Comparative pangenomic analysis of predominant human vaginal lactobacilli strains towards population-specific adaptation: understanding the role in sustaining a balanced and healthy vaginal microenvironment.

The vaginal microenvironment of healthy women has a predominance of Lactobacillus crispatus, L. iners, L. gasseri, and L. jensenii. The genomic repertoire of the strains of each of the species associated with the key attributes thereby regulating a healthy vaginal environment needs a substantial understanding.We studied all available human strains of the four lactobacilli across different countries, isolated from vaginal and urinal sources through phylogenetic and pangenomic approaches. The findings showed that L. iners has the highest retention of core genes, and L. crispatus has more gene gain in the evolutionary stratum. Interestingly, L. gasseri and L. jensenii demonstrated major population-specific gene-cluster gain/loss associated with bacteriocin synthesis, iron chelating, adherence, zinc and ATP binding proteins, and hydrolase activity. Gene ontology enrichment analysis revealed that L. crispatus strains showed greater enrichment of functions related to plasma membrane integrity, biosurfactant, hydrogen peroxide synthesis, and iron sequestration as an ancestral derived core function, while bacteriocin and organic acid biosynthesis are strain-specific accessory enriched functions. L. jensenii showed greater enrichment of functions related to adherence, aggregation, and exopolysaccharide synthesis. Notably, the key functionalities are heterogeneously enriched in some specific strains of L. iners and L. gasseri.This study shed light on the genomic features and their variability that provides advantageous attributes to predominant vaginal Lactobacillus species maintaining vaginal homeostasis. These findings evoke the need to consider region-specific candidate strains of Lactobacillus to formulate prophylactic measures against vaginal dysbiosis for women's health.

Recent advances in understanding of multifaceted changes in the vaginal microenvironment: implications in vaginal health and therapeutics.

The vagina endures multifaceted changes from neonatal to menopausal phases due to hormonal flux, metabolite deposition, and microbial colonization. These features have important implications in women's health. Several pre-factors show dynamic characteristics according to the phases that shift the vaginal microbiota from anaerobes to aerobes which is a hallmark of healthy vaginal environment. These factors include oestrogen levels, glycogen deposition, and vaginal microstructure. In the adult phase, Lactobacillus is highly dominant and regulates pH, adherence, aggregation, immune modulation, synthesis of bacteriocins, and biosurfactants (BSs) which are antagonistic to pathogens. Maternal factors are protective by favouring the colonization of lactobacilli in the vagina in the neonatal phase, which diminishes with age. The dominance of lactobacilli and dysbiosis in the adult phase depends on intrinsic and extrinsic factors in women, which vary between ethnicities. Recent developments in probiotics used against vaginal microbiome dysbiosis have shown great promise in restoring the normal microbiota including preventing the loss of beneficial bacteria. However, further in-depth studies are warranted to ensure long-term protection by probiotics. This review highlights various aspects of the vaginal microenvironment in different phases of growth and diverse ethnicities. Furthermore, it discusses future trends for formulating more effective population-specific probiotics and implications of paraprobiotics and postbiotics as effective therapeutics.

Comprehensive bacterial-metabolite profiles of Hawaijar, Bekang, and Akhone: a comparative study on traditional fermented soybeans of north-east India.

