Knockdown siRNA Targeting GPR55 Reveals Significant Differences Between the Anti-inflammatory Actions of KLS-13019 and Cannabidiol.

KLS-13019 was reported previously to reverse paclitaxel-induced mechanical allodynia in a mouse model of chemotherapy-induced peripheral neuropathy (CIPN). Recent studies demonstrated that paclitaxel-induced increases in inflammatory markers (GPR55, NLRP3, and IL-1ß) of dorsal root ganglion (DRG) cultures were shown to be reversed by KLS-13019 treatment. The mechanism of action for KLS-13019-mediated reversal of paclitaxel-induced neuroinflammation now has been explored using GPR55 siRNA. Pre-treatment of DRG cultures with GPR55 siRNA produced a 21% decrease of immunoreactive (IR) area for GPR55 in cell bodies and a 59% decrease in neuritic IR area, as determined by high-content imaging. Using a 24-h reversal treatment paradigm, paclitaxel-induced increases in the inflammatory markers were reversed back to control levels after KLS-3019 treatment. Decreases in these inflammatory markers produced by KLS-13019 were significantly attenuated by GPR55 siRNA co-treatment, with mean IR area responses being attenuated by 56% in neurites and 53% in cell bodies. These data indicate that the percentage decreases in siRNA-mediated attenuation of KLS-13019-related efficacy on the inflammatory markers were similar to the percentage knockdown observed for neuritic GPR55 IR area. Similar studies conducted with cannabidiol (CBD), the parent compound of KLS-13019, produced low efficacy (25%) reversal of all inflammatory markers that were poorly attenuated (29%) by GPR55 siRNA. CBD was shown previously to be ineffective in reversing paclitaxel-induced mechanical allodynia. The present studies indicated significant differences between the anti-inflammatory properties of KLS-13019 and CBD which may play a role in their observed differences in the reversibility of mechanical allodynia in a mouse model of CIPN.

Knockdown siRNA targeting GPR55 reveals significant differences between the anti-inflammatory actions of KLS-13019 and cannabidiol.

KLS-13019 was reported previously to reverse paclitaxel-induced mechanical allodynia in a mouse model of chemotherapy-induced peripheral neuropathy (CIPN). Recent studies demonstrated that paclitaxel-induced increases in inflammatory markers (GPR55, NLRP3 and IL-1b) of dorsal root ganglion (DRG) cultures were shown to be reversed by KLS-13019 treatment. The mechanism of action for KLS-13019-mediated reversal of paclitaxel-induced neuroinflammation now has been explored using GPR55 siRNA. Pretreatment of DRG cultures with GPR55 siRNA produced a 21% decrease of immunoreactive (IR) area for GPR55 in cell bodies and a 59% decrease in neuritic IR area, as determined by high content imaging. Using a 24-hour reversal treatment paradigm, paclitaxel-induced increases in the inflammatory markers were reversed back to control levels after KLS-3019 treatment. Decreases in these inflammatory markers produced by KLS-13019 were significantly attenuated by GPR55 siRNA co-treatment, with mean IR area responses being attenuated by 56% in neurites and 53% in cell bodies. These data indicate that the percentage decreases in siRNA-mediated attenuation of KLS-13019-related efficacy on the inflammatory markers were similar to the percentage knockdown observed for neuritic GPR55 IR area. Similar studies conducted with cannabidiol (CBD), the parent compound of KLS-13019, produced low efficacy (25%) reversal of all inflammatory markers that were poorly attenuated (29%) by GPR55 siRNA. CBD was shown previously to be ineffective in reversing paclitaxel-induced mechanical allodynia. The present studies indicated significant differences between the anti-inflammatory properties of KLS-13019 and CBD which may play a role in their observed differences in the reversibility of mechanical allodynia in a mouse model of CIPN.

Nonoperative Management of Lateral Epicondyle Tendinopathy: An Umbrella Review.

