CD40 ligand and interferon-γ induce an antimicrobial response against Mycobacterium tuberculosis in human monocytes

Transcriptomics analysis highlights potential ways in human pathogenesis in Leishmania braziliensis infected with the viral endosymbiont LRV1

The parasite Leishmania (Viannia) braziliensis is widely distributed in Brazil and is one of the main species associated with human cases of different forms of tegumentary leishmaniasis (TL) such as cutaneous leishmaniasis (CL) and mucosal leishmaniasis (ML). The mechanisms underlying the pathogenesis of TL are still not fully understood, but it is known that factors related to the host and the parasite act in a synergistic and relevant way to direct the response to the infection. In the host, macrophages have a central connection with the parasite and play a fundamental role in the defense of the organism due to their ability to destroy intracellular parasites and present antigens. In the parasite, some intrinsic factors related to the species or even the strain analyzed are fundamental for the outcome of the disease. One of them is the presence of Leishmania RNA Virus 1 (LRV1), an endosymbiont virus that parasitizes some species of Leishmania that triggers a cascade of signals leading to a more severe TL phenotype, such as ML. One of the strategies for understanding factors associated with the immune response generated after Leishmania/host interaction is through the analysis of molecular patterns after infection. Thus, the gene expression profile in human monocyte-derived macrophages obtained from healthy donors infected in vitro with L. braziliensis positive (LbLRV1+) and negative (LbLRV1-) for LRV1 was evaluated. For this, the microarray assay was used and 162 differentially expressed genes were identified in the comparison LbLRV1+ vs. LbLRV1-, 126 upregulated genes for the type I and II interferons (IFN) signaling pathway, oligoadenylate synthase OAS/RNAse L, non-genomic actions of vitamin D3 and RIG-I type receptors, and 36 down-regulated. The top 10 downregulated genes along with the top 10 upregulated genes were considered for analysis. Type I interferon (IFNI)- and OAS-related pathways results were validated by RT-qPCR and Th1/Th2/Th17 cytokines were analyzed by Cytometric Bead Array (CBA) and enzyme-linked immunosorbent assay (ELISA). The microarray results validated by RT-qPCR showed differential expression of genes related to IFNI-mediated pathways with overexpression of different genes in cells infected with LbLRV1+ compared to LbLRV1- and to the control. No significant differences were found in cytokine levels between LbLRV1+ vs. LbLRV1- and control. The data suggest the activation of gene signaling pathways associated with the presence of LRV1 has not yet been reported so far. This study demonstrates, for the first time, the activation of the OAS/RNase L signaling pathway and the non-genomic actions of vitamin D3 when comparing infections with LbLRV1+ versus LbLRV1- and the control. This finding emphasizes the role of LRV1 in directing the host's immune response after infection, underlining the importance of identifying LRV1 in patients with TL to assess disease progression.

Effect of adjunct Vitamin D treatment in vitamin D deficient pulmonary tuberculosis patients: A randomized, double blind, active controlled clinical trial

BACKGROUND

Since, Vitamin D [1α,25(OH)2D)] enhances antimicrobial activity of Innate immunity and modulate Adaptive immune responses, simultaneously, so it play a potential role for balanced immune activity against Mycobacterium tuberculosis and restricting tissue injuries within the TB patients.(Chun et al., 2011) 9 We aimed to determine the role of adjunct Vitamin D treatment on the outcome of pulmonary tuberculosis patients and evaluated the effect of Vitamin D administration on Differential Leucocyte Count, Erythrocyte Sedimentation Rate, serum Adenosine deaminase, serum C- reactive protein, Oxygen saturation (SpO2) and Body Weight in Vitamin D deficient pulmonary tuberculosis patients.

METHODS

We conducted a prospective, interventional, randomized, double blind, parallel group, active controlled clinical trial. Newly diagnosed Vitamin D deficient pulmonary tuberculosis patients were randomly assigned to intervention group (received standard anti-tubercular treatment with adjunct Vitamin D3) and control group (received standard anti-tubercular treatment without adjunct Vitamin D3). Total four doses [each dose of 2.5 mg (100000 IU)] of Vitamin D3 were given, orally. First dose was given within 7 days of starting anti-tubercular treatment and second, third, fourth dose were given at 2, 4 and 6 weeks respectively. At the time of enrollment, we measured all baseline characteristics. During follow-up, we measured the study variables and monitored adverse events at 2, 4, 6, 8 and 12 weeks. Our safety parameter was serum corrected calcium level to assess the risk of hypercalcemia.

RESULTS

Total 130 pulmonary TB patients, 65 patients in each group, were analyzed. Our study results showed that decrease in Neutrophil count was statistically significant with small effect sizes at every time point of measurement and increase in Lymphocyte count was statistically significant with small and moderate effect sizes at 4, 6 and 8 week for intervention group than for control group. Decrease in erythrocyte sedimentation rate was statistically significant with small effect sizes at 6 and 8 week, decrease in serum adenosine deaminase and serum C- reactive protein was statistically significant with moderate effect sizes at 4, 6 and 8 week for intervention group than for control group. Increase in Oxygen saturation was statistically significant at 4 week with small effect size and increase in body weight was statistically significant with small effect sizes for intervention group than for control group. No case of hypercalcemia was reported.

CONCLUSION

Our findings suggest a potential role of adjunctive Vitamin D3 to accelerate resolution of inflammatory responses and improvement in clinical outcomes of pulmonary TB patients.

TRIAL REGISTRATION

This trial is registered with Clinical Trials Registry - INDIA (http://ctri.nic.in) with CTRI Number - CTRI/2021/11/037914.

PLACE OF STUDY

Room Number 27, first floor out-patients department (OPD) and inpatient Wards, fourth floor, Department of Respiratory Medicine, Uttar Pradesh University of Medical Sciences, Saifai, Etawah (U.P.), INDIA.

A comprehensive review on the impact of calcium and vitamin D insufficiency and allied metabolic disorders in females

Calcium is imperative in maintaining a quality life, particularly during later ages. Its deficiency results in a wide range of metabolic disorders such as dental changes, cataracts, alterations in brain function, and osteoporosis. These deficiencies are more pronounced in females due to increased calcium turnover throughout their life cycle, especially during pregnancy and lactation. Vitamin D perform a central role in the metabolism of calcium. Recent scientific interventions have linked calcium with an array of metabolic disorders in females including hypertension, obesity, premenstrual dysphoric disorder, polycystic ovary syndrome (PCOS), multiple sclerosis, and breast cancer. This review encompasses these female metabolic disorders with special reference to calcium and vitamin D deficiency. This review article aims to present and elaborate on available data regarding the worldwide occurrence of insufficient calcium consumption in females and allied health risks, to provide a basis for formulating strategies and population-level scientific studies to adequately boost calcium intake and position where required.

Vitamin D as a Shield against Aging

Aging can be seen as a physiological progression of biomolecular damage and the accumulation of defective cellular components, which trigger and amplify the process, toward whole-body function weakening. Senescence initiates at the cellular level and consists in an inability to maintain homeostasis, characterized by the overexpression/aberrant expression of inflammatory/immune/stress responses. Aging is associated with significant modifications in immune system cells, toward a decline in immunosurveillance, which, in turn, leads to chronic elevation of inflammation/oxidative stress, increasing the risk of (co)morbidities. Albeit aging is a natural and unavoidable process, it can be regulated by some factors, like lifestyle and diet. Nutrition, indeed, tackles the mechanisms underlying molecular/cellular aging. Many micronutrients, i.e., vitamins and elements, can impact cell function. This review focuses on the role exerted by vitamin D in geroprotection, based on its ability to shape cellular/intracellular processes and drive the immune response toward immune protection against infections and age-related diseases. To this aim, the main biomolecular paths underlying immunosenescence and inflammaging are identified as biotargets of vitamin D. Topics such as heart and skeletal muscle cell function/dysfunction, depending on vitamin D status, are addressed, with comments on hypovitaminosis D correction by food and supplementation. Albeit research has progressed, still limitations exist in translating knowledge into clinical practice, making it necessary to focus attention on the role of vitamin D in aging, especially considering the growing number of older individuals.

