Impact of hepcidin antimicrobial peptide on iron overload in tuberculosis patients

The expansion of CD14+ CD163+ subpopulation of monocytes and myeloid cells-associated cytokine imbalance; candidate diagnostic biomarkers for celiac disease (CD)

Celiac disease (CD) is a chronic autoimmune disorder of small intestine against dietary gluten, among genetically predisposed individuals. Monocytes are versatile innate immune cells involved in the regulation of inflammation, and strongly involved in the intestinal immunity. However, the role of monocytes and their subtypes in CD is not well demonstrated.

METHODS

Here, we assessed the polarization of CD14+ monocytes by evaluating the M1 (CD16) and M2 (CD163) markers by flowcytometry, their soluble forms (sCD16 and sCD163), and the serum levels of IL-10, IL-12, TGF-β, and TNF-α cytokines using ELISA method, among 30 CD patients and 30 sex- and age-matched healthy subjects (HS). We also analyzed the diagnostic values of all variables with significant differences.

RESULTS

CD14+CD163+ monocytes were more frequent in CD patients than HS, while CD14+CD16+ monocytes were higher in HS. IL-10and TNF-α increased, and TGF-β expression was decreased among CD patients. The sCD16 serum levels were elevated in patients, while sCD163 was higher but not significant among CD patients. CD163+/CD16+ and IL-10/IL-12 ratios were higher in CD patients, and TGFβ/TNFα ratio was higher in HS group. IL-10, CD14+CD163+, TNF-α, and IL-10/IL-12 ratios with the AUC over 0.7 were introduced as fair diagnostic markers. Our findings revealed that the M2 (CD14+CD163+) monocytes were more frequent among CD patients, and the cytokine balance was disturbed.

CONCLUSION

According to the significant functional diversities of monocyte subtypes between CD patients and HS group, these immunologic markers could be introduced as specific diagnostic biomarkers for CD.

Differences in the frequency of genetic variants associated with iron imbalance among global populations

Iron deficiency anaemia is a major health problem affecting approximately 1.2 billion people worldwide. Young children, women of reproductive age and pregnant women living in sub-Saharan Africa are the most vulnerable. It is estimated that iron deficiency accounts for half of anaemia cases. Apart from nutritional deficiency, infection, inflammation and genetic factors are the major drivers of anaemia. However, the role of genetic risk factors has not been thoroughly investigated. This is particularly relevant in African populations, as they carry high genetic diversity and have a high prevalence of anaemia. Multiple genetic variations in iron regulatory genes have been linked to impaired iron status. Here we conducted a literature review to identify genetic variants associated with iron imbalance among global populations. We compare their allele frequencies and risk scores and we investigated population-specific selection among populations of varying geographic origin using data from the Keneba Biobank representing individuals in rural Gambia and the 1000 Genomes Project. We identified a significant lack of data on the genetic determinants of iron status in sub-Saharan Africa. Most of the studies on genetic determinants of iron status have been conducted in Europeans. Also, we identified population differences in allele frequencies in candidate putative genetic risk factors. Given the disproportionately high genetic diversity in African populations coupled with their high prevalence of iron deficiency, there is need to investigate the genetic influences of low iron status in Sub-Saharan Africa. The resulting insights may inform the future implementation of iron intervention strategies.

Host Antimicrobial Peptides: The Promise of New Treatment Strategies against Tuberculosis

Tuberculosis (TB) continues to be a devastating infectious disease and remerges as a global health emergency due to an alarming rise of antimicrobial resistance to its treatment. Despite of the serious effort that has been applied to develop effective antitubercular chemotherapies, the potential of antimicrobial peptides (AMPs) remains underexploited. A large amount of literature is now accessible on the AMP mechanisms of action against a diversity of pathogens; nevertheless, research on their activity on mycobacteria is still scarce. In particular, there is an urgent need to integrate all available interdisciplinary strategies to eradicate extensively drug-resistant Mycobacterium tuberculosis strains. In this context, we should not underestimate our endogenous antimicrobial proteins and peptides as ancient players of the human host defense system. We are confident that novel antibiotics based on human AMPs displaying a rapid and multifaceted mechanism, with reduced toxicity, should significantly contribute to reverse the tide of antimycobacterial drug resistance. In this review, we have provided an up to date perspective of the current research on AMPs to be applied in the fight against TB. A better understanding on the mechanisms of action of human endogenous peptides should ensure the basis for the best guided design of novel antitubercular chemotherapeutics.

