Evaluation of circulating haematopoietic progenitor cells in patients with Trauma Haemorrhagic shock and its correlation with outcomes

Background:

Haemorrhagic shock accounts up to 50% of early trauma deaths. Hematopoietic failure has been observed in experimental animals and human following shock and injury. One of the facets of bone marrow failure is multiple organ dysfunction syndrome and is commonly seen in patients recovering from severe trauma and hemorrhagic shock. Bone Marrow (BM) dysfunction is associated with mobilization of hematopoietic progenitor cells (HPCs) into peripheral blood. Present study explored the association of peripheral blood hematopoietic progenitor cells (HPCs) with mortality in trauma haemorrhagic shock patients (T/HS).

Materials and Methods:

Prospective cohort studies of patients presenting within 8 hrs of injury with T/HS to the Department of Emergency Medicine, Jai Prakash Narayan Apex Trauma Center, All India Institute of Medical Sciences were recruited. Peripheral blood samples were collected in each patient for measurement of peripheral blood HPCs. Peripheral blood progenitor cell (PBPC) quantification was performed by measuring HPCs counts using the haematology analyzer (Sysmex XE-2100). Clinical and laboratory data were prospectively collected after consent. Ethical approval was taken and data was analysed by Stata 11.2.

Results:

39 patients with trauma hemorrhagic shock and 30 normal healthy controls were recruited. HPCs were significantly higher (P < 0.001) in the T/HS as compared to control. Among study group, 14 patients died within 24 h. at the hospital admission, and found HPCs concentrations were highly significant (<0.001) in non-survivors (n = 14) when compared with survivors (n = 25) among T/HS patients.

Conclusions:

Our studies suggest the peripheral blood HPCs may be early prognostic marker for mortality among patients who presented with trauma hemorrhagic shock on admission. But the exact molecular mechanism and signalling pathway involved in the change of the behaviour of bone marrow microenvironment is still unclear.

Generation of Catalytic Antibodies Is an Intrinsic Property of an Individual's Immune System: A Study on a Large Cohort of Renal Transplant Patients

Renal transplant is the treatment of choice for patients with terminal end-stage renal disease. We have previously identified low levels of catalytic IgG as a potential prognosis marker for chronic allograft rejection. The origin and physiopathological relevance of catalytic Abs is not well understood, owing to the fact that catalytic Abs have been studied in relatively small cohorts of patients with rare diseases and/or without systematic follow-up. In the current study, we have followed the evolution of the levels of catalytic IgG in a large cohort of renal transplant patients over a 2-y period. Our results demonstrate that, prior to transplant, patients with renal failure present with heterogeneous levels of IgG hydrolyzing the generic proline-phenylalanine-arginine-methylcoumarinamide (PFR-MCA) substrate. PFR-MCA hydrolysis was greater for patients' IgG than for a therapeutic preparation of pooled IgG from healthy donors. Renal transplant was marked by a drastic decrease in levels of catalytic IgG over 3 mo followed by a steady increase during the next 21 mo. Patients who displayed high levels of catalytic IgG pretransplant recovered high levels of catalytic Abs 2 y posttransplant. Interestingly, IgG-mediated hydrolysis of a model protein substrate, procoagulant factor VIII, did not correlate with that of PFR-MCA prior transplantation, whereas it did 12 mo posttransplant. Taken together, our results suggest that the level of circulating catalytic IgG under pathological conditions is an intrinsic property of each individual's immune system and that recovery of pretransplant levels of catalytic IgG is accompanied by changes in the repertoire of target Ags.

Generation of catalytic antibodies is an intrinsic property of an individual’s immune system: a study on a large cohort of renal transplant patients