Reduced vitamin D-induced cathelicidin production and killing of Mycobacterium tuberculosis in macrophages from a patient with a non-functional vitamin D receptor: A case report

Tuberculosis (TB) presents a serious health problem with approximately a quarter of the world’s population infected with Mycobacterium tuberculosis (M. tuberculosis) in an asymptomatic latent state of which 5–10% develops active TB at some point in their lives. The antimicrobial protein cathelicidin has broad antimicrobial activity towards viruses and bacteria including M. tuberculosis. Vitamin D increases the expression of cathelicidin in many cell types including macrophages, and it has been suggested that the vitamin D-mediated antimicrobial activity against M. tuberculosis is dependent on the induction of cathelicidin. However, unraveling the immunoregulatory effects of vitamin D in humans is hampered by the lack of suitable experimental models. We have previously described a family in which members suffer from hereditary vitamin D-resistant rickets (HVDRR). The family carry a mutation in the DNA-binding domain of the vitamin D receptor (VDR). This mutation leads to a non-functional VDR, meaning that vitamin D cannot exert its effect in family members homozygous for the mutation. Studies of HVDRR patients open unique possibilities to gain insight in the immunoregulatory roles of vitamin D in humans. Here we describe the impaired ability of macrophages to produce cathelicidin in a HVDRR patient, who in her adolescence suffered from extrapulmonary TB. The present case is a rare experiment of nature, which illustrates the importance of vitamin D in the pathophysiology of combating M. tuberculosis.

Different modalities of host cell death and their impact on Mycobacterium tuberculosis infection

Mycobacterium tuberculosis (Mtb) is the pathogen that causes tuberculosis (TB), a leading infectious disease of humans worldwide. One of the main histopathological hallmarks of TB is the formation of granulomas comprised of elaborately organized aggregates of immune cells containing the pathogen. Dissemination of Mtb from infected cells in the granulomas due to host and mycobacterial factors induces multiple cell death modalities in infected cells. Based on molecular mechanism, morphological characteristics, and signal dependency, there are two main categories of cell death: programmed and nonprogrammed. Programmed cell death (PCD), such as apoptosis and autophagy, is associated with a protective response to Mtb by keeping the bacteria encased within dead macrophages that can be readily phagocytosed by arriving in uninfected or neighboring cells. In contrast, non-PCD necrotic cell death favors the pathogen, resulting in bacterial release into the extracellular environment. Multiple types of cell death in the PCD category, including pyroptosis, necroptosis, ferroptosis, ETosis, parthanatos, and PANoptosis, may be involved in Mtb infection. Since PCD pathways are essential for host immunity to Mtb, therapeutic compounds targeting cell death signaling pathways have been experimentally tested for TB treatment. This review summarizes different modalities of Mtb-mediated host cell deaths, the molecular mechanisms underpinning host cell death during Mtb infection, and its potential implications for host immunity. In addition, targeting host cell death pathways as potential therapeutic and preventive approaches against Mtb infection is also discussed.

Key features of the genetic architecture and evolution of host-microbe interactions revealed by high-resolution genetic mapping of the mucosa-associated gut microbiome in hybrid mice

Determining the forces that shape diversity in host-associated bacterial communities is critical to understanding the evolution and maintenance of metaorganisms. To gain deeper understanding of the role of host genetics in shaping gut microbial traits, we employed a powerful genetic mapping approach using inbred lines derived from the hybrid zone of two incipient house mouse species. Furthermore, we uniquely performed our analysis on microbial traits measured at the gut mucosal interface, which is in more direct contact with host cells and the immune system. Several mucosa-associated bacterial taxa have high heritability estimates, and interestingly, 16S rRNA transcript-based heritability estimates are positively correlated with cospeciation rate estimates. Genome-wide association mapping identifies 428 loci influencing 120 taxa, with narrow genomic intervals pinpointing promising candidate genes and pathways. Importantly, we identified an enrichment of candidate genes associated with several human diseases, including inflammatory bowel disease, and functional categories including innate immunity and G-protein-coupled receptors. These results highlight key features of the genetic architecture of mammalian host-microbe interactions and how they diverge as new species form.

The digestive system, particularly the large intestine, hosts many types of bacteria which together form the gut microbiome. The exact makeup of different bacterial species is specific to an individual, but microbiomes are often more similar between related individuals, and more generally, across related species. Whether this is because individuals share similar environments or similar genetic backgrounds remains unclear. These two factors can be disentangled by breeding different animal lineages – which have different genetic backgrounds while belonging to the same species – and then raising the progeny in the same environment.

To investigate this question, Doms et al. studied the genes and microbiomes of mice resulting from breeding strains from multiple locations in a natural hybrid zone between different subspecies. The experiments showed that 428 genetic regions affected the makeup of the microbiome, many of which were known to be associated with human diseases. Further analysis revealed 79 genes that were particularly interesting, as they were involved in recognition and communication with bacteria. These results show how the influence of the host genome on microbiome composition becomes more specialized as animals evolve.

Overall, the work by Doms et al. helps to pinpoint the genes that impact the microbiome; this knowledge could be helpful to examine how these interactions contribute to the emergence of conditions such as diabetes or inflammatory bowel disease, which are linked to perturbations in gut bacteria.

Genetic and hormonal mechanisms underlying sex-specific immune responses in tuberculosis

Tuberculosis (TB), the world's deadliest bacterial infection, afflicts more human males than females, with a male/female (M/F) ratio of 1.7. Sex disparities in TB prevalence, pathophysiology, and clinical manifestations are widely reported, but the underlying biological mechanisms remain largely undefined. This review assesses epidemiological data on sex disparity in TB, as well as possible underlying hormonal and genetic mechanisms that might differentially modulate innate and adaptive immune responses in males and females, leading to sex differences in disease susceptibility. We consider whether this sex disparity can be extended to the efficacy of vaccines and discuss novel animal models which may offer mechanistic insights. A better understanding of the biological factors underpinning sex-related immune responses in TB may enable sex-specific personalized therapies for TB.

Vitamin D/vitamin D receptor, autophagy, and infection

Vitamin D plays an important role in mineral and bone homeostasis, immune responses, cardiovascular function and keratinocyte proliferation and differentiation. Vitamin D performs most of its functions by binding to vitamin D receptors (VDR), which interact with other intracellular signaling pathways to regulate bone metabolism, inflammation, immunity, cell cycle progression and apoptosis. Autophagy is a basic stress response in yeast, plants and mammals, and plays a critical role in maintaining optimal functional states at the level of cells and organs. Vitamin D/VDR plays an anti-infection role via inducing and regulating autophagy.

Longitudinal Variations of M. tuberculosis-Induced IFN-γ Responses in HIV-Negative Pregnant Women Exposed to Tuberculosis

Introduction

Pregnancy triggers an alteration of the immune functions and increases the risk of developing the active tuberculosis (TB) symptoms in exposed women. The effect of pregnancy on the Mycobacterium tuberculosis-specific immune responses used for most of the TB immunodiagnostic assays is not well documented. Here we investigated the changes in the M. tuberculosis-specific IFN-γ production in age-matched pregnant and non-pregnant women according to their TB exposition status.

Methods

We conducted a prospective cohort study on HIV-seronegative pregnant and non-pregnant women with compatible pulmonary TB symptoms addressed to TB healthcare facilities in Antananarivo, Madagascar. Active pulmonary TB was bacteriologically assessed with culture from sputum samples. Clinical data and blood samples were collected at inclusion and after 6 months of follow-up for each individual included. Whole blood samples were stimulated with QuantiFERON TB-Gold Plus (QFT-P) assay antigens. Plasma IFN-γ concentrations were then assessed by ELISA.

Results

A total of 284 women were investigated for the study including 209 pregnant women without confirmed TB (pNTB), 24 pregnant women with bacteriologically confirmed active TB (pATB), 16 non-pregnant women with active TB (ATB), and 35 non-pregnant healthy donors (HC). At inclusion, IFN-γ responses are lower in the pregnant women compared to their age-matched non-pregnant counterparts and independently of their TB status. Among the pregnant women, higher concentrations of M. tuberculosis-specific IFN-γ were observed in those exposed to TB, but with a lower magnitude in the active TB compared to the latently infected pregnant women (p < 0.05 with TB1 and p < 0.01 with TB2). After 6 months of follow-up, the M. tuberculosis-specific IFN-γ responses return to their baseline concentrations except for the pregnant women treated for TB for which none of the QFT-P positive reversed to negative (0%, 0/10) at the end of their TB treatment.

Conclusion

These results support the concept of specific immune priorities characterized by a concomitant reduction in inflammatory immunity during pregnancy and corroborate the important role of activating the M. tuberculosis-specific immune responses to control the infection when the pregnant women are exposed to the pathogen.

Effects of in vitro vitamin D treatment on function of T cells and autophagy mechanisms in high-fat diet-induced obese mice

BACKGROUND/OBJECTIVES

Obesity is associated with the impaired regulation of T cells characterized by increased numbers of Th1 and Th17 cells and the dysregulation of vitamin D metabolism. Both obesity and vitamin D have been reported to affect autophagy; however, a limited number of studies have investigated the effects of vitamin D on T cell autophagy in obese mice. Therefore, we aimed to determine whether in vitro treatment with vitamin D affects the proliferation, function, and autophagy of T cells from obese and control mice.

