Tuberculosis screening before anti-hepatitis C virus therapy in prisons

Type I interferon signaling mediates Mycobacterium tuberculosis-induced macrophage death

Macrophages help defend the host against Mycobacterium tuberculosis (Mtb), the major cause of tuberculosis (TB). Once phagocytized, Mtb resists killing by macrophages, replicates inside them, and leads to their death, releasing Mtb that can infect other cells. We found that the death of Mtb-infected mouse macrophages in vitro does not appear to proceed by a currently known pathway. Through genome-wide CRISPR-Cas9 screening, we identified a critical role for autocrine or paracrine signaling by macrophage-derived type I IFNs in the death of Mtb-infected macrophages in vitro, and blockade of type I IFN signaling augmented the effect of rifampin, a first-line TB drug, in Mtb-infected mice. Further definition of the pathway of type I IFN-mediated macrophage death may allow for host-directed therapy of TB that is more selective than systemic blockade of type I IFN signaling.

Screening for HBV, HCV, HIV and syphilis infections among bacteriologically confirmed tuberculosis prisoners: An urgent action required

Viral hepatitis, syphilis, HIV, and tuberculosis infections in prisons have been identified globally as a public health problem. Tuberculosis (TB) and viral hepatitis co-infection may increase the risk of anti-tuberculosis treatment-induced hepatotoxicity, leading to the frequent cause of discontinuation of the first-line anti-tuberculosis drugs. Therefore, the aim of this cross-sectional study was to investigate the epidemiological features of HCV, HBV, syphilis and HIV infections among bacteriologically confirmed tuberculosis prisoners in Campo Grande (MS), Central Brazil. The participants who agreed to participate (n = 279) were interviewed and tested for the presence of active or current HCV, HBV, syphilis and HIV infections. The prevalence of HCV exposure was 4.7% (13/279; 95% CI 2.2-7.1). HCV RNA was detected in 84.6% (11/13) of anti-HCV positive samples. Out of 279 participants, 19 (6.8%; 95% CI 4.4-10.4) were HIV co-infected, 1.4% (4/279, 95% CI 0.5-3.8) had chronic hepatitis B virus (HBsAg positive) and 9.3% (26/279, 95% CI 6.4-13.4) had serological marker of exposure to hepatitis B virus (total anti-HBc positive). The prevalence of lifetime syphilis infection (anti-T. pallidum positive) was 10% (28/279, 95% CI 7.0-14.2) and active syphilis (VDRL ≥ 1/8 titre) was 5% (14/279, 95% CI 2.9-8.3). The prevalence of TB/HCV co-infection among prisoners with HIV (15.8%) was higher than among HIV-non-infected prisoners (3.8%; P<0.05). These results highlight the importance of hepatitis testing among prisoners with bacteriologically confirmed case of TB who can be more effectively and safely treated in order to reduce the side effects of hepatotoxic anti-TB drugs.

Host-directed therapies for bacterial and viral infections

Host-directed therapy (HDT) is a novel approach in the field of anti-infectives for overcoming antimicrobial resistance.

HDT aims to interfere with host cell factors that are required by a pathogen for replication or persistence, to enhance protective immune responses against a pathogen, to reduce exacerbated inflammation and to balance immune reactivity at sites of pathology.

HDTs encompassing the 'shock and kill' strategy or the delivery of recombinant interferons are possible approaches to treat HIV infections. HDTs that suppress the cytokine storm that is induced by some acute viral infections represent a promising concept.

In tuberculosis, HDT aims to enhance the antimicrobial activities of phagocytes through phagosomal maturation, autophagy and antimicrobial peptides. HDTs also curtail inflammation through interference with soluble (such as eicosanoids or cytokines) or cellular (co-stimulatory molecules) factors and modulate granulomas to allow the access of antimicrobials or to restrict tissue damage.

Numerous parallels between the immunological abnormalities that occur in sepsis and cancer indicate that the HDTs that are effective in oncology may also hold promise in sepsis.

Advances in immune phenotyping, genetic screening and biosignatures will help to guide drug therapy to optimize the host response. Combinations of canonical pathogen-directed drugs and novel HDTs will become indispensable in treating emerging infections and diseases caused by drug-resistant pathogens.