The origin and physiopathological relevance of catalytic antibodies is not well understood owing to the fact that catalytic antibodies have been studied in relatively small cohorts of patients with rare diseases and/or without systematic follow-up. In the present study, we have followed the evolution of the levels of catalytic IgG in a large cohort of 100 renal transplant patients over a 2-year period. Prior to transplant, hydrolysis of the generic substrate PFR-MCA was greater for patients’ IgG than for a therapeutic preparation of pooled IgG from healthy donors (6.6±0.9 vs 0.65±0.03 fmol/min per pmol). Renal transplant was marked by a drastic decrease in levels of catalytic IgG over 3 months (6.6±0.9 vs 2.4±0.2 fmol/min/pmol; P&lt;0.0001) followed by a steady increase at 12 months (3.2±0.3 fmol/min/pmol; P=0.015) and further at 24 months (5.1±0.6 fmol/min/pmol; P=0.004). When divided into quartiles based on the rates of IgG-mediated PFR-MCA hydrolysis measured in pre-transplant samples, the IgG catalytic activity in the upper quartile of patients was significantly high both pre-transplant (12.03±1.6 vs 2.7±0.2 fmol/min/pmol, P&lt;0.0001) and 24 months post-transplant (6.8±1.2 vs 4.6±0.7, fmol/min/pmol, P=0.0004). Interestingly, IgG-mediated hydrolysis of a model protein substrate, pro-coagulant factor VIII, did not correlate with that of PFR-MCA prior transplantation, while it did 12 months post-transplant (P&lt;0.0001, R2=0.4). Taken together, our results suggest that the level of circulating catalytic IgG under pathological conditions is an intrinsic property of each individual’s immune system, and that recovery of pre-transplant levels of catalytic IgG is accompanied by changes in the repertoire of target antigens.

Mutations in the nucleotide binding and hydrolysis domains of Helicobacter pylori MutS2 lead to altered biochemical activities and inactivation of its in vivo function

Background

Helicobacter pylori MutS2 (HpMutS2), an inhibitor of recombination during transformation is a non-specific nuclease with two catalytic sites, both of which are essential for its anti-recombinase activity. Although HpMutS2 belongs to a highly conserved family of ABC transporter ATPases, the role of its ATP binding and hydrolysis activities remains elusive.

Results

To explore the putative role of ATP binding and hydrolysis activities of HpMutS2 we specifically generated point mutations in the nucleotide-binding Walker-A (HpMutS2-G338R) and hydrolysis Walker-B (HpMutS2-E413A) domains of the protein. Compared to wild-type protein, HpMutS2-G338R exhibited ~2.5-fold lower affinity for both ATP and ADP while ATP hydrolysis was reduced by ~3-fold. Nucleotide binding efficiencies of HpMutS2-E413A were not significantly altered; however the ATP hydrolysis was reduced by ~10-fold. Although mutations in the Walker-A and Walker-B motifs of HpMutS2 only partially reduced its ability to bind and hydrolyze ATP, we demonstrate that these mutants not only exhibited alterations in the conformation, DNA binding and nuclease activities of the protein but failed to complement the hyper-recombinant phenotype displayed by mutS2-disrupted strain of H. pylori. In addition, we show that the nucleotide cofactor modulates the conformation, DNA binding and nuclease activities of HpMutS2.

Conclusions

These data describe a strong crosstalk between the ATPase, DNA binding, and nuclease activities of HpMutS2. Furthermore these data show that both, ATP binding and hydrolysis activities of HpMutS2 are essential for the in vivo anti-recombinase function of the protein.

Electronic supplementary material

The online version of this article (doi:10.1186/s12866-016-0629-3) contains supplementary material, which is available to authorized users.

Bone marrow hematopoietic stem cells behavior with or without growth factors in trauma hemorrhagic shock

Background:

Hemorrhagic shock (HS) is the major leading cause of death after trauma. Up to 50% of early deaths are due to massive hemorrhage. Excessive release of pro-inflammatory cytokine and hypercatecholamine induces hematopoietic progenitor cells (HPCs) apoptosis, leading to multiorgan failure and death. However, still, result remains elusive for hematopoietic stem cells (HSCs) behavior in trauma HS (T/HS).

Objectives:

Therefore, our aim was to evaluate the in vitro HSCs behavior with or without recombinant human erythropoietin (rhEPO), recombinant human granulocyte macrophage-colony-stimulating factor (rhGM-CSF), recombinant human interleukin-3 (rhIL-3) alone, and combination with rhEPO + rhGM-CSF + rhIL-3 (EG3) in T/HS patients.

Methodology:

Bone marrow (BM) aspirates (n = 14) were collected from T/HS patients, those survived on day 3. BM cells were cultured for HPCs: Colony-forming unit-erythroid (CFU-E), burst-forming unit-erythroid (BFU-E), and colony-forming unit-granulocyte, monocyte/macrophage colonies growth. HPCs were counted with or without rhEPO, rhGM-CSF, rhIL-3 alone, and combination with EG3 in T/HS patients.