MATERIALS/METHODS

Five-week-old male C57BL/6 mice were fed control or high-fat diets (10% or 45% kcal fat: CON or HFDs, respectively) for 12 weeks. Purified T cells were stimulated with anti-CD3 and anti-CD28 monoclonal antibodies and cultured with either 10 nM 1,25(OH)₂D₃ or 0.1% ethanol (vehicle control). The proliferative response; expression of CD25, Foxp3, RORγt, and autophagy-related proteins (LC3A/B, SQSTM1/P62, BECLIN-1, ATG12); and the production of interferon (IFN)-γ, interleukin (IL)-4, IL-17A, and IL-10 by T cells were measured.

RESULTS

Compared with the CON group, T cell proliferation tended to be lower, and the production of IFN-γ was higher in the HFD group. IL-17A production was reduced by 1,25(OH)2D₃ treatment in both groups. The LC3 II/I ratio was higher in the HFD group than the CON group, but P62 did not differ. We observed no effect of vitamin D treatment on T cell autophagy.

CONCLUSIONS

Our findings suggest that diet-induced obesity may impair the function and inhibit autophagy of T cells, possibly leading to the dysregulation of T cell homeostasis, which may be behind the aggravation of inflammation commonly observed in obesity.

Vitamin D in autophagy signaling for health and diseases: Insights on potential mechanisms and future perspectives

Vitamin D regulates the pleiotropic effect to maintain cellular homeostasis and epidemiological evidence establishes an association between vitamin D deficiency and various human diseases. Here, the role of autophagy, the cellular self-degradation process, in vitamin D-dependent function is documented in different cellular settings and discussed the molecular aspects for treating chronic inflammatory, infectious diseases, and cancer. Vitamin D activates autophagy through a genomic and non-genomic signaling pathway to influence a wide variety of physiological functions of different body organs along with bone health and calcium metabolism. Moreover, it induces autophagy as a protective mechanism to inhibit oxidative stress and apoptosis to regulate cell proliferation, differentiation, and immune modulation. Furthermore, vitamin D and its receptor regulate autophagy signaling to control inflammation and host immunity by activating antimicrobial defense mechanisms. Vitamin D has been revealed as a potent anticancer agent and induces autophagy to increase the response to radiation and chemotherapeutic drugs for potential cancer therapy. Increasing vitamin D levels in the human body through timely exposure to sunlight or vitamin D supplements could activate autophagy as part of the homeostasis mechanism to prevent multiple human diseases and aging-associated dysfunctions.

The Paratuberculosis Paradigm Examined: A Review of Host Genetic Resistance and Innate Immune Fitness in Mycobacterium avium subsp. Paratuberculosis Infection

Paratuberculosis, or Johne's Disease (JD) is a debilitating chronic enteritis mainly affecting ruminants caused by Mycobacterium avium subsp. paratuberculosis (MAP). This organism causes worldwide economic losses to the livestock industry, and is of public health importance due to the potential zoonotic risk between MAP and Crohn's disease (CD) in humans. Without economical treatments, or a vaccine capable of preventing infection without causing cross-reactions with bovine tuberculosis, test-and-cull methods for disease control are imperative. Unfortunately, difficulties in diagnostics and long subclinical stage hinder adequate control and is further complicated by variation in MAP exposure outcome. Interestingly, the majority of infections result in asymptomatic presentation and never progress to clinical disease. One contributing factor is host genetics, where polymorphisms in innate immune genes have been found to influence resistance and susceptibility to disease. Candidate genes identified across studies overlap with those found in CD and tuberculosis including; Solute carrier family 11 member 1 gene (SLC11A1), Nucleotide-binding-oligomerization domain containing gene 2 (NOD2), Major histocompatibility complex type II (MHC-II), and Toll-like receptor (TLR) genes. This review will highlight evidence supporting the vital role of these genes in MAP infection outcome, associated challenges, and implications for the future of JD research.

Low vitamin D and risk of bacterial pneumonias: Mendelian randomisation studies in two population-based cohorts

BACKGROUND

Vitamin D may regulate the innate immune system, and randomised controlled trials suggest a beneficial effect of vitamin D supplementation against acute respiratory tract infections. By using a Mendelian randomisation approach, we tested the hypothesis that low 25-hydroxyvitamin D is associated with increased risk of bacterial pneumonia in observational and genetic analyses.

METHODS

We genotyped 116 335 randomly chosen white Danes aged 20 to 100 from the Copenhagen City Heart Study and Copenhagen General Population Study for plasma 25-hydroxyvitamin D decreasing genetic variants around CYP2R1 (rs117913124, rs12794714 and rs10741657), DHCR7 (rs7944926 and rs11234027), GEMIN2 (rs2277458) and HAL (rs3819817). Information on plasma 25-hydroxyvitamin D was available on 35 833 individuals. Individuals were followed from 1981 through 2018 for hospital diagnoses of bacterial pneumonias.

RESULTS

During up to 38 years follow-up, we observed 6342 bacterial pneumonias in observational analyses and 13 916 in genetic analyses. In observational analyses, multivariable adjusted HR for bacterial pneumonias was 1.27 (95% CI: 1.16 to 1.40) for individuals with 25-hydroxyvitamin D<25 nmol/L compared with those with ≥25 nmol/L. In genetic analyses, the OR for bacterial pneumonia per 10 nmol/L lower plasma 25-hydroxyvitamin D was 1.12 (95% CI: 1.02 to 1.23) in Wald's ratio, 1.12 (95% CI: 1.04 to 1.20) in inverse-variance weighted, 1.63 (95% CI: 0.96 to 2.78) in MR-Egger and 1.15 (95% CI: 1.05 to 1.26) in weighted median instrumental variable analysis. This association was strongest for genetic variants around CYP2R1. There was no observational or genetic evidence to support that 25-hydroxyvitamin D is associated with risk of urinary tract infections, skin infections, sepsis or gastroenteritis, which were used as negative control outcomes.

CONCLUSIONS

Low vitamin D is associated observationally and genetically with increased risk of bacterial pneumonias.

Nuclear Receptors as Autophagy-Based Antimicrobial Therapeutics

Autophagy is an intracellular process that targets intracellular pathogens for lysosomal degradation. Autophagy is tightly controlled at transcriptional and post-translational levels. Nuclear receptors (NRs) are a family of transcriptional factors that regulate the expression of gene sets involved in, for example, metabolic and immune homeostasis. Several NRs show promise as host-directed anti-infectives through the modulation of autophagy activities by their natural ligands or small molecules (agonists/antagonists). Here, we review the roles and mechanisms of NRs (vitamin D receptors, estrogen receptors, estrogen-related receptors, and peroxisome proliferator-activated receptors) in linking immunity and autophagy during infection. We also discuss the potential of emerging NRs (REV-ERBs, retinoic acid receptors, retinoic acid-related orphan receptors, liver X receptors, farnesoid X receptors, and thyroid hormone receptors) as candidate antimicrobials. The identification of novel roles and mechanisms for NRs will enable the development of autophagy-adjunctive therapeutics for emerging and re-emerging infectious diseases.

Evaluation of Potential Antigen-specific Host Biomarkers in QuantiFERON Supernatants as Candidates for the Diagnosis of Ocular Tuberculosis

PURPOSE

To evaluate potential host biomarkers detectable in QuantiFERON supernatants as diagnostic candidates for ocular tuberculosis (OTB).

METHODS

We investigated 47 host markers in QuantiFERON supernatants from 92 individuals with uveitis using the Luminex platform. We evaluated the potential of individual and combined biomarkers to distinguish between patients with possible, probable, and no OTB.

RESULTS

Differences were observed in median concentrations of several biomarkers including IL-13, IFN-γ, IFN-α2, and IL-1β, in individuals with OTB versus no OTB regardless of HIV status. Individuals with probable and possible OTB only differed regarding GM-CSF. We identified a four-marker biosignature (CD40 L, IL-33, IFN-γ, and SAP) which diagnosed OTB with an area under the ROC curve of 0.80, sensitivity = 56.3% and specificity = 90.0%.

CONCLUSION

This represents the first attempt at screening QuantiFERON supernatants for biomarkers to diagnose OTB. We identified candidate biosignatures which may aid in diagnosing OTB in both HIV positive and negative patients.