Host-directed therapy (HDT) aims to interfere with host cell factors that are required by a pathogen for replication or persistence. In this Review, Kaufmannet al. describe recent progress in the development of HDTs for the treatment of viral and bacterial infections and the challenges in bringing these approaches to the clinic.

Despite the recent increase in the development of antivirals and antibiotics, antimicrobial resistance and the lack of broad-spectrum virus-targeting drugs are still important issues and additional alternative approaches to treat infectious diseases are urgently needed. Host-directed therapy (HDT) is an emerging approach in the field of anti-infectives. The strategy behind HDT is to interfere with host cell factors that are required by a pathogen for replication or persistence, to enhance protective immune responses against a pathogen, to reduce exacerbated inflammation and to balance immune reactivity at sites of pathology. Although HDTs encompassing interferons are well established for the treatment of chronic viral hepatitis, novel strategies aimed at the functional cure of persistent viral infections and the development of broad-spectrum antivirals against emerging viruses seem to be crucial. In chronic bacterial infections, such as tuberculosis, HDT strategies aim to enhance the antimicrobial activities of phagocytes and to curtail inflammation through interference with soluble factors (such as eicosanoids and cytokines) or cellular factors (such as co-stimulatory molecules). This Review describes current progress in the development of HDTs for viral and bacterial infections, including sepsis, and the challenges in bringing these new approaches to the clinic.

Interactions between Type 1 Interferons and the Th17 Response in Tuberculosis: Lessons Learned from Autoimmune Diseases

The classical paradigm of tuberculosis (TB) immunity, with a central protective role for Th1 responses and IFN-γ-stimulated cellular responses, has been challenged by unsatisfactory results of vaccine strategies aimed at enhancing Th1 immunity. Moreover, preclinical TB models have shown that increasing IFN-γ responses in the lungs is more damaging to the host than to the pathogen. Type 1 interferon signaling and altered Th17 responses have also been associated with active TB, but their functional roles in TB pathogenesis remain to be established. These two host responses have been studied in more detail in autoimmune diseases (AID) and show functional interactions that are of potential interest in TB immunity. In this review, we first identify the role of type 1 interferons and Th17 immunity in TB, followed by an overview of interactions between these responses observed in systemic AID. We discuss (i) the effects of GM-CSF-secreting Th17.1 cells and type 1 interferons on CCR2⁺ monocytes; (ii) convergence of IL-17 and type 1 interferon signaling on stimulating B-cell activating factor production and the central role of neutrophils in this process; and (iii) synergy between IL-17 and type 1 interferons in the generation and function of tertiary lymphoid structures and the associated follicular helper T-cell responses. Evaluation of these autoimmune-related pathways in TB pathogenesis provides a new perspective on recent developments in TB research.

The impact of ISGylation during Mycobacterium tuberculosis infection in mice

Mycobacterium tuberculosis infection results in 1.5 million deaths annually. Type I interferon (IFN) signaling through its receptor IFNAR correlates with increased severity of disease, although how this increases susceptibility to M. tuberculosis remains uncertain. ISG15 is one of the most highly induced interferon stimulated genes (ISGs) during M. tuberculosis infection. ISG15 functions by conjugation to target proteins (ISGylation), by noncovalent association with intracellular proteins, and by release from the cell. Recent studies indicated that ISG15 can function via conjugation-independent mechanisms to suppress the type I IFN response. These data raised the question of whether ISG15 may have diverse and sometimes opposing functions during M. tuberculosis infection. To address this, we analyzed ISGylation during M. tuberculosis infection and show that ISGylated proteins accumulate following infection in an IFNAR-dependent manner. Type I IFN and ISG15 both play transient roles in promoting bacterial replication. However, as the disease progresses, ISGylation deviates from the overall effect of type I IFN and, ultimately, mice deficient in ISGylation are significantly more susceptible than IFNAR mice. Our data demonstrate that ISGs can both protect against and promote disease and are the first to report a role for ISGylation during M. tuberculosis infection.

Management of HCV infection in the penitentiary setting in the direct-acting antivirals era: practical recommendations from an expert panel

BACKGROUND

The prevalence of HCV infection is higher among prisoners than in the general population. The introduction of HCV direct-acting antivirals (DAA) holds the potential to improve clinical outcomes also in inmates. However, treatment of hepatitis C in inmates has to face several clinical and logistical issues which are peculiar of prison environment. Recommendations on the management of HCV infection specific for the penitentiary setting in the DAA era remain scant. The Italian Society for Penitentiary Medicine and Healthcare has, therefore, issued these recommendations, to provide clinicians with a guide for the comprehensive management of HCV infection in the restriction setting, taking into account its peculiar characteristics.