Results:

BM HSCs growth significantly suppressed in T/HS when compared with control group (P < 0.05). In addition, CFU-E and BFU-E colony growth were increased with additional growth factor (AGF) (rhEPO, rhGM-CSF, and rhIL-3) as compared to baseline (without AGF) (P < 0.05).

Conclusion:

Suppressed HPCs may be reactivated by addition of erythropoietin, GM-CSF, IL-3 alone and with combination in T/HS.

Insights into the Functional Roles of N-Terminal and C-Terminal Domains of Helicobacter pylori DprA

DNA processing protein A (DprA) plays a crucial role in the process of natural transformation. This is accomplished through binding and subsequent protection of incoming foreign DNA during the process of internalization. DprA along with Single stranded DNA binding protein A (SsbA) acts as an accessory factor for RecA mediated DNA strand exchange. H. pylori DprA (HpDprA) is divided into an N-terminal domain and a C- terminal domain. In the present study, individual domains of HpDprA have been characterized for their ability to bind single stranded (ssDNA) and double stranded DNA (dsDNA). Oligomeric studies revealed that HpDprA possesses two sites for dimerization which enables HpDprA to form large and tightly packed complexes with ss and dsDNA. While the N-terminal domain was found to be sufficient for binding with ss or ds DNA, C-terminal domain has an important role in the assembly of poly-nucleoprotein complex. Using site directed mutagenesis approach, we show that a pocket comprising positively charged amino acids in the N-terminal domain has an important role in the binding of ss and dsDNA. Together, a functional cross talk between the two domains of HpDprA facilitating the binding and formation of higher order complex with DNA is discussed.

Specificity of the ModA11, ModA12 and ModD1 epigenetic regulator N(6)-adenine DNA methyltransferases of Neisseria meningitidis

Phase variation (random ON/OFF switching) of gene expression is a common feature of host-adapted pathogenic bacteria. Phase variably expressed N(6)-adenine DNA methyltransferases (Mod) alter global methylation patterns resulting in changes in gene expression. These systems constitute phase variable regulons called phasevarions. Neisseria meningitidis phasevarions regulate genes including virulence factors and vaccine candidates, and alter phenotypes including antibiotic resistance. The target site recognized by these Type III N(6)-adenine DNA methyltransferases is not known. Single molecule, real-time (SMRT) methylome analysis was used to identify the recognition site for three key N. meningitidis methyltransferases: ModA11 (exemplified by M.NmeMC58I) (5'-CGY M6A: G-3'), ModA12 (exemplified by M.Nme77I, M.Nme18I and M.Nme579II) (5'-AC M6A: CC-3') and ModD1 (exemplified by M.Nme579I) (5'-CC M6A: GC-3'). Restriction inhibition assays and mutagenesis confirmed the SMRT methylome analysis. The ModA11 site is complex and atypical and is dependent on the type of pyrimidine at the central position, in combination with the bases flanking the core recognition sequence 5'-CGY M6A: G-3'. The observed efficiency of methylation in the modA11 strain (MC58) genome ranged from 4.6% at 5'-GCGC M6A: GG-3' sites, to 100% at 5'-ACGT M6A: GG-3' sites. Analysis of the distribution of modified sites in the respective genomes shows many cases of association with intergenic regions of genes with altered expression due to phasevarion switching.

The nuclease activities of both the Smr domain and an additional LDLK motif are required for an efficient anti-recombination function of Helicobacter pylori MutS2

Helicobacter pylori, a human pathogen, is a naturally and constitutively competent bacteria, displaying a high rate of intergenomic recombination. While recombination events are essential for evolution and adaptation of H. pylori to dynamic gastric niches and new hosts, such events should be regulated tightly to maintain genomic integrity. Here, we analyze the role of the nuclease activity of MutS2, a protein that limits recombination during transformation in H. pylori. In previously studied MutS2 proteins, the C-terminal Smr domain was mapped as the region responsible for its nuclease activity. We report here that deletion of Smr domain does not completely abolish the nuclease activity of HpMutS2. Using bioinformatics analysis and mutagenesis, we identified an additional and novel nuclease motif (LDLK) at the N-terminus of HpMutS2 unique to Helicobacter and related ε-proteobacterial species. A single point mutation (D30A) in the LDLK motif and the deletion of Smr domain resulted in ∼ 5-10-fold loss of DNA cleavage ability of HpMutS2. Interestingly, the mutant forms of HpMutS2 wherein the LDLK motif was mutated or the Smr domain was deleted were unable to complement the hyper-recombination phenotype of a mutS2(-) strain, suggesting that both nuclease sites are indispensable for an efficient anti-recombinase activity of HpMutS2.

