Iron deficiency and NRAMP1 polymorphisms (INT4, D543N and 3'UTR) do not contribute to severity of anaemia in tuberculosis in the Indonesian population

Anaemia of chronic disease among pulmonary tuberculosis patients is associated with inflammatory marker at the start of intensive phase

Background

Tuberculosis (TB) disrupts iron balance through systemic inflammation. Pulmonary tuberculosis (PTB) is linked to diverse anaemia types, necessitating intricate haematological and biochemical assessments for diagnosis. This study aims to describe the prevalence of anaemia of chronic disease (ACD), iron deficiency anaemia (IDA) among PTB patients and factors associated with these types of anaemia.

Methods

A cross-sectional analysis was conducted from community-based cohort study involving sputum-positive PTB patients from 2018 to 2020 in urban Puducherry. Participants were enrolled from 10 primary health centres within 2 weeks of initiating anti-tubercular treatment (ATT). Blood samples were collected for assessing haematological and biochemical parameters. The sTfR/log ferritin ratio was used to distinguish between ACD and IDA. Data were captured using Epicollect5 and analysed using STATA V14.

Result

Of the 176 PTB patients included, 63.07% (111/176) had anaemia, with ACD being the predominant type (84.6%, 94/111). The C-reactive protein (CRP) levels were higher among the anaemic group [40.77 (16.66-58.51) mg/dl vs 24.65 (14.23-47.26) mg/dl] and higher among the ACD as compared to IDA [46.9 (22.3-61.2) vs 20.8 (13.0-39.1) mg/dl]. Undernourished [adjusted prevalence ratio (APR) =3.43; confidence interval (CI): 1.21-9.69] and patients having low risk of dependence on tobacco [APR = 1.52; CI: 1.10-2.11] had higher risk of ACD. Female patients had higher risk of IDA [APR = 4.95, P < 0.01].

Conclusion

The largest proportion of the PTB participants with anaemia had ACD. Acute-phase reactant and inflammatory marker are increased among newly diagnosed new sputum smear-positive (NSP) PTB participants at the start of ATT. Addressing inflammation is needed for combating anaemia in PTB patients.

Predictors of Change in the Anemia Status Among Pulmonary Tuberculosis Patients Following Anti-tuberculosis Treatment in Puducherry, India

Background Pulmonary tuberculosis (PTB) is commonly associated with reversible peripheral blood abnormalities. The evolution of tuberculosis (TB)-associated anemia with anti-tuberculosis treatment (ATT) has not been well elucidated. This study aimed to compare the hematological profiles at the start and end of the ATT among new sputum smear-positive (NSP) PTB patients in Puducherry, India. Methods A prospective cohort study was conducted in the 10 urban primary health centers of Puducherry from 2017 to 2020. All the NSP PTB participants aged ≥18 years registered under the National Tuberculosis Elimination Program (NTEP) were contacted within two weeks of the start of the ATT. All eligible participants were enrolled, and they were followed up till the end of ATT (180 days). Hematological profiles and anthropometric measurements were compared at the start and end of the ATT. Binomial logistic regression analysis was used to assess the predictors of changes in the anemia status at the start and end of the ATT. Results Out of 176 NSP PTB participants, 145 were followed up after treatment. Initially, 63% (111/176) patients had anemia, which decreased to 44% (64/145) by the end of treatment. The risk factors for a negative change in hemoglobin levels were female gender, below poverty level, underweight, and reduced iron intake. The adjusted risk ratios (ARRs) were 1.53 (1.24-1.88), 1.18 (1.01-1.38), 1.29 (1.02-1.64), and 1.26 (1.05-1.51),respectively. Conclusion ATT may lead to the resolution of TB-associated anemia. Moreover, female gender, possession of a red ration card, being underweight, and reduced iron intake were identified as risk factors for negative changes in hemoglobin levels during treatment.

Iron Status and Supplementation during Tuberculosis

Tuberculosis (TB) is characterised by chronic non-resolving inflammation. The effects of the host immune and inflammatory response to reduce iron acquisition by the bacteria, together with other contributing factors, predispose TB patients to anaemia of infection and iron deficiency anaemia (IDA). The presence of anaemia in TB patients has been linked to poor clinical outcomes. However, due to the reliance of the bacteria on iron, the management of anaemia in TB is complicated, and anaemia of infection is likely to resolve with correct TB drug treatment. On the other hand, IDA may require iron supplementation. This review aims to describe iron metabolism in TB and how this contributes to the development of iron deficiency and anaemia. Additionally, we summarise the evidence on the association between iron status and clinical outcomes as well as the available preclinical and clinical trials on iron supplementation in TB.

