Bacillary Clearance Research Articles

MIP vaccine in leprosy: A scoping review and future horizons.

Mycobacterium Indicus Pranii (MIP) vaccine is a killed vaccine developed in India for leprosy with immunotherapeutic as well as immunoprophylactic effects. MIP, earlier known as Mycobacterium welchii, is a rapidly growing non-pathogenic mycobacterium. The novelty of this bacterium is due to its translational application as an immunotherapeutic agent. When administered intradermally, the vaccine induces cell-mediated immunity in the host towards Mycobacterium leprae. It leads to faster clinical and histopathological improvement, rapid bacillary clearance, and also lepromin conversion in anergic leprosy patients. The beneficial role of the MIP vaccine in augmenting the therapeutic efficacy of Multidrug Therapy (MDT), particularly in highly bacillated leprosy patients, is well documented in various studies from India. The role of the vaccine in reactional states is controversial, with varied results in different studies. Overall, it is found to decrease the frequency of type 2 lepra reactions and is useful in recalcitrant erythema nodosum leprosum. Even though there may be an increased likelihood of type 1 reactions, no additional nerve function impairment is attributed to the vaccine in various studies. In household contacts of leprosy who are administered MIP, it is noted to confer protection from disease lasting up to 10 years. It may prove to be a cost-effective strategy in national leprosy programmes. Apart from local injection site reactions, the vaccine is relatively safe, but it is not recommended in pregnancy and lactation. This article provides an overview of the MIP vaccine's clinical application in the context of leprosy spanning over 40 years. It also considers the vaccine's possible future applications in the management of disease-related complications and achieving the long-term goal of zero leprosy.

High Intrapulmonary Rifampicin and Isoniazid Concentrations Are Associated With Rapid Sputum Bacillary Clearance in Patients With Pulmonary Tuberculosis.

Intrapulmonary pharmacokinetics may better explain response to tuberculosis (TB) treatment than plasma pharmacokinetics. We explored these relationships by modeling bacillary clearance in sputum in adult patients on first-line treatment in Malawi. Bacillary elimination rates (BER) were estimated using linear mixed-effects modelling of serial time-to-positivity in mycobacterial growth indicator tubes for sputum collected during the intensive phase of treatment (weeks 0-8) for microbiologically confirmed TB. Population pharmacokinetic models used plasma and intrapulmonary drug levels at 8 and 16 weeks. Pharmacokinetic-pharmacodynamic relationships were investigated using individual-level measures of drug exposure (area-under-the-concentration-time-curve [AUC] and Cmax) for rifampicin, isoniazid, pyrazinamide, and ethambutol, in plasma, epithelial lining fluid, and alveolar cells as covariates in the bacillary elimination models. Among 157 participants (58% human immunodeficiency virus [HIV] coinfected), drug exposure in plasma or alveolar cells was not associated with sputum bacillary clearance. Higher peak concentrations (Cmax) or exposure (AUC) to rifampicin or isoniazid in epithelial lining fluid was associated with more rapid bacillary elimination and shorter time to sputum negativity. More extensive disease on baseline chest radiograph was associated with slower bacillary elimination. Clinical outcome was captured in 133 participants, with 15 (11%) unfavorable outcomes recorded (recurrent TB, failed treatment, or death). No relationship between BER and late clinical outcome was identified. Greater intrapulmonary drug exposure to rifampicin or isoniazid in the epithelial lining fluid was associated with more rapid bacillary clearance. Higher doses of rifampicin and isoniazid may result in sustained high intrapulmonary drug exposure, rapid bacillary clearance, shorter treatment duration and better treatment outcomes.

Lactate Alters Metabolism in Human Macrophages and Improves Their Ability to Kill Mycobacterium tuberculosis.

