Insights into the binding specificity of wild type and mutated wheat germ agglutinin towards Neu5Acα(2‐3)Gal: a study by in silico mutations and molecular dynamics simulations

Wheat germ agglutinin (WGA) is a plant lectin, which specifically recognizes the sugars NeuNAc and GlcNAc. Mutated WGA with enhanced binding specificity can be used as biomarkers for cancer. In silico mutations are performed at the active site of WGA to enhance the binding specificity towards sialylglycans, and molecular dynamics simulations of 20 ns are carried out for wild type and mutated WGAs (WGA1, WGA2, and WGA3) in complex with sialylgalactose to examine the change in binding specificity. MD simulations reveal the change in binding specificity of wild type and mutated WGAs towards sialylgalactose and bound conformational flexibility of sialylgalactose. The mutated polar amino acid residues Asn114 (S114N), Lys118 (G118K), and Arg118 (G118R) make direct and water mediated hydrogen bonds and hydrophobic interactions with sialylgalactose. An analysis of possible hydrogen bonds, hydrophobic interactions, total pair wise interaction energy between active site residues and sialylgalactose and MM‐PBSA free energy calculation reveals the plausible binding modes and the role of water in stabilizing different binding modes. An interesting observation is that the binding specificity of mutated WGAs (cyborg lectin) towards sialylgalactose is found to be higher in double point mutation (WGA3). One of the substituted residues Arg118 plays a crucial role in sugar binding. Based on the interactions and energy calculations, it is concluded that the order of binding specificity of WGAs towards sialylgalactose is WGA3 > WGA1 > WGA2 > WGA. On comparing with the wild type, double point mutated WGA (WGA3) exhibits increased specificity towards sialylgalactose, and thus, it can be effectively used in targeted drug delivery and as biological cell marker in cancer therapeutics. Copyright © 2014 John Wiley & Sons, Ltd.     

Helminth Infections Coincident with Active Pulmonary Tuberculosis Inhibit Mono- and Multifunctional CD4+ and CD8+ T Cell Responses in a Process Dependent on IL-10

Tissue invasive helminth infections and tuberculosis (TB) are co-endemic in many parts of the world and can trigger immune responses that might antagonize each other. We have previously shown that helminth infections modulate the Th1 and Th17 responses to mycobacterial-antigens in latent TB. To determine whether helminth infections modulate antigen-specific and non-specific immune responses in active pulmonary TB, we examined CD4⁺ and CD8⁺ T cell responses as well as the systemic (plasma) cytokine levels in individuals with pulmonary TB with or without two distinct helminth infections—Wuchereria bancrofti and Strongyloides stercoralis infection. By analyzing the frequencies of Th1 and Th17 CD4⁺ and CD8⁺ T cells and their component subsets (including multifunctional cells), we report a significant diminution in the mycobacterial–specific frequencies of mono- and multi–functional CD4⁺ Th1 and (to a lesser extent) Th17 cells when concomitant filarial or Strongyloides infection occurs. The impairment in CD4⁺ and CD8⁺ T cell cytokine responses was antigen-specific as polyclonal activated T cell frequencies were equivalent irrespective of helminth infection status. This diminution in T cell responses was also reflected in diminished circulating levels of Th1 (IFN-γ, TNF-α and IL-2)- and Th17 (IL-17A and IL-17F)-associated cytokines. Finally, we demonstrate that for the filarial co-infections at least, this diminished frequency of multifunctional CD4⁺ T cell responses was partially dependent on IL-10 as IL-10 blockade significantly increased the frequencies of CD4⁺ Th1 cells. Thus, co-existent helminth infection is associated with an IL-10 mediated (for filarial infection) profound inhibition of antigen-specific CD4⁺ T cell responses as well as protective systemic cytokine responses in active pulmonary TB.     

Expansion of Parasite-Specific CD4+ and CD8+ T Cells Expressing IL-10 Superfamily Cytokine Members and Their Regulation in Human Lymphatic Filariasis

Background

Lymphatic filariasis (LF) is known to be associated with an increased production of IL-10. The role of the other IL-10 family members in the pathogenesis of infection and/or disease is not known.