Tuberculosis-Associated Anemia: A Narrative Review

Tuberculosis (TB) is an airborne illness that induces systemic inflammation. It often affects the lungs causing cough, fever, and chest pain. A commonly associated comorbid condition in TB is anemia. This review article has summarized various studies with an aim to gain a better understanding of pathogenesis and the role of cytokines that contribute to the development of anemia in TB. The study has gathered risk factors that enhance the likelihood of TB patients acquiring anemia. It has reviewed therapeutic modalities such as antitubercular therapy and iron therapy in an attempt to find which of them are effective in reducing the severity of anemia. This review article has also emphasized the importance of measuring hepcidin and ferritin and has touched upon the investigations that can be easily implemented.

Effect of breastfeeding on children's health and its relationship to NRAMP1 expression: A cross-sectional study

Toddlers with exclusive breastfeeding can increase immunity in preventing infectious diseases such as Upper Respiratory Tract Infections (ARI). The body's resistance to disease is controlled by Natural Resistance-Associated Macrophage Protein 1 (NRAMP1). NRAMP1 contributes to the pathophysiology of several intercellular infections, including ARI. The purpose of this study was to determine the effect of breastfeeding on children's health and its relationship to NRAMP1 expression. A cross-sectional study was conducted on 124 toddlers in October 2020–June 2021. Toddlers were selected purposively from three Community Health Centers in Central Jakarta. The first group (n = 62) was exclusive breastfeeding and the second group (n = 62) was not exclusive breastfeeding. The characteristics of mothers and toddlers were collected using a structured questionnaire supported by medical record data. Meanwhile, NRAMP1 expression and NRAMP1 protein levels were obtained from the examination of blood samples. Examination of NRAMP1 gene mRNA expression by real-time PCR method and serum NRAMP1 protein levels by ELISA method. Data were analyzed using t-test, ANOVA, and multiple linear regression. The results obtained that the average mRNA expression of NRAMP1 gene and protein levels of NRAMP1 in infants who were not exclusive breastfeeding were 6.88 fold change (FC) and 315.02 pg/ml compared to those who received exclusive breastfeeding of 11.36 FC and 1087.74 pg./ml. Parity, immunization history, exclusive breastfeeding, and frequency of ARI were significantly associated with NRAMP1 gene mRNA expression and NRAMP1 protein levels (P < 0.05). Maternal and under-five age, gender, and nutritional status were not significantly related (P > 0.05). Exclusive breastfeeding was the dominant factor influencing NRAMP1 gene mRNA expression (OR: 4268) and NRAMP1 protein content (OR: 737,362). Antibodies obtained from exclusive breastfeeding in synergy with the NRAMP1 gene form the body's immunity in infants suffering from ARI.

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Breast milk contains antibodies that work in synergy with the NRAMP1 gene mRNA expression and NRAMP1 protein levels to form body immunity in children with ARI.

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Exclusive breastfeeding significantly increased the NRAMP1 gene mRNA expression and NRAMP1 protein levels.

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Immunization can significantly increase NRAMP1 gene mRNA expression and NRAMP1 protein levels.

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Exclusive breastfeeding can increase NRAMP1 gene mRNA expression, and NRAMP1 protein levels improved children's health.

Iron homeostasis during anemia of inflammation: a prospective study in patients with tuberculosis

Anemia of inflammation is a hallmark of tuberculosis. Factors controlling iron metabolism during anemia of inflammation and its resolution are uncertain. Whether iron supplements should be given during anti-tuberculosis treatment to support Hb recovery is unclear. Before and during treatment of tuberculosis, we assessed iron kinetics, and changes in inflammation and iron metabolism indices. In a 26-wk prospective study, Tanzanian adults with tuberculosis (n=18) were studied before treatment and then every two weeks during treatment; oral and intravenous iron tracers were administered before treatment, after intensive phase (8/12 wk) and complete treatment (24 wk); no iron supplements were given. Before treatment, hepcidin and erythroferrone (ERFE) were greatly elevated, erythrocyte iron utilization was high (~80%) and iron absorption was negligible (<1%). During treatment, hepcidin and IL-6 decreased ~70% after only 2 wk (p<0.001); in contrast, ERFE did not significantly decrease until 8 wk (p<0.01). ERFE and IL-6 were the main opposing determinants of hepcidin (p<0.05) and greater ERFE was associated with reticulocytosis and hemoglobin (Hb) repletion (p<0.01). Dilution of baseline tracer concentration was 2.6-fold higher during intensive phase treatment (p<0.01) indicating enhanced erythropoiesis. After treatment completion, iron absorption increased ~20-fold (p<0.001); Hb increased ~25% (p<0.001). In tuberculosis-associated anemia of inflammation, our findings suggest elevated ERFE is unable to suppress hepcidin and iron absorption is negligible. During treatment, as inflammation resolves, ERFE may remain elevated, contributing to hepcidin suppression and Hb repletion. Iron is well-absorbed only after tuberculosis treatment and supplementation should be reserved for patients remaining anemic after treatment. (ClinicalTrials.gov Identifier:NCT02176772).

