All trans retinoic acid as a host-directed immunotherapy for tuberculosis

Microfluidics produced ATRA-loaded PLGA NPs reduced tuberculosis burden in alveolar epithelial cells and enabled high delivered dose under simulated human breathing pattern in 3D printed head models

Tuberculosis, caused by Mycobacterium tuberculosis (Mtb), is second only to COVID-19 as the top infectious disease killer worldwide. Multi-drug resistant TB (MDR-TB) may arise because of poor patient adherence to medications due to lengthy treatment duration and side effects. Delivering novel host directed therapies (HDT), like all trans retinoic acid (ATRA) may help to improve drug regimens and reduce the incidence of MDR-TB. Local delivery of ATRA to the site of infection leads to higher bioavailability and reduced systemic side effects. ATRA is poorly soluble in water and has a short half-life in plasma. Therefore, it requires a formulation step before it can be administered in vivo. ATRA loaded PLGA nanoparticles suitable for nebulization were manufactured and optimized using a scalable nanomanufacturing microfluidics (MF) mixing approach (MF-ATRA-PLGA NPs). MF-ATRA-PLGA NPs demonstrated a dose dependent inhibition of Mtb growth in TB-infected A549 alveolar epithelial cell model while preserving cell viability. The MF-ATRA-PLGA NPs were nebulized with the Aerogen Solo vibrating mesh nebulizer, with aerosol droplet size characterized using laser diffraction and the estimated delivered dose was determined. The volume median diameter (VMD) of the MF-ATRA-PLGA NPs was 3.00 ± 0.18 μm. The inhaled dose delivered in adult and paediatric 3D printed head models under a simulated normal adult and paediatric breathing pattern was found to be 47.05 ± 3 % and 20.15 ± 3.46 % respectively. These aerosol characteristics of MF-ATRA-PLGA NPs supports its suitability for delivery to the lungs via inhalation. The data generated on the efficacy of an inhalable, scalable and regulatory friendly ATRA-PLGA NPs formulation provides a foundation on which further pre-clinical testing can be built. Overall, the results of this project are promising for future research into ATRA loaded NPs formulations as inhaled host directed therapies for TB.

A new method for the detection of Mycobacterium tuberculosis based on the CRISPR/Cas system

OBJECT

Mycobacterium tuberculosis (MTB) is a bacterium that can cause zoonoses by aerosol transmission. Tuberculosis (TB) caused by MTB heavily burdens world public health security. Developing efficient, specific, convenient, and inexpensive MTB assays are essential for preventing and controlling TB.

METHODS

In this study, we established a specific detection method for MTB using the Clustered Regularly Interspersed Short Palindromic Repeats (CRISPR) system, combined with recombinase mediated isothermal nucleic acid amplification (RAA) to improve the sensitivity of the detection system and achieve "two-level" amplification of the detection signal. The sensitivity and specificity of RAA combined with the CRISPR/Cas system were analyzed. Using BACTEC 960 culture as the gold standard for detecting MTB, we established the TB-CRISPR technique by testing 504 samples from patients with suspected TB.

RESULTS

MTB H37Ra could be seen as low as 3.13 CFU/mL by the CRISPR-Cas12a system targeting IS6110. With BACTEC960 culture (120 positives and 384 negatives) as the gold standard, the sensitivity of the TB-CRISPR technique was 0.883 (0.809-0.932), and the specificity was 0.940 (0.910-0.961). According to the receiver operating characteristic (ROC) curve analysis, the area under the curve (AUC) reached 0.944 (0.914-0.975) within 95% CI. The positive likelihood ratio (PLR) was 14.747 (9.870-22.035), and the negative likelihood ratio (NLR) was 0.124 (0.076-0.203). The positive predictive value (PPV) was 0.822 (0.742-0.881), and the negative predictive value (NPV) was 0.963 (0.937-0.979).

CONCLUSION

TB-CRISPR plays an essential role in the molecular diagnosis of TB. The whole detection time is less than 1.5 h. It is easy to operate and does not need complex instruments. It is of great significance for the rapid detection of MTB and the clinical diagnosis of TB.

Tweaking host immune responses for novel therapeutic approaches against Mycobacterium tuberculosis

In TB, combat between the human host and Mycobacterium tuberculosis involves intricate interactions with immune cells. M. tuberculosis has evolved a complex evasion system to circumvent immune cells, leading to persistence and limiting its clearance by the host. Host-directed therapies are emerging approaches to modulate host responses, including inflammatory responses, cytokine responses, and autophagy, by using small molecules to curb mycobacterial infections. Targeting host immune pathways reduces the chances of antibiotic resistance to M. tuberculosis because, unlike antibiotics, this approach acts directly on the cells of the host. In this review, we discuss the role of immune cells during M. tuberculosis proliferation, provide a updated understanding of immunopathogenesis, and explore the range of host-modulating options for the clearance of this pathogen.