Objective: The primary objective of this review was to summarize systematic reviews and meta-analyses reporting on nonoperative management of lateral epicondyle tendinopathy. Methods: An umbrella review of all published systematic reviews and meta-analyses was performed. Three databases were searched using the key words "tennis elbow," "lateral epicondylitis," "non-operative," and "non-surgical modalities." The search was limited to English-language systematic reviews and meta-analyses between the years of 2000 and 2022. Results: There were 114 systematic reviews/meta-analyses, of which 35 met our inclusion criteria. These articles reviewed the following nonoperative management strategies: ultrasound, shockwave therapy, injection procedures, low-level laser therapy, joint mobilizations, exercise therapy, and electrophysical modalities. Exercise therapy was beneficial in decreasing pain regardless of dosage or type. Conflicting results were seen with ultrasound, laser, and shockwave therapy. Corticosteroid injections provided the most short-term pain relief, and platelet-rich plasma and autologous blood injections were most effective in the long term. Conclusion: A variety of nonoperative interventions were found to be effective for short- and long-term pain relief as well as functional improvement, with most interventions indicating mixed results. Due to variations in study populations and study quality, results should be interpreted with caution.

Quantitative Attribution of the Protective Effects of Aminosterols against Protein Aggregates to Their Chemical Structures and Ability to Modulate Biological Membranes.

Natural aminosterols are promising drug candidates against neurodegenerative diseases, like Alzheimer and Parkinson, and one relevant protective mechanism occurs via their binding to biological membranes and displacement or binding inhibition of amyloidogenic proteins and their cytotoxic oligomers. We compared three chemically different aminosterols, finding that they exhibited different (i) binding affinities, (ii) charge neutralizations, (iii) mechanical reinforcements, and (iv) key lipid redistributions within membranes of reconstituted liposomes. They also had different potencies (EC50) in protecting cultured cell membranes against amyloid-ß oligomers. A global fitting analysis led to an analytical equation describing quantitatively the protective effects of aminosterols as a function of their concentration and relevant membrane effects. The analysis correlates aminosterol-mediated protection with well-defined chemical moieties, including the polyamine group inducing a partial membrane-neutralizing effect (79 ± 7%) and the cholestane-like tail causing lipid redistribution and bilayer mechanical resistance (21 ± 7%), linking quantitatively their chemistry to their protective effects on biological membranes.

Efficient Syntheses of KLS-13019 Using Palladium Mediated Cross Couplings.

KLS-13019 is a structural analogue of cannabidiol, that shows improved bioavailability and potency in both preventing and reversing paclitaxel-induced neurotoxicity in vitro and in vivo. KLS-13019 was selected as a development candidate and attention was turned to development of a scalable synthesis. The original synthesis of KLS-13019 was not efficient, regioselective, or high yielding. Two new syntheses are reported that make use of the palladium catalyzed cross couplings to a chemically advanced intermediate 5, dramatically shortening (3-4 steps) and improving the overall yield. In addition, a convenient one pot Boc-cleavage and acetylation procedure is described to avoid impurities generated from a step-wise process.

Genetic Encoding of a Photocaged Histidine for Light-Control of Protein Activity.

The use of light to control protein function is a critical tool in chemical biology. Here we describe the addition of a photocaged histidine to the genetic code. This unnatural amino acid becomes histidine upon exposure to light and allows for the optical control of enzymes that utilize active-site histidine residues. We demonstrate light-induced activation of a blue fluorescent protein and a chloramphenicol transferase. Further, we genetically encoded photocaged histidine in mammalian cells. We then used this approach in live cells for optical control of firefly luciferase and, Renilla luciferase. This tool should have utility in manipulating and controlling a wide range of biological processes.

Genetic encoding of isobutyryl-, isovaleryl-, and ß-hydroxybutryl-lysine in E. coli.

Here we report the synthesis and genetic encoding of the lysine post translational modifications, ß-hydroxybutyryl-lysine, isobutyryl-lysine and isovaleryl-lysine. The ability to obtain a homogenous protein samples with site-specific incorporation of these acylated lysine residues can serve as a powerful tool to study the biological role of lysine post translational modifications.

Oral ENT-01 Targets Enteric Neurons to Treat Constipation in Parkinson Disease : A Randomized Controlled Trial.