Haematological profiles after Intensive phase of Anti Koch Treatment with special emphasis on bone marrow changes

BACKGROUND

Tuberculosis remains a major public health problem in various parts of the world. It leads to various haematological changes. Study of these haematological changes will help better patient management.

OBJECTIVE & METHODS

It is to evaluate haematological changes in tuberculosis patients and compare the result with special emphasis to bone marrow changes as active case search is sharply decreasing the miliary tuberculosis. It is also to evaluate the patients with before and after the Intensive Phase of Anti Koch Treatment. Sputum positive and sputum negative tuberculosis patients confirmed by other ancillary techniques were included into this study. It is conducted at a tertiary level hospital in rural area.

RESULT

In this study bone marrow hypercellularity was of erythroid series with only 1.92% patients showed granuloma in bone marrow aspiration. In addition to bone marrow changes, significant changes were evident in haemoglobin level, Erythrocyte Sedimentation Rate (ESR) Total White Blood Cell count and RBC count.

DISCUSSION

In majority cases this study showed Erythroid Hyperplasia. It is sharp contrast with other study where myeloid hyperplasia was evident. This study also differs from other study where high number of bone marrow granuloma was reported. In this study only 1.92% cases showed bone marrow granuloma. This study also documented higher number of anaemic cases mostly because of the institute serves poor and tribal population.

CONCLUSION

In our study the cases showing granuloma and hyperplasia of myeloid series were limited. With introduction of Directly Observed Treatment and house to house active case search helped to sharply decrease bone marrow granuloma by limiting multi-organ spread. This study showed, ESR level may be considered as prognostic parameters of tuberculosis.

Anemia in tuberculosis cases: A biomarker of severity?

INTRODUCTION

Anemia is a common condition at tuberculosis diagnosis, and there is evidence that its prevalence is higher in patients with tuberculosis than in those infected with Mycobacterium tuberculosis and healthy controls. Information about anemia during tuberculosis diagnosis is still scarce in the Brazilian population. The aim of this study was to describe the prevalence of anemia in patients with tuberculosis cared for at a referral center and its association with clinical forms of tuberculosis and other characteristics of these patients.

MATERIALS AND METHODS

This was a retrospective cross-sectional study of tuberculosis patients diagnosed from January 2015 to December 2018 at the Clinical Research Laboratory on Mycobacteria (LAPCLIN-TB) of Evandro Chagas National Institute of Infectious Diseases (INI)/Oswaldo Cruz Foundation (Fiocruz). A database of an ongoing cohort study underway at this service since 2000 provided the baseline information on tuberculosis cases extracted from a visit template. Exploratory and logistic regression analyses were performed to verify associations between anemia and demographic characteristics, socioeconomic status, clinical conditions, and laboratory results.

RESULTS

Of the 328 cases reviewed, 70 were excluded, with258 retained. The prevalence of anemia was 61.2% (27.5% mild, 27.5% moderate and 6.2% severe). Among patients with anemia, 60.8% had normochromic normocytic anemia, and 27.8% showed hypochromic microcytic anemia. In logistic regression analysis, anemia was associated with a history of weight loss >10%, hospitalizations, coinfection with HIV, increased platelet count and microcytosis. Anemia was more frequent in the most severe clinical forms, such as meningeal and disseminated tuberculosis.

CONCLUSIONS

Anemia was highly prevalent in tuberculosis patients at diagnosis, predominantly as normochromic normocytic anemia and in mild and moderate forms. It was associated with baseline characteristics and conditions indicative of severe disease, suggesting that anemia could be a biomarker of tuberculosis severity.

