The heme oxygenase-1 metalloporphyrin inhibitor stannsoporfin enhances the bactericidal activity of a novel regimen for multidrug-resistant tuberculosis in a murine model

Multidrug-resistant (MDR) Mycobacterium tuberculosis (Mtb) poses significant challenges to global tuberculosis (TB) control efforts. Host-directed therapies (HDTs) offer a novel approach to TB treatment by enhancing immune-mediated clearance of Mtb. Prior preclinical studies found that the inhibition of heme oxygenase-1 (HO-1), an enzyme involved in heme metabolism, with tin-protoporphyrin IX (SnPP) significantly reduced mouse lung bacillary burden when co-administered with the first-line antitubercular regimen. Here, we evaluated the adjunctive HDT activity of a novel HO-1 inhibitor, stannsoporfin (SnMP), in combination with a novel MDR-TB regimen comprising a next-generation diarylquinoline, TBAJ-876 (S), pretomanid (Pa), and a new oxazolidinone, TBI-223 (O) (collectively, SPaO), in Mtb-infected BALB/c mice. After 4 weeks of treatment, SPaO + SnMP 5mg/kg reduced mean lung bacillary burden by an additional 0.69 log10 (P = 0.01) relative to SPaO alone. As early as 2 weeks post-treatment initiation, SnMP adjunctive therapy differentially altered the expression of pro-inflammatory cytokine genes and CD38, a marker of M1 macrophages. Next, we evaluated the sterilizing potential of SnMP adjunctive therapy in a mouse model of microbiological relapse. After 6 weeks of treatment, SPaO + SnMP 10mg/kg reduced lung bacterial burdens to 0.71 ± 0.23 log10 colony-forming units (CFUs), a 0.78 log-fold greater decrease in lung CFU compared to SpaO alone (P = 0.005). However, adjunctive SnMP did not reduce microbiological relapse rates after 5 or 6 weeks of treatment. SnMP was well tolerated and did not significantly alter gross or histological lung pathology. SnMP is a promising HDT candidate requiring further study in combination with regimens for drug-resistant TB.

A SARS-CoV-2 RBD vaccine fused to the chemokine MIP-3α elicits sustained murine antibody responses over 12 months and enhanced lung T-cell responses

Background

Previous studies have demonstrated enhanced efficacy of vaccine formulations that incorporate the chemokine macrophage inflammatory protein 3α (MIP-3α) to direct vaccine antigens to immature dendritic cells. To address the reduction in vaccine efficacy associated with a mutation in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mutants, we have examined the ability of receptor-binding domain vaccines incorporating MIP-3α to sustain higher concentrations of antibody when administered intramuscularly (IM) and to more effectively elicit lung T-cell responses when administered intranasally (IN).

Methods

BALB/c mice aged 6-8 weeks were immunized intramuscularly or intranasally with DNA vaccine constructs consisting of the SARS-CoV-2 receptor-binding domain alone or fused to the chemokine MIP-3α. In a small-scale (n = 3/group) experiment, mice immunized IM with electroporation were followed up for serum antibody concentrations over a period of 1 year and for bronchoalveolar antibody levels at the termination of the study. Following IN immunization with unencapsulated plasmid DNA (n = 6/group), mice were evaluated at 11 weeks for serum antibody concentrations, quantities of T cells in the lungs, and IFN-γ- and TNF-α-expressing antigen-specific T cells in the lungs and spleen.

Results

At 12 months postprimary vaccination, recipients of the IM vaccine incorporating MIP-3α had significantly, approximately threefold, higher serum antibody concentrations than recipients of the vaccine not incorporating MIP-3α. The area-under-the-curve analyses of the 12-month observation interval demonstrated significantly greater antibody concentrations over time in recipients of the MIP-3α vaccine formulation. At 12 months postprimary immunization, only recipients of the fusion vaccine had concentrations of serum-neutralizing activity deemed to be effective. After intranasal immunization, only recipients of the MIP-3α vaccine formulations developed T-cell responses in the lungs significantly above those of PBS controls. Low levels of serum antibody responses were obtained following IN immunization.

Conclusion

Although requiring separate IM and IN immunizations for optimal immunization, incorporating MIP-3α in a SARS-CoV-2 vaccine construct demonstrated the potential of a stable and easily produced vaccine formulation to provide the extended antibody and T-cell responses that may be required for protection in the setting of emerging SARS-CoV-2 variants. Without electroporation, simple, uncoated plasmid DNA incorporating MIP-3α administered intranasally elicited lung T-cell responses.

The heme oxygenase-1 metalloporphyrin inhibitor stannsoporfin enhances the bactericidal activity of a novel regimen for multidrug-resistant tuberculosis in a murine model

Multidrug-resistant (MDR) Mycobacterium tuberculosis (Mtb) poses significant challenges to global tuberculosis (TB) control efforts. Host-directed therapies (HDT) offer a novel approach for TB treatment by enhancing immune-mediated clearance of Mtb. Prior preclinical studies found that inhibition of heme oxygenase-1 (HO-1), an enzyme involved in heme metabolism, with tin-protoporphyrin IX (SnPP) significantly reduced mouse lung bacillary burden when co-administered with the first-line antitubercular regimen. Here we evaluated the adjunctive HDT activity of a novel HO-1 inhibitor, stannsoporfin (SnMP), in combination with a novel MDR-TB regimen comprising a next-generation diarylquinoline, TBAJ-876 (S), pretomanid (Pa), and a new oxazolidinone, TBI-223 (O) (collectively, SPaO) in Mtb-infected BALB/c mice. After 4 weeks of treatment, SPaO + SnMP 5 mg/kg reduced mean lung bacillary burden by an additional 0.69 log10 (P=0.01) relative to SPaO alone. As early as 2 weeks post-treatment initiation, SnMP adjunctive therapy differentially altered the expression of pro-inflammatory cytokine genes, and CD38, a marker of M1 macrophages. Next, we evaluated the sterilizing potential of SnMP adjunctive therapy in a mouse model of microbiological relapse. After 6 weeks of treatment, SPaO + SnMP 10 mg/kg reduced lung bacterial burdens to 0.71 ± 0.23 log10 CFU, a 0.78 log-fold greater decrease in lung CFU compared to SpaO alone (P=0.005). However, adjunctive SnMP did not reduce microbiological relapse rates after 5 or 6 weeks of treatment. SnMP was well tolerated and did not significantly alter gross or histological lung pathology. SnMP is a promising HDT candidate requiring further study in combination with regimens for drug-resistant TB.

HIV/Tuberculosis Coinfection in Pregnancy and the Postpartum Period

The convergence of Human Immunodeficiency Virus (HIV) and tuberculosis (TB) represents a considerable global public health challenge. The concurrent infection of HIV and TB in pregnant women not only intensifies the transmission of HIV from mother to fetus but also engenders adverse outcomes for maternal health, pregnancy, and infant well-being, necessitating the implementation of integrated strategies to effectively address and manage both diseases. In this article, we review the pathophysiology, clinical presentation, treatment, and management of HIV/TB coinfection during pregnancy, the postpartum period, and lactation and highlight the differences compared to the general population.

Functional Whole Genome Screen of Nutrient-Starved Mycobacterium tuberculosis Identifies Genes Involved in Rifampin Tolerance

Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), poses a global health challenge and is responsible for over a million deaths each year. Current treatment is lengthy and complex, and new, abbreviated regimens are urgently needed. Mtb adapts to nutrient starvation, a condition experienced during host infection, by shifting its metabolism and becoming tolerant to the killing activity of bactericidal antibiotics. An improved understanding of the mechanisms mediating antibiotic tolerance in Mtb can serve as the basis for developing more effective therapies. We performed a forward genetic screen to identify candidate Mtb genes involved in tolerance to the two key first-line antibiotics, rifampin and isoniazid, under nutrient-rich and nutrient-starved conditions. In nutrient-rich conditions, we found 220 mutants with differential antibiotic susceptibility (218 in the rifampin screen and 2 in the isoniazid screen). Following Mtb adaptation to nutrient starvation, 82 mutants showed differential antibiotic susceptibility (80 in the rifampin screen and 2 in the isoniazid screen). Using targeted mutagenesis, we validated the rifampin-hypersusceptible phenotype under nutrient starvation in Mtb mutants lacking the following genes: ercc3, moeA1, rv0049, and rv2179c. These findings shed light on potential therapeutic targets, which could help shorten the duration and complexity of antitubercular regimens.

Combination of a MIP3α-antigen fusion therapeutic DNA vaccine with treatments of IFNα and 5-Aza-2'Deoxycytidine enhances activated effector CD8+ T cells expressing CD11c in the B16F10 melanoma model

Previous studies in the B16F10 mouse melanoma model have demonstrated that combining a DNA vaccine comprised of regions of gp100 and tyrosinase-related protein 2 fused to Macrophage-inflammatory protein 3-alpha (MIP3α) with recombinant Interferon alpha (IFN) and 5-Aza-2'-Deoxycytidine (5Aza) treatments resulted in significantly greater anti-tumor activity and immunogenicity in the tumor microenvironment (TME). This brief report details that the combination of vaccine with treatments IFN and 5Aza results in both the upregulation of genes expressing CD11c-interacting proteins and an increase in the TME of a distinct CD11c+ CD8+ T cell population. This cell population correlates with tumor size, is primarily comprised of effector or effector memory T cells, and has a more robust response to ex vivo stimulation as compared to CD11c- CD8+ T cells as measured by surface activation markers 4-1BB (CD137) and KLRG1 (Killer cell lectin-like receptor G1) and intracellular IFNγ production. In conclusion, this combination therapy results in greater presence of highly active effector CD8+ T-cells expressing CD11c in the TME that correlate with and are likely primary contributors to treatment efficacy.