In order to mount an appropriate immune response to infection, the macrophage must alter its metabolism by increasing aerobic glycolysis and concomitantly decreasing oxidative phosphorylation; a process known as the Warburg effect. Consequently, lactate, the end-product of glycolysis, accumulates in the extracellular environment. The subsequent effect of lactate on surrounding macrophages is poorly understood. Mycobacterium tuberculosis (Mtb), the causative organism of Tuberculosis (TB), is phagocytosed by macrophages in the airways. Mtb infected macrophages upregulate aerobic glycolysis and effector functions to try to kill the bacteria. Our lab has previously shown that human macrophages produce lactate in response to infection with Mtb. Although lactate has largely been considered a waste product of aerobic glycolysis, we hypothesised that the presence of extracellular lactate would impact subsequent immunometabolic responses and modulate macrophage function. We demonstrate that the presence of exogenous lactate has an immediate effect on the cellular metabolism of resting human macrophages; causing a decrease in extracellular acidification rate (ECAR; analogous to the rate of glycolysis) and an increase in the oxygen consumption rate (OCR; analogous to oxidative phosphorylation). When lactate-treated macrophages were stimulated with Mtb or LPS, glycolysis proceeds to increase immediately upon stimulation but oxidative phosphorylation remains stable compared with untreated cells that display a decrease in OCR. This resulted in a significantly reduced ECAR/OCR ratio early in response to stimulation. Since altered metabolism is intrinsically linked to macrophage function, we examined the effect of lactate on macrophage cytokine production and ability to kill Mtb. Lactate significantly reduced the concentrations of TNF and IL-1β produced by human macrophages in response to Mtb but did not alter IL-10 and IL-6 production. In addition, lactate significantly improved bacillary clearance in human macrophages infected with Mtb, through a mechanism that is, at least in part, mediated by promoting autophagy. These data indicate that lactate, the product of glycolysis, has a negative feedback effect on macrophages resulting in an attenuated glycolytic shift upon subsequent stimulation and reduced pro-inflammatory cytokine production. Interestingly, this pro-resolution effect of lactate is associated with increased capacity to kill Mtb.

Mycobacterium indicus pranii vaccine immunoprophylaxis in anti-phenolic glycolipid-1-positive leprosy contacts - A pilot study from a tertiary care center in North India.

Contacts of leprosy patients have an increased risk of infection with Mycobacterium leprae. Contact tracing and chemo- or immunoprophylaxis are important means of preventing leprosy transmission. We aimed to evaluate the efficacy of immunoprophylaxis with Mycobacterium indicus pranii vaccine in reducing anti-phenolic glycolipid-1 titers in household contacts of leprosy patients. This prospective single-center study was conducted in a tertiary care center in North India from January 2015 to December 2016. Contacts of leprosy patients (both paucibacillary and multibacillary) were screened for anti-phenolic glycolipid-1 antibodies with enzyme-linked immunosorbent assay. Those found positive were given immunoprophylaxis with a single dose of Mycobacterium indicus pranii vaccine, and anti-phenolic glycolipid-1 titers were evaluated at six and 12 months. All contacts were clinically followed for three years. Of the 135 contacts of 98 leprosy patients that were screened, 128 were recruited. Seventeen of these contacts were positive for anti-phenolic glycolipid-1 antibodies and were given Mycobacterium indicus pranii vaccine. Two contacts were lost to follow-up. After immunoprophylaxis, anti-phenolic glycolipid-1 titers were negative in all patients at all intervals, and no contact developed any clinical signs or symptoms of leprosy during the three-year follow-up. The small number of contacts studied, the short follow-up period and the absence of a control group were limitations of this study. Dicussion: We could not find any papers on natural decline of PGL 1 titres in contacts, although in leprosy patients, these titres may even increase after completion of treatment. However the titres do correlate with bacterial load (reference: Int J Lepr Other Mycobact Dis. 1998 Sep;66(3):356-64) so if the tires decrease or become negative it may be considered as an indirect evidence of bacillary clearance. Hence we may suggest the protective efficacy. Furthermore, as the editor mentioned, considering the small number of positive patients, a control group was not possible in the present pilot study, but such studies may be carried out in the future. Immunoprophylaxis with Mycobacterium indicus pranii vaccine is effective and safe in preventing disease in contacts of leprosy patients. However, these findings need to be replicated in larger studies.

Interim Effectiveness and Safety Comparison of Bedaquiline-Containing Regimens for Treatment of Diabetic Versus Non-Diabetic MDR/XDR-TB Patients in China: A Multicenter Retrospective Cohort Study.