Impact of Persistent Anemia on Systemic Inflammation and Tuberculosis Outcomes in Persons Living With HIV

Tuberculosis (TB) is associated with systemic inflammation and anemia, which are aggravated in persons living with HIV (PLWH). Here, we characterized the dynamics of hemoglobin levels in PLWH coinfected with TB undergoing antitubercular therapy (ATT). We also examined the relationships between anemia and systemic inflammatory disturbance as well as the association between persistent anemia and unfavorable clinical outcomes. Data on several blood biochemical parameters and on blood cell counts were retrospectively analyzed in a cohort of 256 TB/HIV patients from Brazil during 180 days of ATT. Multidimensional statistical analyses were employed to profile systemic inflammation of patients stratified by anemia status (hemoglobin levels <12 g/dL for female and <13.5 g/dL for male individuals) prior to treatment and to perform prediction of unfavorable outcomes, such as treatment failure, loss to follow up and death. We found that 101 (63.63%) of patients with anemia at pre-ATT persisted with such condition until day 180. Such individuals exhibited heightened degree of inflammatory perturbation (DIP), which in turn was inversely correlated with hemoglobin levels. Recovery from anemia was associated with increased pre-ATT albumin levels whereas persistent anemia was related to higher total protein levels in serum. Multivariable regression analysis revealed that lower baseline hemoglobin levels was the major determinant of the unfavorable outcomes. Our findings demonstrate that persistent anemia in PLWH during the course of ATT is closely related with chronic inflammatory perturbation. Early intervention to promote recovery from anemia may improve ATT outcomes.

Correlation of Polymorphisms of Natural Resistance-Associated Macrophage Protein 1 (NRAMP1) Gene and Smoking with the Risk of Rheumatoid Arthritis in Chinese Han People

Background

In this study we report on the possible connection between single nucleotide polymorphisms (SNPs) in natural resistance-associated macrophage protein 1 (NRAMP1) gene and the risk of rheumatoid arthritis (RA) in the Chinese Han population.

Material/Methods

A total of 248 participants consisting of 116 RA cases and 132 healthy individuals were recruited for the current study. Genotyping for NRAMP1 gene polymorphisms was implemented using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The chi-square test was used to detect discrepancies in genotype and allele frequencies between the RA case group and the control group. Odds ratios (ORs) with 95% confidence intervals (CIs) was used to evaluate relative risk of RA. The results were adjusted by logistic regression analysis.

Results

The TT genotype and T allele in rs17221959 showed dramatically different distribution between RA cases and healthy controls. After adjustment, TT genotype (OR=0.338, 95%CI=0.278–1.214, P=0.028) and T allele (OR=0.608, 95%CI=0.298–0.956, P=0.005) showed close association with reduced risk of RA. For rs1059823, no obvious diversity was uncovered in either genotype or allele distribution between the 2 groups. Interaction analysis showed that smoking decreased the protective function of TT in rs17221959.

Conclusions

This study suggested that the TT genotype and T allele in rs17221959 decreased RA risk. Smoking could decrease the protective effect of TT.

3'UTR polymorphisms in NRAMP1 are associated with the susceptibility to pulmonary tuberculosis: A MOOSE-compliant meta-analysis

Many studies have investigated the association between the 3'UTR polymorphism in natural resistance-associated macrophage protein 1 (NRAMP1) and the risk of pulmonary tuberculosis (PTB), Revealing inconclusive results. This study aimed to investigate the correlation between the NRAMP1 3'UTR polymorphism and the risk of PTB.This meta-analysis included 29 case-control studies to better and comprehensively assess this correlation. Pooled odds ratios (ORs) and 95% confidence interval (95% CIs) were calculated to assess the strength of the association.These 29 case-control studies included 4672 cases and 6177 controls. The NRAMP1 3'UTR polymorphism displayed a significant positive correlation with the risk of PTB in 3 models (for del/del vs ins/ins: OR = 1.22, 95% CI = 1.01-1.47; for Ins/del vs ins/ins: OR = 1.19, 95% CI 1.08-1.30; for Ins/del + del/del vs ins/ins: OR = 1.25, 95% CI = 1.08-1.45). A stratified analysis by ethnicity revealed that the NRAMP1 3'UTR polymorphism was associated with an increased risk of PTB in the Asian population, but not in Caucasian, African, and South American populations.The present results indicate that the NRAMP1 3'UTR polymorphism may be considered a risk factor for PTB in the Asian population.

Prevalence of anemia among patients with tuberculosis: A systematic review and meta-analysis

INTRODUCTION

Anemia is one of the most common hematologic problems occurs among patients with tuberculosis (TB). Many studies have been carried out estimating the prevalence of anemia among TB patients in different countries reported various results. This study aims to estimate the combined estimate of the anemia prevalence among these patients using systematic review and meta-analysis.