Preparation of traditionally fermented soybeans varies across ethnicities with distinct tastes, flavour, and nutritional values. The fermented soybean varieties Hawaijar, Bekang, and Akhone of north-east India are associated with diverse ethnic groups from Manipur, Mizoram, and Nagaland, respectively. These varieties differ in substrate and traditional practice that exerts differential bacterial-metabolite profile, which needs an in-depth analysis i. Culture-dependent and independent techniques investigated the bacterial diversity of the fermented soybean varieties. Gas chromatography and mass spectroscopy (GC-MS) studied these varieties' metabolite profiles. The common dominant bacterial genera detected in Hawaijar, Bekang, and Akhone were Bacillus, Ignatzschinaria, and Corynebacterium, with the presence of Brevibacillus and Staphylococcus exclusively in Hawaijar and Oceanobacillus in Bekang and Akhone. The metabolite analysis identified a higher abundance of essential amino acids, amino and nucleotide sugars, and vitamins in Hawaijar, short-chain fatty acids in Bekang, polyunsaturated fatty acids in Akhone and Hawaijar, and prebiotics in Akhone. The bacteria-metabolite correlation analysis predicted four distinct bacterial clusters associated with the differential synthesis of the functional metabolites. While B. subtilis is ubiquitous, cluster-1 comprised B. thermoamylovorans/B. amyloliquefaciens, cluster-2 comprised B. tropicus, cluster-3 comprised B. megaterium/B. borstelensis, and cluster-4 comprised B. rugosus. To the best of our knowledge, this is the first comparative study on traditional fermented soybean varieties of north-east India linking bacterial-metabolite profiles which may help in designing starters for desired functionalities in the future.

Factors associated with women's healthcare decision-making during and after pregnancy in urban slums in Mumbai, India: a cross-sectional analysis.

BACKGROUND: Understanding factors associated with women's healthcare decision-making during and after pregnancy is important. While there is considerable evidence related to general determinants of women's decision-making abilities or agency, there is little evidence on factors associated with women's decision-making abilities or agency with regards to health care (henceforth, health agency), especially for antenatal and postnatal care. We assessed women's health agency during and after pregnancy in slums in Mumbai, India, and examined factors associated with increased participation in healthcare decisions. METHODS: Cross-sectional data were collected from 2,630 women who gave birth and lived in 48 slums in Mumbai. A health agency module was developed to assess participation in healthcare decision-making during and after pregnancy. Linear regression analysis was used to examine factors associated with increased health agency. RESULTS: Around two-thirds of women made decisions about perinatal care by themselves or jointly with their husband, leaving about one-third outside the decision-making process. Participation increased with age, secondary and higher education, and paid employment, but decreased with age at marriage and household size. The strongest associations were with age and household size, each accounting for about a 0.2 standard deviation difference in health agency score for each one standard deviation change (although in different directions). Similar differences were observed for those in paid employment compared to those who were not, and for those with higher education compared to those with no schooling. CONCLUSION: Exclusion of women from maternal healthcare decision-making threatens the effectiveness of health interventions. Factors such as age, employment, education, and household size need to be considered when designing health interventions targeting new mothers living in challenging conditions, such as urban slums in low- and middle-income countries.

Oxidant activated soluble adenylate cyclase of Leishmania donovani regulates the cAMP-PKA signaling axis for its intra-macrophage survival during infection.

Adenosine 3',5'-cyclic monophosphate (cAMP) is a stress sensor molecule that transduces the cellular signal when Leishmania donovani moves from insect vector to mammalian host. At this stage, the parasite membrane-bound receptor adenylate cyclase predominantly produces cAMP to cope with the oxidative assault imposed by host macrophages. However, the role of soluble adenylate cyclase of L. donovani (LdHemAC) has not been investigated fully. In the present investigation, we monitored an alternative pool of cAMP, maintained by LdHemAC. The elevated cAMP effectively transmits signals by binding to Protein Kinase A (PKA) present in the cytosol and regulates antioxidant gene expression and phosphorylates several unknown PKA substrate proteins. Menadione-catalyzed production of reactive oxygen species (ROS) mimics host oxidative condition in vitro in parasites where cAMP production and PKA activity were found increased by ~1.54 ± 0.35, and ~1.78 ± 0.47-fold, respectively while expression of LdHemAC gene elevated by ~2.18 ± 0.17-fold. The LdHemAC sense these oxidants and became activated to cyclize ATP to enhance the cAMP basal level that regulates antioxidant gene expression to rescue parasites from oxidative stress. In knockdown parasites (LdHemAC-KD), the downregulated antioxidant genes expression, namely, Sod (2.30 ± 0.46), Pxn (2.73 ± 0.15), Tdr (2.7 ± 0.12), and Gss (1.57 ± 0.15) results in decreased parasite viability while in overexpressed parasites (LdHemAC-OE), the expression was upregulated by ~5.7 ± 0.35, ~2.57 ± 0.56, ~4.7 ± 0.36, and ~2.4 ± 0.83, respectively, which possibly overcomes ROS accumulation and enhances viability. Furthermore, LdHemAC-OE higher PKA activity regulates phosphorylation of substrate proteins (~56 kDs in membrane fraction and ~25 kDs in the soluble fraction). It reduced significantly when treated with inhibitors like DDA, Rp-cAMP, and H-89 and increased by ~2.1 ± 0.28-fold, respectively under oxidative conditions. The LdHemAC-KD was found less infective to RAW 264.7 macrophages and more prone to oxidative damage as compared to LdHemAC-OE and control parasites. Together, this study demonstrates mechanistic links among LdHemAC, cAMP, and PKA in parasite survival and invasion under host oxidative condition.