IntroductionDiabetes mellitus (DM), a common tuberculosis (TB) comorbidity, is associated with delayed bacillary clearance during anti-TB treatment and unfavorable outcomes. Bedaquiline (BDQ), when used as part of multidrug regimen for multidrug-resistant/extensively drug-resistant tuberculosis (MDR/XDR-TB), has been shown to be effective and safe although treatment outcome and risks for patients with MDR/XDR-TB and DM are unknown. A multicenter retrospective study was conducted to compared the safety and effectiveness of 24-week BDQ-containing anti-TB treatment for patients with MDR/XDR-TB with and without DM.MethodsThe study of patients with MDR/XDR-TB with or without DM (enrolled February 2018–September 2019, 21 Chinese hospitals) was supervised by the New Drug Introduction and Protection Program (NDIP). Of 640 patients with MDR/XDR-TB receiving BDQ-containing anti-TB treatments, two propensity score-matched groups (107 DM/107 non-DM) were compared for cumulative culture conversion rate, time to culture conversion, adverse events, and corrected QT interval.ResultsBody mass index was higher in patients with DM than patients without DM (23.29 ± 3.9 vs. 20.5 ± 3.6, P < 0.001); lung cavity prevalence (86.9% vs. 72.9%, P = 0.037) was also higher in patients with DM; the non-DM group had higher hepatitis prevalence (29.0% vs. 15.9%, P = 0.022). No significant intergroup differences were found for sputum culture conversion rate at week 8 (80.0% vs. 81.4%, P = 0.884), at week 24 (95.6% vs. 98.2%, P = 0.629), or for median time to sputum culture conversion [56 days (IQR 28–63) vs. 56 days (IQR 28–84) (P = 0.687)]. Favorable post-24-week treatment outcomes were presented by 90.7% and 93.5% in the DM group and non-DM group, respectively, without significant intergroup differences (P = 0.448). The DM adverse event rate exceeded non-DM rate (77.6% vs. 64.5%, P = 0.035).ConclusionDespite some differences in baseline characteristics, Chinese patients with MDR/XDR-TB with or without DM had similar sputum culture conversion rates and favorable treatment outcomes post-24-week BDQ-containing anti-TB treatment. Low BMI but not DM is risk factor associated with unfavorable outcome of patients with MDR/XDR-TB.Supplementary InformationThe online version contains supplementary material available at 10.1007/s40121-021-00396-9.

Longitudinal Pharmacokinetic-Pharmacodynamic Biomarkers Correlate With Treatment Outcome in Drug-Sensitive Pulmonary Tuberculosis: A Population Pharmacokinetic-Pharmacodynamic Analysis.

BackgroundThis study aims to explore relationships between baseline demographic covariates, plasma antibiotic exposure, sputum bacillary load, and clinical outcome data to help improve future tuberculosis (TB) treatment response predictions.MethodsData were available from a longitudinal cohort study in Malawian drug-sensitive TB patients on standard therapy, including steady-state plasma antibiotic exposure (154 patients), sputum bacillary load (102 patients), final outcome (95 patients), and clinical details. Population pharmacokinetic and pharmacokinetic-pharmacodynamic models were developed in the software package NONMEM. Outcome data were analyzed using univariate logistic regression and Cox proportional hazard models in R, a free software for statistical computing.ResultsHigher isoniazid exposure correlated with increased bacillary killing in sputum (P < .01). Bacillary killing in sputum remained fast, with later progression to biphasic decline, in patients with higher rifampicin area under the curve (AUC)0-24 (P < .01). Serial sputum colony counting negativity at month 2 (P < .05), isoniazid CMAX (P < .05), isoniazid CMAX/minimum inhibitory concentration ([MIC] P < .01), and isoniazid AUC0-24/MIC (P < .01) correlated with treatment success but not with remaining free of TB. Slower bacillary killing (P < .05) and earlier progression to biphasic bacillary decline (P < .01) both correlate with treatment failure. Posttreatment recurrence only correlated with slower bacillary killing (P < .05).ConclusionsPatterns of early bacillary clearance matter. Static measurements such as month 2 sputum conversion and pharmacokinetic parameters such as CMAX/MIC and AUC0-24/MIC were predictive of treatment failure, but modeling of quantitative longitudinal data was required to assess the risk of recurrence. Pooled individual patient data analyses from larger datasets are needed to confirm these findings.

Desferrioxamine Supports Metabolic Function in Primary Human Macrophages Infected With Mycobacterium tuberculosis.

Tuberculosis is the single biggest infectious killer in the world and presents a major global health challenge. Antimicrobial therapy requires many months of multiple drugs and incidences of drug resistant tuberculosis continues to rise. Consequently, research is now focused on the development of therapies to support the function of infected immune cells. HIF1α-mediated induction of aerobic glycolysis is integral to the host macrophage response during infection with Mtb, as this promotes bacillary clearance. Some iron chelators have been shown to modulate cellular metabolism through the regulation of HIF1α. We examined if the iron chelator, desferrioxamine (DFX), could support the function of primary human macrophages infected with Mtb. Using RT-PCR, we found that DFX promoted the expression of key glycolytic enzymes in Mtb-infected primary human MDMs and human alveolar macrophages. Using Seahorse technology, we demonstrate that DFX enhances glycolytic metabolism in Mtb-stimulated human MDMs, while helping to enhance glycolysis during mitochondrial distress. Furthermore, the effect of DFX on glycolysis was not limited to Mtb infection as DFX also boosted glycolytic metabolism in uninfected and LPS-stimulated cells. DFX also supports innate immune function by inducing IL1β production in human macrophages during early infection with Mtb and upon stimulation with LPS. Moreover, using hypoxia, Western blot and ChIP-qPCR analyses, we show that DFX modulates IL1β levels in these cells in a HIF1α-mediated manner. Collectively, our data suggests that DFX exhibits potential to enhance immunometabolic responses and augment host immune function during early Mtb infection, in selected clinical settings.