Vitamin D-Cathelicidin Axis: at the Crossroads between Protective Immunity and Pathological Inflammation during Infection

Vitamin D signaling plays an essential role in innate defense against intracellular microorganisms via the generation of the antimicrobial protein cathelicidin. In addition to directly binding to and killing a range of pathogens, cathelicidin acts as a secondary messenger driving vitamin D-mediated inflammation during infection. Recent studies have elucidated the biological and clinical functions of cathelicidin in the context of vitamin D signaling. The vitamin D-cathelicidin axis is involved in the activation of autophagy, which enhances antimicrobial effects against diverse pathogens. Vitamin D studies have also revealed positive and negative regulatory effects of cathelicidin on inflammatory responses to pathogenic stimuli. Diverse innate and adaptive immune signals crosstalk with functional vitamin D receptor signals to enhance the role of cathelicidin action in cell-autonomous effector systems. In this review, we discuss recent findings that demonstrate how the vitamin D-cathelicidin pathway regulates autophagy machinery, protective immune defenses, and inflammation, and contributes to immune cooperation between innate and adaptive immunity. Understanding how the vitamin D-cathelicidin axis operates in the host response to infection will create opportunities for the development of new therapeutic approaches against a variety of infectious diseases.

Interferon Gamma Reprograms Host Mitochondrial Metabolism through Inhibition of Complex II To Control Intracellular Bacterial Replication

The mechanisms by which interferon gamma (IFN-γ) controls the replication of cytosolic pathogens independent of responses, such as the generation of reactive oxygen species/reactive nitrogen species (ROS/RNS), have not been fully elucidated. In the current study, we developed a model using Francisella tularensis, the causative agent of tularemia, in which pathways triggered by IFN-γ commonly associated with bacterial control were not required. Using this model, we demonstrated that IFN-γ-mediated production of itaconate and its ability to impair host mitochondrial function, independent of activity on the pathogen, were central for the restriction of bacterial replication in vitro and in vivo We then demonstrate that IFN-γ-driven itaconate production was dispensable, as directly targeting complex II using cell membrane-permeable metabolites also controlled infection. Together, these findings show that while reprogramming of mitochondrial metabolism is a key factor in IFN-γ control of intracellular bacteria, the development of antimicrobial strategies based on targeting host mitochondrial metabolism independent of this cytokine may be an effective therapeutic approach.

Immunomodulatory Effects of Vitamin D in Pregnancy and Beyond

In addition to its role in calcium homeostasis and bone formation, a modulatory role of the active form of vitamin D on cells of the immune system, particularly T lymphocytes, has been described. The effects of vitamin D on the production and action of several cytokines has been intensively investigated in recent years. In this connection, deficiency of vitamin D has been associated with several autoimmune diseases, including rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), antiphospholipid syndrome (APS), Hashimoto Thyroiditis (HT), and multiple sclerosis (MS). In a successful pregnancy, the maternal immune response needs to adapt to accommodate the semiallogeneic fetus. Disturbances in maternal tolerance are implicated in infertility and pregnancy complications such as miscarriages (RM) and preeclampsia (PE). It is well-known that a subset of T lymphocytes, regulatory T cells (Tregs) exhibit potent suppressive activity, and have a crucial role in curtailing the destructive response of the immune system during pregnancy, and preventing autoimmune diseases. Interestingly, vitamin D deficiency is common in pregnant women, despite the widespread use of prenatal vitamins, and adverse pregnancy outcomes such as RM, PE, intrauterine growth restriction have been linked to hypovitaminosis D during pregnancy. Research has shown that autoimmune diseases have a significant prevalence within the female population, and women with autoimmune disorders are at higher risk for adverse pregnancy outcomes. Provocatively, dysregulation of T cells plays a crucial role in the pathogenesis of autoimmunity, and adverse pregnancy outcomes where these pathologies are also associated with vitamin D deficiency. This article reviews the immunomodulatory role of vitamin D in autoimmune diseases and pregnancy. In particular, we will describe the role of vitamin D from conception until delivery, including the health of the offspring. This review highlights an observational study where hypovitaminosis D was correlated with decreased fertility, increased disease activity, placental insufficiency, and preeclampsia in women with APS.

Efeitos contrastantes da vitamina D sobre a resposta imune inata e adquirida e seu impacto na recuperação da tuberculose

A vitamina D é um hormônio essencial para o organismo, podendo ser obtida da dieta ou, principalmente, gerada pela pele após exposição à luz solar ultravioleta B. Na sua forma ativa (1,25(OH)2D) ela controla a absorção de cálcio e fósforo do intestino para a corrente sanguínea e participa de diversos processos celulares e fisiológicos. A ligação da 1,25(OH)2D ao receptor da vitamina D (VDR) presente em diversas células, como as células do sistema imunológico, induz a transcrição de genes que podem, por exemplo, modular a resposta imune inata e adquirida. A deficiência de vitamina D ou do VDR é associada a problemas de saúde como desordens esqueléticas, hipertensão, doenças cardiovasculares, diabetes mellitus, dislipidemias, doenças autoimunes e doenças infecciosas. Neste sentido, a suplementação com vitamina D tem sido proposta como uma possível medida preventiva, podendo ser aplicada em muitas patologias, em especial na tuberculose. Principal causa de morte por um único agente infeccioso, a tuberculose é responsável por cerca de 1,3 milhões de óbitos por ano no mundo. Publicações recentes apontam efeitos diversos da vitamina D na resposta imune inata e adquirida. A 1,25(OH)2D3 na presença do interferon (IFN)-γ é capaz de aumentar a atividade bactericida do macrófago contra o M. tuberculosis, aumentando a produção de peptídios antimicrobianos e estimulando a autofagia, favorecendo assim a lise de bacilos localizados em fagossomos. Por outro lado, a vitamina D em linfócitos T mostra efeito tolerogênico que favorece o controle de respostas inflamatórias excessivas. Neste trabalho de revisão são apresentados estudos recentes envolvendo efeitos da vitamina D na resposta imune inata e adquirida. Além disso, considerações sobre deficiência de vitamina D e maior risco de contrair tuberculose, e efeitos contrastantes da suplementação com vitamina D na prevenção e tratamento da TB, são discutidos.

Modulation of autophagy in human diseases strategies to foster strengths and circumvent weaknesses

Autophagy is central to the maintenance of intracellular homeostasis across species. Accordingly, autophagy disorders are linked to a variety of diseases from the embryonic stage until death, and the role of autophagy as a therapeutic target has been widely recognized. However, autophagy-associated therapy for human diseases is still in its infancy and is supported by limited evidence. In this review, we summarize the landscape of autophagy-associated diseases and current autophagy modulators. Furthermore, we investigate the existing autophagy-associated clinical trials, analyze the obstacles that limit their progress, offer tactics that may allow barriers to be overcome along the way and then discuss the therapeutic potential of autophagy modulators in clinical applications.

Cell death at the cross roads of host-pathogen interaction in Mycobacterium tuberculosis infection

Tuberculosis (TB) continues to be the leading cause of death by any single infectious agent, accounting for around 1.7 million annual deaths globally, despite several interventions and support programs by national and international agencies. With the development of drug resistance in Mycobacterium tuberculosis (M. tb), there has been a paradigm shift in TB research towards host-directed therapy. The potential targets include the interactions between host and bacterial proteins that are crucial for pathogenesis. Hence, collective efforts are being made to understand the molecular details of host-pathogen interaction for possible translation into host-directed therapy. The present review focuses on 'host cell death modalities' of host-pathogen interaction, which play a crucial role in determining the outcome of TB disease progression. Several cell death modalities that occur in response to mycobacterial infection have been identified in human macrophages either as host defences for bacterial clearance or as pathogen strategies for multiplication and dissemination. These cell death modalities include apoptosis, necrosis, pyroptosis, necroptosis, pyronecrosis, NETosis, and autophagy. These processes are highly overlapping with several mycobacterial proteins participating in more than one cell death pathway. Until now, reviews in M. tb and host cell death have discussed either focusing on host evasion strategies, apoptosis, autophagy, and necrosis or describing all these forms with limited discussions of their role in host-pathogen interactions. Here, we present a comprehensive review of various mycobacterial factors modulating host cell death pathways and the cross-talk between them. Besides this, we have discussed the networking of host cell death pathways including the interference of host miRNA during M. tb infection with their respective targets. Through this review, we present the host targets that overlap across several cell death modalities and the technical limitations of methodology in cell death research. Given the compelling need to discover alternative drug target(s), this review identifies these overlapping cell death factors as potential targets for host-directed therapy.

