Arc of a vicious circle: pathways activated by Mycobacterium tuberculosis that target the HIV-1 long terminal repeat

Time to death and its predictors among under-five children on antiretroviral treatment in public hospitals of Addis Ababa, Addis Ababa, Ethiopia, a retrospective follow up study

BACKGROUND

Child mortality remains a global public health problem, particularly in Sub-Saharan Africa. After initiating ART, the mortality rate among HIV-infected children in Ethiopia was 12-17 deaths per 1000 child-year.

OBJECTIVE

To determine the time to death and its predictors among under-five children on antiretroviral treatment in public hospitals of Addis Ababa, Ethiopia, from April 12, 2017, to May 12, 2022.

METHOD

An institution-based retrospective follow-up study was conducted among 415 HIV-infected children at selected public hospitals of the Addis Ababa town administration. Computer generated simple random sampling technique was used to select each sampling unit. Data was extracted using a structured data extraction checklist. Data were entered into EPI data 4.2 and analyzed using STATA 14. The child mortality rate was calculated. The Cox proportional hazards regression model was fitted to identify predictor factors. The result of the study was presented using text, tables, graphs, and charts. An adjusted hazard ratio with a 95% confidence interval and a p-value less than 0.05 was used to declare the level of significance.

RESULT

A total of 415 (97.42%) of the 426 children on ART were included for analysis. Of these, 41(9.88%) children were died during the following period. The study participants were followed for a total of 8237 person- months of risk time. The overall mortality rate was 4.98 (95% CI: 3.67-6.77) per 1000 child-months. The estimated survival after starting ART was 61.42% at 56 months of follow-up. Severe underweight (AHR = 3.19; 95% CI: 1.32-7.71), tuberculosis (AHR = 3.86; CI: 1.76-8.47), low hemoglobin level (AHR = 2.51; CI: 1.02-6.20), and advanced WHO clinical stages at enrolment (AHR = 3.38; CI: 1.08-10.58) were predictors of death among HIV-infected under-five children on ART.

CONCLUSION

The incidence of mortality was 4.98 per 1000 child-months. Severe underweight, tuberculosis infection, low hemoglobin level, and advanced WHO clinical stages at enrolment were predictors of death among under-five children on ART.

Predictors of mortality rate among adult HIV-positive patients on antiretroviral therapy in Metema Hospital, Northwest Ethiopia: a retrospective follow-up study

Background

Globally Human Immunodeficiency Virus/Acquired Immune Deficiency Syndrome (HIV/AIDS) is an ongoing public health issue associated with high morbidity and mortality. Efforts have been made to reduce HIV/AIDS-related morbidity and mortality by delivering antiretroviral therapy. However, the incidence and predictors of mortality in border areas like Metema were not investigated. This study aimed to assess predictors of mortality rate among adult HIV-positive patients on antiretroviral therapy at Metema Hospital.

Methods

Retrospective follow-up study was employed among ART patients from January 1, 2013, to December 30, 2018. Data were entered in Epi-data 3.1 and exported to STATA 14 for analysis. Kaplan–Meier and Log-Rank test was used to compare survival differences among categories of different variables. In bi-variable analysis p-values < 0.20 were entered into a multivariable analysis. Multivariate Weibull model was used to measure the risk of death and identify the significant predictors of death. Variables that were statistically significant at p-value < 0.05 were concluded as predictors of mortality.

Result

A total of 542 study participants were included. The overall incidence rate was 6.7 (95% CI: 5.4–8.4) deaths per 100 person-years of observation. Being male (HR = 2.4; 95% CI: 1.24–4.62), STAGE IV (HR = 5.64; 95% CI: 2.53–12.56), stage III (HR = 3.31; 95% CI: 1.35–8.10), TB-coinfection (HR = 3.71; 95% CI: 1.59–8.64), low hemoglobin (HR = 4.14; 95% CI: 2.18–7.86), BMI ≤ 15.4 kg/m² (HR = 2.45; 95% CI: 1.17–5.10) and viral load > 1000 copy/ml (HR = 6.70; 95% CI: 3.4–13.22) were found to be a significant predictor for mortality among HIV patients on ART treatment.

Conclusion

The incidence of death was high. Being male, viral load, those with advanced STAGE (III & IV), TB co-infected, low BMI, and low hemoglobin were at a higher risk of mortality. Special attention should be given to male patients and high public interventions needed among HIV patients on ART to reduce the mortality rate.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12981-021-00353-z.