Functional whole genome screen of nutrient-starved Mycobacterium tuberculosis identifies genes involved in antibiotic tolerance

Mycobacterium tuberculosis ( Mtb ), the causative agent of tuberculosis (TB), poses a global health challenge and is responsible for over a million deaths each year. Current treatment is lengthy and complex, and new, abbreviated regimens are urgently needed. Mtb adapts to nutrient starvation, a condition experienced during host infection, by shifting its metabolism and becoming tolerant to the killing activity of bactericidal antibiotics. An improved understanding of the mechanisms mediating antibiotic tolerance in Mtb can serve as the basis for developing more effective therapies. We performed a forward genetic screen to identify candidate Mtb genes involved in tolerance to the two key first-line antibiotics, rifampin and isoniazid, under nutrient-rich and nutrient-starved conditions. In nutrient-rich conditions, we found 220 mutants with differential antibiotic susceptibility (218 in the rifampin screen and 2 in the isoniazid screen). Following Mtb adaptation to nutrient starvation, 82 mutants showed differential antibiotic susceptibility (80 in the rifampin screen and 2 in the isoniazid screen). Using targeted mutagenesis, we validated the rifampin-hypersusceptible phenotype under nutrient starvation in Mtb mutants lacking the following genes: ercc3 , moeA1 , rv0049 , and rv2179c . These findings shed light on potential therapeutic targets, which could help shorten the duration and complexity of antitubercular regimens.

Importance

Treatment of Mtb infection requires a long course of combination antibiotics, likely due to subpopulations of tolerant bacteria exhibiting decreased susceptibility to antibiotics. Identifying and characterizing the genetic pathways involved in antibiotic tolerance is expected to yield therapeutic targets for the development of novel TB treatment-shortening regimens.

Metabolic switching and cell wall remodelling of Mycobacterium tuberculosis during bone tuberculosis

OBJECTIVES

Bone tuberculosis (TB) is the third most common types of extrapulmonary tuberculosis. It is critical to understand mycobacterial adaptive strategies within bone lesions to identify mycobacterial factors that may have role in disease pathogenesis.

METHODS

Whole genome microarray was used to characterize the in-vivo transcriptome of Mycobacterium tuberculosis (M.tb) within bone TB specimens. Mycobacterial virulent proteins were identified by bioinformatic software. An in vitro osteoblast cell line model was used to study the role of these proteins in bone TB pathogenesis.

RESULTS

914 mycobacterial genes were significantly overexpressed and 1688 were repressed in bone TB specimens. Pathway analysis of differentially expressed genes demonstrated a non-replicative and hypometabolic state of M.tb, reinforcement of the mycobacterial cell wall and induction of DNA damage repair responses, suggesting possible survival strategies of M.tb within bone. Bioinformatics mining of microarray data led to identification of five virulence proteins. The genes encoding these proteins were also upregulated in the in vitro MC3T3 osteoblast cell line model of bone TB. Further, exposure of osteoblast cells to two of these virulence proteins (Rv1046c and Rv3663c) significantly inhibited osteoblast differentiation.

CONCLUSION

M.tb alters its transcriptome to establish infection in bone by upregulating certain virulence genes which play a key role in disturbing bone homeostasis.

IFNα and 5-Aza-2'-deoxycytidine combined with a dendritic-cell targeting DNA vaccine alter tumor immune cell infiltration in the B16F10 melanoma model

Introduction

DNA vaccines containing a fusion of the gene encoding chemokine MIP-3α (CCL20), the ligand for CCR6 on immature dendritic cells (DCs), to melanoma-associated antigen genes have enhanced anti-tumor immunity and efficacy compared to those lacking the chemokine gene. Previous work has shown that type-I interferon (IFNα or IFN) and 5-Aza-2'-deoxycytidine (5Aza) significantly enhance the therapeutic benefit of DNA vaccines as measured by reduced tumor burden and improved mouse survival.

Methods

Here, we explored mouse intratumoral immune correlates underlying the therapeutic benefit of this combination regimen (vaccine, IFN, and 5Aza) as compared to vaccine alone and IFN and 5Aza without vaccine, focusing on chemokine mRNA expression by qRT-PCR and inflammatory cellular infiltration into the tumor microenvironment (TME) by flow cytometry and immunohistochemistry (IHC).

Results

The combination group significantly upregulated intratumoral mRNA expression of key immune infiltration chemokines XCL1 and CXCL10. Flow cytometric analyses of tumor suspensions exhibited greater tumor infiltration of CD8+ DCs, CCR7+ DCs, and NK cells in the combination group, as well as reduced levels of myeloid-derived suppressor cells (MDSCs) in vaccinated groups. The mice receiving combination therapy also had greater proportions of effector/memory T-cells (Tem), in addition to showing an enhanced infiltration of Tem and central memory CD8+ T-cells, (Tcm). Tem and Tcm populations both correlated with smaller tumor size. Immunohistochemical analysis of tumors confirmed that CD8+ cells were more abundant overall and especially in the tumor parenchyma with combination therapy.

Discussion

Efficient targeting of antigen to immature DCs with a chemokine-fusion vaccine offers a potential alternative approach to classic and dendritic cell-based vaccines. Combining this approach with IFNα and 5Aza treatments significantly improved vaccine efficacy. This treatment creates an environment of increased inflammatory chemokines that facilitates the trafficking of CD8+ DCs, NK cells, and CD8+ T-cells, especially memory cells, while reducing the number of MDSCs. Importantly, in the combination group, CD8+ cells were more able to penetrate the tumor mass in addition to being more numerous. Further analysis of the pathways engaged by our combination therapy is expected to provide additional insights into melanoma pathogenesis and facilitate the development of novel treatment strategies.

An intranasal stringent response vaccine targeting dendritic cells as a novel adjunctive therapy against tuberculosis

Lengthy tuberculosis (TB) treatment is required to overcome the ability of a subpopulation of persistent Mycobacterium tuberculosis (Mtb) to remain in a non-replicating, antibiotic-tolerant state characterized by metabolic remodeling, including induction of the Rel_Mtb-mediated stringent response. We developed a novel therapeutic DNA vaccine containing a fusion of the rel_Mtb gene with the gene encoding the immature dendritic cell-targeting chemokine, MIP-3α/CCL20. To augment mucosal immune responses, intranasal delivery was also evaluated. We found that intramuscular delivery of the MIP-3α/rel_Mtb (fusion) vaccine or intranasal delivery of the rel_Mtb (non-fusion) vaccine potentiate isoniazid activity more than intramuscular delivery of the DNA vaccine expressing rel_Mtb alone in a chronic TB mouse model (absolute reduction of Mtb burden: 0.63 log₁₀ and 0.5 log₁₀ colony-forming units, respectively; P=0.0002 and P=0.0052), inducing pronounced Mtb-protective immune signatures. The combined approach involving intranasal delivery of the DNA MIP-3α/rel_Mtb fusion vaccine demonstrated the greatest mycobactericidal activity together with isoniazid when compared to each approach alone (absolute reduction of Mtb burden: 1.13 log₁₀, when compared to the intramuscular vaccine targeting rel_Mtb alone; P<0.0001), as well as robust systemic and local Th1 and Th17 responses. This DNA vaccination strategy may be a promising adjunctive approach combined with standard therapy to shorten curative TB treatment, and also serves as proof of concept for treating other chronic bacterial infections.

Abstract LB531: The addition of IFNα and 5-Aza-2'deoxycytidine treatments to a dendritic cell-targeting DNA vaccine enhance the expression of Th1-related genes and the infiltration of CD11c+ CD8+ T-cells

Background: DNA vaccines fusing the chemokine MIP-3α (CCL20), which binds to CCR6 on immature dendritic cells (DCs), to melanoma-associated antigens have enhanced anti-tumor immunity and efficacy compared to vaccines lacking the chemokine. To further enhance the therapeutic effects of the vaccine, our laboratory has added type-I interferon (IFNα) and 5-Aza-2’-deoxycitidine (5Aza) to the therapy. Here, we report that the efficacy seen in this combination results in deeper intratumoral penetration of CD8+ cells, enhanced expression of Th1 t-cell related genes, and increased influx of CD11c+ CD8+ T-cells.

Methods: Beginning on day five post-transplantation of B16F10 melanoma, the vaccine was administered intramuscularly (i.m.) by electroporation. CpG adjuvant was given two days later. 5Aza was given intraperitoneally at 1mg/kg and IFNα therapy intratumorally as noted. Tumor sizes over time were assessed. For immunohistochemistry (IHC), formalin-fixed tumors were processed, embedded, cut into slides, and stained for CD8 by on-site core facility. Stained slides were analyzed by a pathologist in a blinded fashion. Tumor lysate gene expression levels and tumor-infiltrating lymphocytes (TILs) were assessed by qRT-PCR and flow cytometry respectively.