Nasal delivery of PLG microparticle encapsulated defensin peptides adjuvanted gp41 antigen confers strong and long-lasting immunoprotective response against HIV-1

Defensins display immunostimulatory activities including a chemotactic effect for T lymphocytes/immature dendritic cells and secretion of pro-inflammatory cytokines suggest their role in bridging innate and adaptive immunity. We hypothesized whether defensins with separately emulsified HIV-1 immunogen would elicit peptide-specific systemic and mucosal antibody response in mice. The HIV-1 peptide alone in microsphere showed low peptide-specific antibody response in sera and different washes, while the presence of defensins markedly increased the antibody peak titre both in sera (102,400-409,600) (p < 0.05) and in washes (800-25,600) (p < 0.001). Defensins with HIV-1 peptide were showing 43.0-83.2% and 38.7-72.3% in vitro neutralization against laboratory isolates in serum and lavage samples, respectively, higher than HIV-1 peptide alone. Our findings may have implications in the development of new mucosal adjuvant for AIDS vaccination.

Comparison of haematological and biochemical changes between non-anaemic and anaemic primigravid women in a north Indian population to establish normative values

Pregnancy is accompanied by several haemodynamic, biochemical and haematological changes, which may lead to severe problems, if they are not suitably addressed. The current study highlights the haematological and biochemical differences observed in anaemic (AP) and non-anaemic primigravida (NAP), in the 2nd trimester, in a north Indian population. There were significant differences (p < 0.05) in the body weight and body temperature of NAP compared with AP. A significant decrease (p < 0.001) in haematological parameters including haemoglobin, haematocrit, erythrocyte count, MCH and MCHC, was observed in AP; however, MCV was found to be significantly higher (p = 0.038). Many biochemical parameters viz. potassium, albumin, total protein and calcium levels were significantly reduced (p < 0.01) in AP, except alkaline phosphatase whose level was found significantly increased (p < 0.01). The findings of the study suggest that haematological and biochemical changes take place in anaemia during pregnancy. Further, the results obtained should be used for establishing normative values for similar populations.

Mycobacterium tuberculosis DinG is a structure-specific helicase that unwinds G4 DNA: implications for targeting G4 DNA as a novel therapeutic approach

The significance of G-quadruplexes and the helicases that resolve G4 structures in prokaryotes is poorly understood. The Mycobacterium tuberculosis genome is GC-rich and contains >10,000 sequences that have the potential to form G4 structures. In Escherichia coli, RecQ helicase unwinds G4 structures. However, RecQ is absent in M. tuberculosis, and the helicase that participates in G4 resolution in M. tuberculosis is obscure. Here, we show that M. tuberculosis DinG (MtDinG) exhibits high affinity for ssDNA and ssDNA translocation with a 5' → 3' polarity. Interestingly, MtDinG unwinds overhangs, flap structures, and forked duplexes but fails to unwind linear duplex DNA. Our data with DNase I footprinting provide mechanistic insights and suggest that MtDinG is a 5' → 3' polarity helicase. Notably, in contrast to E. coli DinG, MtDinG catalyzes unwinding of replication fork and Holliday junction structures. Strikingly, we find that MtDinG resolves intermolecular G4 structures. These data suggest that MtDinG is a multifunctional structure-specific helicase that unwinds model structures of DNA replication, repair, and recombination as well as G4 structures. We finally demonstrate that promoter sequences of M. tuberculosis PE_PGRS2, mce1R, and moeB1 genes contain G4 structures, implying that G4 structures may regulate gene expression in M. tuberculosis. We discuss these data and implicate targeting G4 structures and DinG helicase in M. tuberculosis could be a novel therapeutic strategy for culminating the infection with this pathogen.

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.