Impact of HIV status and predictors of successful treatment outcomes among tuberculosis patients: A six-year retrospective cohort study

Tuberculosis (TB) remains a major global public health problem. Hence, the study aimed to assess the impact of human immune virus (HIV) status and predictors of successful treatment outcomes of TB patients enrolled at Nekemte specialized hospital. An institution-based retrospective cohort study was conducted and the data analyzed using SPSS version 24.0. A multivariable logistic regression model was fitted to identify the association between treatment outcome and potential predictor variables. The association was calculated using the Adjusted Odds ratio (AOR) and the statistical significance was considered at p < 0.05. Out of the total 506 study participants, 50.2% of them were males. The overall treatment success rate was 81.4% and 58.06% among HIV co-infected TB patients. Female sex (AOR = 2.01, 95%CI: 1.04–16.11), age 25–34 years (AOR = 3.982, 95%CI: 1.445–10.971), age 35–49 years (AOR = 5.392, 95%CI: 1.674–17.368), high school educational level (AOR = 5.330, 95% CI: 1.753–16.209), urban residence (AOR = 3.093, 95%CI: 1.003–9.541) and HIV negative (AOR = 10.3, 95%CI, 3.216–32.968) were positively associated with favorable TB treatment outcome. Whereas, being single (AOR = 0.293, 95%CI: 0.1–0.854), smear-negative pulmonary TB (AOR = 0.360, 95%CI: 0.156–0.834), extra-pulmonary TB (AOR = 0.839, 95%CI: 0.560–0.955) and retreatment case (AOR: 0.54, 95%CI: 0.004–0.098) were negatively associated with successful treatment outcome. The treatment success rate of TB patients was lower than World Health Organization target set of 85%. The increased unsuccessful outcome among TB/HIV patients requires urgent public health interventions to improve the evaluation policy and control framework.

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Tuberculosis (TB) remains a major global public health problem.

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TB is the leading cause of death for HIV-infected patients, and HIV is also risk factor for developing active TB.

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The co-infection has emerged as a major public health threat throughout the world and have worse treatment outcomes.

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Management of co-infected patients can be complex because of overlapping drug toxicities and interactions.

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The increased unsuccessful outcome among TB/HIV patients requires urgent public health interventions.

The Mtb-HIV syndemic interaction: why treating M. tuberculosis infection may be crucial for HIV-1 eradication

Accelerated tuberculosis and AIDS progression seen in HIV-1 and Mycobacterium tuberculosis (Mtb)-coinfected individuals indicates the important interaction between these syndemic pathogens. The immunological interaction between HIV-1 and Mtb has been largely defined by how the virus exacerbates tuberculosis disease pathogenesis. Understanding of the mechanisms by which pre-existing or subsequent Mtb infection may favor the replication, persistence and progression of HIV, is less characterized. We present a rationale for the critical consideration of ‘latent’ Mtb infection in HIV-1 prevention and cure strategies. In support of this position, we review evidence of the effect of Mtb infection on HIV-1 acquisition, replication and persistence. We propose that ‘latent’ Mtb infection may have considerable impact on HIV-1 pathogenesis and the continuing HIV-1 epidemic in sub-Saharan Africa.

Cytoplasmic RNA Sensor Pathways and Nitazoxanide Broadly Inhibit Intracellular Mycobacterium tuberculosis Growth

To establish stable infection, Mycobacterium tuberculosis (MTb) must overcome host innate immune mechanisms, including those that sense pathogen-derived nucleic acids. Here, we show that the host cytosolic RNA sensing molecules RIG-I-like receptor (RLR) signaling proteins RIG-I and MDA5, their common adaptor protein MAVS, and the RNA-dependent kinase PKR each independently inhibit MTb growth in human cells. Furthermore, we show that MTb broadly stimulates RIG-I, MDA5, MAVS, and PKR gene expression and their biological activities. We also show that the oral FDA-approved drug nitazoxanide (NTZ) significantly inhibits intracellular MTb growth and amplifies MTb-stimulated RNA sensor gene expression and activity. This study establishes prototypic cytoplasmic RNA sensors as innate restriction factors for MTb growth in human cells and it shows that targeting this pathway is a potential host-directed approach to treat tuberculosis disease.