Adjunctive interferon-γ immunotherapy in a pediatric case of Aspergillus terreus infection

Aspergillus terreus causes invasive aspergillosis (IA) in immunocompromised patients. Treatment is complicated by intrinsic resistance to amphotericin B and thereby contributing to a high mortality. Therefore, we conducted in vitro studies to investigate the effectivity of adjunctive recombinant interferon-γ immunotherapy. We describe a pediatric patient with A. terreus IA who received adjunctive recombinant interferon-γ (rIFNγ) immunotherapy. In vitro studies were conducted to investigate the capacity of rIFNγ to improve antifungal host defense in terms of fungal killing ability and the release of pro-inflammatory cytokines in cells of the patient as well as healthy controls. An 8-year-old female pediatric patient with leukemia developed A. terreus IA. She clinically deteriorated and had high serum galactomannan levels despite broad antifungal therapy. Therefore, adjunctive immune stimulatory therapy with rIFNγ was initiated. After 3 weeks of treatment, galactomannan levels decreased and the patient clinically showed improvement. Addition of rIFNγ boosted the capacity of monocytes of healthy volunteers to mount TNFα and IL-1β cytokine responses to Escherichia coli LPS, and increased TNFα response to both A. terreus and Aspergillus fumigatus. Monocytes isolated from the patient's blood demonstrated a similar augmented cytokine induction in response to rIFNγ. In addition, rIFNγ increased the capacity of monocytes from healthy volunteers as well as monocytes from the patient to kill A. terreus spores. Adjuvant immunotherapy with rIFNγ might be a promising additional treatment strategy that could be used to improve outcome in patients with refractory invasive A. terreus infections or other resistant invasive Aspergillus infections.

Interferon-gamma (IFN-γ): Exploring its implications in infectious diseases

A key player in driving cellular immunity, IFN-γ is capable of orchestrating numerous protective functions to heighten immune responses in infections and cancers. It can exhibit its immunomodulatory effects by enhancing antigen processing and presentation, increasing leukocyte trafficking, inducing an anti-viral state, boosting the anti-microbial functions and affecting cellular proliferation and apoptosis. A complex interplay between immune cell activity and IFN-γ through coordinated integration of signals from other pathways involving cytokines and Pattern Recognition Receptors (PRRs) such as Interleukin (IL)-4, TNF-α, Lipopolysaccharide (LPS), Type-I Interferons (IFNS) etc. leads to initiation of a cascade of pro-inflammatory responses. Microarray data has unraveled numerous genes whose transcriptional regulation is influenced by IFN-γ. Consequently, IFN-γ stimulated cells display altered expression of many such target genes which mediate its downstream effector functions. The importance of IFN-γ is further reinforced by the fact that mice possessing disruptions in the IFN-γ gene or its receptor develop extreme susceptibility to infectious diseases and rapidly succumb to them. In this review, we attempt to elucidate the biological functions and physiological importance of this versatile cytokine. The functional implications of its biological activity in several infectious diseases and autoimmune pathologies are also discussed. As a counter strategy, many virulent pathogenic species have devised ways to thwart IFN-γ endowed immune-protection. Thus, IFN-γ mediated host-pathogen interactions are critical for our understanding of disease mechanisms and these aspects also manifest enormous therapeutic importance for the annulment of various infections and autoimmune conditions.

Microdeletion on chromosome 8p23.1 in a familial form of severe Buruli ulcer

Buruli ulcer (BU), the third most frequent mycobacteriosis worldwide, is a neglected tropical disease caused by Mycobacterium ulcerans. We report the clinical description and extensive genetic analysis of a consanguineous family from Benin comprising two cases of unusually severe non-ulcerative BU. The index case was the most severe of over 2,000 BU cases treated at the Centre de Dépistage et de Traitement de la Lèpre et de l’Ulcère de Buruli, Pobe, Benin, since its opening in 2003. The infection spread to all limbs with PCR-confirmed skin, bone and joint infections. Genome-wide linkage analysis of seven family members was performed and whole-exome sequencing of both patients was obtained. A 37 kilobases homozygous deletion confirmed by targeted resequencing and located within a linkage region on chromosome 8 was identified in both patients but was absent from unaffected siblings. We further assessed the presence of this deletion on genotyping data from 803 independent local individuals (402 BU cases and 401 BU-free controls). Two BU cases were predicted to be homozygous carriers while none was identified in the control group. The deleted region is located close to a cluster of beta-defensin coding genes and contains a long non-coding (linc) RNA gene previously shown to display highest expression values in the skin. This first report of a microdeletion co-segregating with severe BU in a large family supports the view of a key role of human genetics in the natural history of the disease.

Buruli ulcer (BU) is a tropical infectious disease caused by Mycobacterium ulcerans. Although being the third most common mycobacterial disease in the world after tuberculosis and leprosy, BU remains a neglected tropical disease and an emerging health emergency in several developing countries. It causes profound skin ulcerations and eventually bone infections. Life-long functional sequelae are observed in more than 20% of patients, most of whom are children. Several observations, in particular the large variability in the clinical severity of the disease after infection, suggested the role of human genetic factors in the development of BU. We report the case of a 5-year old girl from Benin, born of consanguineous parents, who suffered from extensive dissemination of the mycobacterium in the skin, bones and joints. One of her siblings was also affected. The deep genetic exploration of this family led to the identification of a small deletion on chromosome 8 in both patients but absent from unaffected siblings. Interestingly, the deletion is located within a region containing genes encoding for beta-defensins, a family of antimicrobial peptides involved in both innate immunity and healing process of skin wounds. This first report of a microdeletion associated with severe BU in a large family supports the view of a key role of human genetics in the natural history of the disease.

Mycobacterium tuberculosis Transfer RNA Induces IL-12p70 via Synergistic Activation of Pattern Recognition Receptors within a Cell Network

Upon recognition of a microbial pathogen, the innate and adaptive immune systems are linked to generate a cell-mediated immune response against the foreign invader. The culture filtrate of Mycobacterium tuberculosis contains ligands, such as M. tuberculosis tRNA, that activate the innate immune response and secreted Ags recognized by T cells to drive adaptive immune responses. In this study, bioinformatics analysis of gene-expression profiles derived from human PBMCs treated with distinct microbial ligands identified a mycobacterial tRNA-induced innate immune network resulting in the robust production of IL-12p70, a cytokine required to instruct an adaptive Th1 response for host defense against intracellular bacteria. As validated by functional studies, this pathway contained a feed-forward loop, whereby the early production of IL-18, type I IFNs, and IL-12p70 primed NK cells to respond to IL-18 and produce IFN-γ, enhancing further production of IL-12p70. Mechanistically, tRNA activates TLR3 and TLR8, and this synergistic induction of IL-12p70 was recapitulated by the addition of a specific TLR8 agonist with a TLR3 ligand to PBMCs. These data indicate that M. tuberculosis tRNA activates a gene network involving the integration of multiple innate signals, including types I and II IFNs, as well as distinct cell types to induce IL-12p70.

Prospective study of immunomodulation in osteoarticular tuberculosis non responsive to anti tubercular therapy

BACKGROUND

Tuberculosis is one of the common disease of Indian subcontinent. India has the highest TB burden, accounting for one fifth of the global incidence. Previous studies have shown positive response of immunomodulation in patients of ostearticular tuberculosis We did this prospective study to assess the role of immunomodulation in the cases of osteoarticular tuberculosis who were not responding to anti tubercular therapy.

MATERIALS AND METHOD

This study was conducted in our institute. New patients presenting to OPD who were diagnosed with tuberculosis with no previous history of taking anti tubercular treatment were enrolled. Total of 109 patients were diagnosed clinicoradiologically. Four patients, where diagnosis was not confirmed, histopathological examination of tissue was done and the diagnosis was confirmed as tubercular in origin. Newly diagnosed patients were put on anti tubercular therapy(ATT) after documenting there blood parameters (complete hemogram,ESR, serum proteins, CD4 & CD8 counts). After 3 months patients were re-evaluated and favourably responding patients were labelled group A. Those who did not respond to therapy were put on immunomodulation along with continuation of ATT. These were designated as group B and blood parameters were compared with pre immunomodulation values.

RESULTS

Out of total 109 patients registered, 73 patients were enlisted in group A, while 30 patients were found to be non-responsive to ATT and were included in non-responder group B (six lost to follow up). In group B the blood parameters after one month of completion of immunomodulation showed statistically significant increase in CD4 & CD8 counts (p = 0.04). Mean CD4 count increased from 488/mm³ to 747/mm³ while CD8 count showed increment from 494/mm³ to 617/mm³. Mean haemoglobin values increased along with decrease in ESR and total leucocyte count. In group A mean CD4 and CD8 counts increased with ATT though the results were not significant statistically.

CONCLUSION

Treatment: of tuberculosis has been a great success after introduction of chemotherapy specifically targeting Mycobacterium tuberculosis. In this study relationship between the increase in the peripheral T-cell count and a favourable clinical outcome was further associated with concomitant increase in the haemoglobin level as well as by a decrease in the ESR, total leucocyte count. In our study immunomodulation has shown a good promise to be of adjunctive use in patients on ATT with non-responsiveness.