Evaluation of the Hindi version of the London Measure of Unplanned Pregnancy among pregnant and postnatal women in urban India.

BACKGROUND: Valid and reliable measures such as London Measure of Unplanned Pregnancy (LMUP) are imperative for understanding fertility-related behaviors and estimating unintended pregnancy. The aim of this study was to validate the LMUP in the Hindi language for a wider reach in India. METHODS: An interviewer administered version of the LMUP was translated and pretested in Hindi. The LMUP was field tested with married women in the reproductive age group across forty informal settlements in Mumbai in the post intervention census of a cluster randomized control trial to improve the health of women and children. Analyses involved the full sample and sub-groups according to time-from-conception. Reliability (internal consistency) was assessed using Cronbach's alpha, inter-item correlations, and item-rest correlations. Construct validity was assessed by hypothesis testing and confirmatory factor analysis. RESULTS: 4991 women were included in the study (1180 were pregnant, 2126 in their first- and 1685 in their second postnatal year). LMUP item completion rates were 100 % and the full range of LMUP scores was captured. Reliability: the scale was internally consistent (Cronbach's α = 0.84), inter-item correlations were positive, and item-rest correlations were above 0.2 for all items except item six (0.07). Construct validity: hypotheses were met, and confirmatory factor analysis showed that a one-factor model was a good fit for the data, confirming unidimensional measurement. The sub-group analysis (by pregnant, first-, and second postnatal year) showed that the psychometric properties of the LMUP were similar across the groups. In terms of LMUP scores, the women in the postnatal groups were very slightly, but significantly, more likely to have an LMUP score of 10 + compared to pregnant women; the difference between the first and second postnatal year was not significant. CONCLUSIONS: The Hindi LMUP is valid and reliable measure of pregnancy intention that may be used in India. TRIAL REGISTRATION: This study is registered with ISRCTN, number ISRCTN56183183, and Clinical Trials Registry of India, number CTRI/2012/09/003004.

Leishmania infection activates host mTOR for its survival by M2 macrophage polarization.

Mammalian target of rapamycin (mTOR) is a central regulator of growth and immunity of host cells. It's involvement in cancer and tuberculosis is well documented but least explored in Leishmania donovani invasion of host cells. Therefore, in the present study, we aimed to investigate the role of mTOR in M2 macrophage polarization for Leishmania survival. We observed that Leishmania infection activated host mTOR pathway characterized by phosphorylation of mTOR, 70S6K and 4-EBP1. Inhibition of mTOR resulted in decreased parasite load and percent infectivity. Moreover, Leishmania infection triggered cell proliferation as was evidenced by increased expression of cyclin A and p-RPS6. mTOR activation during Leishmania infection resulted in reduced expression of M1 macrophage markers (eg, ROS, NO, iNOS, NOX-1, IL-12, IL-1ß and TNF-α), and increased expression of M2 macrophage markers (eg, arginase-1, IL-10, TGF-ß, CD206 and CD163). Furthermore, we observed that in case of Leishmania infection, mTOR inhibition increased the translocation of NF-κB to nucleus and deactivation of STAT-3. Eventually, we observed that inhibition of M2 macrophage polarization reduced Leishmania survival inside macrophages. Therefore, our findings suggest that mTOR plays a crucial role in regulation of M2 macrophage polarization and direct the innate immune homeostasis towards parasite survival inside host.