METHODS

Required primary studies were provided after a comprehensive and systematic search in PubMed, Scopus, Science direct, Web of Science and also Google scholar search engine. These studies were then quality assessed using Newcastle-Ottawa Scale checklist. Random effects model was applied for combining the point prevalence with 95% confidence intervals.

RESULTS

Of 41 papers entered into the meta-analysis, prevalence (95% confidence interval) of anemia among all TB patients as well as men and women were 61.53% (53.44-69.63), 66.95% (51.75-82.14) and 72.67% (60.79-84.54) respectively. Prevalence (95% confidence intervals) of mild, moderate and severe anemia were 35.67% (27.59-43.46), 31.19% (25.15-37.24) and 11.61% (7.88-15.34) respectively. In addition, prevalence (95% confidence intervals) of chronic disease anemia and iron deficiency anemia were 49.82% (15.58-84.07) and 20.17% (6.68-33.65) respectively.

CONCLUSION

Prevalence of anemia among TB patients was high especially among women. More than 43% of these patients suffered from moderate and severe anemia and about half of them had chronic disease anemia.

Prevalence, characteristics, and predictors of tuberculosis associated anemia

Tuberculosis is an infectious disease caused by mycobacterium tuberculosis. It is one of the deadliest disease and a major burden on the healthcare system in India. India, a second most populous country in the world, has a very high global annual incidence of tuberculosis. Multiple hematological changes have been reported in patients with tuberculosis such as iron deficiency anemia, folate deficiency, and sideroblastic anemia.

The Role of Host Genetics (and Genomics) in Tuberculosis

Familial risk of tuberculosis (TB) has been recognized for centuries. Largely through studies of mono- and dizygotic twin concordance rates, studies of families with Mendelian susceptibility to mycobacterial disease, and candidate gene studies performed in the 20th century, it was recognized that susceptibility to TB disease has a substantial host genetic component. Limitations in candidate gene studies and early linkage studies made the robust identification of specific loci associated with disease challenging, and few loci have been convincingly associated across multiple populations. Genome-wide and transcriptome-wide association studies, based on microarray (commonly known as genechip) technologies, conducted in the past decade have helped shed some light on pathogenesis but only a handful of new pathways have been identified. This apparent paradox, of high heritability but few replicable associations, has spurred a new wave of collaborative global studies. This review aims to comprehensively review the heritability of TB, critically review the host genetic and transcriptomic correlates of disease, and highlight current studies and future prospects in the study of host genomics in TB. An implicit goal of elucidating host genetic correlates of susceptibility to Mycobacterium tuberculosis infection or TB disease is to identify pathophysiological features amenable to translation to new preventive, diagnostic, or therapeutic interventions. The translation of genomic insights into new clinical tools is therefore also discussed.

Anemia in hospitalized patients with pulmonary tuberculosis

OBJECTIVE:

To describe the prevalence of anemia and of its types in hospitalized patients with pulmonary tuberculosis.

METHODS:

This was a descriptive, longitudinal study involving pulmonary tuberculosis inpatients at one of two tuberculosis referral hospitals in the city of Rio de Janeiro, Brazil. We evaluated body mass index (BMI), triceps skinfold thickness (TST), arm muscle area (AMA), ESR, mean corpuscular volume, and red blood cell distribution width (RDW), as well as the levels of C-reactive protein, hemoglobin, transferrin, and ferritin.

RESULTS:

We included 166 patients, 126 (75.9%) of whom were male. The mean age was 39.0 ± 10.7 years. Not all data were available for all patients: 18.7% were HIV positive; 64.7% were alcoholic; the prevalences of anemia of chronic disease and iron deficiency anemia were, respectively, 75.9% and 2.4%; and 68.7% had low body weight (mean BMI = 18.21 kg/m²⁾. On the basis of TST and AMA, 126 (78.7%) of 160 patients and 138 (87.9%) of 157 patients, respectively, were considered malnourished. Anemia was found to be associated with the following: male gender (p = 0.03); low weight (p = 0.0004); low mean corpuscular volume (p = 0.03);high RDW (p = 0; 0003); high ferritin (p = 0.0005); and high ESR (p = 0.004). We also found significant differences between anemic and non-anemic patients in terms of BMI (p = 0.04), DCT (p = 0.003), and ESR (p < 0.001).