IL-12+IL-18 Cosignaling in Human Macrophages and Lung Epithelial Cells Activates Cathelicidin and Autophagy, Inhibiting Intracellular Mycobacterial Growth

The ability of Mycobacterium tuberculosis to block host antimicrobial responses in infected cells provides a key mechanism for disease pathogenesis. The immune system has evolved to overcome this blockade to restrict the infection, but it is not clear whether two key innate cytokines (IL-12/IL-18) involved in host defense can enhance antimycobacterial mechanisms. In this study, we demonstrated that the combination of IL-12 and IL-18 triggered an antimicrobial response against mycobacteria in infected macrophages (THP-1 and human primary monocyte-derived macrophages) and pulmonary epithelial A549 cells. The inhibition of intracellular bacterial growth required p38-MAPK and STAT4 pathways, the vitamin D receptor, the vitamin D receptor-derived antimicrobial peptide cathelicidin, and autophagy, but not caspase-mediated apoptosis. Finally, the ability of IL-12+IL-18 to activate an innate antimicrobial response in human primary macrophages was dependent on the autonomous production of IFN-γ and the CAMP/autophagy pathway. Together, these data suggest that IL-12+IL-18 cosignaling can trigger the antimicrobial protein cathelicidin and autophagy, resulting in inhibition of intracellular mycobacteria in macrophages and lung epithelial cells.

Bolstering Immunity through Pattern Recognition Receptors: A Unique Approach to Control Tuberculosis

The global control of tuberculosis (TB) presents a continuous health challenge to mankind. Despite having effective drugs, TB still has a devastating impact on human health. Contributing reasons include the emergence of drug-resistant strains of Mycobacterium tuberculosis (Mtb), the AIDS-pandemic, and the absence of effective vaccines against the disease. Indeed, alternative and effective methods of TB treatment and control are urgently needed. One such approach may be to more effectively engage the immune system; particularly the frontline pattern recognition receptor (PRR) systems of the host, which sense pathogen-associated molecular patterns (PAMPs) of Mtb. It is well known that 95% of individuals infected with Mtb in latent form remain healthy throughout their life. Therefore, we propose that clues can be found to control the remainder by successfully manipulating the innate immune mechanisms, particularly of nasal and mucosal cavities. This article highlights the importance of signaling through PRRs in restricting Mtb entry and subsequently preventing its infection. Furthermore, we discuss whether this unique therapy employing PRRs in combination with drugs can help in reducing the dose and duration of current TB regimen.

Vitamin D Counteracts Mycobacterium tuberculosis-Induced Cathelicidin Downregulation in Dendritic Cells and Allows Th1 Differentiation and IFNγ Secretion

Tuberculosis (TB) presents a serious health problem with approximately one-third of the world's population infected with Mycobacterium tuberculosis in a latent state. Experience from the pre-antibiotic era and more recent clinical studies have established a beneficial role of sunlight and vitamin D in patients with TB. At the same time, experimental data have shown that Th1 cells through production of IFNγ are crucial for cathelicidin release by macrophages, bacterial killing, and containment of M. tuberculosis in granulomas. Paradoxically, vitamin D has repeatedly been ascribed an immune-suppressive function inhibiting Th1 differentiation and production of IFNγ in T cells. The aim of this study was to investigate this apparent paradox. We studied naïve human CD4⁺ T cells activated either with CD3 and CD28 antibodies or with allogeneic dendritic cells (DC) stimulated with heat-killed M. tuberculosis (HKMT) or purified toll-like receptor (TLR) ligands. We show that vitamin D does not block differentiation of human CD4⁺ T cells to Th1 cells and that interleukin (IL)-12 partially counteracts vitamin D-mediated inhibition of IFNγ production promoting production of equal amounts of IFNγ in Th1 cells in the presence of vitamin D as in T cells activated in the absence of vitamin D and IL-12. Furthermore, we show that HKMT and TLR2 ligands strongly downregulate cathelicidin expression in DC and that vitamin D counteracts this by upregulating cathelicidin expression. In conclusion, we demonstrate that vitamin D counteracts M. tuberculosis-induced cathelicidin downregulation and allows Th1 differentiation and IFNγ secretion.

LL37:DNA complexes provide antimicrobial activity against intracellular bacteria in human macrophages

As part of the innate host response neutrophils release neutrophil extracellular traps (NETs), protein:DNA complexes that contain a number of antimicrobial peptides (AMPs), such as cathelicidin. Human cathelicidin in its active form, LL37, has potent antimicrobial activity against bacteria. However, whether LL37 derived from NETs contributes to antimicrobial activity against intracellular pathogens remains unclear. Here, we report that NETs induced by mycobacteria contain cathelicidin. Human macrophages internalized NET-bound cathelicidin, which is transported to lysosomal compartments. Furthermore, using a model of in vitro-generated LL37:DNA complexes we found that LL37 derived from such complexes attacks mycobacteria in macrophage phagolysosomes resulting in antimicrobial activity. Taken together, our results suggest a mechanism by which LL37 in complex with DNA contributes to host defence against intracellular bacteria in human macrophages.

Primary macrophages and J774 cells respond differently to infection with Mycobacterium tuberculosis

Macrophages play an essential role in the early immune response to Mycobacterium tuberculosis and are the cell type preferentially infected in vivo. Primary macrophages and macrophage-like cell lines are commonly used as infection models, although the physiological relevance of cell lines, particularly for host-pathogen interaction studies, is debatable. Here we use high-throughput RNA-sequencing to analyse transcriptome dynamics of two macrophage models in response to M. tuberculosis infection. Specifically, we study the early response of bone marrow-derived mouse macrophages and cell line J774 to infection with live and γ-irradiated (killed) M. tuberculosis. We show that infection with live bacilli specifically alters the expression of host genes such as Rsad2, Ifit1/2/3 and Rig-I, whose potential roles in resistance to M. tuberculosis infection have not yet been investigated. In addition, the response of primary macrophages is faster and more intense than that of J774 cells in terms of number of differentially expressed genes and magnitude of induction/repression. Our results point to potentially novel processes leading to immune containment early during M. tuberculosis infection, and support the idea that important differences exist between primary macrophages and cell lines, which should be taken into account when choosing a macrophage model to study host-pathogen interactions.

Autophagy Is an Innate Mechanism Associated with Leprosy Polarization

Leprosy is a chronic infectious disease that may present different clinical forms according to the immune response of the host. Levels of IFN-γ are significantly raised in paucibacillary tuberculoid (T-lep) when compared with multibacillary lepromatous (L-lep) patients. IFN-γ primes macrophages for inflammatory activation and induces the autophagy antimicrobial mechanism. The involvement of autophagy in the immune response against Mycobacterium leprae remains unexplored. Here, we demonstrated by different autophagic assays that LC3-positive autophagosomes were predominantly observed in T-lep when compared with L-lep lesions and skin-derived macrophages. Accumulation of the autophagic receptors SQSTM1/p62 and NBR1, expression of lysosomal antimicrobial peptides and colocalization analysis of autolysosomes revealed an impairment of the autophagic flux in L-lep cells, which was restored by IFN-γ or rapamycin treatment. Autophagy PCR array gene-expression analysis revealed a significantly upregulation of autophagy genes (BECN1, GPSM3, ATG14, APOL1, and TPR) in T-lep cells. Furthermore, an upregulation of autophagy genes (TPR, GFI1B and GNAI3) as well as LC3 levels was observed in cells of L-lep patients that developed type 1 reaction (T1R) episodes, an acute inflammatory condition associated with increased IFN-γ levels. Finally, we observed increased BCL2 expression in L-lep cells that could be responsible for the blockage of BECN1-mediated autophagy. In addition, in vitro studies demonstrated that dead, but not live M. leprae can induce autophagy in primary and lineage human monocytes, and that live mycobacteria can reduce the autophagy activation triggered by dead mycobacteria, suggesting that M. leprae may hamper the autophagic machinery as an immune escape mechanism. Together, these results indicate that autophagy is an important innate mechanism associated with the M. leprae control in skin macrophages.

Leprosy is an interesting model to study immune responses in humans due to the dichotomy observed among the poles of the disease. While in the self-limited tuberculoid form (T-lep) there are high systemic levels of the cytokine IFN-γ, in the clinically progressive lepromatous form (L-lep) low IFN-γ levels are found. IFN-γ activates an antimicrobial mechanism called autophagy, which has been implicated in control of Mycobacterium tuberculosis infection. However, the role played by autophagy in the immunopathogenesis of leprosy remains unknown. Here we show that autophagy was differentially regulated in T-lep and L-lep patients. In T-lep skin lesion cells autophagy contributes for bacilli control, whereas in L-lep cells the BCL2-mediated block of autophagy promotes the mycobacterial persistence. We also observed that IFN-γ may counteract the inhibition of autophagy triggered by M. leprae infection in L-lep macrophages. In addition, the levels of autophagy were restored in L-lep patients who developed the reversal reaction, an inflammatory state associated with augmented IFN-γ, which is the most important cause of nerve damage and deformities in leprosy. These findings suggest that the modulation of autophagy has the potential to be useful in the treatment of the disease, and provides new insights to prevent leprosy reactional episodes.