BACKGROUND: Parkinson disease (PD) is associated with α-synuclein (αS) aggregation within enteric neurons. ENT-01 inhibits the formation of αS aggregates and improved constipation in an open-label study in patients with PD. OBJECTIVE: To evaluate the safety and efficacy of oral ENT-01 for constipation and neurologic symptoms in patients with PD and constipation. DESIGN: Randomized, placebo-controlled phase 2b study. (ClinicalTrials.gov: NCT03781791). SETTING: Outpatient. PATIENTS: 150 patients with PD and constipation. INTERVENTION: ENT-01 or placebo daily for up to 25 days. After baseline assessment of constipation severity, daily dosing was escalated to the prokinetic dose, the maximum dose (250 mg), or the tolerability limit, followed by a washout period. MEASUREMENTS: The primary efficacy end point was the number of complete spontaneous bowel movements (CSBMs) per week. Neurologic end points included dementia (assessed using the Mini-Mental State Examination [MMSE]) and psychosis (assessed using the Scale for the Assessment of Positive Symptoms adapted for PD [SAPS-PD]). RESULTS: The weekly CSBM rate increased from 0.7 to 3.2 in the ENT-01 group versus 0.7 to 1.2 in the placebo group (P < 0.001). Improvement in secondary end points included SBMs (P = 0.002), stool consistency (P < 0.001), ease of passage (P = 0.006), and laxative use (P = 0.041). In patients with dementia, MMSE scores improved by 3.4 points 6 weeks after treatment in the ENT-01 group (n = 14) versus 2.0 points in the placebo group (n = 14). Among patients with psychosis, SAPS-PD scores improved from 6.5 to 1.7 six weeks after treatment in the ENT-01 group (n = 5) and from 6.3 to 4.4 in the placebo group (n = 6). ENT-01 was well tolerated, with no deaths or drug-related serious adverse events. Adverse events were predominantly gastrointestinal, including nausea (34.4% [ENT-01] vs. 5.3% [placebo]; P < 0.001) and diarrhea (19.4% [ENT-01] vs. 5.3% [placebo]; P = 0.016). LIMITATION: Longer treatment periods need to be investigated in future studies. CONCLUSION: ENT-01 was safe and significantly improved constipation. PRIMARY FUNDING SOURCE: Enterin, Inc.

Anti-Inflammatory Properties of KLS-13019: a Novel GPR55 Antagonist for Dorsal Root Ganglion and Hippocampal Cultures.

KLS-13019, a novel devised cannabinoid-like compound, was explored for anti-inflammatory actions in dorsal root ganglion cultures relevant to chemotherapy-induced peripheral neuropathy (CIPN). Time course studies with 3 µM paclitaxel indicated > 1.9-fold increases in immunoreactive (IR) area for cell body GPR55 after 30 min as determined by high content imaging. To test for reversibility of paclitaxel-induced increases in GPR55, cultures were treated for 8 h with paclitaxel alone and then a dose response to KLS-13019 added for another 16 h. This "reversal" paradigm indicated established increases in cell body GPR55 IR areas were decreased back to control levels. Because GPR55 had previously reported inflammatory actions, IL-1ß and NLRP3 (inflammasome-3 marker) were also measured in the "reversal" paradigm. Significant increases in all inflammatory markers were produced after 8 h of paclitaxel treatment alone that were reversed to control levels with KLS-13019 treatment. Accompanying studies using alamar blue indicated that decreased cellular viability produced by paclitaxel treatment was reverted back to control levels by KLS-13019. Similar studies conducted with lysophosphatidylinositol (GPR55 agonist) in DRG or hippocampal cultures demonstrated significant increases in neuritic GPR55, NLRP3 and IL-1ß areas that were reversed to control levels with KLS-13019 treatment. Studies with a human GPR55-ß-arrestin assay in Discover X cells indicated that KLS-13019 was an antagonist without agonist activity. These studies indicated that KLS-13019 has anti-inflammatory properties mediated through GPR55 antagonist actions. Together with previous studies, KLS-13019 is a potent neuroprotective, anti-inflammatory cannabinoid with therapeutic potential for high efficacy treatment of neuropathic pain.

Behavioural and pharmacological effects of cannabidiol (CBD) and the cannabidiol analogue KLS-13019 in mouse models of pain and reinforcement.