Results: Previous work has shown that the combination of IFNα, 5Aza, and vaccine led to significantly reduced tumor burden and overall increases in mouse survival dependent upon all three components. We have since discovered by IHC that CD8+ cells are more abundant and penetrate further into the tumor with the combination treatment compared to vaccine or therapeutics alone. The tumor immune genetic profile shows broad increases of expression for genes responsible for T-cell activation, efficacy, and trafficking. Of note, the combination therapy doubled the proportion of CD8+ T cells in the tumor microenvironment expressing CD11c (p = 0.027), and the proportions of these cells correlated more strongly to tumor size than do the proportions of CD11c- CD8+ T-cells (r2=0.51; p&lt;0.0001 compared to r2=0.19; p = 0.02).

Conclusions: Efficient targeting of antigen to immature dendritic cells with a chemokine-fusion vaccine offers a potential alternative approach to classic and dendritic cell-based vaccines. Combining this approach with IFNα and 5Aza treatments significantly improved vaccine efficacy. This treatment creates a complex intratumoral network that facilitates T-cell trafficking, Th1-associated gene expression, and an increase of CD11c+CD8+ T-cells, which have recently been shown in the literature to have greater anti-tumor activity than CD11c- T-cells. Further analysis of the pathways engaged by our treatment protocol should provide insights into how to more efficiently activate this recently described, highly effective T cell population.

Citation Format: James T. Gordy, Kaitlyn Comstock, Avinaash K. Sandhu, Yinan Hui, Styliani Karanika, Joel Sunshine, Petros C. Karakousis, Richard B. Markham. The addition of IFNα and 5-Aza-2'deoxycytidine treatments to a dendritic cell-targeting DNA vaccine enhance the expression of Th1-related genes and the infiltration of CD11c+ CD8+ T-cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr LB531.

Association of Lipid Levels With COVID-19 Infection, Disease Severity and Mortality: A Systematic Review and Meta-Analysis

Background

Coronavirus disease 2019 (COVID-19) ranges from asymptomatic infection to severe illness. Cholesterol in the host cell plasma membrane plays an important role in the SARS-CoV-2 virus entry into cells. Serum lipids, especially low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C), are in constant interaction with the lipid rafts in the host cell membranes and can modify the interaction of virus with host cells and the resultant disease severity. Recent studies on serum lipid levels and COVID-19 disease severity lack consistency.

Objectives

Our systematic review and meta-analysis compared the serum levels of total cholesterol (TC), LDL-C, HDL-C, and triglycerides (TG) between (1) COVID-19 patients vs. healthy controls; (2) severe vs. non-severe COVID-19 disease; (3) deceased vs. surviving COVID-19 patients.

Methods

PRISMA guidelines were followed. We included peer-reviewed articles on observational (case-control and cohort) studies from PubMed and Embase published from the database inception until September 1, 2021. We used random-effects meta-analysis for pooled mean-differences (pMD) in lipid levels (mg/dL) for the above groups.

Results

Among 441 articles identified, 29 articles (26 retrospective and 3 prospective cohorts), with an aggregate of 256,721 participants, were included. COVID-19 patients had lower TC (pMD-14.9, 95%CI-21.6 to −8.3) and HDL-C (pMD-6.9, 95%CI −10.2 to −3.7) levels (mg/dL). Severe COVID-19 patients had lower TC (pMD-10.4, 95%CI −18.7 to −2.2), LDL-C (pMD-4.4, 95%CI −8.4 to −0.42), and HDL-C (pMD-4.4, 95%CI −6.9 to −1.8) at admission compared to patients with non-severe disease. Deceased patients had lower TC (pMD-14.9, 95%CI −21.6 to −8.3), LDL-C (pMD-10.6, 95%CI −16.5 to −4.6) and HDL-C (pMD-2.5, 95%CI −3.9 to −1.0) at admission. TG levels did not differ based on COVID-19 severity or mortality. No publication bias was noted.

Conclusion

We demonstrated lower lipid levels in patients with COVID-19 infection and an association with disease severity and mortality. Their potential role in COVID-19 pathogenesis and their utility as prognostic factors require further investigation.

The Kynurenine/Tryptophan Ratio Is a Sensitive Biomarker for the Diagnosis of Pediatric Tuberculosis Among Indian Children

Objectives

Pediatric tuberculosis (TB) remains difficult to diagnose. The plasma kynurenine to tryptophan ratio (K/T ratio) is a potential biomarker for TB diagnosis and treatment response but has not been assessed in children.

Methods

We performed a targeted diagnostic accuracy analysis of four biomarkers: kynurenine abundance, tryptophan abundance, the K/T ratio, and IDO-1 gene expression. Data were obtained from transcriptome and metabolome profiling of children with confirmed tuberculosis and age- and sex-matched uninfected household contacts of pulmonary tuberculosis patients. Each biomarker was assessed as a baseline diagnostic and in response to successful TB treatment.

Results

Despite non-significant between-group differences in unbiased analysis, the K/T ratio achieved an area under the receiver operator characteristic curve (AUC) of 0.667 and 81.5% sensitivity for TB diagnosis. Kynurenine, tryptophan, and IDO-1 demonstrated diagnostic AUCs of 0.667, 0.602, and 0.463, respectively. None of these biomarkers demonstrated high AUCs for treatment response. The AUC of the K/T ratio was lower than biomarkers identified in unbiased analysis, but improved sensitivity over existing commercial assays for pediatric TB diagnosis.

Conclusions

Plasma kynurenine and the K/T ratio may be useful biomarkers for pediatric TB. Ongoing studies in geographically diverse populations will determine optimal use of these biomarkers worldwide.

Male Sex Is Associated With Worse Microbiological and Clinical Outcomes Following Tuberculosis Treatment: A Retrospective Cohort Study, a Systematic Review of the Literature, and Meta-analysis

BACKGROUND

Although the incidence of tuberculosis is higher in men than in women, the relationship of sex with tuberculosis treatment outcomes has not been adequately studied.

METHODS

We performed a retrospective cohort study and a systematic review and meta-analysis of observational studies during the last 10 years to assess sex differences in clinical and microbiological outcomes in tuberculosis.

RESULTS

In our cohort of 2894 Taiwanese patients with drug-susceptible pulmonary tuberculosis (1975 male and 919 female), male patients had higher adjusted hazards of 9-month mortality due to all causes (hazard ratio, 1.43 [95% confidence interval (CI), 1.03-1.98]) and infections (1.70 [1.09-2.64]) and higher adjusted odds of 2-month sputum culture positivity (odds ratio [OR], 1.56 [95% CI, 1.05-2.33]) compared with female patients. Smear positivity at 2 months did not differ significantly (OR, 1.27 [95% CI, .71-2.27]) between the sexes. Among 7896 articles retrieved, 398 were included in our systematic review describing a total of 3 957 216 patients. The odds of all-cause mortality were higher in men than in women in the pooled unadjusted (OR, 1.26 [95% CI, 1.19-1.34]) and adjusted (1.31 [1.18-1.45]) analyses. Men had higher pooled odds of sputum culture (OR, 1.44 [95% CI, 1.14-1.81]) and sputum smear (1.58 [1.41-1.77]) positivity, both at the end of the intensive phase and on completion of treatment.

CONCLUSIONS

Our retrospective cohort showed that male patients with tuberculosis have higher 9-month all-cause and infection-related mortality, with higher 2-month sputum culture positivity after adjustment for confounding factors. In our meta-analysis, male patients showed higher all-cause and tuberculosis-related mortality and higher sputum culture and smear positivity rates during and after tuberculosis treatment.

Genetic Determinants of Intrinsic Antibiotic Tolerance in Mycobacterium avium

The Mycobacterium avium complex (MAC) is one of the most prevalent causes of nontuberculous mycobacteria pulmonary infection in the United States, and yet it remains understudied. Current MAC treatment requires more than a year of intermittent to daily combination antibiotic therapy, depending on disease severity. In order to shorten and simplify curative regimens, it is important to identify the innate bacterial factors contributing to reduced antibiotic susceptibility, namely, antibiotic tolerance genes. In this study, we performed a genome-wide transposon screen to elucidate M. avium genes that play a role in the bacterium's tolerance to first- and second-line antibiotics. We identified a total of 193 unique M. avium mutants with significantly altered susceptibility to at least one of the four clinically used antibiotics we tested, including two mutants (in DFS55_00905 and DFS55_12730) with panhypersusceptibility. The products of the antibiotic tolerance genes we have identified may represent novel targets for future drug development studies aimed at shortening the duration of therapy for MAC infections. IMPORTANCE The prolonged treatment required to eradicate Mycobacterium avium complex (MAC) infection is likely due to the presence of subpopulations of antibiotic-tolerant bacteria with reduced susceptibility to currently available drugs. However, little is known about the genes and pathways responsible for antibiotic tolerance in MAC. In this study, we performed a forward genetic screen to identify M. avium antibiotic tolerance genes, whose products may represent attractive targets for the development of novel adjunctive drugs capable of shortening the curative treatment for MAC infections.