Proteomic analysis of infected primary human leucocytes revealed PSTK as potential treatment-monitoring marker for active and latent tuberculosis.

Markers for monitoring clearance of Mycobacterium tuberculosis (Mtb) infection during anti-TB drug treatment could facilitate management of tuberculosis (TB) treatment, but are lacking. We aimed to screen for Mtb clearance markers from in-vitro-infected leucocytes and to evaluate these markers in followed-up active TB (ATB) patients and latent TB (LTBI) cases after anti-TB drug treatment. Extracellular proteins from primary leucocytes infected with each of the Mtb lineages (East-Asian, Indo-Oceanic, Euro-American and the laboratory strain H37Rv) were screened as possible clearance markers. Leucocytes infected with Staphylococcus aureus acted as controls. The proteomic analysis was performed using GeLC-MS/MS. Several quantitative and qualitative candidate clearance markers were found. These proteins were suppressed during the infection stage of all Mtb lineages and re-expressed after bacillary clearance. PSTK, FKBP8 and MGMT were common clearance markers among the four Mtb lineages in our model. Only PSTK was a potential clearance marker based on western blot validation analysis from culture supernatants. The PSTK marker was further validated with western blot analysis using serum samples (n = 6) from ATB patients and LTBI cases during anti-TB drug treatment, and from healthy controls (n = 3). Time-dependent increase of PSTK was found both in ATB and LTBI patients during the course of anti-TB drug treatment, but not in healthy controls. We have demonstrated that PSTK is a potential treatment-monitoring marker for active and latent TB.

Improved Mycobacterium tuberculosis clearance after the restoration of IFN-γ+ TNF-α+ CD4+ T cells: Impact of PD-1 inhibition in active tuberculosis patients.

Prolonged therapy, drug toxicity, noncompliance, immune suppression, and alarming emergence of drug resistance necessitate the search for therapeutic vaccine strategies for tuberculosis (TB). Such strategies ought to elicit not only IFN-γ, but polyfunctional response including TNF-α, which is essential for protective granuloma formation. Here, we investigated the impact of PD-1 inhibition in facilitating protective polyfunctional Tcells (PFTs), bacillary clearance, and disease resolution. We have observed PD-1 inhibition preferentially rescued the suppressed PFTs in active tuberculosis patients. In addition, polyfunctional cytokine milieu favored apoptosis of infected MDMs over necrosis with markedly reduced bacillary growth (≪CFU) in our in vitro monocyte-derived macrophages (MDMs) infection model. Furthermore, the animal study revealed a significant decline in the bacterial burden in the lungs and spleen of infected mice after in vivo administration of α-PD-1 along with antitubercular treatment. Our findings suggest that rescuing polyfunctional immune response by PD-1 inhibition works synergistically with antituberculosis chemotherapy to confer improved control over bacillary growth and dissemination. In summary, our data strongly indicate the therapeutic potential of α-PD-1 as adjunct immunotherapy that can rejuvenate suppressed host immunity and enhance the efficacy of candidate therapeutic vaccine(s).

Inhibiting PD-1 Restores Poly-Functional T Cell Response in Tuberculosis and Synergizes with Chemotherapy

Background: Prolonged anti-tubercular therapy associated with toxicity, non-compliance, immune suppression and alarming emergence of drug resistance necessitates the search for therapeutic vaccine strategies for tuberculosis (TB). Such strategies ought to elicit not only IFN-?, but poly-functional response including TNF-a, which is essential for protective granuloma formation. Here, we investigated the impact of PD-1 inhibition in facilitating protective poly-functional T cells (PFTs), bacillary clearance and disease resolution. The objectives were to i) determine the PFTs profile in active tuberculosis patients as compared to latent (PPD ) tuberculosis patients and healthy controls (PPD-), ii) understand the role of PD-1 pathway and Treg cells in the suppression of protective PFTs response and iii) validate the efficacy of a-PD-1 in vitro and in vivo in rescuing protective PFTs and disease resolution. Methods: Flow cytometry, real-time polymerase chain reaction, western blotting, in vitro monocyte derived macrophages (MDMs) infection studies, and in vivo mice infection studies. Findings: We observed reduced PFTs response in TB patients and their preferential rescue by blocking PD-1 due to higher expression of PD-1 on them. PFTs favored the apoptotic death of infected MDMs over necrosis and showed markedly reduced bacillary growth in MDMs. Animal study revealed significant decline in the bacterial burden in lungs and spleen of infected mice after in vivo administration of a-PD-1 in combination with anti-tubercular treatment. Interpretation: Our data strongly indicates the therapeutic potential of a-PD-1 as an adjunct immunotherapy which can rejuvenate suppressed host immunity and potentially improve drug potency of candidate therapeutic vaccine(s). Funding: Supported by Indian Council of Medical Research (ICMR) and Department of Biotechnology (DBT), Government of India. Declaration of Interest: The authors declare no competing financial interests. Ethical Approval: The study was approved by Institutional Ethics Committee.