Effects of women's groups practising participatory learning and action on preventive and care-seeking behaviours to reduce neonatal mortality: A meta-analysis of cluster-randomised trials.

BACKGROUND: The World Health Organization recommends participatory learning and action (PLA) in women's groups to improve maternal and newborn health, particularly in rural settings with low access to health services. There have been calls to understand the pathways through which this community intervention may affect neonatal mortality. We examined the effect of women's groups on key antenatal, delivery, and postnatal behaviours in order to understand pathways to mortality reduction. METHODS AND FINDINGS: We conducted a meta-analysis using data from 7 cluster-randomised controlled trials that took place between 2001 and 2012 in rural India (2 trials), urban India (1 trial), rural Bangladesh (2 trials), rural Nepal (1 trial), and rural Malawi (1 trial), with the number of participants ranging between 6,125 and 29,901 live births. Behavioural outcomes included appropriate antenatal care, facility delivery, use of a safe delivery kit, hand washing by the birth attendant prior to delivery, use of a sterilised instrument to cut the umbilical cord, immediate wrapping of the newborn after delivery, delayed bathing of the newborn, early initiation of breastfeeding, and exclusive breastfeeding. We used 2-stage meta-analysis techniques to estimate the effect of the women's group intervention on behavioural outcomes. In the first stage, we used random effects models with individual patient data to assess the effect of groups on outcomes separately for the different trials. In the second stage of the meta-analysis, random effects models were applied using summary-level estimates calculated in the first stage of the analysis. To determine whether behaviour change was related to group attendance, we used random effects models to assess associations between outcomes and the following categories of group attendance and allocation: women attending a group and allocated to the intervention arm; women not attending a group but allocated to the intervention arm; and women allocated to the control arm. Overall, women's groups practising PLA improved behaviours during and after home deliveries, including the use of safe delivery kits (odds ratio [OR] 2.92, 95% CI 2.02-4.22; I2 = 63.7%, 95% CI 4.4%-86.2%), use of a sterile blade to cut the umbilical cord (1.88, 1.25-2.82; 67.6%, 16.1%-87.5%), birth attendant washing hands prior to delivery (1.87, 1.19-2.95; 79%, 53.8%-90.4%), delayed bathing of the newborn for at least 24 hours (1.47, 1.09-1.99; 68.0%, 29.2%-85.6%), and wrapping the newborn within 10 minutes of delivery (1.27, 1.02-1.60; 0.0%, 0%-79.2%). Effects were partly dependent on the proportion of pregnant women attending groups. We did not find evidence of effects on uptake of antenatal care (OR 1.03, 95% CI 0.77-1.38; I2 = 86.3%, 95% CI 73.8%-92.8%), facility delivery (1.02, 0.93-1.12; 21.4%, 0%-65.8%), initiating breastfeeding within 1 hour (1.08, 0.85-1.39; 76.6%, 50.9%-88.8%), or exclusive breastfeeding for 6 weeks after delivery (1.18, 0.93-1.48; 72.9%, 37.8%-88.2%). The main limitation of our analysis is the high degree of heterogeneity for effects on most behaviours, possibly due to the limited number of trials involving women's groups and context-specific effects. CONCLUSIONS: This meta-analysis suggests that women's groups practising PLA improve key behaviours on the pathway to neonatal mortality, with the strongest evidence for home care behaviours and practices during home deliveries. A lack of consistency in improved behaviours across all trials may reflect differences in local priorities, capabilities, and the responsiveness of health services. Future research could address the mechanisms behind how PLA improves survival, in order to adapt this method to improve maternal and newborn health in different contexts, as well as improve other outcomes across the continuum of care for women, children, and adolescents.