RESULTS

Dedicated diagnostic and treatment procedures should be established in each prison. In particular, the use of DAAs appears crucial to provide patients with an effective therapeutic option, able to overcome the limitations of IFN-based regimens with a short period of treatment. DAA treatment should be initiated as soon as possible in all eligible subjects with the aim to cure the patient, as well as to limit the transmission of HCV infection both inside the penitentiary system and to the free community, once the inmates ends his/her release. Importantly, efforts should be made to open a discussion with regulatory bodies, to define specific regulations aimed to guarantee wide access to effective therapies of all eligible patients, to optimize the management of and the adherence to the HCV treatment, and to ensure the therapeutic continuity after discharge from prison.

High incidence of tuberculosis in patients treated for hepatitis C chronic infection

Brazil is one of the 22 countries that concentrates 80% of global tuberculosis cases concomitantly to a large number of hepatitis C carriers and some epidemiological risk scenarios are coincident for both diseases. We analyzed tuberculosis cases that occurred during α-interferon-based therapy for hepatitis C in reference centers in Brazil between 2001 and 2012 and reviewed their medical records. Eighteen tuberculosis cases were observed in patients submitted to hepatitis C α-interferon-based therapy. All patients were human immunodeficiency virus-negative. Nine patients (50%) had extra-pulmonary tuberculosis; 15 (83%) showed significant liver fibrosis. Hepatitis C treatment was discontinued in 12 patients (67%) due to tuberculosis reactivation and six (33%) had sustained virological response. The majority of patients had a favorable outcome but one died. Considering the evidences of α-IFN interference over the containment of Mycobacterium tuberculosis, the immune impairment of cirrhotic patients, the increase of tuberculosis case reports during hepatitis C treatment with atypical and severe presentations and the negative impact on sustained virological response, we think these are strong arguments for latent tuberculosis infection screening before starting α-interferon-based therapy for any indication and even to consider IFN-free regimens against hepatitis C when a patient tests positive for latent tuberculosis infection.

Onset of Tuberculosis from a Pulmonary Latent Tuberculosis Infection during Antiviral Triple Therapy for Chronic Hepatitis C

A 62-year-old man was diagnosed with the onset of tuberculosis (Tb) from a pulmonary latent tuberculosis infection (LTBI) during triple therapy with pegylated interferon α2a, ribavirin, and telaprevir for a chronic hepatitis C infection in 2013 before interferon (IFN)-free anti-viral therapy was introduced in Japan. A liver biopsy before IFN treatment revealed the presence of epithelioid cell granulomas (ECGs). IFN may also be employed for chronic hepatitis B infection and malignant tumors, thus, special attention must be paid to the development of Tb from a LTBI when ECGs are observed before treatment. It is also necessary to review the significance of the liver biopsy.

Incidence rates of tuberculosis in chronic hepatitis C infected patients with or without interferon based therapy: a population-based cohort study in Taiwan

BACKGROUND

It is debated whether interferon-based therapy (IBT) would affect the incidence of active tuberculosis (TB) among hepatitis C virus (HCV) infected patients. Although some case reports have demonstrated a possible association, the results are currently inconclusive. Therefore, we conducted a nation-wide population study to investigate the incidence of active TB in HCV infected patients receiving IBT in Taiwan.

METHODS

This 9-year cohort study was based on the Longitudinal Health Insurance Database 2000 (LHID 2000) consisting of 1,000,000 beneficiaries randomly selected from all Taiwan National Health Insurance enrollees in 2000 ( >23.7 million). This insurance program covers all citizens in Taiwan. We conducted a retrospective cohort study that identified subjects with HCV infection. IBTs were defined as regimens that included interferon α, peginterferon α2a and peginterferon α2b for at least 2 months. Among them, 621 subjects received IBT, and 2,460 age- and gender-matched subjects were enrolled for analysis. The Cox proportional hazards models were used to estimate the hazard ratio (HR) for active TB, and associated confidence intervals (CIs), comparing IBT cohort and untreated cohort. The endpoint in this study was whether an enrolled subject had a new diagnosis of active TB.

