Usefulness of IL-21, IL-7, and IL-15 conditioned media for expansion of antigen-specific CD8+ T cells from healthy donor-PBMCs suitable for immunotherapy.

Clonal anergy and depletion of antigen-specific CD8+ T cells are characteristics of immunosuppressed patients such as cancer and post-transplant patients. This has promoted translational research on the adoptive transfer of T cells to restore the antigen-specific cellular immunity in these patients. In the present work, we compared the capability of PBMCs and two types of mature monocyte-derived DCs (moDCs) to prime and to expand ex-vivo antigen-specific CD8+ T cells using culture conditioned media supplemented with IL-7, IL-15, and IL-21. The data obtained suggest that protocols involving moDCs are as efficient as PBMCs-based cultures in expanding antigen-specific CD8+ T cell to ELA and CMV model epitopes. These three gamma common chain cytokines promote the expansion of naïve-like and central memory CD8+ T cells in PBMCs-based cultures and the expansion of effector memory T cells when moDCs were used. Our results provide new insights into the use of media supplemented with IL-7, IL-15, and IL-21 for the in-vitro expansion of early-differentiated antigen-specific CD8+ T cells for immunotherapy purposes.

Monitoring the responsiveness of T and antigen presenting cell compartments in breast cancer patients is useful to predict clinical tumor response to neoadjuvant chemotherapy.

BACKGROUND: Vaccination of mice with tumors treated with Doxorubicin promotes a T cell immunity that relies on dendritic cell (DC) activation and is responsible for tumor control in vaccinated animals. Despite Doxorubicin in combination with Cyclophosphamide (A/C) is widely used to treat breast cancer patients, the stimulating effect of A/C on T and APC compartments and its correlation with patient's clinical response remains to be proved. METHODS: In this prospective study, we designed an in vitro system to monitor various immunological readouts in PBMCs obtained from a total of 17 breast cancer patients before, and after neoadjuvant anti-tumor therapy with A/C. RESULTS: The results show that before treatment, T cells and DCs, exhibit a marked unresponsiveness to in vitro stimulus: whereas T cells exhibit poor TCR internalization and limited expression of CD154 in response to anti-CD3/CD28/CD2 stimulation, DCs secrete low levels of IL-12p70 and limited CD83 expression in response to pro-inflammatory cytokines. Notably, after treatment the responsiveness of T and APC compartments was recovered, and furthermore, this recovery correlated with patients' residual cancer burden stage. CONCLUSIONS: Our results let us to argue that the model used here to monitor the T and APC compartments is suitable to survey the recovery of immune surveillance and to predict tumor response during A/C chemotherapy.

Autologous Dendritic Cells in Combination With Chemotherapy Restore Responsiveness of T Cells in Breast Cancer Patients: A Single-Arm Phase I/II Trial.

Introduction: Animal studies and preclinical studies in cancer patients suggest that the induction of immunogenic cell death (ICD) by neoadjuvant chemotherapy with doxorubicin and cyclophosphamide (NAC-AC) recovers the functional performance of the immune system. This could favor immunotherapy schemes such as the administration of antigen-free autologous dendritic cells (DCs) in combination with NAC-AC to profit as cryptic vaccine immunogenicity of treated tumors. Objective: To explore the safety and immunogenicity of autologous antigen-free DCs administered to breast cancer patients (BCPs) in combination with NAC-AC. Materials and Methods: A phase I/II cohort clinical trial was performed with 20 BCPs treated with NAC-AC [nine who received DCs and 11 who did not (control group)]. The occurrence of adverse effects and the functional performance of lymphocytes from BCPs before and after four cycles of NAC-AC receiving DCs or not were assessed using flow cytometry and compared with that from healthy donors (HDs). Flow cytometry analysis using manual and automated algorithms led us to examine functional performance and frequency of different lymphocyte compartments in response to a stimulus in vitro. This study was registered at clinicaltrials.gov (NCT03450044). Results: No grade II or higher adverse effects were observed associated with the transfer of DCs to patients during NAC-AC. Interestingly, in response to the in vitro stimulation, deficient phosphorylation of Zap70 and AKT proteins observed before chemotherapy in most patients' CD4 T cells significantly recovered after NAC-AC only in patients who received DCs. Conclusions: The transfer of autologous DCs in combination with NAC-AC in BCPs is a safe procedure. That, in BCPs, the administration of DCs in combination with NAC-AC favors the recovery of the functional capacity of T cells suggests that this combination may potentiate the adjuvant effect of ICD induced by NAC-AC on T cells and, hence, potentiate the immunogenicity of tumors as cryptic vaccines.