Glucose deprivation induced upregulation of phosphoenolpyruvate carboxykinase modulates virulence in Leishmania donovani.

Various physiological stimuli trigger the conversion of noninfective Leishmania donovani promastigotes to the infective form. Here, we present the first evidence of the effect of glucose starvation, on virulence and survival of these parasites. Glucose starvation resulted in a decrease in metabolically active parasites and their proliferation. However, this was reversed by supplementation of gluconeogenic amino acids. Glucose starvation induced metacyclogenesis and enhanced virulence through protein kinase A regulatory subunit (LdPKAR1) mediated autophagy. Glucose starvation driven oxidative stress upregulated the antioxidant machinery, culminating in increased infectivity and greater parasitic load in primary macrophages. Interestingly, phosphoenolpyruvate carboxykinase (LdPEPCK), a gluconeogenic enzyme, exhibited the highest activity under glucose starvation to regulate growth of L. donovani by alternatively utilising amino acids. Deletion of LdPEPCK (Δpepck) decreased virulent traits and parasitic load in primary macrophages but increased autophagosome formation in the mutant parasites. Furthermore, Δpepck parasites failed to activate the Pentose Phosphate Pathway shunt, abrogating NADPH/NADP+ homoeostasis, conferring increased susceptibility towards oxidants following glucose starvation. In conclusion, this study showed that L. donovani undertakes metabolic rearrangements via gluconeogenesis under glucose starvation for acquiring virulence and its survival in the hostile environment.

In Vitro Evaluation of Antileishmanial Activity of Computationally Screened Compounds against Ascorbate Peroxidase To Combat Amphotericin B Drug Resistance.

In visceral leishmaniasis (VL), the host macrophages generate oxidative stress to destroy the pathogen, while Leishmania combats the harmful effect of radicals by redox homeostasis through its unique trypanothione cascade. Leishmania donovani ascorbate peroxidase (LdAPx) is a redox enzyme that regulates the trypanothione cascade and detoxifies the effect of H2O2 The absence of an LdAPx homologue in humans makes it an excellent drug target. In this study, the homology model of LdAPx was built, including heme, and diverse compounds were prefiltered (PAINS, ADMET, and Lipinski's rule of five) and thereafter screened against the LdAPx model. Compounds having good affinity in terms of the Glide XP (extra precision) score were clustered to select diverse compounds for experimental validation. A total of 26 cluster representatives were procured and tested on promastigote culture, yielding 12 compounds with good antileishmanial activity. Out of them, six compounds were safer on the BALB/c peritoneal macrophages and were also effective against disease-causing intracellular amastigotes. Three out of six compounds inhibited recombinant LdAPx in a noncompetitive manner and also demonstrated partial reversion of the resistance property in an amphotericin B (AmB)-resistant strain, which may be due to an increased level of reactive oxygen species (ROS) and decrease of glutathione (GSH) content. However, inhibition of LdAPx in resistant parasites enhanced annexin V staining and activation of metacaspase-like protease activity, which may help in DNA fragmentation and apoptosis-like cell death. Thus, the present study will help in the search for specific hits and templates of potential therapeutic interest and therefore may facilitate the development of new drugs for combination therapy against VL.

Metabolic reconfiguration of the central glucose metabolism: a crucial strategy of Leishmania donovani for its survival during oxidative stress.