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MTb infection induces RNA sensor (RIG-I, MDA5, PKR) mRNA levels and activities

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RIG-I, MDA5, MAVS, and PKR restrict intracellular MTb growth in human cells

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NTZ enhances MTb-driven RNA sensor mRNA levels and RLR activities

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NTZ and NTZ derivatives inhibit intracellular MTb growth in primary human cells

LEPROSY AND HUMAN IMMUNODEFICIENCY VIRUS COINFECTION: A RARE CASE REPORT

Leprosy, or Hansen disease, is a chronic infectious disease caused by Mycobacterium leprae which is associated with inflammation that may damage the skin and the peripheral nerves. Leprosy remains an important public health problem in Southeast Asia, America, and Africa. It has been speculated that, as with TB, HIV infection may exacerbate leprosy lesions and/or lead to increased susceptibility to leprosy. We report the case of leprosy and HIV co-infection and reveals its clinical manifestation. A 34-year-old female came to outpatient clinic complaining of rednessplaque on her face of 2-months duration. It was also accompanied with thick sensation but without itchy or burning sensation. We found thick erythematous plaque with sharp margin and hypoesthesia on her face and body. There were no madarosis, saddle nose, lagophthalmos, nor sign of neuritis. The slit-skin smear revealed BI 1+ globi and MI 2%. From laboratory examination we found CBC was within normal limit, IgM anti PGL-1 titer was 1265 u/mL and IgG anti PGL-1 was 834 u/mL Both histological examination on her ear lobe and extremity revealed that was similar to the lesion of leprosy. The detection of HIV antibody was positive with CD4 count on 325 cells/μL. We treat her with MDT for MB leprosy along with ART (Tenofovir, Lamivudine, and Efavirenz). After 6-months follow-up we observed no progression of the lesions though the slit-skin smear after completing 6 months of therapy become negative. M. leprae does not seem to accelerate the decline of immune function when associated with HIV infection. HIV infection does not seem to affect the clinical classification and progression of leprosy. Treatment of the HIV-leprosy co-infected patient consists of the combination of ARTs and anti-leprosy agents. So that, the treatment of leprosy and HIV co-infection does not differ from that of a seronegative leprosy patient.

The Immune Response to Mycobacterium tuberculosis in HIV-1-Coinfected Persons

Globally, about 36.7 million people were living with HIV infection at the end of 2015. The most frequent infection co-occurring with HIV-1 is Mycobacterium tuberculosis-374,000 deaths per annum are attributable to HIV-tuberculosis, 75% of those occurring in Africa. HIV-1 infection increases the risk of tuberculosis by a factor of up to 26 and alters its clinical presentation, complicates diagnosis and treatment, and worsens outcome. Although HIV-1-induced depletion of CD4⁺ T cells underlies all these effects, more widespread immune deficits also contribute to susceptibility and pathogenesis. These defects present a challenge to understand and ameliorate, but also an opportunity to learn and optimize mechanisms that normally protect people against tuberculosis. The most effective means to prevent and ameliorate tuberculosis in HIV-1-infected people is antiretroviral therapy, but this may be complicated by pathological immune deterioration that in turn requires more effective host-directed anti-inflammatory therapies to be derived.

The Immune Interaction between HIV-1 Infection and Mycobacterium tuberculosis

The modulation of tuberculosis (TB)-induced immunopathology caused by human immunodeficiency virus (HIV)-1 coinfection remains incompletely understood but underlies the change seen in the natural history, presentation, and prognosis of TB in such patients. The deleterious combination of these two pathogens has been dubbed a "deadly syndemic," with each favoring the replication of the other and thereby contributing to accelerated disease morbidity and mortality. HIV-1 is the best-recognized risk factor for the development of active TB and accounts for 13% of cases globally. The advent of combination antiretroviral therapy (ART) has considerably mitigated this risk. Rapid roll-out of ART globally and the recent recommendation by the World Health Organization (WHO) to initiate ART for everyone living with HIV at any CD4 cell count should lead to further reductions in HIV-1-associated TB incidence because susceptibility to TB is inversely proportional to CD4 count. However, it is important to note that even after successful ART, patients with HIV-1 are still at increased risk for TB. Indeed, in settings of high TB incidence, the occurrence of TB often remains the first presentation of, and thereby the entry into, HIV care. As advantageous as ART-induced immune recovery is, it may also give rise to immunopathology, especially in the lower-CD4-count strata in the form of the immune reconstitution inflammatory syndrome. TB-immune reconstitution inflammatory syndrome will continue to impact the HIV-TB syndemic.