CONCLUSIONS:

In this sample, high proportions of pulmonary tuberculosis patients were classified as underweight and malnourished, and there was a high prevalence of anemia of chronic disease. In addition, anemia was associated with high ESR and malnutrition.

Complex anemia in tuberculosis: the need to consider causes and timing when designing interventions

BACKGROUND

Anemia is common in tuberculosis, and multiple etiologies necessitate targeted interventions. The proportion of iron-responsive anemia due to iron deficiency compared with iron-unresponsive anemia due to impaired iron absorption/redistribution from tuberculosis-associated immune activation or inflammation is unknown. This impedes selection of safe and effective treatment and appropriate intervention timing.

METHODS

Baseline hemoglobin, ferritin, hepcidin, soluble transferrin receptor (sTfR), and transferrin were measured in 45 patients with confirmed pulmonary tuberculosis (cases), 47 tuberculin skin test (TST)-positive controls, and 39 TST-negative controls in The Gambia. Tuberculosis cases were additionally followed 2 and 6 months after tuberculosis treatment initiation. Mutually exclusive anemia categories based on iron biomarker concentrations were iron deficiency anemia (IDA), anemia of inflammation (AI), and multifactorial anemia (IDA+AI).

RESULTS

Anemia was more frequent in tuberculosis cases (67%) than in TST-positive (36%) or TST-negative (21%) controls. AI was the predominant anemia at tuberculosis diagnosis, declining from 36% to 8% after 6 months of treatment; however, a corresponding reduction was not evident for anemia with iron-responsive components (IDA, IDA+AI). Iron biomarkers discriminated between active tuberculosis and TST-positive or TST-negative controls, as well as between active untreated and treated tuberculosis. This was most noticeable for hepcidin, which decreased from a median of 84.0 ng/mL at diagnosis to 9.7 ng/mL after 2 months (P < .001).

CONCLUSIONS

Tuberculosis chemotherapy is associated with significant reductions in AI, but IDA and IDA+AI remain unresolved. Iron-based interventions are needed for IDA and IDA+AI, and monitoring of iron biomarkers reveals a window for intervention opening as early as 2 months into tuberculosis treatment.

Iron in intracellular infection: to provide or to deprive?

Due to their chemical versatility, transition metals were incorporated as cofactors for several basic metabolic pathways in living organisms. This same characteristic makes them potentially harmful, since they can be engaged in deleterious reactions like Fenton chemistry. As such, organisms have evolved highly specialized mechanisms to supply their own metal needs while keeping their toxic potential in check. This dual character comes into play in host-pathogen interactions, given that the host can either deprive the pathogen of these key nutrients or exploit them to induce toxicity toward the invading agent. Iron stands as the prototypic example of how a metal can be used to limit the growth of pathogens by nutrient deprivation, a mechanism widely studied in Mycobacterium infections. However, the host can also take advantage of iron-induced toxicity to control pathogen proliferation, as observed in infections caused by Leishmania. Whether we may harness either of the two pathways for therapeutical purposes is still ill-defined. In this review, we discuss how modulation of the host iron availability impacts the course of infections, focusing on those caused by two relevant intracellular pathogens, Mycobacterium and Leishmania.

Host iron redistribution as a risk factor for incident tuberculosis in HIV infection: an 11-year retrospective cohort study

BACKGROUND

Identifying people at higher risk of developing tuberculosis with human immunodeficiency virus (HIV) infection may improve clinical management of co-infections. Iron influences tuberculosis (TB) pathogenesis, but understanding the exact mechanisms of how and timing of when iron is involved remains challenging since biological samples are rarely available from the disease susceptibility period due to the difficulty in predicting in who and when, if ever, TB will develop. The objective of this research was to determine how host iron status measured at HIV diagnosis and genotypes related to host iron metabolism were associated with incident TB.

METHODS

Archived clinical data, plasma and DNA were analyzed from 1139 adult participants in a large HIV-1, HIV-2 and dual seroprevalent cohort based at the Medical Research Council Laboratories in The Gambia. Incident pulmonary and/or extrapulmonary TB diagnoses a minimum of 28 days after HIV diagnosis were independently re-confirmed using available evidence (n=152). Multiple host iron status biomarkers, Haptoglobin and solute carrier family 11, member 1 (SLC11A1) genotypes were modeled to characterize how indicators of host iron metabolism were associated with TB susceptibility.

RESULTS

Hemoglobin (incidence rate ratio, IRR=0.88, 95% CI=0.79-0.98), plasma transferrin (IRR=0.53, 0.33-0.84) and ferritin (IRR=1.26, 1.05-1.51) were significantly associated with TB after adjusting for TB susceptibility factors. While genotype associations were not statistically significant, SLC11A1 associations replicated similar directions as reported in HIV-seronegative meta-analyses.