Type III restriction-modification enzymes: a historical perspective

Restriction endonucleases interact with DNA at specific sites leading to cleavage of DNA. Bacterial DNA is protected from restriction endonuclease cleavage by modifying the DNA using a DNA methyltransferase. Based on their molecular structure, sequence recognition, cleavage position and cofactor requirements, restriction-modification (R-M) systems are classified into four groups. Type III R-M enzymes need to interact with two separate unmethylated DNA sequences in inversely repeated head-to-head orientations for efficient cleavage to occur at a defined location (25-27 bp downstream of one of the recognition sites). Like the Type I R-M enzymes, Type III R-M enzymes possess a sequence-specific ATPase activity for DNA cleavage. ATP hydrolysis is required for the long-distance communication between the sites before cleavage. Different models, based on 1D diffusion and/or 3D-DNA looping, exist to explain how the long-distance interaction between the two recognition sites takes place. Type III R-M systems are found in most sequenced bacteria. Genome sequencing of many pathogenic bacteria also shows the presence of a number of phase-variable Type III R-M systems, which play a role in virulence. A growing number of these enzymes are being subjected to biochemical and genetic studies, which, when combined with ongoing structural analyses, promise to provide details for mechanisms of DNA recognition and catalysis.

Preparation of peptide microspheres using tumor antigen-derived peptides

Due to its distinct biological attributes, poly(D,L lactide-co glycolide) (PLGA) is one of the most preferred methods for DNA/protein/peptide encapsulation for therapeutics. Importantly, PLGA acts as an adjuvant for weakly immunogenic antigens and mimics booster responses after a single dose of administration, thereby serving as a single-shot vaccine delivery vehicle. Efficient delivery of antigens to antigen-presenting cells (APC) has been made possible by the use of a PLGA particle-based vaccine delivery system. Also, the plasma half-life of the PLGA-encapsulated vaccine increases as it is protected from degradation, prior to its further release. PLGAs are reported to be catabolized into individual nontoxic units once inside the host and further degraded via normal metabolic pathways. In this chapter, we have described the preparation and characterization of tumor peptide encapsulated PLGA microparticles as a model for controlled-release peptide delivery system.

Multiple antigen peptide containing B and T cell epitopes of F1 antigen of Yersinia pestis showed enhanced Th1 immune response in murine model

Yersinia pestis is a facultative bacterium that can survive and proliferate inside host macrophages and cause bubonic, pneumonic and systemic infection. Apart from humoral response, cell-mediated protection plays a major role in combating the disease. Fraction 1 capsular antigen (F1-Ag) of Y. pestis has long been exploited as a vaccine candidate. In this study, F1-multiple antigenic peptide (F1-MAP or MAP)-specific cell-mediated and cytokine responses were studied in murine model. MAP consisting of three B and one T cell epitopes of F1-antigen with one palmitoyl residue was synthesized using Fmoc chemistry. Mice were immunized with different formulations of MAP in poly DL-lactide-co-glycolide (PLGA) microspheres. F1-MAP with CpG oligodeoxynucleotide (CpG-ODN) as an adjuvant showed enhanced in vitro T cell proliferation and Th1 (IL-2, IFN-γ and TNF-α) and Th17 (IL-17A) cytokine secretion. Similar formulation also showed significantly higher numbers of cytokine (IL-2, IFN-γ)-secreting cells. Moreover, F1-MAP with CpG formulation showed significantly high (P < 0.001) percentage of CD4(+) IFN-γ(+) cells as compared to CD8(+) IFN-γ(+) cells, and also more (CD4- IFN-γ)(+) cells secrete perforin and granzyme as compared to (CD8- IFN-γ)(+) showing Th1 response. Thus, the study highlights the importance of Th1 cytokine and existence of CD4(+) and CD8(+) immune response. This study proposes a new perspective for the development of vaccination strategies for Y. pestis that trigger T cell immune response.

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 peyer's 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.

Helicobacter pylori DprA alleviates restriction barrier for incoming DNA

Helicobacter pylori is a Gram-negative bacterium that colonizes human stomach and causes gastric inflammation. The species is naturally competent and displays remarkable diversity. The presence of a large number of restriction-modification (R-M) systems in this bacterium creates a barrier against natural transformation by foreign DNA. Yet, mechanisms that protect incoming double-stranded DNA (dsDNA) from restriction enzymes are not well understood. A DNA-binding protein, DNA Processing Protein A (DprA) has been shown to facilitate natural transformation of several Gram-positive and Gram-negative bacteria by protecting incoming single-stranded DNA (ssDNA) and promoting RecA loading on it. However, in this study, we report that H. pylori DprA (HpDprA) binds not only ssDNA but also dsDNA thereby conferring protection to both from various exonucleases and Type II restriction enzymes. Here, we observed a stimulatory role of HpDprA in DNA methylation through physical interaction with methyltransferases. Thus, HpDprA displayed dual functional interaction with H. pylori R-M systems by not only inhibiting the restriction enzymes but also stimulating methyltransferases. These results indicate that HpDprA could be one of the factors that modulate the R-M barrier during inter-strain natural transformation in H. pylori.