BACKGROUND AND PURPOSE: Cannabidiol (CBD) is a non-euphorigenic component of Cannabis sativa that prevents the development of paclitaxel-induced mechanical sensitivity in a mouse model of chemotherapy-induced peripheral neuropathy (CIPN). We recently reported that the CBD structural analogue KLS-13019 shows efficacy in an in vitro model of CIPN. The present study was to characterize the behavioural effects of KLS-13019 compared to CBD and morphine in mouse models of CIPN, nociceptive pain and reinforcement. EXPERIMENTAL APPROACH: Prevention or reversal of paclitaxel-induced mechanical sensitivity were assessed following intraperitoneal or oral administration of CBD, KLS-13019 or morphine. Antinociceptive activity using acetic acid-induced stretching and hot plate assay, anti-reinforcing effects on palatable food or morphine self-administration and binding to human opioid receptors were also determined. KEY RESULTS: Like CBD, KLS-13019 prevented the development of mechanical sensitivity associated with paclitaxel administration. In contrast to CBD, KLS-13019 was also effective at reversing established mechanical sensitivity. KLS-13019 significantly attenuated acetic acid-induced stretching and produced modest effects in the hot plate assay. KLS-13019 was devoid of activity at µ-, δ- or κ-opioid receptors. Lastly, KLS-13019, but not CBD, attenuated the reinforcing effects of palatable food or morphine. CONCLUSIONS AND IMPLICATIONS: KLS-13019 like CBD, prevented the development of CIPN, while KLS-13019 uniquely attenuated established CIPN. Because KLS-13019 binds to fewer biological targets, this will help to identifying molecular mechanisms shared by these two compounds and those unique to KLS-13019. Lastly, KLS-13019 may possess the ability to attenuate reinforced behaviour, an effect not observed in the present study with CBD.

4F-MDMB-BINACA: A New Synthetic Cannabinoid Widely Implicated in Forensic Casework.

This is the first report regarding the characterization of the new synthetic cannabinoid 4F-MDMB-BINACA. 4F-MDMB-BINACA was first analytically confirmed in seized drug material using gas chromatography-mass spectrometry (GC-MS), liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-QTOF), and nuclear magnetic resonance (NMR) spectroscopy. Subsequent to this characterization, 4F-MDMB-BINACA was detected in biological specimens collected as part of forensically relevant casework, including medicolegal death investigations and drug impaired driving investigations, from a variety of regions in the United States. Further analysis of biological specimens resulted in the identification of the metabolites 4F-MDMB-BINACA 3,3-dimethylbutanoic acid and 4-OH-MDMB-BINACA. 4F-MDMB-BINACA is appearing with increasing frequency as a contributory factor in deaths, creating morbidity and mortality risks for drug users. Laboratories must be aware of its presence and impact, incorporating 4F-MDMB-BINACA into workflows for detection and confirmation.

Knockdown siRNA Targeting the Mitochondrial Sodium-Calcium Exchanger-1 Inhibits the Protective Effects of Two Cannabinoids Against Acute Paclitaxel Toxicity.

Treatment with cannabidiol (CBD) or KLS-13019 (novel CBD analog), has previously been shown to prevent paclitaxel-induced mechanical allodynia in a mouse model of chemotherapy-induced peripheral neuropathy (CIPN). The mechanism of action for CBD- and KLS-13019-mediated protection now has been explored with dissociated dorsal root ganglion (DRG) cultures using small interfering RNA (siRNA) to the mitochondrial Na+ Ca2+ exchanger-1 (mNCX-1). Treatment with this siRNA produced a 50-55% decrease in the immunoreactive (IR) area for mNCX-1 in neuronal cell bodies and a 72-80% decrease in neuritic IR area as determined with high-content image analysis. After treatment with 100 nM KLS-13019 and siRNA, DRG cultures exhibited a 75 ± 5% decrease in protection from paclitaxel-induced toxicity; whereas siRNA studies with 10 µM CBD produced a 74 ± 3% decrease in protection. Treatment with mNCX-1 siRNA alone did not produce toxicity. The protective action of cannabidiol and KLS-13019 against paclitaxel-induced toxicity during a 5-h test period was significantly attenuated after a 4-day knockdown of mNCX-1 that was not attributable to toxicity. These data indicate that decreases in neuritic mNCX-1 corresponded closely with decreased protection after siRNA treatment. Pharmacological blockade of mNCX-1 with CGP-37157 produced complete inhibition of cannabinoid-mediated protection from paclitaxel in DRG cultures, supporting the observed siRNA effects on mechanism.

Eternal Inflation and the Refined Swampland Conjecture.

I apply recently proposed "swampland" conjectures to eternal inflation in single-scalar field theories. Eternal inflation is a phase of infinite self-reproduction of a quasi-de Sitter universe which has been argued to be a generic consequence of cosmological inflation. The originally proposed de Sitter swampland conjectures were shown by Matsui and Takahashi, and by Dimopoulos, to be generically incompatible with eternal inflation. However, the more recently proposed "refined" swampland conjecture imposes a slightly weaker criterion on the scalar field potential in inflation, and is consistent with the existence of a tachyonic instability. In this Letter, I show that eternal inflation is marginally consistent with the refined de Sitter swampland conjecture. Thus, if the refined conjecture is correct, the existence of a landscape-based "multiverse" in string theory is not incompatible with a self-consistent ultraviolet completion, with significant consequences for model building in string theory.