Targeting the Mycobacterium tuberculosis Stringent Response as a Strategy for Shortening Tuberculosis Treatment

The stringent response is well conserved across bacterial species and is a key pathway involved both in bacterial survival and virulence and in the induction of antibiotic tolerance in Mycobacteria. It is mediated by the alarmone (p)ppGpp and the regulatory molecule inorganic polyphosphate in response to stress conditions such as nutrient starvation. Efforts to pharmacologically target various components of the stringent response have shown promise in modulating mycobacterial virulence and antibiotic tolerance. In this review, we summarize the current understanding of the stringent response and its role in virulence and tolerance in Mycobacteria, including evidence that targeting this pathway could have therapeutic benefit.

The Global Health Security Index is not predictive of vaccine rollout responses among OECD countries

Objective: This study sought to evaluate the utility of the Global Health Security (GHS) index in predicting the launch of COVID-19 vaccine rollout by Organization for Economic Cooperation and Development (OECD) member countries.

Methods: Country-level data on the preparedness to respond to infectious disease threats through vaccination rollout were collected using the GHS index. OECD member countries were rank-ordered based on the percentage of their populations fully vaccinated against COVID-19. Rank-ordering was conducted from the lowest to the highest, with each country assigned a score ranging from 1 to 33. Spearman's rank correlation between the GHS index and the percentage of the population that is fully vaccinated was also performed.

Results: Israel, ranked 34^th in the world on the GHS index for pandemic preparedness, had the highest percentage of the population that was fully vaccinated against COVID-19 within 2 months of the global vaccine rollout. The Spearman rank correlation coefficient between GHS index and the percentage of population fully vaccinated was -0.1378, with a p-value of 0.43.

Conclusion: The findings suggest an absence of correlation between the GHS index rating and the COVID-19 vaccine rollout of OECD countries, indicating that the preparedness of OECD countries for infectious disease threats may not be accurately reflected by the GHS index.

Statins use and COVID-19 outcomes in hospitalized patients

Background

There is an urgent need for novel therapeutic strategies for reversing COVID-19-related lung inflammation. Recent evidence has demonstrated that the cholesterol-lowering agents, statins, are associated with reduced mortality in patients with various respiratory infections. We sought to investigate the relationship between statin use and COVID-19 disease severity in hospitalized patients.

Methods

A retrospective analysis of COVID-19 patients admitted to the Johns Hopkins Medical Institutions between March 1, 2020 and June 30, 2020 was performed. The outcomes of interest were mortality and severe COVID-19 infection, as defined by prolonged hospital stay (≥ 7 days) and/ or invasive mechanical ventilation. Logistic regression, Cox proportional hazards regression and propensity score matching were used to obtain both univariable and multivariable associations between covariates and outcomes in addition to the average treatment effect of statin use.

Results

Of the 4,447 patients who met our inclusion criteria, 594 (13.4%) patients were exposed to statins on admission, of which 340 (57.2%) were male. The mean age was higher in statin users compared to non-users [64.9 ± 13.4 vs. 45.5 ± 16.6 years, p <0.001]. The average treatment effect of statin use on COVID-19-related mortality was RR = 1.00 (95% CI: 0.99–1.01, p = 0.928), while its effect on severe COVID-19 infection was RR = 1.18 (95% CI: 1.11–1.27, p <0.001).

Conclusion

Statin use was not associated with altered mortality, but with an 18% increased risk of severe COVID-19 infection.

Sex Differences in Lung Imaging and SARS-CoV-2 Antibody Responses in a COVID-19 Golden Syrian Hamster Model

In the coronavirus disease 2019 (COVID-19) pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), more severe outcomes are reported in males than in females, including hospitalizations and deaths. Animal models can provide an opportunity to mechanistically interrogate causes of sex differences in the pathogenesis of SARS-CoV-2. Adult male and female golden Syrian hamsters (8 to 10 weeks of age) were inoculated intranasally with 105 50% tissue culture infective dose (TCID50) of SARS-CoV-2/USA-WA1/2020 and euthanized at several time points during the acute (i.e., virus actively replicating) and recovery (i.e., after the infectious virus has been cleared) phases of infection. There was no mortality, but infected male hamsters experienced greater morbidity, losing a greater percentage of body mass, developed more extensive pneumonia as noted on chest computed tomography, and recovered more slowly than females. Treatment of male hamsters with estradiol did not alter pulmonary damage. Virus titers in respiratory tissues, including nasal turbinates, trachea, and lungs, and pulmonary cytokine concentrations, including interferon-β (IFN-β) and tumor necrosis factor-α (TNF-α), were comparable between the sexes. However, during the recovery phase of infection, females mounted 2-fold greater IgM, IgG, and IgA responses against the receptor-binding domain of the spike protein (S-RBD) in both plasma and respiratory tissues. Female hamsters also had significantly greater IgG antibodies against whole-inactivated SARS-CoV-2 and mutant S-RBDs as well as virus-neutralizing antibodies in plasma. The development of an animal model to study COVID-19 sex differences will allow for a greater mechanistic understanding of the SARS-CoV-2-associated sex differences seen in the human population. IMPORTANCE Men experience more severe outcomes from coronavirus disease 2019 (COVID-19) than women. Golden Syrian hamsters were used to explore sex differences in the pathogenesis of a human isolate of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). After inoculation, male hamsters experienced greater sickness, developed more severe lung pathology, and recovered more slowly than females. Sex differences in disease could not be reversed by estradiol treatment in males and were not explained by either virus replication kinetics or the concentrations of inflammatory cytokines in the lungs. During the recovery period, antiviral antibody responses in the respiratory tract and plasma, including to newly emerging SARS-CoV-2 variants, were greater in female than in male hamsters. Greater lung pathology during the acute phase combined with lower antiviral antibody responses during the recovery phase of infection in males than in females illustrate the utility of golden Syrian hamsters as a model to explore sex differences in the pathogenesis of SARS-CoV-2 and vaccine-induced immunity and protection.

The association of atherosclerotic cardiovascular disease and statin use with inflammation and treatment outcomes in tuberculosis

Tuberculosis (TB) and atherosclerotic cardiovascular disease (ASCVD) have a close epidemiological and pathogenetic overlap. Thus, it becomes essential to understand the relationship between ASCVD and TB outcomes. From our retrospective cohort on drug-susceptible TB patients at the National Taiwan University Hospital, we assessed the association of pre-existing ASCVD (coronary artery disease (CAD) and atherothrombotic stroke (ATS)) with 9-month all-cause and infection-related mortality and the extent of mediation by systemic inflammatory markers. We determined the effect of pre-existing ASCVD on 2-month sputum microbiological status. Among ASCVD patients, we assessed the association of statin use on mortality. Nine-month all-cause mortality was higher in CAD patients with prior acute myocardial infarction (CAD⁺AMI⁺) (adjusted HR 2.01, 95%CI 1.38–3.00) and ATS patients (aHR 2.79, 95%CI 1.92–4.07) and similarly, for infection-related mortality was higher in CAD⁺AMI⁺ (aHR 1.95, 95%CI 1.17–3.24) and ATS (aHR 2.04, 95%CI 1.19–3.46) after adjusting for confounding factors. Pre-existing CAD (AMI^- or AMI⁺) or ATS did not change sputum culture conversion or sputum smear AFB positivity at 2 months. The CAD⁺AMI⁺ group had significantly higher levels of CRP at TB diagnosis in the multivariable linear regression analysis (Adjusted B(SE) 1.24(0.62)). CRP mediated 66% (P = 0.048) and 25% (P = 0.033) of the association all-cause mortality with CAD⁺AMI⁻ and CAD⁺AMI⁺, respectively. In summary, patients with ASCVD have higher hazards of 9-month all-cause and infection-related mortality, with elevated serum inflammation mediating one to three-quarters of this association when adjusted for confounders. Statin use was associated with lower all-cause mortality among patients with ASCVD.

Higher Serum Cholesterol Levels Are Associated With Reduced Systemic Inflammation and Mortality During Tuberculosis Treatment Independent of Body Mass Index

Background: Lipids play a central role in the pathogenesis of tuberculosis (TB). The effect of serum lipid levels on TB treatment (ATT) outcomes and their association with serum inflammatory markers have not yet been characterized. Methods: Our retrospective cohort study on drug-susceptible TB patients, at the National Taiwan University Hospital, assessed the association of baseline serum lipid levels such as low-density lipoprotein (LDL), high-density lipoprotein (HDL), total cholesterol (TC) and triglycerides (TG) with all-cause and infection-related mortality during first 9 months of ATT and baseline inflammatory markers namely C-reactive protein (CRP), total leukocyte count (WBC), and neutrophil-lymphocyte ratio (NL ratio). Results: Among 514 patients, 129 (26.6%) died due to any-cause and 72 (14.0%) died of infection. Multivariable Cox-regression showed a lower adjusted hazard ratio (aHR) of all-cause mortality in the 3rd tertiles of HDL (aHR 0.17, 95% CI 0.07-0.44) and TC (aHR 0.30, 95% CI 0.14-0.65), and lower infection-related mortality in the 3rd tertile of HDL (aHR 0.30, 95% CI 0.14-0.65) and TC (aHR 0.30, 95% CI 0.14-0.65) compared to the 1st tertile. The 3rd tertiles of LDL and TG showed no association in multivariable analysis. Similarly, 3rd tertiles of HDL and TC had lower levels of baseline inflammatory markers such as CRP, WBC, and NL ratio using linear regression analysis. Body mass index (BMI) did not show evidence of confounding or effect modification. Conclusions: Higher baseline serum cholesterol levels were associated with lower hazards of all-cause and infection-related mortality and lower levels of inflammatory markers in TB patients. BMI did not modify or confound this association.