Understanding the mechanism that allows the intracellular protozoan parasite Leishmania donovani (Ld) to respond to reactive oxygen species (ROS) is of increasing therapeutic importance because of the continuing resistance toward antileishmanial drugs and for determining the illusive survival strategy of these parasites. A shift in primary carbon metabolism is the fastest response to oxidative stress. A (14)CO2 evolution study, expression of glucose transporters together with consumption assays, indicated a shift in metabolic flux of the parasites from glycolysis toward pentose phosphate pathway (PPP) when exposed to different oxidants in vitro/ex vivo. Changes in gene expression, protein levels, and enzyme activities all pointed to a metabolic reconfiguration of the central glucose metabolism in response to oxidants. Generation of glucose-6-phosphate dehydrogenase (G6PDH) (∼5-fold) and transaldolase (TAL) (∼4.2-fold) overexpressing Ld cells reaffirmed that lethal doses of ROS were counterbalanced by effective manipulation of NADPH:NADP(+) ratio and stringent maintenance of reduced thiol content. The extent of protein carbonylation and accumulation of lipid peroxidized products were also found to be less in overexpressed cell lines. Interestingly, the LD50 of sodium antimony gluconate (SAG), amphotericin-B (AmB), and miltefosine were significantly high toward overexpressing parasites. Consequently, this study illustrates that Ld strategizes a metabolic reconfiguration for replenishment of NADPH pool to encounter oxidative challenges.

Institutional delivery in public and private sectors in South Asia: a comparative analysis of prospective data from four demographic surveillance sites.

BACKGROUND: Maternity care in South Asia is available in both public and private sectors. Using data from demographic surveillance sites in Bangladesh, Nepal and rural and urban India, we aimed to compare institutional delivery rates and public-private share. METHODS: We used records of maternity care collected in socio-economically disadvantaged communities between 2005 and 2011. Institutional delivery was summarized by four potential determinants: household asset index, maternal schooling, maternal age, and parity. We developed logistic regression models for private sector institutional delivery with these as independent covariates. RESULTS: The data described 52 750 deliveries. Institutional delivery proportion varied and there were differences in public-private split. In Bangladesh and urban India, the proportion of deliveries in the private sector increased with wealth, maternal education, and age. The opposite was observed in rural India and Nepal. CONCLUSIONS: The proportion of institutional delivery increased with economic status and education. The choice of sector is more complex and provision and perceived quality of public sector services is likely to play a role. Choices for safe maternity are influenced by accessibility, quantity and perceived quality of care. Along with data linkage between private and public sectors, increased regulation should be part of the development of the pluralistic healthcare systems that characterize south Asia.

Up-regulation of silent information regulator 2 (Sir2) is associated with amphotericin B resistance in clinical isolates of Leishmania donovani.

OBJECTIVE: Silent information regulator 2 (Sir2) is involved in parasite survival and apoptosis. Here, we aimed to explore the involvement of Sir2 in amphotericin B (AmB) resistance mechanism in Leishmania donovani. METHODS: The expression levels of Sir2, MDR1 and NAD(+) biosynthetic pathway enzymes in AmB-resistant and -susceptible parasites were measured and total intracellular NAD(+)/NADH ratios were compared. Overexpression and knockout constructs of Sir2 were transfected in AmB-resistant and -susceptible parasites. Both resistant and susceptible parasites were inhibited with sirtinol for 4 h. The deacetylase activity of Sir2, the expression level of MDR1, the rate of AmB efflux, concentrations of reactive oxygen species (ROS) and levels of apoptosis were examined in WT, inhibited and transfected parasites, and the AmB susceptibility of the respective parasites was measured by determining the LD50 of AmB. RESULTS: Levels of mRNA, protein and NAD(+)-dependent deacetylase activity of Sir2 were elevated in resistant versus susceptible parasites. Inhibition and/or deletion of Sir2 allele showed a decreased mRNA level of MDR1, lower drug efflux, increased ROS concentration, apoptosis-like phenomenon and decreased LD50 of AmB in resistant parasites. In contrast, Sir2 overexpression in susceptible parasites reversed drug susceptibility producing a resistant phenotype. This was associated with increased LD50 of AmB along with increased expression levels of MDR1, drug efflux and reduced concentrations of ROS, corresponding to decreased apoptosis of resistant to WT sensitive. CONCLUSIONS: Sir2 plays a critical role in AmB resistance by regulating MDR1, ROS concentration and apoptosis-like phenomena and may be a new resistance marker for visceral leishmaniasis.