Targeting neurons in the gastrointestinal tract to treat Parkinson's disease.

BACKGROUND: Parkinson's disease (PD) is associated with α-synuclein (αS) aggregation within the enteric nervous system (ENS) and constipation. Squalamine displaces proteins that are electrostatically bound to intracellular membranes and through this mechanism suppresses aggregation of αS monomers into neurotoxic oligomers. OBJECTIVE: We sought to evaluate the safety of ENT-01 oral tablets (a synthetic squalamine salt), its pharmacokinetics, and its effect on bowel function in PD patients with constipation. METHODS: In Stage 1, 10 patients received escalating single doses from 25 to 200 mg/day or maximum tolerated dose (MTD). In Stage 2, 34 patients received daily doses escalating from 75 to a maximum of 250 mg/day, a dose that induced change in bowel function or MTD, followed by a fixed dose for 7 days, and a 2-week washout. Primary efficacy endpoint was defined as an increase of 1 complete spontaneous bowel movement (CSBM)/week, or 3 CSBM/week over the baseline period, as defined by FDA guidelines for prokinetic agents. Safety was also assessed. RESULTS: Over 80% of patients achieved the primary efficacy endpoint, with the mean number of CSBM/week increasing from 1.2 at baseline to 3.6 during fixed dosing (p = 1.2 × 10-7). Common adverse events included nausea in 21/44 (47%) and diarrhea in 18/44 (40%) patients. Systemic absorption was <0.3%. CONCLUSIONS: Orally administered ENT-01 was safe and significantly improved bowel function in PD, suggesting that the ENS is not irreversibly damaged in PD. Minimal systemic absorption suggests that improvements result from local stimulation of the ENS. A double-blind, placebo-controlled study is now ongoing.

Pharmacological Comparisons Between Cannabidiol and KLS-13019.

Cannabidiol (CBD) exhibits neuroprotective properties in many experimental systems. However, development of CBD as a drug has been confounded by the following: (1) low potency; (2) a large number of molecular targets; (3) marginal pharmacokinetic properties; and (4) designation as a schedule 1 controlled substance. The present work compared the properties of CBD with a novel molecule (KLS-13019) that has structural similarities to CBD. The design strategy for KLS-13019 was to increase hydrophilicity while optimizing neuroprotective potency against oxidative stress toxicity relevant to hepatic encephalopathy. The protective responses of CBD and KLS-13019 were compared in dissociated rat hippocampal cultures co-treated with toxic levels of ethanol and ammonium acetate. This comparison revealed that KLS-13019 was 31-fold more potent than CBD in preventing neuronal toxicity from the combined toxin treatment, while both compounds exhibited complete protective efficacy back to control values. In addition, treatment with KLS-13019 alone was 5-fold less toxic (TC50) than CBD. Previous studies suggested that CBD targeted the Na+-Ca2+ exchanger in mitochondria (mNCX) to regulate intracellular calcium levels, an important determinant of neuronal survival. After treatment with an inhibitor of mNCX (CGP-37157), no detectable neuroprotection from ethanol toxicity was observed for either CBD or KLS-13019. Furthermore, AM630 (CB2 antagonist) significantly attenuated CBD-mediated neuroprotection, while having no detectable effect on neuroprotection from KLS-13019. Our studies indicated KLS-13019 was more potent and less toxic than CBD. Both compounds can act through mNCX. KLS-13019 may provide an alternative to CBD as a therapeutic candidate to treat diseases associated with oxidative stress.

Nature's combinatorial biosynthesis and recently engineered production of nucleoside antibiotics in Streptomyces.

Modified nucleosides produced by Streptomyces and related actinomycetes are widely used in agriculture and medicine as antibacterial, antifungal, anticancer and antiviral agents. These specialized small-molecule metabolites are biosynthesized by complex enzymatic machineries encoded within gene clusters in the genome. The past decade has witnessed a burst of reports defining the key metabolic processes involved in the biosynthesis of several distinct families of nucleoside antibiotics. Furthermore, genome sequencing of various Streptomyces species has dramatically increased over recent years. Potential biosynthetic gene clusters for novel nucleoside antibiotics are now apparent by analysis of these genomes. Here we revisit strategies for production improvement of nucleoside antibiotics that have defined mechanisms of action, and are in clinical or agricultural use. We summarize the progress for genetically manipulating biosynthetic pathways for structural diversification of nucleoside antibiotics. Microorganism-based biosynthetic examples are provided and organized under genetic principles and metabolic engineering guidelines. We show perspectives on the future of combinatorial biosynthesis, and present a working model for discovery of novel nucleoside natural products in Streptomyces.