Integrative Multi-Omics Reveals Serum Markers of Tuberculosis in Advanced HIV

Tuberculosis (TB) accounts for disproportionate morbidity and mortality among persons living with HIV (PLWH). Conventional methods of TB diagnosis, including smear microscopy and Xpert MTB/RIF, have lower sensitivity in PLWH. Novel high-throughput approaches, such as miRNAomics and metabolomics, may advance our ability to recognize subclinical and difficult-to-diagnose TB, especially in very advanced HIV. We conducted a case-control study leveraging REMEMBER, a multi-country, open-label randomized controlled trial comparing 4-drug empiric standard TB treatment with isoniazid preventive therapy in PLWH initiating antiretroviral therapy (ART) with CD4 cell counts <50 cells/μL. Twenty-three cases of incident TB were site-matched with 32 controls to identify microRNAs (miRNAs), metabolites, and cytokines/chemokines, associated with the development of newly diagnosed TB in PLWH. Differentially expressed miRNA analysis revealed 11 altered miRNAs with a fold change higher than 1.4 or lower than -1.4 in cases relative to controls (p<0.05). Our analysis revealed no differentially abundant metabolites between cases and controls. We found higher TNFα and IP-10/CXCL10 in cases (p=0.011, p=0.0005), and higher MDC/CCL22 in controls (p=0.0072). A decision-tree algorithm identified gamma-glutamylthreonine and hsa-miR-215-5p as the optimal variables to classify incident TB cases (AUC 0.965; 95% CI 0.925-1.000). hsa-miR-215-5p, which targets genes in the TGF-β signaling pathway, was downregulated in cases. Gamma-glutamylthreonine, a breakdown product of protein catabolism, was less abundant in cases. To our knowledge, this is one of the first uses of a multi-omics approach to identify incident TB in severely immunosuppressed PLWH.

Key Macrophage Responses to Infection With Mycobacterium tuberculosis Are Co-Regulated by microRNAs and DNA Methylation

Tuberculosis (TB) is the leading cause of death from infection with a single bacterial pathogen. Host macrophages are the primary cell type infected with Mycobacterium tuberculosis (Mtb), the organism that causes TB. Macrophage response pathways are regulated by various factors, including microRNAs (miRNAs) and epigenetic changes that can shape the outcome of infection. Although dysregulation of both miRNAs and DNA methylation have been studied in the context of Mtb infection, studies have not yet investigated how these two processes may jointly co-regulate critical anti-TB pathways in primary human macrophages. In the current study, we integrated genome-wide analyses of miRNA abundance and DNA methylation status with mRNA transcriptomics in Mtb-infected primary human macrophages to decipher which macrophage functions may be subject to control by these two types of regulation. Using in vitro macrophage infection models and next generation sequencing, we found that miRNAs and methylation changes co-regulate important macrophage response processes, including immune cell activation, macrophage metabolism, and AMPK pathway signaling.

Modes of transmission of SARS-CoV-2 and evidence for preventive behavioral interventions

COVID-19 is a novel disease caused by SARS-CoV-2. During the global vaccination rollout, it is vital to thoroughly understand the modes of transmission of the virus in order to prevent further spread of variants and ultimately to end the pandemic. The current literature suggests that SARS-CoV-2 is transmitted among the human population primarily through respiratory droplets and, to a lesser extent, via aerosols. Transmission appears to be affected by temperature, humidity, precipitation, air currents, pH, and radiation in the ambient environment. Finally, the use of masks or facial coverings, social distancing, and hand washing are effective public health strategies in reducing the risk of exposure and transmission. Additional research is needed to further characterize the relative benefits of specific nonpharmaceutical interventions.

Sex differences in lung imaging and SARS-CoV-2 antibody responses in a COVID-19 golden Syrian hamster model

In the ongoing coronavirus disease 2019 (COVID-19) pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), more severe outcomes are reported in males compared with females, including hospitalizations and deaths. Animal models can provide an opportunity to mechanistically interrogate causes of sex differences in the pathogenesis of SARS-CoV-2. Adult male and female golden Syrian hamsters (8-10 weeks of age) were inoculated intranasally with 10 ⁵ TCID ₅₀ of SARS-CoV-2/USA-WA1/2020 and euthanized at several time points during the acute (i.e., virus actively replicating) and recovery (i.e., after the infectious virus has been cleared) phases of infection. There was no mortality, but infected male hamsters experienced greater morbidity, losing a greater percentage of body mass, developing more extensive pneumonia as noted on chest computed tomography, and recovering more slowly than females. Treatment of male hamsters with estradiol did not alter pulmonary damage. Virus titers in respiratory tissues, including nasal turbinates, trachea, and lungs, and pulmonary cytokine concentrations, including IFNb and TNFa, were comparable between the sexes. However, during the recovery phase of infection, females mounted two-fold greater IgM, IgG, and IgA responses against the receptor-binding domain of the spike protein (S-RBD) in both plasma and respiratory tissues. Female hamsters also had significantly greater IgG antibodies against whole inactivated SARS-CoV-2 and mutant S-RBDs, as well as virus neutralizing antibodies in plasma. The development of an animal model to study COVID-19 sex differences will allow for a greater mechanistic understanding of the SARS-CoV-2 associated sex differences seen in the human population.

The New Frontier of Host-Directed Therapies for Mycobacterium avium Complex

Mycobacterium avium complex (MAC) is an increasingly important cause of morbidity and mortality, and is responsible for pulmonary infection in patients with underlying lung disease and disseminated disease in patients with AIDS. MAC has evolved various virulence strategies to subvert immune responses and persist in the infected host. Current treatment for MAC is challenging, requiring a combination of multiple antibiotics given over a long time period (for at least 12 months after negative sputum culture conversion). Moreover, even after eradication of infection, many patients are left with residual lung dysfunction. In order to address similar challenges facing the management of patients with tuberculosis, recent attention has focused on the development of novel adjunctive, host-directed therapies (HDTs), with the goal of accelerating the clearance of mycobacteria by immune defenses and reducing or reversing mycobacterial-induced lung damage. In this review, we will summarize the evidence supporting specific adjunctive, HDTs for MAC, with a focus on the repurposing of existing immune-modulatory agents targeting a variety of different cellular pathways. We also highlight areas meriting further investigation.

The Global Health Security Index is not predictive of coronavirus pandemic responses among Organization for Economic Cooperation and Development countries

The ongoing COVID-19 pandemic has devastated many countries with ripple effects felt in various sectors of the global economy. In November 2019, the Global Health Security (GHS) Index was released as the first detailed assessment and benchmarking of 195 countries to prevent, detect, and respond to infectious disease threats. This paper presents the first comparison of Organization for Economic Cooperation and Development OECD countries' performance during the pandemic, with the pre-COVID-19 pandemic preparedness as determined by the GHS Index. Using a rank-based analysis, four indices were compared between select countries, including total cases, total deaths, recovery rate, and total tests performed, all standardized for comparison. Our findings suggest a discrepancy between the GHS index rating and the actual performance of countries during this pandemic, with an overestimation of the preparedness of some countries scoring highly on the GHS index and underestimation of the preparedness of other countries with relatively lower scores on the GHS index.

Mechanisms of Antibiotic Tolerance in Mycobacterium avium Complex: Lessons From Related Mycobacteria

Mycobacterium avium complex (MAC) species are the most commonly isolated nontuberculous mycobacteria to cause pulmonary infections worldwide. The lengthy and complicated therapy required to cure lung disease due to MAC is at least in part due to the phenomenon of antibiotic tolerance. In this review, we will define antibiotic tolerance and contrast it with persistence and antibiotic resistance. We will discuss physiologically relevant stress conditions that induce altered metabolism and antibiotic tolerance in mycobacteria. Next, we will review general molecular mechanisms underlying bacterial antibiotic tolerance, particularly those described for MAC and related mycobacteria, including Mycobacterium tuberculosis, with a focus on genes containing significant sequence homology in MAC. An improved understanding of antibiotic tolerance mechanisms can lay the foundation for novel approaches to target antibiotic-tolerant mycobacteria, with the goal of shortening the duration of curative treatment and improving survival in patients with MAC.

The Impact of Hypertension and Use of Calcium Channel Blockers on Tuberculosis Treatment Outcomes

BACKGROUND

Hypertension induces systemic inflammation, but its impact on the outcome of infectious diseases like tuberculosis (TB) is unknown. Calcium channel blockers (CCB) improve TB treatment outcomes in pre-clinical models, but their effect in patients with TB remain unclear.