CONCLUSIONS

Evidence of host iron redistribution at HIV diagnosis was associated with incident TB, and genetic influences on iron homeostasis may be involved. Low hemoglobin was associated with subsequent diagnosis of TB, but when considered in combination with additional iron status biomarkers, the collective findings point to a mechanism whereby anemia and iron redistribution are likely due to viral and/or bacteria-driven processes and the host immune response to infection. As a result, iron supplementation may not be efficacious or safe under these circumstances. Clinical and nutritional management of HIV and Mycobacterium tuberculosis co-infected individuals, especially in regions where food insecurity and malnutrition co-exist, may be further improved when the iron-related TB risk factors identified here are better understood and managed to favor host rather than pathogen outcomes.

Iron status predicts treatment failure and mortality in tuberculosis patients: a prospective cohort study from Dar es Salaam, Tanzania

Background

Experimental data suggest a role for iron in the course of tuberculosis (TB) infection, but there is limited evidence on the potential effects of iron deficiency or iron overload on the progression of TB disease in humans. The aim of the present analysis was to examine the association of iron status with the risk of TB progression and death.

Methodology/Principal Findings

We analyzed plasma samples and data collected as part a randomized micronutrient supplementation trial (not including iron) among HIV-infected and HIV-uninfected TB patients in Dar es Salaam, Tanzania. We prospectively related baseline plasma ferritin concentrations from 705 subjects (362 HIV-infected and 343 HIV-uninfected) to the risk of treatment failure at one month after initiation, TB recurrence and death using binomial and Cox regression analyses. Overall, low (plasma ferritin<30 µg/L) and high (plasma ferritin>150 µg/L for women and>200 µg/L for men) iron status were seen in 9% and 48% of patients, respectively. Compared with normal levels, low plasma ferritin predicted an independent increased risk of treatment failure overall (adjusted RR = 1.95, 95% CI: 1.07 to 3.52) and of TB recurrence among HIV-infected patients (adjusted RR = 4.21, 95% CI: 1.22 to 14.55). High plasma ferritin, independent of C-reactive protein concentrations, was associated with an increased risk of overall mortality (adjusted RR = 3.02, 95% CI: 1.95 to 4.67).

Conclusions/Significance

Both iron deficiency and overload exist in TB patients and may contribute to disease progression and poor clinical outcomes. Strategies to maintain normal iron status in TB patients could be helpful to reduce TB morbidity and mortality.

Iron deficiency and anemia predict mortality in patients with tuberculosis

Many studies have documented a high prevalence of anemia among tuberculosis (TB) patients and anemia at TB diagnosis has been associated with an increased risk of death. However, little is known about the factors contributing to the development of TB-associated anemia and their importance in TB disease progression. Data from a randomized clinical trial of micronutrient supplementation in patients with pulmonary TB in Tanzania were analyzed. Repeated measures of anemia with iron deficiency, anemia without iron deficiency, and iron deficiency without anemia were assessed as risk factors for treatment failure, TB recurrence, and mortality. The prevalence of anemia (hemoglobin < 110 g/L) at baseline was 64%, more than one-half of which was related to iron deficiency (mean corpuscular volume , 80 fL). We found no evidence of an association between anemia (with or without iron deficiency) or iron deficiency without anemia at baseline and the risk of treatment failure at 1 mo after initiation. Anemia without iron deficiency was associated with an independent, 4-fold increased risk of TB recurrence [adjusted RR = 4.10 (95% CI = 1.88, 8.91); P < 0.001]. Iron deficiency and anemia (with and without iron deficiency) were associated with a 2- to nearly 3-fold independent increase in the risk of death [adjusted RR for iron deficiency without anemia = 2.89 (95% CI = 1.53, 5.47); P = 0.001; anemia without iron deficiency = 2.72 (95% CI = 1.50, 4.93); P = 0.001; iron deficiency anemia = 2.13 (95% CI = 1.10, 4.11); P = 0.02]. Efforts to identify and address the conditions contributing to TB-associated anemia, including iron deficiency, could play an important role in reducing morbidity and mortality in areas heavily affected by TB.

SLC11A1 (NRAMP1) polymorphisms and tuberculosis susceptibility: updated systematic review and meta-analysis

BACKGROUND

Natural resistance associated macrophage protein 1 (NRAMP1), encoded by the SLC11A1 gene, has been described to regulate macrophage activation and be associated with infectious and autoimmune diseases. The relation between SLC11A1 polymorphisms and tuberculosis susceptibility has been studied in different populations.

