Teena Mohan

Modulation of HIV peptide antigen specific cellular immune response by synthetic α- and β-defensin peptides

Defensin peptides have their direct role in host defense against microbial infection as innate molecules and also thought to contribute to adaptive immunity by recruiting naïve T-cells and immature dendritic cells at the site of infection through CCR6 receptor. The main aim of the present study is to investigate the efficacy of defensins for the induction of cell mediated immune response against the peptide antigen of HIV-1 encapsulated in PLG microparticles through intranasal (IN) route in mice model. To characterized, we have analyzed T-cell proliferation, Th1/Th2 cytokines, β-chemokines production and IFN-γ/perforin secretion from CD4(+)/CD8(+) T-cells in response to HIV immunogen alone and with defensins at different mucosal site i.e. lamina propria (LP), spleen (SP) and peyers patches (PP). The cellular immunogenicity of HIV peptide with defensin formulations showed a significantly higher (p<0.001) proliferation response as compared to individual HIV peptide. The enhanced cytokines measurement profile showed mixed Th1 and Th2 type of peptide specific immune response by the incorporation of defensins. In the continuation, enhancement in MIP-1α and RANTES level was also observed in HIV peptide-defensin formulations. The FACS data had revealed that CD4(+)/CD8(+) T-cells showed significantly (p<0.001) higher IFN-γ and perforin secretion in HIV with defensin peptide formulations than HIV antigen alone group. Thus, the study emphasized here that defensin peptides have a potential role as mucosal adjuvant, might be responsible for the induction of cell mediated immunity when administered in mice through IN route with HIV peptide antigen.

Comparative mucosal immunogenicity of HIV gp41 membrane-proximal external region (MPER) containing single and multiple repeats of ELDKWA sequence with defensin peptides

The MPER of gp41 of HIV-1 has received great attention and is widely recognized as a promising target for the development of AIDS vaccine. We investigated the ability of trirepeat of ELDKWA sequence of gp41 antigen with defensins in liposome using multiple-shot immunization strategy in the mice model. The designed was used to enhance the immunogenicity and exposure of MPER in its native conformation for the induction of MPER-specific HIV-1 neutralizing antibodies. To characterize, we estimated the antibody levels (IgG/IgA) in serum as well as in lung, intestinal, vaginal and rectal washes till day 120 in outbred and inbred (H-2(b) and H-2(d)) mice using liposome as delivery vehicle. The representative sera and washes were also tested for in vitro neutralization with CCR5-tropic Indian HIV-1 primary isolates. We observed that the modified HIV antigen containing trirepeat of ELDKWA with defensins was showing significantly (p<0.001) higher IgG/IgA antibody titre (102,400-204,800) in sera as well as in different mucosal washes (1600-6400) than standard HIV-1 antigen. Furthermore, sera from the modified HIV-1 antigen with defensins found to exhibit higher neutralizing activities (ranging from 59.3% to 84.6%) than the standard HIV-1 antigen. These results show that the induction of MPER-specific HIV-1 neutralizing antibodies could be achieved through a rationally designed vaccine strategy.

Induction of cell-mediated immune responses to peptide antigens of P. vivax in microparticles using intranasal immunization.

T-cells play a critical role in resistance to malaria, not only because they function as helper cells for an antibody response, but also because they serve as effector cells. Such cellular immunity is directly implicated in protection from sporozoites as well as from blood stage parasites. The aim of this study was to induce cell mediated immune responses to peptide antigens of Plasmodium vivax co-encapsulated with CpG oligodeoxynucleotide (ODN) in microparticles. In the present study, we have investigated the immunomodulatory effects of two CpG adjuvants, CpG 1826 and CpG 2006 to the five peptide antigens of Plasmodium vivax derived from circumsporozoite protein, merozoite surface protein-1, apical membrane antigen-1 and gametocyte surface antigen (Pvs24) in microparticle delivery. The T-cell proliferation response study of the cells collected from spleen, lamina propria and peyers patches showed significantly high (p<0.001) stimulation index when primed with peptide antigens in microparticles co-encapsulating CpG ODN adjuvant as compared to peptide alone primed mice. The cytokine measurement profile of IFN-γ, TNF-α, IL-2, IL-4 and IL-10 in culture supernatants of cells primed with peptide antigens in microparticles co-encapsulating CpG ODN showed higher levels of IFN- γ followed by TNF-α and IL-2, with relatively low levels of IL-4 and IL-10.