1,25 (OH)2D3 treatment alters the granulomatous response in M. tuberculosis infected mice

Induction of cathelicidin-mediated antimicrobial pathway against intracellular M. tuberculosis by 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃), the active form of vitamin D, has been documented in vitro. However, in in vivo studies related to inflammatory disorders, 1,25(OH)₂D₃ has been demonstrated to induce an anti-inflammatory response. We therefore examined whether in the murine model of tuberculosis, the anti-inflammatory effects of 1,25(OH)₂D₃ would affect the outcome of M. tuberculosis infection. We show here that administration of 1,25(OH)₂D₃ to M. tuberculosis infected mice led to a change in lung granuloma architecture, characterized by a marked decrease in B cell lymphocytic aggregates. Consistent with the altered granulomas, 1,25(OH)₂D₃-treated mice also exhibited significantly higher bacterial burden in the lungs compared to the control group. These findings highlight the need to further investigate the effect of vitamin D on host immunity to M. tuberculosis in the context of the granulomatous response.

Immunization with Protein D from Non-Typeable Haemophilus influenzae (NTHi) Induced Cytokine Responses and Bioactive Antibody Production

Background

Outer membrane protein D (PD) is a highly conserved and stable protein in the outer membrane of both encapsulated (typeable) and non-capsulated (non-typeable) strains of Haemophilus influenzae. As an immunogen, PD is a potential candidate vaccine against non-typeable H. influenzae (NTHi) strains.

Objectives

The aim of this study was to determine the cytokine pattern and the opsonic antibody response in a BALB/c mouse model versus PD from NTHi as a vaccine candidate.

Methods

Protein D was formulated with Freund’s and outer membrane vesicle (OMV) adjuvants and injected into experimental mice. Sera from all groups were collected. The bioactivity of the anti-PD antibody was determined by opsonophagocytic killing test. To evaluate the cytokine responses, the spleens were assembled, suspension of splenocytes was recalled with antigen, and culture supernatants were analyzed by ELISA for IL-4, IL-10, and IFN-γ cytokines.

Results

Anti-PD antibodies promoted phagocytosis of NTHi in both immunized mice groups (those administered PD + Freund’s and those administered PD + OMV adjuvants, 92.8% and 83.5%, respectively, compared to the control group). In addition, the concentrations of three cytokines were increased markedly in immunized mice.

Conclusions

We conclude that immunization with PD protects mice against NTHi. It is associated with improvements in both cellular and humoral immune responses and opsonic antibody activity.

Identification of Signaling Pathways by Which CD40 Stimulates Autophagy and Antimicrobial Activity against Toxoplasma gondii in Macrophages

CD40 is an important stimulator of autophagy and autophagic killing of Toxoplasma gondii in host cells. In contrast to autophagy induced by nutrient deprivation or pattern recognition receptors, less is known about the effects of cell-mediated immunity on Beclin 1 and ULK1, key regulators of autophagy. Here we studied the molecular mechanisms by which CD40 stimulates autophagy in macrophages. CD40 ligation caused biphasic Jun N-terminal protein kinase (JNK) phosphorylation. The second phase of JNK phosphorylation was dependent on autocrine production of tumor necrosis factor alpha (TNF-α). TNF-α and JNK signaling were required for the CD40-induced increase in autophagy. JNK signaling downstream of CD40 caused Ser-87 phosphorylation of Bcl-2 and dissociation between Bcl-2 and Beclin 1, an event known to stimulate the autophagic function of Beclin 1. However, TNF-α alone was unable to stimulate autophagy. CD40 also stimulated autophagy via a pathway that included calcium/calmodulin-dependent kinase kinase β (CaMKKβ), AMP-activated protein kinase (AMPK), and ULK1. CD40 caused AMPK phosphorylation at its activating site, Thr-172. This effect was mediated by CaMKKβ and was not impaired by neutralization of TNF-α. CD40 triggered AMPK-dependent Ser-555 phosphorylation of ULK1. CaMKKβ, AMPK, and ULK1 were required for CD40-induced increase in autophagy. CD40-mediated autophagic killing of Toxoplasma gondii is known to require TNF-α. Knockdown of JNK, CaMKKβ, AMPK, or ULK1 prevented T. gondii killing in CD40-activated macrophages. The second phase of JNK phosphorylation-Bcl-2 phosphorylation-Bcl-2-Beclin 1 dissociation and AMPK phosphorylation-ULK1 phosphorylation occurred simultaneously at ∼4 h post-CD40 stimulation. Thus, CaMKKβ and TNF-α are upstream molecules by which CD40 acts on ULK1 and Beclin 1 to stimulate autophagy and killing of T. gondii.

Prenatal high-dose vitamin D3 supplementation has balanced effects on cord blood Th1 and Th2 responses

Background

Antenatal vitamin D₃ (vitD₃) supplementation significantly increases maternal and neonatal 25-hydroxyvitamin D₃ (25(OH)D₃) concentration, yet the effect of an improvement in maternal-fetal vitamin D status on the neonatal immune response is unclear.

Method

To assess the effect of prenatal vitD₃ supplementation on cord blood T cell function, healthy pregnant Bangladeshi women (n = 160) were randomized to receive either oral 35,000 IU/week vitD₃ or placebo from 26 to 29 weeks of gestation to delivery. In a subset of participants (n = 80), cord blood mononuclear cells (CBMC) were cultured, non-adherent lymphocytes were isolated to assess T cell cytokine responses to phytohemagglutinin (PHA) and anti-CD3/anti-CD28 (iCD3/iCD28), measured by multiplex assay. In 12 participants, lymphocyte gene expression profiles were analyzed by PCR array.

Result

In supplemented group, increased concentrations of IL-10 (P < 0.000) and TNF-α (P = 0.05) with iCD3/iCD28 stimulation and IFN-γ (p = 0.05) with PHA stimulation were obtained compared to placebo group. No differences in the gene expression profile were noted between the two groups. However, PHA stimulation significantly induced the expression of genes encoding Th1 and Th2 cytokines and down-regulated a number of genes involved in T-cell development, proliferation and differentiation of B cells, signal transduction pathway, transcriptional regulation and pattern recognition receptors (PRRs) in the vitamin D group (vitD group).

Conclusion

Third-trimester high-dose vitD₃ supplementation in healthy pregnant women had balanced effects on biomarkers of cord blood Th1 and Th2 responses.

Trial registration

ClinicalTrials.gov (NCT01126528).

Electronic supplementary material

The online version of this article (doi:10.1186/s12937-016-0194-5) contains supplementary material, which is available to authorized users.

Targeted pulmonary delivery of inducers of host macrophage autophagy as a potential host-directed chemotherapy of tuberculosis

One of the promising host-directed chemotherapeutic interventions in tuberculosis (TB) is based on inducing autophagy as an immune effector. Here we consider the strengths and weaknesses of potential autophagy-based pharmacological intervention. Using the existing drugs that induce autophagy is an option, but it has limitations given the broad role of autophagy in most cells, tissues, and organs. Thus, it may be desirable that the agent being used to modulate autophagy is applied in a targeted manner, e.g. delivered to affected tissues, with infected macrophages being an obvious choice. This review addresses the advantages and disadvantages of delivering drugs to induce autophagy in M. tuberculosis-infected macrophages. One option, already being tested in models, is to design particles for inhalation delivery to lung macrophages. The choice of drugs, drug release kinetics and intracellular residence times, non-target cell exposure and feasibility of use by patients is discussed. We term here this (still experimental) approach, of compartment-targeting, autophagy-based, host-directed therapy as "Track-II antituberculosis chemotherapy."

Potential of immunomodulatory agents as adjunct host-directed therapies for multidrug-resistant tuberculosis

Treatment of multidrug-resistant tuberculosis (MDR-TB) is extremely challenging due to the virulence of the etiologic strains of Mycobacterium tuberculosis (M. tb), the aberrant host immune responses and the diminishing treatment options with TB drugs. New treatment regimens incorporating therapeutics targeting both M. tb and host factors are urgently needed to improve the clinical management outcomes of MDR-TB. Host-directed therapies (HDT) could avert destructive tuberculous lung pathology, facilitate eradication of M. tb, improve survival and prevent long-term functional disability. In this review we (1) discuss the use of HDT for cancer and other infections, drawing parallels and the precedent they set for MDR-TB treatment, (2) highlight preclinical studies of pharmacological agents commonly used in clinical practice which have HDT potential, and (3) outline developments in cellular therapy to promote clinically beneficial immunomodulation to improve treatment outcomes in patients with pulmonary MDR-TB. The use of HDTs as adjuncts to MDR-TB therapy requires urgent evaluation.