Methodology/Principal Findings

We examined the expression patterns of IL-10 family members – IL-19, IL-24 and IL-26 in LF. We demonstrate that both CD4⁺ and CD8⁺ T cells express IL-19, IL-24 and IL-26 and that the frequency of CD4⁺ T cells expressing IL-19 and IL-24 (as well as IL-10) is significantly increased at baseline and following filarial antigen stimulation in patients with LF in comparison to individuals with filarial lymphedema and uninfected individuals. This CD4⁺ T cell expression pattern was associated with increased production of IL-19 and IL-24 by filarial – antigen stimulated PBMC. Moreover, the frequency of CD4⁺ and CD8⁺ T cells expressing IL-26 was significantly increased following filarial antigen stimulation in filarial lymphedema individuals. Interestingly, IL-10 blockade resulted in diminished frequencies of IL-19⁺ and IL-24⁺ T cells, whereas the addition of recombinant IL-10 resulted in significantly increased frequency of IL-19⁺ and IL-24⁺ T cells as well as significantly up regulated IL-19 and IL-24 gene expression, suggesting that IL-10 regulates IL-19 and IL-24 expression in T cells. In addition, IL-1β and IL-23 blockade also induced a diminution in the frequency of IL-19⁺ and IL-24⁺ T cells, indicating a novel role for these cytokines in the induction of IL-19 and IL-24 expressing T cells. Finally, elimination of infection resulted in significantly decreased frequencies of antigen – specific CD4⁺ T cells expressing IL-10, IL-19 and IL-24.

Conclusions

Our findings, therefore, suggest that IL-19 and IL-24 are associated with the regulation of immune responses in active filarial infection and potentially with protection against development of pathology, while IL-26 is predominantly associated with pathology in LF.     

Parasite-Antigen Driven Expansion of IL-5? and IL-5+ Th2 Human Subpopulations in Lymphatic Filariasis and Their Differential Dependence on IL-10 and TGFβ

Background

Two different Th2 subsets have been defined recently on the basis of IL-5 expression – an IL-5⁺Th2 subset and an IL-5⁻Th2 subset in the setting of allergy. However, the role of these newly described CD4⁺ T cells subpopulations has not been explored in other contexts.

Methods

To study the role of the Th2 subpopulation in a chronic, tissue invasive parasitic infection (lymphatic filariasis), we examined the frequency of IL-5⁺IL-4⁺IL-13⁺ CD4⁺ T cells and IL-5⁻IL-4 IL-13⁺ CD4⁺ T cells in asymptomatic, infected individuals (INF) and compared them to frequencies (F_o) in filarial-uninfected (UN) individuals and to those with filarial lymphedema (CP).

Results

INF individuals exhibited a significant increase in the spontaneously expressed and antigen-induced F_o of both Th2 subpopulations compared to the UN and CP. Interestingly, there was a positive correlation between the F_o of IL-5⁺Th2 cells and the absolute eosinophil and neutrophil counts; in addition there was a positive correlation between the frequency of the CD4⁺IL-5⁻Th2 subpopulation and the levels of parasite antigen – specific IgE and IgG4 in INF individuals. Moreover, blockade of IL-10 and/or TGFβ demonstrated that each of these 2 regulatory cytokines exert opposite effects on the different Th2 subsets. Finally, in those INF individuals cured of infection by anti-filarial therapy, there was a significantly decreased F_o of both Th2 subsets.

Conclusions

Our findings suggest that both IL-5⁺ and IL-5⁻Th2 cells play an important role in the regulation of immune responses in filarial infection and that these two Th2 subpopulations may be regulated by different cytokine-receptor mediated processes.     

Seroprevalence of Strongyloides stercoralis infection in a South Indian adult population

BackgroundThe prevalence of Strongyloides stercoralis infection is estimated to be 30–100 million worldwide, although this an underestimate. Most cases remain undiagnosed due to the asymptomatic nature of the infection. We wanted to estimate the seroprevalence of S. stercoralis infection in a South Indian adult population.MethodsTo this end, we performed community-based screening of 2351 individuals (aged 18–65) in Kanchipuram District of Tamil Nadu between 2013 and 2020. Serological testing for S. stercoralis was performed using the NIE ELISA.ResultsOur data shows a seroprevalence of 33% (768/2351) for S. stercoralis infection which had a higher prevalence among males 36% (386/1069) than among females 29.8% (382/1282). Adults aged ≥55 (aOR = 1.65, 95% CI: 1.25–2.18) showed higher adjusted odds of association compared with other age groups. Eosinophil levels (39%) (aOR = 1.43, 95% CI: 1.19–1.74) and hemoglobin levels (24%) (aOR = 1.25, 95% CI: 1.11–1.53) were significantly associated with S. stercoralis infection. In contrast, low BMI (aOR = 1.15, 95% CI: 0.82–1.61) or the presence of diabetes mellitus (OR = 1.18, 95% CI: 0.83–1.69) was not associated with S. stercoralis seropositivity.ConclusionsOur study provides evidence for a very high baseline prevalence of S. stercoralis infection in South Indian communities and this information could provide realistic and concrete planning of control measures.     