METHODS

This retrospective cohort study, including all patients > 18 years receiving treatment for culture-confirmed, drug-sensitive TB from 2000 to 2016 at the National Taiwan University Hospital, assessed the association of hypertension and CCB use with all-cause and infection-related mortality during the first 9 months of TB treatment, as well as sputum-smear microscopy and sputum-culture positivity at 2 and 6 months.

RESULTS

1052 of the 2894 patients (36.4%) had hypertension. Multivariable analysis revealed that hypertension was associated with increased mortality due to all causes (HR 1.57, 95% confidence interval[CI], 1.23-1.99) and infections (HR 1.87, 95%CI, 1.34-2.6), but there was no statistical difference in microbiological outcomes when stratified based on hypertensive group. Dihydropyridine-CCB (DHP-CCB) use was associated with reduced all-cause mortality (HR 0.67, 95%CI: 0.45-0.98) only by univariate Cox regression. There was no association between DHP-CCB use and infection-related mortality (HR 0.78, 95%CI: 0.46-1.34) or microbiological outcomes in univariate or multivariate regression analyses.

CONCLUSIONS

Patients with hypertension have increased all-cause mortality and infection-related mortality during the 9 months following TB treatment initiation. DHP-CCB use may lower all-cause mortality in TB patients with hypertension. The presence of hypertension or the use of CCB did not result in a significant change in microbiological outcomes.

Mycobacterium tuberculosis Infection Drives Mitochondria-Biased Dysregulation of Host Transfer RNA-Derived Fragments

BACKGROUND

Mycobacterium tuberculosis (Mtb), the bacterium that causes tuberculosis, causes 10 million infections and 1.5 million deaths per year worldwide. The success of Mtb as a human pathogen is directly related to its ability to suppress host responses, which are critical for clearing intracellular pathogens. Emerging evidence suggests that key response pathways may be regulated by a novel class of small noncoding RNA, called transfer RNA (tRNA)-derived fragments (tRFs). tRFs can complex with Argonaute proteins to target and degrade messenger RNA targets, similarly to micro RNAs, but have thus far been overlooked in the context of bacterial infections.

METHODS

We generated a novel miRge2.0-based tRF-analysis tool, tRFcluster, and used it to analyze independently generated and publicly available RNA-sequencing datasets to assess tRF dysregulation in host cells following infection with Mtb and other intracellular bacterial pathogens.

RESULTS

We found that Mtb and Listeria monocytogenes drive dramatic tRF dysregulation, whereas other bacterial pathogens do not. Interestingly, Mtb infection uniquely increased the expression of mitochondria-derived tRFs rather than genomic-derived tRFs, suggesting an association with mitochondrial damage in Mtb infection.

CONCLUSIONS

tRFs are dysregulated in some, but not all, bacterial infections. Biased dysregulation of mitochondria-derived tRFs in Mtb infection suggests a link between mitochondrial distress and tRF production.

The anti-tubercular activity of simvastatin is mediated by cholesterol-driven autophagy via the AMPK-mTORC1-TFEB axis

The rise of drug-resistant tuberculosis poses a major risk to public health. Statins, which inhibit both cholesterol biosynthesis and protein prenylation branches of the mevalonate pathway, increase anti-tubercular antibiotic efficacy in animal models. However, the underlying molecular mechanisms are unknown. In this study, we used an in vitro macrophage infection model to investigate simvastatin's anti-tubercular activity by systematically inhibiting each branch of the mevalonate pathway and evaluating the effects of the branch-specific inhibitors on mycobacterial growth. The anti-tubercular activity of simvastatin used at clinically relevant doses specifically targeted the cholesterol biosynthetic branch rather than the prenylation branches of the mevalonate pathway. Using Western blot analysis and AMP/ATP measurements, we found that simvastatin treatment blocked activation of mechanistic target of rapamycin complex 1 (mTORC1), activated AMP-activated protein kinase (AMPK) through increased intracellular AMP:ATP ratios, and favored nuclear translocation of transcription factor EB (TFEB). These mechanisms all induce autophagy, which is anti-mycobacterial. The biological effects of simvastatin on the AMPK-mTORC1-TFEB-autophagy axis were reversed by adding exogenous cholesterol to the cells. Our data demonstrate that the anti-tubercular activity of simvastatin requires inhibiting cholesterol biosynthesis, reveal novel links between cholesterol homeostasis, the AMPK-mTORC1-TFEB axis, and Mycobacterium tuberculosis infection control, and uncover new anti-tubercular therapy targets.

Abstract 2198: The anti-tumor enhancement of a dendritic-cell targeting MIP3α-Gp100-Trp2 DNA vaccine by IFNα and 5-Aza-2'-deoxycytidine treatments correlates with intratumoral CCL19 but not CCL21 expression

Background: The chemokine MIP-3α (CCL20) binds to CCR6 on immature dendritic cells (DCs). DNA vaccines fusing MIP-3α to melanoma-associated antigens gp100 and/or tyrosinase-related protein 2 (Trp2) have delayed tumor growth and increased survival time in the B16F10 mouse melanoma model system compared to vaccines lacking the chemokine. To further enhance the therapeutic effects of the vaccine, our laboratory has added type-I interferon (IFNα) and 5-Aza-2'-deoxycitidine (5Aza) to the therapy. Here, we report that the enhancement previously seen by the combination of IFNα, 5Aza, and a MIP-3α-Gp100-Trp2 (MGpTrp2) DNA vaccine correlates with increases of tumor-infiltrating CD8+T-cells (CD8 TILs) and intratumoral expression of CCL19 but not CCL21.

Methods: Beginning on day five post-transplantation of B16F10 melanoma, vaccine was administered intramuscularly (i.m.) by electroporation. CpG adjuvant was given two days later. 5Aza was given intraperitoneally at 1mg/kg and IFNα therapy either intratumorally or i.m. as noted. Tumor sizes, tumor growth, and mouse survival were assessed. Tumor lysate gene expression levels and tumor-infiltrating lymphocytes (TILs) were assessed by qRT-PCR and flow cytometry with intracellular cytokine staining, respectively.

Results: Previous work has shown that the combination of IFNα, 5Aza, and MGpTrp2 led to significantly reduced tumor burden and overall increases in mouse survival dependent upon all three components. The addition of 5Aza and IFNα to the vaccine affected T-cell tumor infiltration, increasing the proportion of CD3+CD8+ cells in gated TILs by 92% over vaccine alone (p&lt;0.0001), which correlated with tumor size (r2: 0.507; p&lt;0.0001). Interferon stimulated genes such as Mx1, MHC1, CXCL10, and GranzymeB were modestly upregulated in the tumor lysate. However, CCL19, normally expressed constitutively in lymphoid tissues, was upregulated 10-fold compared to vaccine alone (p&lt;0.0001) and was correlated with tumor size (r2: 0.195; p=0.002). The CCL19 receptor, CCR7, was upregulated to a lesser degree (5-fold over vaccine; p&lt;0.001), and interestingly its partner chemokine CCL21 did not have significantly different expression patterns across groups (p=0.14 to vaccine).

Conclusions: Efficient targeting of antigen to immature dendritic cells with a chemokine-fusion vaccine offers a potential alternative approach to classic and dendritic cell-based vaccines.

Combining this approach with IFNα and 5Aza treatments significantly improved vaccine efficacy. This enhancement was correlated with CD8+ TIL recruitment and with the expression of the T-cell trafficking chemokine CCL19. Further potential therapy optimization currently undergoing investigation offers promise for this line of investigation to become a novel melanoma therapy.

Citation Format: James T. Gordy, Avinaash K. Sandhu, Samuel K. Ayeh, Aakanksha Kapoor, Emily Kim, Petros C. Karakousis, Richard B. Markham. The anti-tumor enhancement of a dendritic-cell targeting MIP3α-Gp100-Trp2 DNA vaccine by IFNα and 5-Aza-2'-deoxycytidine treatments correlates with intratumoral CCL19 but not CCL21 expression [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2198.

Antibiotic Treatment Shapes the Antigenic Environment During Chronic TB Infection, Offering Novel Targets for Therapeutic Vaccination

The lengthy and complicated current regimen required to treat drug-susceptible tuberculosis (TB) reflects the ability of Mycobacterium tuberculosis (Mtb) to persist in host tissues. The stringent response pathway, governed by the dual (p)ppGpp synthetase/hydrolase, Rel_Mtb, is a major mechanism underlying Mtb persistence and antibiotic tolerance. In the current study, we addressed the hypothesis that Rel_Mtb is a “persistence antigen” presented during TB chemotherapy and that enhanced immunity to Rel_Mtb can enhance the tuberculocidal activity of the first-line anti-TB drug, isoniazid, which has reduced efficacy against Mtb persisters. C57BL/6 mice and Hartley guinea pigs were aerosol-infected with M. tuberculosis (Mtb) and, 4 weeks later, received either human-equivalent daily doses of isoniazid alone, or isoniazid in combination with a DNA vaccine targeting rel_Mtb. After isoniazid treatment, there was a significant reduction in dominant antigen ESAT6-reactive CD4⁺ or TB10.4-reactive CD8⁺ T cells in the lungs and spleens of mice. However, the total number of Rel_Mtb-reactive CD4⁺ T cells remained stable in mouse lungs and spleens, as did the number of Rel_Mtb-reactive CD8⁺T cells. Therapeutic vaccination with rel_Mtb DNA vaccine enhanced the activity of isoniazid in Mtb-infected C57BL/6 mice and guinea pigs. When treatment with isoniazid was discontinued, mice immunized with the rel_Mtb DNA vaccine showed a lower mean lung bacterial burden at relapse compared to the control group. Our work shows that antitubercular treatment shapes the antigenic environment, and that therapeutic vaccination targeting the Mtb stringent response may represent a novel approach to enhance immunity against Mtb persisters, with the ultimate goal of shortening curative TB treatment.