Multimodal plasma metabolomics and lipidomics in elucidating metabolic perturbations in tuberculosis patients with concurrent type 2 diabetes

Type 2 diabetes mellitus (DM) poses a major burden for the treatment and control of tuberculosis (TB). Characterization of the underlying metabolic perturbations in DM patients with TB infection would yield insights into the pathophysiology of TB-DM, thus potentially leading to improvements in TB treatment. In this study, a multimodal metabolomics and lipidomics workflow was applied to investigate plasma metabolic profiles of patients with TB and TB-DM. Significantly different biological processes and biomarkers in TB-DM vs. TB were identified using a data-driven, knowledge-based framework. Changes in metabolic and signaling pathways related to carbohydrate and amino acid metabolism were mainly captured by amide HILIC column metabolomics analysis, while perturbations in lipid metabolism were identified by the C18 metabolomics and lipidomics analysis. Compared to TB, TB-DM exhibited elevated levels of bile acids and molecules related to carbohydrate metabolism, as well as the depletion of glutamine, retinol, lysophosphatidylcholine, and phosphatidylcholine. Moreover, arachidonic acid metabolism was determined as a potential important factor in the interaction between TB and DM pathophysiology. In a correlation network of the significantly altered molecules, among the central nodes, chenodeoxycholic acid was robustly associated with TB and DM. Fatty acid (22:4) was a component of all significant modules. In conclusion, the integration of multimodal metabolomics and lipidomics provides a thorough picture of the metabolic changes associated with TB-DM. The results obtained from this comprehensive profiling of TB patients with DM advance the current understanding of DM comorbidity in TB infection and contribute to the development of more effective treatment.

Acute Promyelocytic Leukemia Treatment Masking Hepatic Tuberculosis: A Management Dilemma

Acute promyelocytic leukemia is a form of acute myeloid leukemia (AML) that is characterized by presence of a promyelocytic leukemia-retinoic acid receptor alpha fusion. In most patients, this fusion is detected on conventional karyotype as the t(15;17)(q24.1;q21.2) translocation, but some patients have cryptic translocations with a normal karyotype. Historically, AML is associated with a poor prognosis. Treatment with all-trans retinoic acid and arsenic trioxide assures long-term survival in the majority of patients. This treatment is generally well-tolerated but may cause hepatotoxicity. This is usually identified by transaminitis but resolves after temporary cessation of treatment. Our patient's hepatotoxicity did not resolve following all-trans retinoic acid and arsenic trioxide cessation which posed a diagnostic dilemma. This prompted exploration of other possible causes of hepatotoxicity. An eventual liver biopsy identified acid-fast bacilli, confirming a diagnosis of hepatic tuberculosis. A broad differential diagnosis is imperative when investigating abnormalities in liver function, especially in chemotherapy patients when treatment cessation may cause cancer progression.

Development of Inhalable ATRA-Loaded PLGA Nanoparticles as Host-Directed Immunotherapy against Tuberculosis

Developing new effective treatment strategies to overcome the rise in multi-drug resistant tuberculosis cases (MDR-TB) represents a global challenge. A host-directed therapy (HDT), acting on the host immune response rather than Mtb directly, could address these resistance issues. We developed an HDT for targeted TB treatment, using All Trans Retinoic Acid (ATRA)-loaded nanoparticles (NPs) that are suitable for nebulization. Efficacy studies conducted on THP-1 differentiated cells infected with the H37Ra avirulent Mycobacterium tuberculosis (Mtb) strain, have shown a dose-dependent reduction in H37Ra growth as determined by the BACT/ALERT^® system. Confocal microscopy images showed efficient and extensive cellular delivery of ATRA-PLGA NPs into THP-1-derived macrophages. A commercially available vibrating mesh nebulizer was used to generate nanoparticle-loaded droplets with a mass median aerodynamic diameter of 2.13 μm as measured by cascade impaction, and a volumetric median diameter of 4.09 μm as measured by laser diffraction. In an adult breathing simulation experiment, 65.1% of the ATRA PLGA-NP dose was inhaled. This targeted inhaled HDT could offer a new adjunctive TB treatment option that could enhance current dosage regimens leading to better patient prognosis and a decreasing incidence of MDR-TB.