p = 0.008). All these immunologic parameters were independent indicators of chronic GVHD and relapse, also considering the possible effect of previous steroid-therapy for acute GVHD. Specific time-varying immunologic profiles were associated to GVHD and relapse. Pre-SCT host immune-microenvironment and changes of B cell homeostasis could influence GVH- and Graft-versus-Tumor reactions. The paradoxical increase of EM Treg in PB of patients with GVHD could be explained by their compartmentalization outside lymphoid tissues, which are of critical relevance for regulation of GVH reactions

Pre-Existing T- and B-Cell Defects in One Progressive Multifocal Leukoencephalopathy Patient

Progressive multifocal leukoencephalopathy (PML) usually occurs in patients with severe immunosuppression, hematological malignancies, chronic inflammatory conditions or receiving organ transplant. Recently, PML has also been observed in patients treated with monoclonal antibodies. By taking advantage of the availability of samples from a multiple sclerosis (MS) patient treated with natalizumab, the antibody anti-α4 integrin, who developed PML and was monitored starting before therapy initiation, we investigated the fate of T and B lymphocytes in the onset of PML. Real-time PCR was used to measure new T- and B-cell production by means of T-cell receptor excision circle (TREC) and K-deleting recombination excision circle (KREC) analysis and to quantify transcripts for CD34, terminal-deoxynucleotidyltransferase, and V pre-B lymphocyte gene 1. T- and B-cell subsets and T-cell heterogeneity were measured by flow cytometry and spectratyping. The data were compared to those of untreated and natalizumab-treated MS patients and healthy donors. Before therapy, a patient who developed PML had a low TREC and KREC number; TRECs remained low, while KRECs and pre-B lymphocyte gene 1 transcripts peaked at 6 months of therapy and then decreased at PML diagnosis. Flow cytometry confirmed the deficient number of newly produced T lymphocytes, counterbalanced by an increase in TEMRA cells. The percentage of naive B cells increased by approximately 70% after 6 months of therapy, but B lymphocyte number remained low for the entire treatment period. T-cell heterogeneity and immunoglobulins were reduced

Immunopathological signatures in multisystem inflammatory syndrome in children and pediatric COVID-19

: Pediatric Coronavirus Disease 2019 (pCOVID-19) is rarely severe; however, a minority of children infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) might develop multisystem inflammatory syndrome in children (MIS-C), with substantial morbidity. In this longitudinal multi-institutional study, we applied multi-omics (analysis of soluble biomarkers, proteomics, single-cell gene expression and immune repertoire analysis) to profile children with COVID-19 (n = 110) and MIS-C (n = 76), along with pediatric healthy controls (pHCs; n = 76). pCOVID-19 was characterized by robust type I interferon (IFN) responses, whereas prominent type II IFN-dependent and NF-κB-dependent signatures, matrisome activation and increased levels of circulating spike protein were detected in MIS-C, with no correlation with SARS-CoV-2 PCR status around the time of admission. Transient expansion of TRBV11-2 T cell clonotypes in MIS-C was associated with signatures of inflammation and T cell activation. The association of MIS-C with the combination of HLA A*02, B*35 and C*04 alleles suggests genetic susceptibility. MIS-C B cells showed higher mutation load than pCOVID-19 and pHC. These results identify distinct immunopathological signatures in pCOVID-19 and MIS-C that might help better define the pathophysiology of these disorders and guide therapy

Vaccine breakthrough hypoxemic COVID-19 pneumonia in patients with auto-Abs neutralizing type I IFNs

Life-threatening `breakthrough' cases of critical COVID-19 are attributed to poor or waning antibody response to the SARS- CoV-2 vaccine in individuals already at risk. Pre-existing autoantibodies (auto-Abs) neutralizing type I IFNs underlie at least 15% of critical COVID-19 pneumonia cases in unvaccinated individuals; however, their contribution to hypoxemic breakthrough cases in vaccinated people remains unknown. Here, we studied a cohort of 48 individuals ( age 20-86 years) who received 2 doses of an mRNA vaccine and developed a breakthrough infection with hypoxemic COVID-19 pneumonia 2 weeks to 4 months later. Antibody levels to the vaccine, neutralization of the virus, and auto- Abs to type I IFNs were measured in the plasma. Forty-two individuals had no known deficiency of B cell immunity and a normal antibody response to the vaccine. Among them, ten (24%) had auto-Abs neutralizing type I IFNs (aged 43-86 years). Eight of these ten patients had auto-Abs neutralizing both IFN-a2 and IFN-., while two neutralized IFN-omega only. No patient neutralized IFN-ss. Seven neutralized 10 ng/mL of type I IFNs, and three 100 pg/mL only. Seven patients neutralized SARS-CoV-2 D614G and the Delta variant (B.1.617.2) efficiently, while one patient neutralized Delta slightly less efficiently. Two of the three patients neutralizing only 100 pg/mL of type I IFNs neutralized both D61G and Delta less efficiently. Despite two mRNA vaccine inoculations and the presence of circulating antibodies capable of neutralizing SARS-CoV-2, auto-Abs neutralizing type I IFNs may underlie a significant proportion of hypoxemic COVID-19 pneumonia cases, highlighting the importance of this particularly vulnerable population

Lack of specific T- and B-cell clonal expansions in multiple sclerosis patients with progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) is a rare, potentially devastating myelin-degrading disease caused by the JC virus. PML occurs preferentially in patients with compromised immune system, but has been also observed in multiple sclerosis (MS) patients treated with disease-modifying drugs. We characterized T and B cells in 5 MS patients that developed PML, 4 during natalizumab therapy and one after alemtuzumab treatment, and in treated patients who did not develop the disease. Results revealed that: i) thymic and bone marrow output was impaired in 4 out 5 patients at the time of PML development; ii) T-cell repertoire was restricted; iii) clonally expanded T cells were present in all patients. However, common usage or pairings of T-cell receptor beta variable or joining genes, specific clonotypes or obvious "public" T-cell response were not detected at the moment of PML onset. Similarly, common restrictions were not found in the immunoglobulin heavy chain repertoire. The data indicate that no JCV-related specific T- and B-cell expansions were mounted at the time of PML. The current results enhance our understanding of JC virus infection and PML, and should be taken into account when choosing targeted therapies