Adjunctive Host-Directed Therapy With Statins Improves Tuberculosis-Related Outcomes in Mice

BACKGROUND

Tuberculosis (TB) treatment is lengthy and complicated and patients often develop chronic lung disease. Recent attention has focused on host-directed therapies aimed at optimizing immune responses to Mycobacterium tuberculosis (Mtb), as adjunctive treatment given with antitubercular drugs. In addition to their cholesterol-lowering properties, 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) have broad anti-inflammatory and immunomodulatory activities.

METHODS

In the current study, we screened 8 commercially available statins for cytotoxic effect, anti-TB activity, synergy with first-line drugs in macrophages, pharmacokinetics and adjunctive bactericidal activity, and, in 2 different mouse models, as adjunctive therapy to first-line TB drugs.

RESULTS

Pravastatin showed the least toxicity in THP-1 and Vero cells. At nontoxic doses, atorvastatin and mevastatin were unable to inhibit Mtb growth in THP-1 cells. Simvastatin, fluvastatin, and pravastatin showed the most favorable therapeutic index and enhanced the antitubercular activity of the first-line drugs isoniazid, rifampin, and pyrazinamide in THP-1 cells. Pravastatin modulated phagosomal maturation characteristics in macrophages, phenocopying macrophage activation, and exhibited potent adjunctive activity in the standard mouse model of TB chemotherapy and in a mouse model of human-like necrotic TB lung granulomas.

CONCLUSIONS

These data provide compelling evidence for clinical evaluation of pravastatin as adjunctive, host-directed therapy for TB.

Treatment with an immature dendritic cell-targeting vaccine supplemented with IFN-α and an inhibitor of DNA methylation markedly enhances survival in a murine melanoma model

BACKGROUND

The chemokine MIP-3α (CCL20) binds to CCR6 on immature dendritic cells. DNA vaccines fusing MIP-3α to melanoma-associated antigens have shown improved efficacy and immunogenicity in the B16F10 mouse melanoma model. Here, we report that the combination of type-I interferon therapy (IFNα) with 5-Aza-2'-deoxycitidine (5Aza) profoundly enhanced the therapeutic efficacy of a MIP-3α-Gp100-Trp2 DNA vaccine.

METHODS

Beginning on day 5 post-transplantation of B16F10 melanoma, vaccine was administered intramuscularly (i.m.) by electroporation. CpG adjuvant was given 2 days later. 5Aza was given intraperitoneally at 1 mg/kg and IFNα therapy either intratumorally or i.m. as noted. Tumor sizes, tumor growth, and mouse survival were assessed. Tumor lysate gene expression levels and tumor-infiltrating lymphocytes (TILs) were assessed by qRT-PCR and flow cytometry, respectively.

RESULTS

Adding IFNα and 5Aza treatments to mice vaccinated with MIP-3α-Gp100-Trp2 leads to reduced tumor burden and increased median survival (39% over vaccine and 95% over controls). Tumor lysate expression of CCL19 and CCR7 were upregulated ten and fivefold over vaccine, respectively. Vaccine-specific and overall CD8+ TILs were increased over vaccine (sevenfold and fourfold, respectively), as well as the proportion of TILs that were CD8+ (twofold).

CONCLUSIONS

Efficient targeting of antigen to immature dendritic cells with a chemokine-fusion vaccine offers an alternative to classic and dendritic cell vaccines. Combining this approach with IFNα and 5Aza treatment significantly improved vaccine efficacy. This improved efficacy correlated with changes in chemokine gene expression and CD8+ TIL infiltration and was dependent on the presence of all therapeutic components.

Identifying the essential genes of Mycobacterium avium subsp. hominissuis with Tn-Seq using a rank-based filter procedure

Mycobacterium avium subsp. hominissuis (MAH) is increasingly recognized as a significant cause of morbidity, particularly in elderly patients or those with immune deficiency or underlying lung impairment. Disease due to MAH is particularly difficult to treat, often requiring years of antibiotic therapy. Identification of genes essential for MAH growth may lead to novel strategies for improving curative therapy. Here we have generated saturating genome-wide transposon mutant pools in a strain of MAH (MAC109) and developed a novel computational technique for classifying annotated genomic features based on the in vitro effect of transposon mutagenesis. Our findings may help guide future genetic and biochemical studies of MAH pathogenesis and aid in the identification of new drugs to improve the treatment of these serious infections.

Remembering the Host in Tuberculosis Drug Development

New therapeutics to augment current approaches and shorten treatment duration are of critical importance for combating tuberculosis (TB), especially those with novel mechanisms of action to counter the emergence of drug-resistant TB. Host-directed therapy (HDT) offers a novel strategy with mechanisms that include activating immune defense mechanisms or ameliorating tissue damage. These and related concepts will be discussed along with issues that emerged from the workshop organized by the Stop TB Working Group on New Drugs, held at the Gordon Research Conference for Tuberculosis Drug Development in Lucca, Italy in June 2017, titled "Strategic Discussion on Repurposing Drugs & Host Directed Therapies for TB." In this review, we will highlight recent data regarding drugs, pathways, and concepts that are important for successful development of HDTs for TB.

Factors associated with disease severity and mortality among patients with COVID-19: A systematic review and meta-analysis

BACKGROUND

Understanding the factors associated with disease severity and mortality in Coronavirus disease (COVID-19) is imperative to effectively triage patients. We performed a systematic review to determine the demographic, clinical, laboratory and radiological factors associated with severity and mortality in COVID-19.

METHODS

We searched PubMed, Embase and WHO database for English language articles from inception until May 8, 2020. We included Observational studies with direct comparison of clinical characteristics between a) patients who died and those who survived or b) patients with severe disease and those without severe disease. Data extraction and quality assessment were performed by two authors independently.

RESULTS

Among 15680 articles from the literature search, 109 articles were included in the analysis. The risk of mortality was higher in patients with increasing age, male gender (RR 1.45, 95%CI 1.23-1.71), dyspnea (RR 2.55, 95%CI 1.88-2.46), diabetes (RR 1.59, 95%CI 1.41-1.78), hypertension (RR 1.90, 95%CI 1.69-2.15). Congestive heart failure (OR 4.76, 95%CI 1.34-16.97), hilar lymphadenopathy (OR 8.34, 95%CI 2.57-27.08), bilateral lung involvement (OR 4.86, 95%CI 3.19-7.39) and reticular pattern (OR 5.54, 95%CI 1.24-24.67) were associated with severe disease. Clinically relevant cut-offs for leukocytosis(>10.0 x109/L), lymphopenia(< 1.1 x109/L), elevated C-reactive protein(>100mg/L), LDH(>250U/L) and D-dimer(>1mg/L) had higher odds of severe disease and greater risk of mortality.

CONCLUSION

Knowledge of the factors associated of disease severity and mortality identified in our study may assist in clinical decision-making and critical-care resource allocation for patients with COVID-19.

Small Animal Models for Human Immunodeficiency Virus (HIV), Hepatitis B, and Tuberculosis: Proceedings of an NIAID Workshop

The main advantage of animal models of infectious diseases over in vitro studies is the gain in the understanding of the complex dynamics between the immune system and the pathogen. While small animal models have practical advantages over large animal models, it is crucial to be aware of their limitations. Although the small animal model at least needs to be susceptible to the pathogen under study to obtain meaningful data, key elements of pathogenesis should also be reflected when compared to humans. Well-designed small animal models for HIV, hepatitis viruses and tuberculosis require, additionally, a thorough understanding of the similarities and differences in the immune responses between humans and small animals and should incorporate that knowledge into the goals of the study. To discuss these considerations, the NIAID hosted a workshop on 'Small Animal Models for HIV, Hepatitis B, and Tuberculosis' on May 30, 2019. Highlights of the workshop are outlined below.

Inhibiting the stringent response blocks Mycobacterium tuberculosis entry into quiescence and reduces persistence

The stringent response enables Mycobacterium tuberculosis (Mtb) to shut down its replication and metabolism under various stresses. Here we show that Mtb lacking the stringent response enzyme Rel_Mtb was unable to slow its replication rate during nutrient starvation. Metabolomics analysis revealed that the nutrient-starved rel_Mtb -deficient strain had increased metabolism similar to that of exponentially growing wild-type bacteria in nutrient-rich broth, consistent with an inability to enter quiescence. Deficiency of rel_Mtb increased the susceptibility of mutant bacteria to killing by isoniazid during nutrient starvation and in the lungs of chronically infected mice. We screened a pharmaceutical library of over 2 million compounds for inhibitors of Rel_Mtb and showed that the lead compound X9 was able to directly kill nutrient-starved M. tuberculosis and enhanced the killing activity of isoniazid. Inhibition of Rel_Mtb is a promising approach to target M. tuberculosis persisters, with the potential to shorten the duration of TB treatment.