METHODS

We systematically reviewed published studies on SLC11A1 polymorphisms and tuberculosis susceptibility until September 15, 2010 and quantitatively summarized associations of the most widely studied polymorphisms using meta-analysis.

RESULTS

In total, 36 eligible articles were included in this review. In Meta-analysis, significant associations were observed between tuberculosis risk and widely studied SLC11A1 polymorphisms with summarized odds ratio of 1.35 (95%CI, 1.17-1.54), 1.25 (95% CI, 1.04-1.50), 1.23 (95% CI, 1.04-1.44), 1.31 (95%CI, 1.08-1.59) for 3' UTR, D543N, INT4, and 5' (GT)n, respectively. Heterogeneity between studies was not pronounced, and the associations did not remarkably vary in the stratified analysis with respect to study population and study base.

CONCLUSIONS

The association between SLC11A1 polymorphisms and tuberculosis susceptibility observed in our analyses supports the hypothesis that NRAMP1 might play an important role in the host defense to the development of tuberculosis.

Mortality in HIV infection is independently predicted by host iron status and SLC11A1 and HP genotypes, with new evidence of a gene-nutrient interaction

BACKGROUND

Iron-related genes and iron status may independently contribute to variable HIV outcomes. The nature of the biologically plausible gene-nutrient interaction remains unknown.

OBJECTIVES

The objectives were to investigate whether iron-related genotypes and clinically abnormal iron status independently predict mortality in HIV and whether a gene-nutrient interaction exists.

DESIGN

Baseline plasma, DNA, and clinical data were obtained from 1362 HIV-seropositive Gambian adults followed for 11.5 y to ascertain all-cause mortality. Iron status was estimated on the basis of plasma iron, soluble transferrin receptor (sTfR), ferritin, transferrin, transferrin index, and log(sTfR/ferritin). One haptoglobin (HP) and 5 SLC11A1 (NRAMP1) polymorphisms were genotyped.

RESULTS

SLC11A1-SLC3 and CAAA polymorphisms were the best independent genetic predictors of mortality [adjusted mortality rate ratio (95% CI)]: SLC3:G/C = 0.59 (95% CI: 0.45, 0.85), CAAA:del/ins = 1.51 (95% CI: 1.10, 2.07). In an adjusted model that included all polymorphisms, SLC1:199/199, SLC1:other/other, SLC6a:A/A, and CAAA:del/ins were associated with significantly greater mortality, whereas Hp 2-1 and SLC3:G/C were protective. In unadjusted analyses, all biomarker concentrations were significantly associated with mortality. In an extension of previous findings, both low and elevated iron states were associated with mortality, but the nature of the risk was variable, with linear, inversely linear, and U-shaped associations depending on the biomarker. Mortality was significantly lower in HIV-2 than in HIV-1 infection in the presence of abnormal (low or elevated) iron status. A gene-iron interaction was detected (likelihood-ratio test P = 0.018); however, subject numbers restricted category-specific interpretation.

CONCLUSIONS

Iron-related genes, iron status, and their interaction predict mortality in HIV. These findings illustrate the complexity and uncertainty surrounding best practice for managing abnormal iron status and anemia during HIV infection and in regions with a high risk of infection.

Diet, tuberculosis, and the paleopathological record

Osseous manifestation of infectious disease is of paramount importance to paleopathologists seeking to interpret ancient health, but the relationships among infectious agent exposure, development of disease, and skeletal involvement are complex. The outcome of an exposure strongly depends on multiple factors, including ecology, diet, nutrition, immune function, and the genetics of pathogen and host. Mycobacterial diseases are often studied in ancient remains but also are especially influenced by these factors; individual and population differences in severity and course are apparent following onset of active disease. The osteological record for these diseases represents the complex interplay of host and pathogen characteristics influencing within- and among-individual skeletal lesion prevalence and distribution. However, many of these characteristics may be assessed independently through the archaeological record. Here, we explore the contributions of dietary protein and iron to immune function, particularly the course and outcome of infection with Mycobacterium tuberculosis. We emphasize how nutrition may influence the dissemination of bacilli to the skeleton and subsequent formation of diagnostic lesions. We then generate models and hypotheses informed by this interplay and apply them to four prehistoric New World areas. Finally, discrepancies between our expectations and the observed record are explored as a basis for new hypotheses.