Active and latent tuberculosis among inmates in La Esperanza prison in Guaduas, Colombia.

INTRODUCTION: Active tuberculosis (TB) and latent tuberculosis infection (LTBI) are a public health threat in prisons around the world. The objectives of the study were to estimate the prevalence of LTBI and TB as well as to investigate TB transmission inside one prison, in Colombia. METHODS: A Cross-sectional study was conducted in inmates who agreed to participate. Inmates with respiratory symptoms (RS) of any duration underwent to medical evaluation and three sputum samples were taken for smear microscopy and culture for TB diagnosis. Drug susceptibility was analyzed using BACTEC MGIT 960 and GenoType MTBDRplus. Molecular genotyping of Mycobacterium tuberculosis isolates was performed by 24-Locus MIRU-VNTR and spoligotyping. LTBI was evaluated according to the result of the tuberculin skin test (TST). Close contact investigation was conducted inside the prison for inmates that shared the cell with the index TB case. RESULTS: Among 301/2,020 (15%) inmates with RS of any duration, 8% were diagnosed with active TB. The prevalence of active TB was 1,026 cases/100,000 inmates. We isolated M. tuberculosis in 19/24 (79%) TB cases, 94.7% were susceptible to first line drugs and only one was monoresistant to isoniazid. The most prevalent sub-lineage was Haarlem (68.4%), followed by LAM (26.3%) and T superfamily (5.3%). 24-Locus MIRU-VNTR typing results alone or in combination with spoligotyping identified three clusters containing two isolates each. Two clusters corresponded to inmates that shared the same cell, but each one was located in different blocks of the prison. Inmates from the last cluster were in the same block in nearby cells. TST reading was performed in 95.6% inmates, and 67.6% had a positive reaction. CONCLUSIONS: The prevalence of LTBI and TB was higher in prison than in the general population. Molecular genotyping suggests that TB in this prison is mainly caused by strains imported by inmates or endogenous reactivation.

Comparative genomic analysis of Mycobacterium tuberculosis Beijing-like strains revealed specific genetic variations associated with virulence and drug resistance.

Isolates of the Mycobacterium tuberculosis lineage 2/East-Asian are considered one of the most successful strains due to their increased pathogenicity, hyper-virulence associated with drug resistance, and high transmission. Recent studies in Colombia have shown that the Beijing-like genotype is associated with multidrug-resistance and high prevalence in the southwest of the country, but the genetic basis of its success in dissemination is unknown. In contribution to this matter, we obtained the whole sequences of six genomes of clinical isolates assigned to the Beijing-like genotype. The genomes were compared with the reference genome of M. tuberculosis H37Rv and 53 previously published M. tuberculosis genomes. We found that the six Beijing-like isolates belong to a modern Beijing sub-lineage and share specific genomic variants: i.e. deletion in the PPE8 gene, in Rv3806c (ubiA) responsible of high ethambutol resistance and in Rv3862c (whiB6) which is involved in granuloma formation and virulence, are some of them. Moreover, each isolated has exclusively single nucleotide polymorphisms (SNPs) in genes related with cell wall processes and cell metabolism. We identified polymorphisms in genes related to drug resistance that could explain the drug-resistant phenotypes found in the six isolates from Colombia. We hypothesize that changes due to these genetic variations contribute to the success of these strains. Finally, we analyzed the IS6110 insertion sequences finding very low variance between them, suggesting that SNPs is the major cause of variability found in Beijing-like strains circulating in Colombia.

Circulating human rotavirus specific CD4 T cells identified with a class II tetramer express the intestinal homing receptors α4ß7 and CCR9.