Genome analysis of Mycobacterium avium subspecies hominissuis strain 109

Infection with Mycobacterium avium is a significant cause of morbidity and its treatment requires the use of multiple antibiotics for more than 12 months. In the current work, we provide the genome sequence, gene annotations, gene ontology annotations, and protein homology data for M. avium strain 109 (MAC109), which has been used extensively in preclinical studies. The de novo assembled genome consists of a circular chromosome of length 5,188,883 bp and two circular plasmids of sizes 147,100 bp and 16,516 bp. We have named the plasmids pMAC109a and pMAC109b, respectively. Based on its genome, we confirm that MAC109 should be classified as Mycobacterium avium subsp. hominissuis. Using genome annotation software, we identified 4,841 coding sequences and annotated these with Gene Ontology (GO) terms. Additionally, we wrote software to generate a database of homologous proteins among MAC109 and eight other commonly used mycobacterial laboratory strains. The resulting database may be useful for translating genetic data between various strains of mycobacteria, and the software may be applied readily to other organisms.

Transcriptional Approach for Decoding the Mechanism of rpoC Compensatory Mutations for the Fitness Cost in Rifampicin-Resistant Mycobacterium tuberculosis

Multidrug-resistant tuberculosis (TB), defined as TB resistant to the two first-line drugs, isoniazid and rifampin, is a serious challenge to global TB eradication efforts. Although mutations in rpoA or rpoC have been proposed to compensate for this fitness cost due to rpoB mutation in rifampicin-resistant Mycobacterium tuberculosis mutants, whether the compensatory effect exists and the underlying mechanisms of compensation remain unclear. Here, we used RNA sequencing to investigate the global transcriptional profiles of 6 rifampin-resistant clinical isolates with either single mutation in rpoB or dual mutations in rpoB/rpoC, as well as 3 rifampin-susceptible clinical isolates, trying to prove the potential compensatory effect of rpoC by transcriptomic alteration. In rifampin-free conditions, rpoC mutation was associated with M. tuberculosis upregulation of ribosomal protein-coding genes, dysregulation of growth-related essential genes and balancing the expression of arginine and glutamate synthesis-associated genes. Upon rifampin exposure of M. tuberculosis isolates, rpoC mutations were associated with the upregulation of the oxidative phosphorylation machinery, which was inhibited in the rpoB single mutants, as well as stabilization of the expression of rifampin-regulated essential genes and balancing the expression of genes involved in metabolism of sulfur-containing amino acids. Taken together, our data suggest that rpoC mutation may compensate for the fitness defect of rifampicin-resistant M. tuberculosis by altering gene expression in response to rifampin exposure.

Unprecedented in Vitro Antitubercular Activitiy of Manganese(II) Complexes Containing 1,10-Phenanthroline and Dicarboxylate Ligands: Increased Activity, Superior Selectivity, and Lower Toxicity in Comparison to Their Copper(II) Analogs

Mycobacterium tuberculosis is the etiologic agent of tuberculosis. The demand for new chemotherapeutics with unique mechanisms of action to treat (multi)resistant strains is an urgent need. The objective of this work was to test the effect of manganese(II) and copper(II) phenanthroline/dicarboxylate complexes against M. tuberculosis. The water-soluble Mn(II) complexes, [Mn₂(oda)(phen)₄(H₂O)₂][Mn₂(oda)(phen)₄(oda)₂]·4H₂O (1) and {[Mn(3,6,9-tdda)(phen)₂]·3H₂O·EtOH}n (3) (odaH₂ = octanedioic acid, phen = 1,10-phenanthroline, tddaH₂ = 3,6,9-trioxaundecanedioic acid), and water-insoluble complexes, [Mn(ph)(phen)(H₂O)₂] (5), [Mn(ph)(phen)₂(H₂O)]·4H₂O (6), [Mn₂(isoph)₂(phen)₃]·4H₂O (7), {[Mn(phen)₂(H₂O)₂]}₂(isoph)₂(phen)·12H₂O (8) and [Mn(tereph)(phen)₂]·5H₂O (9) (phH₂ = phthalic acid, isophH₂ = isophthalic acid, terephH₂ = terephthalic acid), robustly inhibited the viability of M. tuberculosis strains, H37Rv and CDC1551. The water-soluble Cu(II) analog of (1), [Cu₂(oda)(phen)₄](ClO₄)₂·2.76H₂O·EtOH (2), was significantly less effective against both strains. Whilst (3) retarded H37Rv growth much better than its soluble Cu(II) equivalent, {[Cu(3,6,9-tdda)(phen)₂]·3H₂O·EtOH}n (4), both were equally efficient against CDC1551. VERO and A549 mammalian cells were highly tolerant to the Mn(II) complexes, culminating in high selectivity index (SI) values. Significantly, in vivo studies using Galleria mellonella larvae indicated that the metal complexes were minimally toxic to the larvae. The Mn(II) complexes presented low MICs and high SI values (up to 1347), indicating their auspicious potential as novel antitubercular lead agents.

Gene Enrichment Analysis Reveals Major Regulators of Mycobacterium tuberculosis Gene Expression in Two Models of Antibiotic Tolerance

The development of antibiotic tolerance is believed to be a major factor in the lengthy duration of current tuberculosis therapies. In the current study, we have modeled antibiotic tolerance in vitro by exposing Mycobacterium tuberculosis to two distinct stress conditions: progressive hypoxia and nutrient starvation [phosphate-buffered saline (PBS)]. We then studied the bacterial transcriptional response using RNA-seq and employed a bioinformatics approach to identify important transcriptional regulators, which was facilitated by a novel Regulon Enrichment Test (RET). A total of 17 transcription factor (TF) regulons were enriched in the hypoxia gene set and 16 regulons were enriched in the nutrient starvation, with 12 regulons enriched in both conditions. Using the same approach to analyze previously published gene expression datasets, we found that three M. tuberculosis regulons (Rv0023, SigH, and Crp) were commonly induced in both stress conditions and were also among the regulons enriched in our data. These regulators are worthy of further study to determine their potential role in the development and maintenance of antibiotic tolerance in M. tuberculosis following stress exposure.

Altered Mycobacterium tuberculosis Cell Wall Metabolism and Physiology Associated With RpoB Mutation H526D

Background:Mycobacterium tuberculosis (Mtb) rpoB mutations are associated with global metabolic remodeling. However, the net effects of rpoB mutations on Mtb physiology, metabolism and function are not completely understood. Based on previous work, we hypothesized that changes in the expression of cell wall molecules in Mtb mutant RpoB 526D lead to changes in cell wall permeability and to altered resistance to environmental stresses and drugs.

Methods: The phenotypes of a fully drug-susceptible clinical strain of Mtb and its paired rifampin-monoresistant, RpoB H526D mutant progeny strain were compared.

Results: The rpoB mutant showed altered colony morphology, bacillary length and cell wall thickness, which were associated with increased cell wall permeability and susceptibility to the cell wall detergent sodium dodecyl sulfate (SDS) after exposure to nutrient starvation. Relative to the isogenic rifampin-susceptible strain, the RpoB H526D mutant showed altered bacterial cellular metabolic activity and an eightfold increase in susceptibility to the cell-wall acting drug vancomycin.

Conclusion: Our data suggest that RpoB mutation H526D is associated with altered cell wall physiology and resistance to cell wall-related stress. These findings are expected to contribute to an improved understanding of the pathogenesis of drug-resistant M. tuberculosis infections.

Intranasal Immunization with DnaK Protein Induces Protective Mucosal Immunity against Tuberculosis in CD4-Depleted Mice

Mycobacterium tuberculosis (Mtb) remains a global health challenge due to the limited efficacy of the Mtb vaccine in current use, Bacillus Calmette-Guérin (BCG). To date, there is no available vaccine for immunocompromised individuals. Thus, there is an urgent need to develop a new vaccine candidate which can induce mucosal immunity in hosts with different immune statuses. DnaK (HSP70) has been shown to induce protective immunity against Mtb infection when administered by DNA vaccine; however, the protection is inferior to that induced by the BCG vaccine. In our study, we vaccinated C57BL/6J mice with DnaK protein alone. Subcutaneous or intranasal vaccination with DnaK generated IFNγ-secreting CD4⁺ T cells in the spleen, but only intranasal vaccination generated IL-17-releasing CD4⁺ T cells in the lungs, even when circulating CD4⁺ T cells were diminished. Furthermore, intranasal vaccination with DnaK generated tissue resident CD4⁺ T cells in the lungs. Vaccination with DnaK alone resulted in protective immunity comparable to BCG vaccination against tuberculosis in mice. Our results demonstrate that intranasal vaccination with DnaK can generate mucosal immunity in immunocompromised or immunocompetent mice and DnaK vaccination can generate protection against Mtb similar to BCG, underscoring its potential utility as an Mtb vaccine candidate in humans.