Total Delay Is Associated with Unfavorable Treatment Outcome among Pulmonary Tuberculosis Patients in West Gojjam Zone, Northwest Ethiopia: A Prospective Cohort Study

BACKGROUND

delay in diagnosis and treatment of tuberculosis (TB) may worsen the disease, increase mortality and enhance transmission in the community. This study aimed at assessing the association between total delay and unfavorable treatment outcome among newly diagnosed pulmonary TB (PTB) patients.

METHODS

A prospective cohort study was conducted in West Gojjam Zone, Amhara Region of Ethiopia from October 2013 to May 2015. Newly diagnosed PTB patients who were ≥15 years of age were consecutively enrolled in the study from 30 randomly selected public health facilities. Total delay (the time period from onset of TB symptoms to first start of anti-TB treatment) was measured. Median total delay was calculated. Mixed effect logistics regression was used to analyze factors associated with unfavorable treatment outcome.

RESULTS

Seven hundred six patients were enrolled in the study. The median total delay was 60 days. Patients with total delay of > 60 days were more likely to have unfavorable TB treatment outcome than patients with total delay of ≤ 60 days (adjusted odds ratio [AOR], 2.33; 95% confidence interval [CI], 1.04-5.26). Human immunodeficiency virus (HIV) positive TB patients were 8.46 times more likely to experience unfavorable treatment outcome than HIV negative TB patients (AOR, 8.46; 95% CI, 3.14-22.79).

CONCLUSIONS

Long total delay and TB/HIV coinfection were associated with unfavorable treatment outcome. Targeted interventions that can reduce delay in diagnosis and treatment of TB, and early comprehensive management of TB/HIV coinfection are needed to reduce increased risk of unfavorable treatment outcome.

Impact of HIV Status on Treatment Outcome of Tuberculosis Patients Registered at Arsi Negele Health Center, Southern Ethiopia: A Six Year Retrospective Study

Background

Despite implementation of different strategies, the burden and mortality of human immunodeficiency virus (HIV)-associated tuberculosis (TB) remains a challenge in Ethiopia. The aim of this study was to assess the impact of HIV status on treatment outcome of tuberculosis patients registered at Arsi Negele Health Center, Southern Ethiopia.

Methods

A six-year retrospective data (from September 2008 to August 2014) of tuberculosis patients (n = 1649) registered at the directly observed therapy short-course (DOTS) clinic of Arsi Negele Health Center was reviewed. Treatment outcome and tuberculosis type were categorized according to the national tuberculosis control program guideline. Data were entered and analyzed using SPSS version 20. Multinomial logistic regression analysis was used to examine the effect of HIV status separately on default/failure and death in relation to those who were successfully treated. Odds ratios with 95% confidence intervals were used to check the presence and strength of association between TB treatment outcome and HIV status and other independent variables.

Results

Out of the 1649 TB patients, 94.7% (1562) have been tested for HIV of whom 156(10%) were HIV co-infected. The mean (standard deviation) age of the patients was 28.5(15.5) years. The majority were new TB cases (96.7%), male (53.7%), urban (54.7%), and had smear negative pulmonary TB (44.1%). Overall, the treatment success rate of TB patients with or without HIV was 87.3%. Using cure/completion as reference, patients without known HIV status had significantly higher odds of default /failure [aOR, 4.26; 95%CI, 1.684–10.775] and transfer-out [aOR, 2.92; 95%CI, 1.545–5.521] whereas those who tested positive for HIV had a significantly higher odds of death [aOR, 6.72; 95%CI, 3.704–12.202] and transfer-out [aOR, 2.02; 95%CI, 1.111–3.680].

Conclusion

Overall, treatment outcome and HIV testing coverage for TB patients is promising to reach the WHO target in the study area. However, default/failure among patients without known HIV status, and higher rate of mortality among HIV positive TB patients and transfer-out cases deserves concern. Therefore further prospective studies on quality of services, socioeconomics and psychology of this group should be conducted.