Coexistence of Th1/Th2 and Th17/Treg imbalances in patients with post traumatic sepsis

INTRODUCTION Multiple organ dysfunction syndrome (MODS) developed due to the insult of trauma is a leading cause of death. The high mortality rate in these patients with and without sepsis has been reported up to 50%, throughout the world and thus required an urgent insight to overcome this problem. OBJECTIVE The aim of this study is to examine the differential changes in subsets of T cells, imbalance in cytokine profile, immune-paralysis (T cell anergy) in Trauma hemorrhagic shock (THS) and post traumatic sepsis patients. METHODOLOGY 114, THS patients and 50 healthy controls were recruited in the present study. We have measured the T cell proliferation assay using dominant antigens of both gram positive (LTA, 100ng/ml) and gram negative (LPS-100ng/ml) bacteria and PHA (4μg/ml) using radioactive thymidine (1H3) assay. Simultaneously, we have measured the culture supernatant level of cytokines using Cytokine bead assay (CBA). The other parts of this study include the analysis of different subsets of T cells. RESULTS AND CONCLUSION We observed significantly (P<0.05) reduced T cell proliferation in THS patients as compared to control. Our study also showed patients died due to sepsis/septic shock, had significantly (p<0.05) lower T cell response and had significantly elevated levels of IL-4, IL-10andTGF-β, but low level of IL-2andIFN-γ in culture supernatant. THS patients who developed sepsis complication had significantly higher T regulatory cells and lower Th17 cells in comparison to non-sepsis. In conclusion, our study showed an imbalance in cell mediated immune response and disturbance in Th1/Th2/Th17 and T reg population of T helper cells and also the shifts towards Th2 and T17 in THS patients who had developed sepsis and showed poor outcomes.

Current understanding of HIV-1 and T-cell adaptive immunity: Progress to date

The cellular immune response to human immunodeficiency virus (HIV) has different components originating from both the adaptive and innate immune systems. HIV cleverly utilizes the host machinery to survive by its intricate nature of interaction with the host immune system. HIV evades the host immune system at innate ad adaptive, allows the pathogen to replicate and transmit from one host to another. Researchers have shown that HIV has multipronged effects especially on the adaptive immunity, with CD4(+) cells being the worst effect T-cell populations. Various analyses have revealed that, the exposure to HIV results in clonal expansion and excessive activation of the immune system. Also, an abnormal process of differentiation has been observed suggestive of an alteration and blocks in the maturation of various T-cell subsets. Additionally, HIV has shown to accelerate immunosenescence and exhaustion of the overtly activated T-cells. Apart from causing phenotypic changes, HIV has adverse effects on the functional aspect of the immune system, with evidences implicating it in the loss of the capacity of T-cells to secrete various antiviral cytokines and chemokines. However, there continues to be many aspects of the immune- pathogenesis of HIV that are still unknown and thus required further research in order to convert the malaise of HIV into a manageable epidemic.

A synthetic chimeric peptide harboring human papillomavirus 16 cytotoxic T lymphocyte epitopes shows therapeutic potential in a murine model of cervical cancer

Abstract Infection with human papillomavirus (HPV) such as HPV16 is known to be associated with cervical cancer. The E6 and E7 oncoproteins of this virus are attractive targets for T-cell-based immunotherapy to cervical cancer. In our study, software predicted, multiple H-2Db restricted HPV16 cytotoxic T lymphocytes (CTL) epitopes on a synthetic chimeric peptide, was used along with different immunopotentiating adjuvants such as alum, heat-killed Mycobacterium w (Mw) cells, and poly d,l-lactic-co-glycolide (PLGA) microspheres. We have shown that subcutaneous immunization with H-2Db-restricted HPV16 peptide was able to generate CTL-mediated cytolysis of HPV16 E6- and E7-expressing TC-1 tumor cells in vitro, as well as protect against in vivo challenge with TC-1 cells in C57BL/6 mice. In vitro, this chimeric peptide showed best efficacy with PLGA microspheres, moderate with alum, and least with Mw as adjuvant. This approach may thus provide a potential peptide-based therapeutic candidate vaccine for the control of HPV infection and hence cervical cancer.

Comparative In-Vitro Functional Analysis of Synthetic Defensins and Their Corresponding Peptide Variants Against HIV-1NL4.3, E. coli, S. aureus and P. aeruginosa

Defensins found in mammals belong to mainly two subfamilies α- and β-defensins. Mammalian defensins are small molecules (18–45 residues) that are cysteine, arginine rich compounds. Antimicrobial activities of these peptides were shown against a wide variety of microbes including bacteria, fungi, viruses and protozoan parasites. To investigate the structure and activity relationship, amino acid substitutions that alter charge were introduced into synthetic defensin peptides by adding 2–2 Arg (RR) and Asp (DD) at both the terminal and tested their effects on HIV-1, E. coli, S. aureus, and P. aeruginosa. In the present study, we have chemically synthesized native defensin peptides and their variants with Arg (RR) and Asp (DD) amino acid residues at N- and C-termini. Later, we assayed their anti-HIV, anti-microbial activities, stability, cytotoxicity and hemolytic properties. We reported that anti-HIV and antimicrobial activities of native defensins is increased significantly by adding Arg (RR) residues at both the termini while the substitution of Arg (RR) with Asp (DD), eliminate anti-HIV and antimicrobial activity against all bacterial species tested. While other physical features i.e. stability, cell toxicity and hemolytic property were not affected by any of the changes in the sequence. The results suggest that the terminal residues in defensins are crucial functional elements that determine their microbicidal potency. The enhanced microbicidal activity observed for defensin peptides with Arg (RR) residues could be due to optimization of amphiphilicity of the structure, which could facilitate specific interactions with the microbial membranes.