Examining inequalities in uptake of maternal health care and choice of provider in underserved urban areas of Mumbai, India: a mixed methods study.

BACKGROUND: Discussions of maternity care in developing countries tend to emphasise service uptake and overlook choice of provider. Understanding how families choose among health providers is essential to addressing inequitable access to care. Our objectives were to quantify the determinants and choice of maternity care provider in Mumbai's informal urban settlements, and to explore the reasons underlying their choices. METHODS: The study was conducted in informal urban communities in eastern Mumbai. We developed regression models using data from a census of married women aged 15-49 to test for associations between maternal characteristics and uptake of care and choice of provider. We then conducted seven focus group discussions and 16 in-depth interviews with purposively selected participants, and used grounded theory methods to examine the reasons for their choices. RESULTS: Three thousand eight hundred forty-eight women who had given birth in the preceding 2 years were interviewed in the census. The odds of institutional prenatal and delivery care increased with education, economic status, and duration of residence in Mumbai, and decreased with parity. Tertiary public hospitals were the commonest site of care, but there was a preference for private hospitals with increasing socio-economic status. Women were more likely to use tertiary public hospitals for delivery if they had fewer children and were Hindu. The odds of delivery in the private sector increased with maternal education, wealth, age, recent arrival in Mumbai, and Muslim faith. Four processes were identified in choosing a health care provider: exploring the options, defining a sphere of access, negotiating autonomy, and protective reasoning. Women seeking a positive health experience and outcome adopted strategies to select the best or most suitable, accessible provider. CONCLUSIONS: In Mumbai's informal settlements, institutional maternity care is the norm, except among recent migrants. Poor perceptions of primary public health facilities often cause residents to bypass them in favour of tertiary hospitals or private sector facilities. Families follow a complex selection process, mediated by their ability to mobilise economic and social resources, and a concern for positive experiences of health care and outcomes. Health managers must ensure quality services, a functioning regulatory mechanism, and monitoring of provider behaviour.

Ascorbate peroxidase, a key molecule regulating amphotericin B resistance in clinical isolates of Leishmania donovani.

Amphotericin B (AmB), a polyene macrolide, is now a first-line treatment of visceral leishmaniasis cases refractory to antimonials in India. AmB relapse cases and the emergence of secondary resistance have now been reported. To understand the mechanism of AmB, differentially expressed genes in AmB resistance strains were identified by a DNA microarray and real-time reverse transcriptase PCR (RT-PCR) approach. Of the many genes functionally overexpressed in the presence of AmB, the ascorbate peroxidase gene from a resistant Leishmania donovani strain (LdAPx gene) was selected because the gene is present only in Leishmania, not in humans. Apoptosis-like cell death after exposure to AmB was investigated in a wild-type (WT) strain in which the LdAPx gene was overexpressed and in AmB-sensitive and -resistant strains. A higher percentage of apoptosis-like cell death after AmB treatment was noticed in the sensitive strain than in both the resistant isolate and the strain sensitive to LdAPx overexpression. This event is preceded by AmB-induced formation of reactive oxygen species and elevation of the cytosolic calcium level. Enhanced cytosolic calcium was found to be responsible for depolarization of the mitochondrial membrane potential and the release of cytochrome c (Cyt c) into the cytosol. The redox behavior of Cyt c showed that it has a role in the regulation of apoptosis-like cell death by activating metacaspase- and caspase-like proteins and causing concomitant nuclear alterations, as determined by terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL) and DNA fragmentation in the resistant strain. The present study suggests that constitutive overexpression of LdAPx in the L. donovani AmB-resistant strain prevents cells from the deleterious effect of oxidative stress, i.e., mitochondrial dysfunction and cellular death induced by AmB.