Using a consensus epitope prediction approach, three rotavirus (RV) peptides that induce cytokine secretion by CD4 T cells from healthy volunteers were identified. The peptides were shown to bind HLA-DRB1*0101 and then used to generate MHC II tetramers. RV specific T cell lines specific for one of the three peptides studied were restricted by MHC class II molecules and contained T cells that bound the tetramer and secreted cytokines upon activation with the peptide. The majority of RV and Flu tetramer(+) CD4 T cells in healthy volunteers expressed markers of antigen experienced T cells, but only RV specific CD4 T cells expressed intestinal homing receptors. CD4 T cells from children that received a RV vaccine, but not placebo recipients, were stained with the RV-VP6 tetramer and also expressed intestinal homing receptors. Circulating RV-specific CD4 T cells represent a unique subset that expresses intestinal homing receptors.

An unstable Th epitope of P. falciparum fosters central memory T cells and anti-CS antibody responses.

Malaria is transmitted by Plasmodium-infected anopheles mosquitoes. Widespread resistance of mosquitoes to insecticides and resistance of parasites to drugs highlight the urgent need for malaria vaccines. The most advanced malaria vaccines target sporozoites, the infective form of the parasite. A major target of the antibody response to sporozoites are the repeat epitopes of the circumsporozoite (CS) protein, which span almost one half of the protein. Antibodies to these repeats can neutralize sporozoite infectivity. Generation of protective antibody responses to the CS protein (anti-CS Ab) requires help by CD4 T cells. A CD4 T cell epitope from the CS protein designated T* was previously identified by screening T cells from volunteers immunized with irradiated P. falciparum sporozoites. The T* sequence spans twenty amino acids that contains multiple T cell epitopes restricted by various HLA alleles. Subunit malaria vaccines including T* are highly immunogenic in rodents, non-human primates and humans. In this study we characterized a highly conserved HLA-DRß1*04:01 (DR4) restricted T cell epitope (QNT-5) located at the C-terminus of T*. We found that a peptide containing QNT-5 was able to elicit long-term anti-CS Ab responses and prime CD4 T cells in HLA-DR4 transgenic mice despite forming relatively unstable MHC-peptide complexes highly susceptible to HLA-DM editing. We attempted to improve the immunogenicity of QNT-5 by replacing the P1 anchor position with an optimal tyrosine residue. The modified peptide QNT-Y formed stable MHC-peptide complexes highly resistant to HLA-DM editing. Contrary to expectations, a linear peptide containing QNT-Y elicited almost 10-fold lower long-term antibody and IFN-γ responses compared to the linear peptide containing the wild type QNT-5 sequence. Some possibilities regarding why QNT-5 is more effective than QNT-Y in inducing long-term T cell and anti-CS Ab when used as vaccine are discussed.

Characterizing cellular immune response to kinetoplastid membrane protein-11 (KMP-11) during Leishmania (Viannia) panamensis infection using dendritic cells (DCs) as antigen presenting cells (APCs).

In vitro peptide binding assays and DCs pulsed with recombinant KMP-11 (rKMP-11) plus six 20-mer overlapping peptides covering the entire protein of Leishmania (Viannia) panamensis (L(V)p) promastigotes were used to identify T-cell epitopes in this protein. Such in vitro binding assays, using HLA DRB1* 0101, -0401, -0701 and -1101 alleles, demonstrated that two peptide sequences (DEEFNKKMQEQNAKFFADKP and FKHKFAELLEQQKAAQYPSK) exhibited high HLA DRB1* 0401 allele binding capacity. rKMP-11 specific T-cell proliferation and cytokine production, derived from 13 volunteers exposed to the parasite, suggested that using autologous DCs as APCs becomes advantageous in uncovering T-cell epitopes promoting proliferation and differences in IFN-gamma and IL-4 production in T-cells from volunteers with ACTIVE and CURED undetectable disease when other APCs were used. The two peptides which bound in vitro to the HLA DRB1* 0401 allele were immunogenic in HLA DRB1* 04 volunteers, thus validating the use of in vitro binding assays for predicting epitopes in this protein. The experimental approach used here may prove useful for characterizing T-cell epitopes in a protein useful in designing peptide-based vaccine candidates for Leishmania and other intracellular pathogens.