Role of DNA methyltransferases in epigenetic regulation in bacteria

In prokaryotes, alteration in gene expression was observed with the modification of DNA, especially DNA methylation. Such changes are inherited from generation to generation with no alterations in the DNA sequence and represent the epigenetic signal in prokaryotes. DNA methyltransferases are enzymes involved in DNA modification and thus in epigenetic regulation of gene expression. DNA methylation not only affects the thermodynamic stability of DNA, but also changes its curvature. Methylation of specific residues on DNA can affect the protein-DNA interactions. DNA methylation in prokaryotes regulates a number of physiological processes in the bacterial cell including transcription, DNA mismatch repair and replication initiation. Significantly, many reports have suggested a role of DNA methylation in regulating the expression of a number of genes in virulence and pathogenesis thus, making DNA methlytransferases novel targets for the designing of therapeutics. Here, we summarize the current knowledge about the influence of DNA methylation on gene regulation in different bacteria, and on bacterial virulence.

Multiple antigen peptide consisting of B- and T-cell epitopes of F1 antigen of Y. pestis showed enhanced humoral and mucosal immune response in different strains of mice

Yersinia pestis is a causative agent of plague. F1 and V antigen based vaccines have shown remarkable protection in experimental animals. In order to develop epitope based immunogen, three B and one T-cell epitopes of F1 antigen with palmitate residue at amino terminal were assembled on a lysine backbone as multiple antigen peptide (MAP or F1-MAP). MAP was characterized by SDS-PAGE, immunoblot and immunoreactivity with anti F1 sera. MAP was entrapped in PLGA (polylactide-co-glycolide) microparticles and humoral, mucosal immune responses were studied after intranasal immunization with/without CpG ODN 1826 (CpG)/murabutide in different strains of mice. Serum and mucosal washes were measured for MAP specific IgG, IgA, sIgA and IgG subclasses in three strains of mice. F1-MAP showed high serum antibody and mucosal IgG and IgA peak antibody titers. MAP with CpG showed significantly high (p<0.001) peak antibody titer ranging from 102,400 to 204,800 for IgG and 6400 to 12,800 for IgA. High mucosal sIgA and its secretary component detection confirmed generation of mucosal response in intestinal and lung washes. MAP antisera also showed significant immunoreactivity with individual peptides. Moreover, antibody specific activity (IgG, IgA and sIgA) positively correlates with peak antibody titers. Predominantly IgG2a/IgG2b subclass was observed with CpG formulation but in other formulation a mixed IgG1 and IgG2a response was observed. The present study highlights the importance of multiple antigen peptide approach of F1-antigen with CpG as an alternative approach for subunit vaccine.

Immunomodulation of ovalbumin-specific IgG and other classes of antibody response by honey in mice

It was reported earlier that intraperitoneal administration of honey had immunosuppressive activity on elicitation of allergen-specific murine antibody response as evaluated by passive cutaneous anaphylaxis and double immunodiffusion methods. In this study, the immunomudulatory effect of honey is evaluated by enzyme linked immunosorbent assay (ELISA) using ovalbumin as model allergen. It was found that ovalbumin (OVA)-specific IgG antibody responses elicited with various doses of OVA were significantly suppressed by rock bee honey (p<0.01). Honey was also found to have inhibited the production of OVA-specific IgM, IgA, IgG(1), and IgG(2b) whereas that of IgG(2a) and IgG(3) were not affected. Furthermore, honey also suppressed the OVA-specific total IgG antibody response in various inbred mice with different genetic background. In addition, the suppressive activity of honey was examined in different groups of mice by injecting honey at different time intervals, before and after immunization with OVA. The anti-OVA IgG antibody response was suppressed significantly when honey was injected 12 hours prior/latter to OVA injection. These results confirm the suppressive activity of honey on antibody response and suggest possible clinical application.

Observations on some chemical and physical characteristics of buffalo meat

Proximate composition, sarcoplasmic and myofibrillar protein fractions of buffalo meat were similar to those of beef. Buffalo meat was also rich in lysine. Meat from young animals had a lower collagen content than that from old ones. As the temperature of holding the carcasses was increased, the rate of pH fall was faster. Meat from stressed animals showed a higher ultimate pH. Percentage of cooking loss and thermal shrinkage was higher in muscles of old animals than in young ones, which probably reflected the poor condition of the older animals. Meat cooked by pressure cooking showed lower Warner-Bratzler shear values as compared with meat cooked in boiling water.