Specific noninvasive detection of Leishmania donovani in desquamated buccal cell swab samples from human visceral Leishmaniasis-HIV coinfected patients.

Diagnosis of human immunodeficiency virus (HIV) infection with visceral leishmaniasis (VL) coinfection is challenging. Specific diagnosis of VL in HIV-coinfected patients was evaluated by molecular methods in desquamated buccal swab samples, demonstrating 86.3% sensitivity and 98.3% specificity in controls. This test holds significant potential for development as a noninvasive diagnostic tool for VL in HIV-coinfected patients.

Leishmania donovani mevalonate kinase regulates host actin for inducing phagocytosis.

Despite the well-established role of macrophages in phagocytosing Leishmania, the contribution of the parasite to this process is not well understood. Present study provides insights into the mechanism underlying the MVK-induced entry of L. donovani and improve our knowledge of host-pathogen interactions. We have discussed Mevalonate kinase (MVK)-induced actin reorganization, modulation of signaling pathways and host cell functions. Our results show that LdMVK gains access to macrophage cytosol and induces actin assembly modulation through the activation of actin-related proteins: VASP, Src and ERM. We have also demonstrated that LdMVK induces Ca2+ signaling and Akt pathway in macrophages, which are critical components of Leishmania survival and proliferation. Interestingly, we found that antibodies against LdMVK can kill Leishmania-infected macrophages in culture by forming extracellular traps, highlighting the potential of LdMVK in inhibiting parasite death. Overall, LdMVK is a virulent factor in Leishmania that mediates parasite internalization and host modulation by targeting host proteins phosphorylation and calcium homeostasis having significant implications in disease progression.

Effectiveness of miltefosine treatment in targeting anti-leishmanial HO-1/Nrf-2-mediated oxidative responses in visceral leishmaniasis patients.

OBJECTIVES: Miltefosine, an alkylphosphocholine anti-cancer drug, exhibits direct activity against Leishmania donovani and also promotes anti-leishmanial host immunomodulatory functions. Nuclear factor-erythroid 2-related factor 2 (Nrf-2), a redox-sensitive transcription factor, regulates the host stress responses leading to effective microbial clearance by a positive effect on haem oxygenase-1 (HO-1) enzyme expression/activity. We aimed to investigate the role of miltefosine in regulating HO-1/Nrf-2-mediated oxidative responses in visceral leishmaniasis (VL) patients in vivo and in vitro. METHODS: Splenic aspirate and bone marrow aspirate cells of VL patients (n = 23) were used in the study. RT-PCR of HO-1, Nrf-2 translocation analysis and HO-1 ELISA were used to investigate the HO-1/Nrf-2-mediated modulation of oxidative responses by miltefosine in vivo. Fluorometric measurement of reactive oxygen species (ROS) was performed, determination of glutathione peroxidase (GPx) activity was performed, and bilirubin and superoxide dismutase (SOD) levels were determined. The in vitro HO-1/Nrf-2-dependent anti-leishmanial effect of miltefosine was assessed by the use of specific inhibitors/inducers and subsequent microscopic measurement of parasite killing and Th1/Th2 cytokine regulation by ELISA. RESULTS: Increased levels of transcript and serum HO-1, Nrf-2 nuclear translocation, serum bilirubin, GPx and SOD activity in untreated VL patients were reversed after miltefosine chemotherapy. The effectiveness of miltefosine for positive induction of ROS via NADPH correlated with a decrease in HO-1/ERK/Nrf-2-dependent parasite load. Furthermore, HO-1 blockade by miltefosine led to suppression of interleukin-10 and transforming growth factor-ß, but enhanced interleukin-12 and tumour necrosis factor-α production, in VL patients. CONCLUSIONS: The antioxidant promoting property of L. donovani is crucial for protection against the mounting redox threat in the host. Therefore, these findings provide direct evidence for targeting HO-1/Nrf-2 as an anti-leishmanial approach for chemotherapy in human VL.