Surface functionalization of nanobiomaterials for application in stem cell culture,tissue engineering,and regenerative medicine

Stem cell‐based approaches offer great application potential in tissue engineering and regenerative medicine owing to their ability of sensing the microenvironment and respond accordingly (dynamic behavior). Recently, the combination of nanobiomaterials with stem cells has paved a great way for further exploration. Nanobiomaterials with engineered surfaces could mimic the native microenvironment to which the seeded stem cells could adhere and migrate. Surface functionalized nanobiomaterial‐based scaffolds could then be used to regulate or control the cellular functions to culture stem cells and regenerate damaged tissues or organs. Therefore, controlling the interactions between nanobiomaterials and stem cells is a critical factor. However, surface functionalization or modification techniques has provided an alternative approach for tailoring the nanobiomaterials surface in accordance to the physiological surrounding of a living cells; thereby, enhancing the structural and functional properties of the engineered tissues and organs. Currently, there are a variety of methods and technologies available to modify the surface of biomaterials according to the specific cell or tissue properties to be regenerated. This review highlights the trends in surface modification techniques for nanobiomaterials and the biological relevance in stem cell‐based tissue engineering and regenerative medicine. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:554–567, 2016     

Role of exogenous hemin in the synthesis of hemoproteins and nonheme proteins during glucose repression in Saccharomyces cerevisiae

Exogenous addition of hemin to glucose-repressed cells of Saccharomyces cerevisiae stimulates the incorporation of amino acid into cytoplasmic proteins twofold. There was no significant change in the synthesis of total cytoplasmic RNA whereas a 40% increase in the synthesis of poly(A)-containing RNA was observed upon hemin treatment. Cell-free translation of cytoplasmic mRNAs and immunoprecipitation analysis of the translated products with antibodies against subunit V of cytochrome oxidase and the alpha and beta subunits of F1-ATPase reveals that there is an eightfold enrichment of the mRNA for subunit V of cytochrome oxidase upon hemin treatment. The effect of hemin on the alpha and beta subunits of F1-ATPase is only marginal, suggesting a differential role for heme in the synthesis of hemoproteins and nonheme proteins during glucose repression.     

Phytoremediation potential of some agricultural plants on heavy metal contaminated mine waste soils,salem district,tamilnadu

The Pot culture experiment performed for phytoextraction potential of selected agricultural plants [millet (Eleusine coracana), mustard (Brassica juncea), jowar (Sorghum bicolor), black gram (Vigna mungo), pumpkin (Telfairia occidentalis)] grown in metal contaminated soils around the Salem region, Tamilnadu, India. Physiochemical characterization of soils, reported as low to medium level of N, P, K was found in test soils. The Cr content higher in mine soils than control and the values are 0.176 mg/L in Dalmia soil and 0.049 mg/L in Burn &; Co soil. The germination rate low in mine soil than control soils (25 to 85%). The content of chlorophyll, carotenoid, carbohydrate and protein decreased in mine soils than control. The morphological parameters and biomass values decreased in experimental plants due to metal accumulation. Proline content increased in test plants and ranged from 0.113 mg g^?1 to 0.858 mg g^?1 which indicate the stress condition due to toxicity of metals. Sorghum and black gram plants reported as metal tolerant capacity. Among the plants, Sorghum produced good results (both biomass and biochemical parameters) which equal to control plant and suggests Sorghum plant is an ideal for remediation of metal contaminated soils.     

Deciphering the diversity of culturable thermotolerant bacteria from Manikaran hot springs

The aim of this study was to analyze and characterize the diversity of culturable thermotolerant bacteria in Manikaran hot springs. A total of 235 isolates were obtained employing different media, and screened for temperature tolerance (40 °C–70 °C). A set of 85 isolates tolerant to 45 °C or above were placed in 42 phylogenetic clusters after amplified ribosomal DNA restriction analysis (16S rRNA-ARDRA). Sequencing of the 16S rRNA gene of 42 representative isolates followed by BLAST search revealed that the majority of isolates belonged to Firmicutes, followed by equal representation of Actinobacteria and Proteobacteria. Screening of representative isolates (42 ARDRA phylotypes) for amylase activity revealed that 26 % of the isolates were positive, while 45 % exhibited protease activity, among which one amylase and six protease producers were tolerant up to 70 °C. BIOLOG-based identification of 13 isolates exhibiting temperature tolerance up to 70 °C, using carbon utilization patterns and sensitivity to chemicals, revealed a high degree of correlation with identification based on 16S rRNA gene sequencing for all isolates, except one (M48). These promising isolates showing a range of useful metabolic attributes demand to be explored further for industrial and agricultural applications.