Imatinib Triggers Phagolysosome Acidification and Antimicrobial Activity against Mycobacterium bovis Bacille Calmette-Guérin in Glucocorticoid-Treated Human Macrophages

Glucocorticoids are extensively used to treat inflammatory diseases; however, their chronic intake increases the risk for mycobacterial infections. Meanwhile, the effects of glucocorticoids on innate host responses are incompletely understood. In this study, we investigated the direct effects of glucocorticoids on antimycobacterial host defense in primary human macrophages. We found that glucocorticoids triggered the expression of cathelicidin, an antimicrobial critical for antimycobacterial responses, independent of the intracellular vitamin D metabolism. Despite upregulating cathelicidin, glucocorticoids failed to promote macrophage antimycobacterial activity. Gene expression profiles of human macrophages treated with glucocorticoids and/or IFN-γ, which promotes induction of cathelicidin, as well as antimycobacterial activity, were investigated. Using weighted gene coexpression network analysis, we identified a module of highly connected genes that was strongly inversely correlated with glucocorticoid treatment and associated with IFN-γ stimulation. This module was linked to the biological functions autophagy, phagosome maturation, and lytic vacuole/lysosome, and contained the vacuolar H(+)-ATPase subunit a3, alias TCIRG1, a known antimycobacterial host defense gene, as a top hub gene. We next found that glucocorticoids, in contrast with IFN-γ, failed to trigger expression and phagolysosome recruitment of TCIRG1, as well as to promote lysosome acidification. Finally, we demonstrated that the tyrosine kinase inhibitor imatinib induces lysosome acidification and antimicrobial activity in glucocorticoid-treated macrophages without reversing the anti-inflammatory effects of glucocorticoids. Taken together, we provide evidence that the induction of cathelicidin by glucocorticoids is not sufficient for macrophage antimicrobial activity, and identify the vacuolar H(+)-ATPase as a potential target for host-directed therapy in the context of glucocorticoid therapy.

Gene expression and TB pathogenesis in rhesus macaques: TR4, CD40, CD40L, FAS (CD95), and TNF are host genetic markers in peripheral blood mononuclear cells that are associated with severity of TB lesions

Tuberculosis (TB) pathologic lesions in rhesus macaques resemble those in humans. The expression levels of several host TB candidate genes in the peripheral blood mononuclear cells (PBMCs) of six rhesus macaques experimentally infected with Mycobacterium tuberculosis were quantified pre-infection and at several dates post-infection. Quantitative measures of TB histopathology in the lungs including: granuloma count, granuloma size, volume of granulomatous and non-granulomatous lesions, and direct bacterial load, were used as the outcomes of a multi-level Bayesian regression model in which expression levels of host genes at various dates were used as predictors. The results indicate that the expression levels of TR4, CD40, CD40L, FAS (CD95) and TNF in PBMC were associated with quantitative measures of the severity of TB histopathologic lesions in the lungs of the study animals. Moreover, no reliable association between the expression levels of IFNE in PBMCs and the severity of TB lesions in the lungs of the study animals was found. In conclusion, PBMC expression profiles derived from the above-listed host genes might be appropriate biomarkers for probabilistic diagnosis and/or prognosis of TB severity in rhesus macaques.

Novel and recurrent AID mutations underlie prevalent autosomal recessive form of HIGM in consanguineous patients

Immunoglobulin class switch recombination deficiencies (Ig-CSR-D) are characterized by normal or elevated serum IgM level and absence of IgG, IgA, and IgE. Most reported cases are due to X-linked CD40L deficiency. Activation-induced cytidine deaminase deficiency is the most frequent autosomal recessive form, whereas CD40 deficiency is more rare. Herein, we present the first North African study on hyper IgM (HIGM) syndrome including 16 Tunisian patients. Phenotypic and genetic studies allowed us to determine their molecular basis. Three CD40LG mutations have been identified including two novels (c.348_351dup and c.782_*2del) and one already reported mutation (g.6182G>A). No mutation has been found in another patient despite the lack of CD40L expression. Interestingly, three AICDA mutations have been identified in 11 patients. Two mutations were novel (c.91T>C and c.389A>C found in one and five patients respectively), and one previously reported splicing mutation (c.156+1T>G) was found in five patients. Only one CD40-deficient patient, bearing a novel mutation (c.109T>G), has been identified. Thus, unlike previous reports, AID deficiency is the most frequent underlying molecular basis (68%) of Ig-CSR-D in Tunisian patients. This finding and the presence of specific recurrent mutations are probably due to the critical role played by inbreeding in North African populations.

Vitamin D regulates cytokine patterns secreted by dendritic cells to promote differentiation of IL-22-producing T cells

One central mechanism, by which vitamin D regulates human immune responses, is the direct modulation of dendritic cells (DCs). However, the effect of vitamin D on several key DC functions, such as the secretion of central inflammatory cytokines, remains controversial. Moreover, whether vitamin D treatment of DCs regulates their ability to promote differentiation of IL-17-/IL-22-producing T cell subsets, such as Th17 and Th22 cell, is not known. Here, we report that vitamin D treatment during differentiation of monocytes into DCs markedly enhanced their ability to secrete TNF-α, IL-6, IL-1β and IL-23. Cytokines secreted by vitamin D-treated DC were significantly more potent in driving differentiation of IL-22-producing T cells, but not IL-17-producing T cells, as compared to secreted cytokines of not-vitamin D-treated DCs. Finally, we found that the differentiation of IL-22-producing T cells mediated by supernatants of vitamin D-treated DCs was dependent on TNF-α IL-6 and IL-23. In summary, our study suggests a novel role of vitamin D in regulating DC-mediated immune responses in humans.

Vitamin D every day to keep the infection away?

Within the last decade, vitamin D has emerged as a central regulator of host defense against infections. In this regard, vitamin D triggers effective antimicrobial pathways against bacterial, fungal and viral pathogens in cells of the human innate immune system. However, vitamin D also mediates potent tolerogenic effects: it is generally believed that vitamin D attenuates inflammation and acquired immunity, and thus potentially limits collateral tissue damage. Nevertheless, several studies indicate that vitamin D promotes aspects of acquired host defense. Clinically, vitamin D deficiency has been associated with an increased risk for various infectious diseases in epidemiological studies; yet, robust data from controlled trials investigating the use of vitamin D as a preventive or therapeutic agent are missing. In this review, we summarize the current knowledge regarding the effect of vitamin D on innate and acquired host defense, and speculate on the difficulties to translate the available molecular medicine data into practical therapeutic or preventive recommendations.

Vitamin D supplementation and antibacterial immune responses in adolescents and young adults with HIV/AIDS

Human monocytes activated by toll-like receptor 2/1 ligand (TLR2/1L) show enhanced expression of the vitamin D receptor (VDR) and the vitamin D-activating enzyme 1α-hydroxylase (CYP27B1). The resulting intracrine conversion of precursor 25-hydroxyvitamin D3 (25OHD) to active 1,25-dihydroxyvitamin D (1,25(OH)2D) can stimulate expression of antibacterial cathelicidin (CAMP). To determine whether this response is functional in HIV-infected subjects (HIV+ ), serum from HIV+ subjects pre- and post-vitamin D supplementation was utilized in monocyte cultures with or without TLR2/1L. Expression of CYP27B1 and VDR was enhanced following treatment with TLR2/1L, although this effect was lower in HIV+ vs HIV- serum (p<0.05). CAMP was also lower in TLR2/1L-treated monocytes cultured in HIV+ serum (p<0.01). In a dose study, supplementation of HIV+ subjects with 4000IU or 7000IU vitamin D/day increased serum 25OHD from 17.3±8.0 and 20.6±6.2ng/ml (43nM and 51nM) at baseline to 41.1±12.0 and 51.9±23.1ng/ml (103nM and 130nM) after 12 weeks (both p<0.001). Greater percent change from baseline 25OHD was significantly associated with enhanced TLR2/1L-induced monocyte CAMP adjusted for baseline expression (p=0.009). In a randomized placebo-controlled trial, 7000IU vitamin D/day increased serum 25OHD from 18.0±8.6 to 32.7±13.8ng/ml (45nM and 82nM) after 12 weeks. Expression of CAMP increased significantly from baseline after 52 weeks of vitamin D-supplementation. At this time point, TLR2/1L-induced CAMP was positively associated with percent change from baseline in 25OHD (p=0.029 overall and 0.002 within vitamin D-supplemented only). These data indicate that vitamin D supplementation in HIV-infected subjects can promote improved antibacterial immunity, but also suggest that longer periods of supplementation are required to achieve this.