Comparative transcriptomics of H. pylori strains AM5, SS1 and their hpyAVIBM deletion mutants: possible roles of cytosine methylation

Helicobacter pylori is an important human pathogen and one of the most successful chronic colonizers of the human body. H. pylori uses diverse mechanisms to modulate its interaction with the host in order to promote chronic infection and overcome host immune response. Restriction-modification genes are a major part of strain-specific genes present in H. pylori. The role of N⁶ - adenine methylation in bacterial gene regulation and virulence is well established but not much is known about the effect of C⁵ -cytosine methylation on gene expression in prokaryotes. In this study, it was observed by microarray analysis and RT-PCR, that deletion of an orphan C⁵ -cytosine methyltransferase, hpyAVIBM in H. pylori strains AM5and SS1 has a significant effect on the expression of number of genes belonging to motility, adhesion and virulence. AM5ΔhpyAVIBM mutant strain has a different LPS profile and is able to induce high IL-8 production compared to wild-type. hpyAVIBM from strain 26695 is able to complement mutant SS1 and AM5 strains. This study highlights a possible significance of cytosine methylation in the physiology of H. pylori.

Cell-mediated immune response to epitopic MAP (multiple antigen peptide) construct of LcrV antigen of Yersinia pestis in murine model

Yersinia pestis is the causative agent of plague. Cellular immunity seems to play an important role in defense against this disease. The subunit vaccine based on V (Lcr V) antigen has been proved to be immunogenic in animals and in humans. The multiple antigen peptide (MAP), incorporating all the relevant B and T cell epitopes is highly immunogenic in mice through intranasal route of immunization in PLGA particles containing CpG-ODN as an immunoadjuvant inducing humoral and mucosal immune response. In the present study, cell-mediated immune response using same MAP was studied in murine model. Primary and memory T cell responses were studied in outbred and inbred mice immunized intranasally with MAP in the presence of two immunoadjuvants (Murabutide and CpG-ODN). All the three compartments (Spleen, Lamina propria and Peyer's patches) of the lymphoid system showed increased lymphoproliferative response. Highest lymphoproliferative response was observed especially with CpG-ODN. Cytokine profile in the culture supernatant showed highest Th(1) and Th(17) levels. FACS analysis showed expansion of both CD4(+) and CD8(+) T cells producing gamma-interferon, perforin and granzyme-B with major contribution from CD4(+) T cells.

Functional characterization of UvrD helicases from Haemophilus influenzae and Helicobacter pylori

Haemophilus influenzae and Helicobacter pylori are major bacterial pathogens that face high levels of genotoxic stress within their host. UvrD, a ubiquitous bacterial helicase that plays important roles in multiple DNA metabolic pathways, is essential for genome stability and might, therefore, be crucial in bacterial physiology and pathogenesis. In this study, the functional characterization of UvrD helicase from Haemophilus influenzae and Helicobacter pylori is reported. UvrD from Haemophilus influenzae (HiUvrD) and Helicobacter pylori (HpUvrD) exhibit strong single-stranded DNA-specific ATPase and 3'-5' helicase activities. Mutation of highly conserved arginine (R288) in HiUvrD and glutamate (E206) in HpUvrD abrogated their activities. Both the proteins were able to bind and unwind a variety of DNA structures including duplexes with strand discontinuities and branches, three- and four-way junctions that underpin their role in DNA replication, repair and recombination. HiUvrD required a minimum of 12 nucleotides, whereas HpUvrD preferred 20 or more nucleotides of 3'-single-stranded DNA tail for efficient unwinding of duplex DNA. Interestingly, HpUvrD was able to hydrolyze and utilize GTP for its helicase activity although not as effectively as ATP, which has not been reported to date for UvrD characterized from other organisms. HiUvrD and HpUvrD were found to exist predominantly as monomers in solution together with multimeric forms. Noticeably, deletion of distal C-terminal 48 amino acid residues disrupted the oligomerization of HiUvrD, whereas deletion of 63 amino acids from C-terminus of HpUvrD had no effect on its oligomerization. This study presents the characteristic features and comparative analysis of Haemophilus influenzae and Helicobacter pylori UvrD, and constitutes the basis for understanding the role of UvrD in the biology and virulence of these pathogens.