RESULTS

During the 9-year enrollment period, the treated and untreated cohorts were followed for a mean (± SD) duration of 6.97 ± 0.02 years and 8.21 ± 0.01 years, respectively. The cumulative incidence rate of active TB during this study period was 0.150 and 0.151 per 100 person-years in the IBT treated and untreated cohorts, respectively. There was no significant difference in the incidence of active TB in either cohort during a 1-year follow-up (Adjusted Hazard Ratio (AHR): 2.81, 95% Confidence Interval (95% CI): 0.61-12.98) or the long-term follow-up (AHR: 1.02, 95% CI: 0.28-3.78). The Cox proportional hazards model demonstrated that IBT was not a risk factor for active TB . The only risk factor for active TB was the occurrence of hepatic encephalopathy.

CONCLUSION

Our results showed that IBT is associated with increased hazard of active TB in HCV infected patients in 1-year follow-up; however, the effect sizes were not statistically significant.

Type I IFN signaling triggers immunopathology in tuberculosis-susceptible mice by modulating lung phagocyte dynamics

General interest in the biological functions of IFN type I in Mycobacterium tuberculosis (Mtb) infection increased after the recent identification of a distinct IFN gene expression signature in tuberculosis (TB) patients. Here, we demonstrate that TB-susceptible mice lacking the receptor for IFN I (IFNAR1) were protected from death upon aerogenic infection with Mtb. Using this experimental model to mimic primary progressive pulmonary TB, we dissected the immune processes affected by IFN I. IFNAR1 signaling did not affect T-cell responses, but markedly altered migration of inflammatory monocytes and neutrophils to the lung. This process was orchestrated by IFNAR1 expressed on both immune and tissue-resident radioresistant cells. IFNAR1-driven TB susceptibility was initiated by augmented Mtb replication and in situ death events, along with CXCL5/CXCL1-driven accumulation of neutrophils in alveoli, followed by the discrete compartmentalization of Mtb in lung phagocytes. Early depletion of neutrophils rescued TB-susceptible mice to levels observed in mice lacking IFNAR1. We conclude that IFN I alters early innate events at the site of Mtb invasion leading to fatal immunopathology. These data furnish a mechanistic explanation for the detrimental role of IFN I in pulmonary TB and form a basis for understanding the complex roles of IFN I in chronic inflammation.

Antitubercular therapy in patients with cirrhosis: Challenges and options

Tuberculosis (TB) has been a human disease for centuries. Its frequency is increased manyfold in patients with liver cirrhosis. The gold standard of TB management is a 6-mo course of isoniazid, rifampicin, pyrazinamide and ethambutol. Although good results are seen with this treatment in general, the management of patients with underlying cirrhosis is a challenge. The underlying depressed immune response results in alterations in many diagnostic tests. The tests used for latent TB have many flaws in this group of patients. Three of four first-line antitubercular drugs are hepatotoxic and baseline liver function is often disrupted in patients with underlying cirrhosis. Frequency of hepatotoxicity is increased in patients with liver cirrhosis, frequently leading to severe liver failure. There are no established guidelines for the treatment of TB in relation to the severity of liver disease. There is no consensus on the frequency of liver function tests required or the cut-off used to define hepatotoxicity. No specific treatment exists for prevention or treatment of hepatotoxicity, making monitoring even more important. A high risk of multidrug-resistant TB is another major worry due to prolonged and interrupted treatment.

Pulmonary tuberculoma in a patient with chronic hepatitis C: a clinical pitfall in the treatment strategy

We herein report a clinical pitfall regarding the treatment of a case of pulmonary tuberculoma in a patient with chronic hepatitis C. The patient presented with both chronic hepatitis C and pulmonary tuberculoma, and we initiated treatment of the chronic hepatitis C first due to the potential for liver injury; however, the patient's condition worsened in terms of the pulmonary tuberculosis. This case highlights the need to select the initial treatment for pulmonary tuberculoma, not chronic hepatitis C. In addition, we report that, although the administration of anti-tuberculosis chemotherapy regimens containing pyrazinamide (PZA) substantially increases the incidence of drug-induced hepatitis in patients with chronic hepatitis, we were fortunately able to use PZA without observing drug-induced hepatitis in this case because we closely monitored the patient's liver function.