Gp120 binding with DC-SIGN induces reactivation of HIV-1 provirus via the NF-κB signaling pathway

The reactivation mechanism of latent human immunodeficiency virus type 1 (HIV-1) infection is unclear, especially in dendritic cells (DC). DC-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN) binds with HIV-1 and other pathogens to activate the extracellular regulated protein kinase (ERK) and nuclear factor-kappa B (NF-κB) pathways and regulate cytokine expression. We hypothesized that DC-SIGN-induced signaling pathways may activate HIV-1 provirus. To investigate this hypothesis, we generated a model by transfecting 293T cells with a DC-SIGN expression plasmid and an HIV-1 5' long terminal repeat (LTR) reporter plasmid, and then stimulated the 293T cells with HIV-1 gp120 protein, wild-type HIV-1 or VSV-G-pNL4.3 pseudotype virus (without gp120 protein). It was found that the HIV-1 5'LTR was reactivated by HIV-1 gp120 in DC-SIGN-expressing 293T cells. Then the HIV-1 chronically infected CEM-Bru cells were transfected with DC-SIGN expression plasmid and stimulated by HIV-1 gp120 protein. It was found that early and late HIV-1 provirus replication was reactivated by the HIV-1 gp120/DC-SIGN stimulation. We then investigated the involvement of the ERK, p38 mitogen-activated protein kinases and NF-κB signaling pathways in HIV-1 gp120/DC-SIGN-induced activation of HIV-1 provirus by inhibiting the pathways specifically. Our results indicated that HIV-1 gp120/DC-SIGN stimulation reactivates latent HIV-1 provirus via the NF-κB signal pathway.

A Role for IFITM Proteins in Restriction of Mycobacterium tuberculosis Infection

The interferon (IFN)-induced transmembrane (IFITM) proteins are critical mediators of the host antiviral response. Here, we expand the role of IFITM proteins to host defense against intracellular bacterial infection by demonstrating that they restrict Mycobacterium tuberculosis (MTb) intracellular growth. Simultaneous knockdown of IFITM1, IFITM2, and IFITM3 by RNAi significantly enhances MTb growth in human monocytic and alveolar/epithelial cells, whereas individual overexpression of each IFITM impairs MTb growth in these cell types. Furthermore, MTb infection, Toll-like receptor 2 and 4 ligands, and several proinflammatory cytokines induce IFITM1–3 gene expression in human myeloid cells. We find that IFITM3 co-localizes with early and, in particular, late MTb phagosomes, and overexpression of IFITM3 enhances endosomal acidification in MTb-infected monocytic cells. These findings provide evidence that the antiviral IFITMs participate in the restriction of mycobacterial growth, and they implicate IFITM-mediated endosomal maturation in its antimycobacterial activity.

Proteomics approach to understand reduced clearance of mycobacteria and high viral titers during HIV-mycobacteria co-infection

Environmental mycobacteria, highly prevalent in natural and artificial (including chlorinated municipal water) niches, are emerging as new threat to human health, especially to HIV-infected population. These seemingly harmless non-pathogenic mycobacteria, which are otherwise cleared, establish as opportunistic infections adding to HIV-associated complications. Although immune-evading strategies of pathogenic mycobacteria are known, the mechanisms underlying the early events by which opportunistic mycobacteria establish infection in macrophages and influencing HIV infection are unclear. Proteomics of phagosome-enriched fractions from Mycobacterium bovis Bacillus Calmette-Guérin (BCG) mono-infected and HIV-M. bovis BCG co-infected THP-1 cells by LC-MALDI-MS/MS revealed differential distribution of 260 proteins. Validation of the proteomics data showed that HIV co-infection helped the survival of non-pathogenic mycobacteria by obstructing phagosome maturation, promoting lipid biogenesis and increasing intracellular ATP equivalents. In turn, mycobacterial co-infection up-regulated purinergic receptors in macrophages that are known to support HIV entry, explaining increased viral titers during co-infection. The mutualism was reconfirmed using clinically relevant opportunistic mycobacteria, Mycobacterium avium, Mycobacterium kansasii and Mycobacterium phlei that exhibited increased survival during co-infection, together with increase in HIV titers. Additionally, the catalogued proteins in the study provide new leads that will significantly add to the understanding of the biology of opportunistic mycobacteria and HIV coalition.