Title: role of matrix metalloproteinase -9 in progression of tuberculous meningitis: a pilot study in patients at different stages of the disease.

BackgroundTBM (Tuberculous meningitis) is severe form of tuberculosis causing death of one third of the affected individuals or leaving two-third of the survivors disabled. MMP-9 (Matrix metalloproteinase-9) is produced by the central nervous system in a variety of inflammatory conditions and has a role in the breakdown of extracellular matrix and blood–brain barrier.MethodsIn this study, the levels of MMP-9 and its inhibitor, TIMP-1 (tissue inhibitor of metalloproteinases-1), were screened using zymography and reverse zymography in cerebrospinal fluid and serum of tuberculous meningitis patients at different stages of the disease. Further, role of MMP-9 as therapeutic target was studied in C6 glioma cells infected with Mycobacterium tuberculosis H37Rv. Cells were treated with dexamethasone or SB-3CT (specific inhibitor of MMP-9) in combination with conventional antitubercular drugs.ResultsMMP-9 levels in patients were increased as the disease progressed to advanced stages. The infection led to increased MMP-9 levels in C6 glioma cells and specific inhibition of MMP-9 by SB-3CT augmented bacillary clearance when used along with antitubercular drugs.ConclusionMMP-9 plays a prominent role in progression of tuberculous meningitis from initial to advanced stages. Increased levels of MMP-9 during advancement of the disease leads to degeneration of nervous tissue and blood brain barrier disruption. Hence, MMP-9 can be considered as a therapeutic target for efficient management of TBM and can be explored to inhibit further progression of the disease if used at an early stage.

Adjunctive role of MMP-9 inhibition along with conventional anti-tubercular drugs against experimental tuberculous meningitis.

Tuberculous meningitis (TBM) is an outcome of neuroinflammatory degeneration caused due to Mycobacterium tuberculosis infection and leads to death or neurological disabilities in the affected individuals. It causes the highest morbidity and mortality amongst all forms of tuberculosis. Matrix metalloproteinase-9 levels increase and cause inflammatory destruction during progression of the disease. Although corticosteroids are usually given as an adjuvant therapy to overcome these complications, treatment outcome is contradictory. This study was designed to evaluate whether specific inhibition of MMP-9 can be beneficial in management of the disease. MMP-9 levels were inhibited using SB-3CT or dexamethasone along with conventional drugs for treatment of tuberculous meningitis. Both SB-3CT and dexamethasone decreased the elevated levels of MMP-9 in sera and tissues of the infected mice. However, dexamethasone administration had an inhibitory effect on bacillary clearance, while SB-3CT potentiated the bacillary clearance, suggesting that MMP-9, if specifically inhibited, can be beneficial in the management of TBM.

Adjunctive Phosphodiesterase-4 Inhibitor Therapy Improves Antibiotic Response to Pulmonary Tuberculosis in a Rabbit Model

ObjectivesAdjunctive host-directed therapy is emerging as a new potential approach to improve the outcome of conventional antimicrobial treatment for tuberculosis (TB). We tested the ability of a phosphodiesterase-4 inhibitor (PDE4i) CC-11050, co-administered with the first-line anti-TB drug isoniazid (INH), to accelerate bacillary killing and reduce chronic inflammation in the lungs of rabbits with experimental Mycobacterium tuberculosis (Mtb) infection. MethodsA rabbit model of pulmonary TB that recapitulates the pathologic manifestations seen in humans was used. Rabbits were infected with virulent Mtb by aerosol exposure and treated for eight weeks with INH with or without CC-11050, starting at four weeks post infection. The effect of CC-11050 treatment on disease severity, pathology, bacillary load, T cell proliferation and global lung transcriptome profiles were analyzed. ResultsSignificant improvement in bacillary clearance and reduced lung pathology and fibrosis were noted in the rabbits treated for eight weeks with INH+CC-11050, compared to those treated with INH or CC-11050 only. In addition, expression of host genes associated with tissue remodeling, tumor necrosis factor alpha (TNF-α) regulation, macrophage activation and lung inflammation networks was dampened in CC-11050-treated, compared to the untreated rabbits. ConclusionsAdjunctive CC-11050 therapy significantly improves the response of rabbits with experimental pulmonary TB to INH treatment. We propose that CC-11050 may be a promising candidate for host directed therapy of patients with pulmonary TB, reducing the duration and improving clinical outcome of antibiotic treatment.