Ester Prodrugs of IHVR-19029 with Enhanced Oral Exposure and Prevention of Gastrointestinal Glucosidase Interaction.

IHVR-19029 (6) is a lead endoplasmic reticulum α-glucosidases I and II inhibitor, which efficiently protected mice from lethal Ebola and Marburg virus infections via injection route, but suffered from low bioavailability and off-target interactions with gut glucosidases when administered orally. In an effort to improve efficacious exposure levels and avoid side effects, we designed and synthesized ester prodrugs. Not only were the prodrugs stable in simulated gastric and intestinal fluids and were inactive against glucosidases but they also exhibited antiviral activities against dengue virus infection in a cell based assay. Further in vitro evaluation showed that the bioconversion of the prodrugs is species dependent: in mice, the prodrugs were converted to 6 in the plasma and liver; while in human, the conversion occurred mainly in liver. An in vivo pharmacokinetic study in mice demonstrated that the tetrabutyrate prodrug 8 achieved the most improved overall exposure of 6 upon both oral and intravenous administration.

Novel substituted aminothiazoles as potent and selective anti-hepatocellular carcinoma agents.

Based on our previous identification of a disubstituted aminothiazole termed HBF-0079 with promising selective toxicity for HCC-derived cell lines versus non-HCC liver lines, a series of tri-substituted aminothiazole derivatives were prepared and evaluated. This work resulted in the discovery of isopropyl 4-(pyrazin-2-yl)-2-(pyrimidin-2-ylamino)thiazole-5-carboxylate, 14, which displayed EC50 value of 0.11µM and more than 450times of selectivity, and its methyl carbonate prodrug 24 with improved solubility in organic solvents. Furthermore, 14, was shown to reduce the proliferation of several liver cancer cells derived directly from patients.

Discovery of KLS-13019, a Cannabidiol-Derived Neuroprotective Agent, with Improved Potency, Safety, and Permeability.

Cannabidiol is the nonpsychoactive natural component of C. sativa that has been shown to be neuroprotective in multiple animal models. Our interest is to advance a therapeutic candidate for the orphan indication hepatic encephalopathy (HE). HE is a serious neurological disorder that occurs in patients with cirrhosis or liver failure. Although cannabidiol is effective in models of HE, it has limitations in terms of safety and oral bioavailability. Herein, we describe a series of side chain modified resorcinols that were designed for greater hydrophilicity and "drug likeness", while varying hydrogen bond donors, acceptors, architecture, basicity, neutrality, acidity, and polar surface area within the pendent group. Our primary screen evaluated the ability of the test agents to prevent damage to hippocampal neurons induced by ammonium acetate and ethanol at clinically relevant concentrations. Notably, KLS-13019 was 50-fold more potent and >400-fold safer than cannabidiol and exhibited an in vitro profile consistent with improved oral bioavailability.

Curcumin enhances human macrophage control of Mycobacterium tuberculosis infection.

BACKGROUND AND OBJECTIVE: With the worldwide emergence of highly drug-resistant tuberculosis (TB), novel agents that have direct antimycobacterial effects or that enhance host immunity are urgently needed. Curcumin is a polyphenol responsible for the bright yellow-orange colour of turmeric, a spice derived from the root of the perennial herb Curcuma longa. Curcumin is a potent inducer of apoptosis-an effector mechanism used by macrophages to kill intracellular Mycobacterium tuberculosis (MTB). METHODS: An in vitro human macrophage infection model was used to determine the effects of curcumin on MTB survival. RESULTS: We found that curcumin enhanced the clearance of MTB in differentiated THP-1 human monocytes and in primary human alveolar macrophages. We also found that curcumin was an inducer of caspase-3-dependent apoptosis and autophagy. Curcumin mediated these anti-MTB cellular functions, in part, via inhibition of nuclear factor-kappa B (NFκB) activation. CONCLUSION: Curcumin protects against MTB infection in human macrophages. The host-protective role of curcumin against MTB in macrophages needs confirmation in an animal model; if validated, the immunomodulatory anti-TB effects of curcumin would be less prone to drug resistance development.