Multifaceted Impact of Host C-C Chemokine CCL2 in the Immuno-Pathogenesis of HIV-1/M. tuberculosis Co-Infection

Active tuberculosis remains the leading cause of death among the HIV-1 seropositive individuals. Although significant success has been achieved in bringing down the number of HIV/AIDS-related mortality and morbidity following implementation of highly active anti-retroviral therapy (HAART). Yet, co-infection of Mycobacterium tuberculosis (Mtb) has posed severe clinical and preventive challenges in our efforts to eradicate the virus from the body. Both HIV-1 and Mtb commonly infect macrophages and trigger production of host inflammatory mediators that subsequently regulate the immune response and disease pathogenesis. These inflammatory mediators can impose beneficial or detrimental effects on each pathogen and eventually on host. Among these, inflammatory C–C chemokines play a central role in HIV-1 and Mtb pathogenesis. However, their role in lung-specific mechanisms of HIV-1 and Mtb interaction are poorly understood. In this review we highlight current view on the role of C–C chemokines, more precisely CCL2, on HIV-1: Mtb interaction, potential mechanisms of action and adverse clinical consequences in a setting HIV-1/Mtb co-infection. Targeting common chemokine regulators of HIV-1/Mtb pathogenesis can be an attractive and potential anti-inflammatory intervention in HIV/AIDS-related comorbidities.

TB treatment outcomes among TB-HIV co-infections in Karnataka, India: how do these compare with non-HIV tuberculosis outcomes in the province?

Background

India accounts for 23% of the global incidence of TB cases; it also has an estimated 2.3 million HIV infections. Of the 2 million TB incident cases, 5% occurred in HIV infected persons. The country has large national TB and HIV control programs. This paper describes characteristics of TB-HIV co-infection cases registered under the program in Karnataka province, India. Treatment outcomes for coinfected patients are compared with those for TB patients in the province.

Methods

Program reports from the National AIDS Control program and the National TB control program for Karnataka province (a high HIV prevalence state, population 61 million) were analysed. Data from patients registered in each program in 2010–2011 was studied.

Results

Of the 6,480 adult co-infections, a third occurred in women; 78% of patients were initiated on ART. Among the cohort 73% had pulmonary TB, and 46% reported sputum positivity for acid fast bacilli. Treatment success among co-infected patients not on ART (54%) were significantly lower compared to those already on ART (80%); death and default rates were higher in the non-ART group. Treatment success proportions (75%) for the co-infected patients were similar to those for the 51,966 patients registered under the TB program. Death rates among co-infected patients (15%) were twice as high as for TB patients under the program, though default and failure rates were lower.

Conclusion

Co-infected patients already on ART demonstrated better TB outcomes in than those not on ART. Compared to those with TB only, co-infected patients had similar TB treatment success rates and lower rates of treatment default and failure. Integration of TB-HIV collaborative activities will strengthen our battle to control TB and HIV globally.

Immunohistological characterization of spinal TB granulomas from HIV-negative and -positive patients

Tuberculosis (TB) is mainly a disease of the lungs, but Mycobacterium tuberculosis (Mtb) can establish infection in virtually any organ in the body. Rising rates of extrapulmonary (EP) TB have been largely associated with the HIV epidemic, as patients co-infected with HIV show a four-fold higher risk of EPTB. Spinal TB (Pott's Disease), one of the most debilitating extrapulmonary forms of disease, is difficult to diagnose and can cause deformity and/or neurological deficits. This study examined the histopathology and distribution of immune cells within spinal TB lesions and the impact of HIV on pathogenesis. The overall structure of the spinal granulomas resembled that seen in lung lesions from patients with pulmonary TB. Evidence of efficient macrophage activation and differentiation were detectable within organized structures in the spinal tissue, irrespective of HIV status. Interestingly, the granulomatous architecture and macroscopic features were similar in all samples examined, despite a reversal in the ratio of infiltrating CD4 to CD8 T cells in the lesions from HIV-infected patients. This study provides a foundation to understand the mechanism of tissue destruction and disease progression in Spinal TB, enabling the future development of novel therapeutic strategies and diagnostic approaches for this devastating disease.

HIV-tuberculosis co-infection in an Indian scenario: the role of associated evidence of immunosuppression

OBJECTIVE

To determine the relationship between tuberculosis and the degree of immunosuppression as determined by CD4 count. The impact of immunosuppression on the severity of tuberculosis was also studied.