Addition of immunotherapy to chemotherapy in pediatric borderline leprosy: a clinical evaluation

Background: Immunotherapy with BCG, BCG + M. leprae, ICRC, MIP has been observed to be effective in improving the treatment in adulthood leprosy. Clinical improvement with accelerated bacterial clearance and histological up grading using MIP vaccine as an immunotherapeutic with standard WHO-MDT has been reported in adult cases with high bacillary load. However, there is lack of information in borderline pediatric leprosy which is characterized by a state of shifting immunity and would therefore be ideally suited to such observations. This pilot study is originated from involvement of our Institute in a trial aimed for improving the therapy of pediatric borderline leprosy by using combined immunotherapy and chemotherapy. The study was aimed to assess the clinical improvement by adding immunotherapy (MIP vaccine) with chemotherapy (WHO -MDT) in pediatric borderline leprosy. Methods: A total of 98 new pediatric borderline leprosy cases were included, after formal written consent, detailed clinical examination. A non-randomized trial was conducted. In this study, patients attending the OPD were serially recruited in two treatment groups. In group-1 (Mw vaccine plus WHO- MDT) 50 pediatric cases and in Group-2 (MDT only), 48 pediatric borderline cases were recruited. The therapeutic regimens containing MIP vaccine was injected intra-dermally at the start of therapy and every six months in addition to chemotherapy (WHO- MDT) in group 1 pediatric patient and chemotherapy only (WHO- MDT) were given in group-2 pediatric cases and effect was observed on clinical parameters (size of lesions, erythema, infiltration, sensory improvement) and bacillary clearance. Results: Addition of immunotherapy resulted in faster clinical recovery from disease, faster bacillary clearance in pediatric borderline leprosy cases. Conclusions: This study shows the usefulness of adding immunotherapy (MIP vaccine) to chemotherapy (WHO- MDT) in pediatric borderline leprosy for faster clinical improvement.

Kinetics of Mycobacterium tuberculosis-specific IFN-γ responses and sputum bacillary clearance in HIV-infected adults during treatment of pulmonary tuberculosis

SummaryIn HIV-uninfected adults with pulmonary tuberculosis (TB), anti-TB treatment is associated with changes in Mycobacterium tuberculosis (Mtb)-specific immune responses, which correlate with sputum bacillary load. It is unclear if this occurs in HIV-infected TB patients. We investigated changes in Mtb-specific immune responses and sputum bacillary clearance during anti-TB treatment in HIV-infected and HIV-uninfected adults with pulmonary TB. Sputum bacillary load was assessed by smear microscopy and culture. Mtb-specific IFN-γ secreting peripheral blood mononuclear cells were enumerated using an ELISPOT assay following stimulation with PPD, ESAT-6 and CFP-10. The baseline frequency of Mtb-specific IFN-γ secreting cells was lower in HIV-infected than HIV-uninfected patients (median PPD 32 vs. 104 Spot Forming Units (SFU), p = 0.05; CFP-10 19 vs. 74 SFU, p = 0.01). ESAT-6-specific IFN-γ secreting cells and sputum bacillary load declined progressively during treatment in both HIV-infected and HIV-uninfected patients. HIV infection did not influence the 2-month sputum culture conversion rate (Odds Ratio 0.89, p = 0.95). These findings suggest that changes in ESAT-6-specific immune responses during anti-TB treatment correspond with changes in sputum bacillary load irrespective of host HIV infection status. The utility of Mtb-specific IFN-γ responses as a proxy measure of treatment response in HIV-infected TB patients warrants further evaluation in other settings.