Indole-3-carbinol induces G1 cell cycle arrest and apoptosis through aryl hydrocarbon receptor in THP-1 monocytic cell line

OBJECTIVES

The role of aryl hydrocarbon receptor (AhR) in carcinogenesis has been studied recently. Indole-3-carbinol (I3C) is an AhR agonist and a potential anticancer agent. Here, we investigated the effects of I3C on cell cycle progression and apoptosis through activation of AhR on THP-1 acute myeloid leukemia (AML) cell line.

METHODS

MTT viability assay was used to measure the cytotoxic effects of I3C on THP-1 cells. Apoptosis and cell cycle assays were investigated using flow cytometry. Real time RT-PCR was conducted to measure the alterations in the expression of AhR gene, key genes associated with AhR activation (IL1β and CYP1A1) and major genes involved in cell cycle regulation and apoptosis including P27, P21, CDK2, P53, BCL2 and FasR.

RESULTS

Our findings revealed that I3C inhibits the proliferation of THP-1 cells in a dose- and time-dependent manner with minimal toxicity over normal monocytes. The AhR target genes (CYP1A1, IL1β) were overexpressed upon I3C treatment (p < .05 to p < .001). The antiproliferative effects of I3C were in association with programed cell death. I3C downregulated BCL2 and upregulated FasR in THP-1 cells (p < .05 to p < .001). G1 cell cycle arrest was also observed using flow cytometry. G1-acting cell cycle genes (P21, P27 and P53) were overexpressed (p < .05 to p < .001), while CDK2 was downregulated upon I3C treatment (p < .01 to p < .001).

CONCLUSIONS

I3C could exert its antileukemic effects through AhR activation which is associated with programed cell death and G1 cell cycle arrest in a dose- and time-dependent manner. Therefore, AhR could be targeted as a novel treatment possibility in AML.

Effects of berberine on the secretion of cytokines and expression of genes involved in cell cycle regulation in THP-1 monocytic cell line

OBJECTIVES

Current acute myeloid leukemia (AML) therapeutic strategies have irreversible side-effects. Berberine (BBR) is an isoquinoline alkaloid, which has been known as an aryl hydrocarbon receptor (AhR) ligand. AhR is a cytoplasmic receptor, which is involved in the regulation of cellular and immune responses. Here, we investigated the expression profile of genes involved in the cell cycle and different cytokines upon BBR-mediated AhR activation on AML THP-1 cell line.

MATERIALS AND METHODS

THP-1 cells and normal monocytes were treated with different concentrations of BBR (10 μM, 25 μM, 50 μM, and 100 μM) for 24 and 48 hr. The cell viability was measured by MTT assay. Real-time RT-PCR was conducted to evaluate the expression of AhR, cytochrome P450 1A1 (CYP1A1), interleukin 1 beta (IL1β), p21, p27, cyclin-dependent kinase 2 (CDK2) and p53. Cellular expression of AhR was also assessed using immunofluorescence method. ELISA was used to determine the level of IL-10 and IL-12 cytokines.

RESULTS

BBR inhibits the proliferation of THP-1 cells in a dose- and time-dependent manner with minimal toxicity on normal monocytes. Phorbol 12-myristate 13-acetate (PMA) treatment increased the cellular expression of AhR. The AhR target genes (CYP1A1, IL1β) were overexpressed upon BBR treatment. BBR downregulated Cdk2 and upregulated p21, p27 and p53 genes in THP-1 cells. IL-10 was significantly increased upon BBR treatment, while IL-12 was not significantly changed in all combinations.

CONCLUSION

BBR could be introduced as an effective chemotherapeutic agent against AML by giving rise to the expression of CDK inhibitors and anti-inflammatory cytokines and downregulation of CDK2.

Mycobacteria, metals, and the macrophage

Mycobacterium tuberculosis is a facultative intracellular pathogen that thrives inside host macrophages. A key trait of M. tuberculosis is to exploit and manipulate metal cation trafficking inside infected macrophages to ensure survival and replication inside the phagosome. Here, we describe the recent fascinating discoveries that the mammalian immune system responds to infections with M. tuberculosis by overloading the phagosome with copper and zinc, two metals which are essential nutrients in small quantities but are toxic in excess. M. tuberculosis has developed multi-faceted resistance mechanisms to protect itself from metal toxicity including control of uptake, sequestration inside the cell, oxidation, and efflux. The host response to infections combines this metal poisoning strategy with nutritional immunity mechanisms that deprive M. tuberculosis from metals such as iron and manganese to prevent bacterial replication. Both immune mechanisms rely on the translocation of metal transporter proteins to the phagosomal membrane during the maturation process of the phagosome. This review summarizes these recent findings and discusses how metal-targeted approaches might complement existing TB chemotherapeutic regimens with novel anti-infective therapies.