METHODS

A retrospective analysis was performed in patients newly diagnosed with HIV infection and antiretroviral therapy (ART)-naive patients with known HIV seropositivity. All patients were diagnosed with active tuberculosis between January 2008 and December 2010, based on review of their medical records. Patients on chemoprophylaxis for opportunistic infection were excluded. Pattern and severity of tuberculosis, associated stigmata of immunosuppression, and CD4 counts were noted.

RESULTS

Of 140 patients satisfying the inclusion criteria, 52 had mild tuberculosis with no other evidence of immunosuppression, 52 had tuberculosis of variable severity with associated evidence of immunosuppression, and 36 had severe tuberculosis with no other evidence of immunosuppression. The CD4 count was highest in the first group [(109.2±99.9) cells/μL] and least in the second group [(58.4±39.8) cells/μL], and the difference was statistically significant (P=0.004). No statistical difference was observed in the CD4 count between those with mild tuberculosis and those with severe tuberculosis.

CONCLUSIONS

In developing countries with a high prevalence of tuberculosis in the general population, the possibility of incidental tuberculosis in patients with HIV should always be considered. CD4 count does not appear to influence the severity of tuberculosis. The presence of concomitant evidence of immunosuppression in the form of category B and C conditions is indicative of underlying immunosuppression and associated with a significantly lower CD4 count.

HIV infection disrupts the sympatric host-pathogen relationship in human tuberculosis

The phylogeographic population structure of Mycobacterium tuberculosis suggests local adaptation to sympatric human populations. We hypothesized that HIV infection, which induces immunodeficiency, will alter the sympatric relationship between M. tuberculosis and its human host. To test this hypothesis, we performed a nine-year nation-wide molecular-epidemiological study of HIV–infected and HIV–negative patients with tuberculosis (TB) between 2000 and 2008 in Switzerland. We analyzed 518 TB patients of whom 112 (21.6%) were HIV–infected and 233 (45.0%) were born in Europe. We found that among European-born TB patients, recent transmission was more likely to occur in sympatric compared to allopatric host–pathogen combinations (adjusted odds ratio [OR] 7.5, 95% confidence interval [95% CI] 1.21–infinity, p = 0.03). HIV infection was significantly associated with TB caused by an allopatric (as opposed to sympatric) M. tuberculosis lineage (OR 7.0, 95% CI 2.5–19.1, p<0.0001). This association remained when adjusting for frequent travelling, contact with foreigners, age, sex, and country of birth (adjusted OR 5.6, 95% CI 1.5–20.8, p = 0.01). Moreover, it became stronger with greater immunosuppression as defined by CD4 T-cell depletion and was not the result of increased social mixing in HIV–infected patients. Our observation was replicated in a second independent panel of 440 M. tuberculosis strains collected during a population-based study in the Canton of Bern between 1991 and 2011. In summary, these findings support a model for TB in which the stable relationship between the human host and its locally adapted M. tuberculosis is disrupted by HIV infection.

Human tuberculosis (TB) caused by Mycobacterium tuberculosis kills 1.5 million people each year. M. tuberculosis has been affecting humans for millennia, suggesting that different strain lineages may be adapted to specific human populations. The combination of a particular strain lineage and its corresponding patient population can be classified as sympatric (e.g. Euro-American lineage in Europeans) or allopatric (e.g. East-Asian lineage in Europeans). We hypothesized that infection with the human immunodeficiency virus (HIV), which impairs the human immune system, will interfere with this host–pathogen relationship. We performed a nation-wide molecular-epidemiological study of HIV–infected and HIV–negative TB patients between 2000 and 2008 in Switzerland. We found that HIV infection was associated with the less adapted allopatric lineages among patients born in Europe, and this was not explained by social or other patient factors such as increased social mixing in HIV–infected individuals. Strikingly, the association between HIV infection and less adapted M. tuberculosis lineages was stronger in patients with more pronounced immunodeficiency. Our observation was replicated in a second independent panel of M. tuberculosis strains collected during a population-based study in the Canton of Bern. In summary, our study provides evidence that the sympatric host–pathogen relationship in TB is disrupted by HIV infection.