Chemotherapeutic efficacy of thioridazine as an adjunct drug in a murine model of latent tuberculosis

Thioridazine, a potent phenothiazine compound was evaluated for its chemotherapeutic efficacy against experiment model of tuberculosis. Thioridazine potentiated the activities of both isoniazid and rifampicin (>1 log CFU reduction) against the in vitro latent Mycobacterium tuberculosis bacilli. Further, a murine model of latent tuberculosis was used and the standard 9-month isoniazid and 4-month rifampicin regimen along with thioridazine as an adjunct drug were evaluated. Thioridazine led to an accelerated clearance of bacilli with both the regimen, thereby leading to completion of therapy much earlier than the standard end-point. In the case of 9-month isoniazid regimen, when thioridazine was used along with isoniazid as an adjunct drug, complete clearance was observed as early as 24 weeks as compared to the 36 week standard isoniazid monotherapy regimen. Also, in the 4-month rifampicin regimen, it was observed that the bacillary clearance was more robust when rifampicin was used along with thioridazine (>3 log CFU reduction) than rifampicin alone (>2 log CFU reduction). Our findings implicate that thioridazine, when used as an adjunct drug along with isoniazid or rifampicin has the potential to augment their chemotherapeutic efficacy against experimental latency.

Relationship between host Mycobacterium tuberculosis-specific CD4 T cell responses and sputum bacillary clearance during early anti-tuberculosis treatment

Event Abstract Back to Event Relationship between host Mycobacterium tuberculosis-specific CD4 T cell responses and sputum bacillary clearance during early anti-tuberculosis treatment David T. Mzinza1*, Derek Sloan1, 2, Katalin Wilkinson3, Robert Wilkinson3, Gerry Davies1, 2, Robert Heyderman1 and Henry Mwandumba1, 2 1 Malawi Liverpool Wellcome Trust Clinical Research Programme, Malawi 2 University of Liverpool, United Kingdom 3 University of Cape Town, South Africa Tuberculosis treatment is associated with changes in host Mycobacterium tuberculosis (Mtb) antigen-specific T cell responses. It is unclear how these changes relate to treatment outcomes. We investigated the relationship between Mtb-specific immune response, quantitative bacteriology and clinical outcomes of treatment in sputum smear-positive adult TB patients receiving anti-TB treatment at Queen Elizabeth Central Hospital, Malawi. Peripheral blood and sputum samples for PBMC isolation and serial mycobacterial culture respectively were collected from 45 patients irrespective of their HIV status before and after 56 days of treatment. Mtb-specific immune responses were assessed by quantification of IFN-γ secreting T cells in response to CFP-10 and ESAT-6 using an ELISPOT assay. Mtb clearance from sputum was evaluated by mycobacteria growth indicator tube culture system. Results are given as median and differences were considered statistically significant if P≤0.05. Preliminary results show a difference in the rate of bacillary clearance and host responses with respect to HIV. 71% of HIV-uninfected and 50% of HIV-infected patients were culture negative by 2 months of treatment. Similarly, the number of IFN- secreting T cells reduced during treatment in HIV-uninfected patients (median change -60 SFU/106 PBMC, IQR 4-204), while there was a smaller reduction in HIV-infected patients (median change -14 SFU/106 PBMC, IQR 0-51) (Mann-Whitney U-test p = 0.085). Preliminary findings suggest an association between magnitude of host Mtb-specific T cell responses and mycobacterial load. We plan to analyze the data further by doing regression modeling to investigate the relationship between immunological parameters, HIV status and bacillary clearance. Keywords: Tuberculosis, T cell, IFN- γ, CFP-10, ESAT-6 Conference: 15th International Congress of Immunology (ICI), Milan, Italy, 22 Aug - 27 Aug, 2013. Presentation Type: Abstract Topic: Host-pathogen interactions Citation: Mzinza DT, Sloan D, Wilkinson K, Wilkinson R, Davies G, Heyderman R and Mwandumba H (2013). Relationship between host Mycobacterium tuberculosis-specific CD4 T cell responses and sputum bacillary clearance during early anti-tuberculosis treatment. Front. Immunol. Conference Abstract: 15th International Congress of Immunology (ICI). doi: 10.3389/conf.fimmu.2013.02.00095 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 09 Mar 2013; Published Online: 22 Aug 2013. * Correspondence: Mr. David T Mzinza, Malawi Liverpool Wellcome Trust Clinical Research Programme, Blantyre, Malawi, dmzinza@mlw.mw Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers David T Mzinza Derek Sloan Katalin Wilkinson Robert Wilkinson Gerry Davies Robert Heyderman Henry Mwandumba Google David T Mzinza Derek Sloan Katalin Wilkinson Robert Wilkinson Gerry Davies Robert Heyderman Henry Mwandumba Google Scholar David T Mzinza Derek Sloan Katalin Wilkinson Robert Wilkinson Gerry Davies Robert Heyderman Henry Mwandumba PubMed David T Mzinza Derek Sloan Katalin Wilkinson Robert Wilkinson Gerry Davies Robert Heyderman Henry Mwandumba Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Spontaneous Latency in a Rabbit Model of Pulmonary Tuberculosis

Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), is an exquisitely adapted human pathogen capable of surviving for decades in the lungs of immune-competent individuals in the absence of disease. The World Health Organization estimates that 2 billion people have latent TB infection (LTBI), defined by a positive immunological response to Mtb antigens, with no clinical signs of disease. A better understanding of host and pathogen determinants of LTBI and subsequent reactivation would benefit TB control efforts. Animal models of LTBI have been hampered generally by an inability to achieve complete bacillary clearance. Herein, we have characterized a rabbit model of LTBI in which, similar to most humans, complete clearance of pulmonary Mtb infection and pathological characteristics occurs spontaneously. The evidence that Mtb-CDC1551-infected rabbits achieve LTBI, rather than sterilization, is based on the ability of the bacilli to be reactivated after immune suppression. These rabbits showed early activation of T cells and macrophages and an early peak in the TNFα level, which decreased in association with clearance of bacilli from the lungs. In the absence of sustained tumor necrosis factor-α production, no necrosis was seen in the evolving lung granulomas. In addition, bacillary control was associated with down-regulation of several metalloprotease genes and an absence of lung fibrosis. This model will be used to characterize molecular markers of protective immunity and reactivation.

Phosphodiesterase-4 Inhibition Alters Gene Expression and Improves Isoniazid – Mediated Clearance of Mycobacterium tuberculosis in Rabbit Lungs

Tuberculosis (TB) treatment is hampered by the long duration of antibiotic therapy required to achieve cure. This indolent response has been partly attributed to the ability of subpopulations of less metabolically active Mycobacterium tuberculosis (Mtb) to withstand killing by current anti-TB drugs. We have used immune modulation with a phosphodiesterase-4 (PDE4) inhibitor, CC-3052, that reduces tumor necrosis factor alpha (TNF-α) production by increasing intracellular cAMP in macrophages, to examine the crosstalk between host and pathogen in rabbits with pulmonary TB during treatment with isoniazid (INH). Based on DNA microarray, changes in host gene expression during CC-3052 treatment of Mtb infected rabbits support a link between PDE4 inhibition and specific down-regulation of the innate immune response. The overall pattern of host gene expression in the lungs of infected rabbits treated with CC-3052, compared to untreated rabbits, was similar to that described in vitro in resting Mtb infected macrophages, suggesting suboptimal macrophage activation. These alterations in host immunity were associated with corresponding down-regulation of a number of Mtb genes that have been associated with a metabolic shift towards dormancy. Moreover, treatment with CC-3052 and INH resulted in reduced expression of those genes associated with the bacterial response to INH. Importantly, CC-3052 treatment of infected rabbits was associated with reduced ability of Mtb to withstand INH killing, shown by improved bacillary clearance, from the lungs of co-treated animals compared to rabbits treated with INH alone. The results of our study suggest that changes in Mtb gene expression, in response to changes in the host immune response, can alter the responsiveness of the bacteria to antimicrobial agents. These findings provide a basis for exploring the potential use of adjunctive immune modulation with PDE4 inhibitors to enhance the efficacy of existing anti-TB treatment.

Phosphodiesterase 4 Inhibition Reduces Innate Immunity and Improves Isoniazid Clearance of Mycobacterium tuberculosis in the Lungs of Infected Mice

Tuberculosis (TB) caused by Mycobacterium tuberculosis (Mtb) is one of the leading infectious disease causes of morbidity and mortality worldwide. Though current antibiotic regimens can cure the disease, treatment requires at least six months of drug therapy. One reason for the long duration of therapy is that the currently available TB drugs were selected for their ability to kill replicating organisms and are less effective against subpopulations of non-replicating persistent bacilli. Evidence from in vitro models of Mtb growth and mouse infection studies suggests that host immunity may provide some of the environmental cues that drive Mtb towards non-replicating persistence. We hypothesized that selective modulation of the host immune response to modify the environmental pressure on the bacilli may result in better bacterial clearance during TB treatment. For this proof of principal study, we compared bacillary clearance from the lungs of Mtb-infected mice treated with the anti-TB drug isoniazid (INH) in the presence and absence of an immunomodulatory phosphodiesterase 4 inhibitor (PDE4i), CC-3052. The effects of CC-3052 on host global gene expression, induction of cytokines, and T cell activation in the lungs of infected mice were evaluated. We show that CC-3052 modulates the innate immune response without causing generalized immune suppression. Immune modulation combined with INH treatment improved bacillary clearance and resulted in smaller granulomas and less lung pathology, compared to treatment with INH alone. This novel strategy of combining anti-TB drugs with an immune modulating molecule, if applied appropriately to patients, may shorten the duration of TB treatment and improve clinical outcome.