The transcription factor NFATp plays a key role in susceptibility to TB in mice

In T cells, the transcription factor nuclear factor of activated T cells p (NFATp) is a key regulator of the cytokine genes tumor necrosis factor (TNF) and interferon-γ (IFN-γ). Here, we show that NFATp-deficient (NFATp(-/-)) mice have a dramatic and highly significant increase in mortality after Mycobacterium tuberculosis (MTb) infection as compared to mortality of control animals after MTb infection. Animals deficient in NFATp have significantly impaired levels of TNF and IFN-γ transcription and protein expression in naïve or total CD4(+) T cells, but display wild-type levels of TNF mRNA or protein from MTb-stimulated dendritic cells (DC). The rapid mortality and disease severity observed in MTb-infected NFATp(-/-) mice is associated with dysregulated production of TNF and IFN-γ in the lungs, as well as with increased levels of TNF, in their serum. Furthermore, global blocking of TNF production by injection of a TNF neutralizaing agent at 6 weeks, but not 12 weeks, post-MTb-infection further decreased the survival rate of both wild-type and NFATp(-/-) mice, indicating an early role for TNF derived from cells from the monocyte lineage in containment of infection. These results thus demonstrate that NFATp plays a critical role in immune containment of TB disease in vivo, through the NFATp-dependent expression of TNF and IFN-γ in T cells.

Human immunodeficiency virus and leprosy coinfection: challenges in resource-limited setups

Mycobacteria leprae(leprosy) and HIV coinfection are rare in Kenya. This is likely related to the low prevalence (1 per 10,000 of population) of leprosy. Because leprosy is no longer a public health challenge there is generally a low index of suspicion amongst clinicians for its diagnosis. Management of a HIV-1-leprosy-coinfected individual in a resource-constrained setting is challenging. Some of these challenges include difficulties in establishing a diagnosis of leprosy; the high pill burden of cotreatment with both antileprosy and antiretroviral drugs (ARVs); medications' side effects; drug interactions; scarcity of drug choices for both diseases. This challenge is more profound when managing a patient who requires second-line antiretroviral therapy (ART). We present an adult male patient coinfected with HIV and leprosy, who failed first-line antiretroviral therapy (ART) and required second-line treatment. Due to limited choices in antileprosy drugs available, the patient received monthly rifampicin and daily lopinavir-/ritonavir-based antileprosy and ART regimens, respectively. Six months into his cotreatment, he seemed to have adequate virological control. This case report highlights the challenges of managing such a patient.

Regulation of Mycobacterium tuberculosis-dependent HIV-1 transcription reveals a new role for NFAT5 in the toll-like receptor pathway

Tuberculosis (TB) disease in HIV co-infected patients contributes to increased mortality by activating innate and adaptive immune signaling cascades that stimulate HIV-1 replication, leading to an increase in viral load. Here, we demonstrate that silencing of the expression of the transcription factor nuclear factor of activated T cells 5 (NFAT5) by RNA interference (RNAi) inhibits Mycobacterium tuberculosis (MTb)-stimulated HIV-1 replication in co-infected macrophages. We show that NFAT5 gene and protein expression are strongly induced by MTb, which is a Toll-like receptor (TLR) ligand, and that an intact NFAT5 binding site in the viral promoter of R5-tropic HIV-1 subtype B and subtype C molecular clones is required for efficent induction of HIV-1 replication by MTb. Furthermore, silencing by RNAi of key components of the TLR pathway in human monocytes, including the downstream signaling molecules MyD88, IRAK1, and TRAF6, significantly inhibits MTb-induced NFAT5 gene expression. Thus, the innate immune response to MTb infection induces NFAT5 gene and protein expression, and NFAT5 plays a crucial role in MTb regulation of HIV-1 replication via a direct interaction with the viral promoter. These findings also demonstrate a general role for NFAT5 in TLR- and MTb-mediated control of gene expression.

The major cause of AIDS deaths globally has been tuberculosis (TB), which is caused by the bacterium Mycobacterium tuberculosis (MTb). Co-infection with MTb exacerbates human immunodeficiency virus type1 (HIV-1) replication and disease progression via both innate and adaptive host immune responses to MTb infection. In this report, we present evidence that the transcription factor NFAT5 plays a crucial role in MTb-induced HIV-1 replication in human peripheral blood cells and monocytes. We also show that MTb infection itself stimulates NFAT5 gene expression in human monocytes and that its expression involves the TLR signalling pathway and requires the downstream adaptor proteins MyD88, IRAK1, and TRAF6. This identification of a novel role for NFAT5 in TB/HIV-1 co-infection reveals that NFAT5 is a major mediator of TLR-dependent gene expression and thus provides a potential new therapeutic target for treatment of HIV-1 and possibly other diseases.