A systemically administered detoxified TLR4 agonist displays potent antitumor activity and an acceptable tolerance profile in preclinical models

Post-cerebral ischemia energy crisis: the role of glucose metabolism in the energetic crisis

BACKGROUND

Cells universally employ an efficiency-driven metabolic switch mechanism during nutritional changes, growth, and differentiation, transitioning from oxidative phosphorylation (OXPHOS) to glycolysis to ensure survival under hypoxic conditions or high energy demands. In cerebral ischemia, inadequate blood supply causes oxygen and energy deprivation, prompting brain cells to initiate glycolytic reprogramming to meet urgent energy needs. While this adaptation is a temporary solution, it may lead to lactic acidosis, aggravated inflammation, and increased free radical production. Prolonged reperfusion with sustained glycolysis can exacerbate brain cell damage, potentially causing irreversible harm.

OBJECTIVES

This review systematically examines the dynamic changes in glucose metabolic transport mechanisms and the roles of immediate, early, intermediate, and late responder cells, along with their regulatory factors, in glycolytic reprogramming.

METHODS

Using a temporal analysis framework based on the body's natural response sequence to pathological events, we elucidate how cells at different stages collaborate to address glucose metabolism reprogramming under pathological conditions.

CONCLUSIONS

Reversing glucose metabolism reprogramming and inhibiting glycolysis may improve the pathological processes of ischemic stroke, offering potential therapeutic benefits.

A detoxified TLR4 agonist inhibits tumour growth and lung metastasis of osteosarcoma by promoting CD8+ cytotoxic lymphocyte infiltration

BACKGROUND

Osteosarcoma is the most common malignant bone tumour with limited treatment options and poor outcomes in advanced metastatic cases. Current immunotherapies show limited efficacy, highlighting the need for novel therapeutic approaches. Systemic immune activation by Toll-like receptor 4 (TLR4) immunostimulants has shown great promise; however, current TLR4 agonists' toxicity hinders this systemic approach in patients with osteosarcoma.

METHODS

We compared the antitumour effect of lipopolysaccharides (LPS) with that of an innovative chemically detoxified TLR4 agonist (Lipo-MP-LPS) in a syngeneic metastatic osteosarcoma mouse model. Lipo-MP-LPS exhibited an optimal safety and solubility profile for systemic administration at an effective dose. We evaluated tumour growth, lung metastases, and immune cell infiltration in wild-type and TLR4-mutant mice and performed selective immunodepletion.

RESULTS

Lipo-MP-LPS exhibited antitumour effects against localised osteosarcoma tumours and lung metastases, like those of natural LPS. Lipo-MP-LPS promoted CD8+ T cells and M1 macrophages infiltration in primary tumours and CD8+ T cells in metastases, with an M1-phenotype macrophage shift. The Lipo-MP-LPS antitumour effects were found to depend on TLR4 and CD8+ T cells, but not on macrophages.

CONCLUSION

Lipo-MP-LPS inhibited tumour growth and lung metastasis of osteosarcoma by promoting CD8 + T cell infiltration, indicating its therapeutic potential for advanced osteosarcoma.

Impact on Human Health of Salmonella spp. and Their Lipopolysaccharides: Possible Therapeutic Role and Asymptomatic Presence Consequences

Epidemiologically, one of the most important concerns associated with introducing Salmonella spp. into the environment and food chain is the presence of asymptomatic carriers. The oncogenic and oncolytic activity of Salmonella and their lipopolysaccharides (LPSs) is important and research on this topic is needed. Even a single asymptomatic dose of the S. Enteritidis LPS (a dose that has not caused any symptoms of illness) in in vivo studies induces the dysregulation of selected cells and bioactive substances of the nervous, immune, and endocrine systems. LPSs from different species, and even LPSs derived from different serotypes of one species, can define different biological activities. The activity of low doses of LPSs derived from three different Salmonella serotypes (S. Enteritidis, S. Typhimurium, and S. Minnesota) affects the neurochemistry of neurons differently in in vitro studies. Studies on lipopolysaccharides from different Salmonella serotypes do not consider the diversity of their activity. The presence of an LPS from S. Enteritidis in the body, even in amounts that do not induce any symptoms of illness, may lead to unknown long-term consequences associated with its action on the cells and biologically active substances of the human body. These conclusions should be important for both research strategies and the pharmaceutical industry &.

Combination of lipopolysaccharide and polygalacturonic acid exerts antitumor activity and augments anti-PD-L1 immunotherapy

Polygalacturonic acid (PGA) restored the alpha-diversity of gut microbiota and promoted T cells infiltration in tumors. Here, we investigated whether oral administration of PGA could improve the anti-cancer effect of lipopolysaccharide-encapsulated PLGA-PEG-PLGA (LPS/PPP) in mice bearing CT26 tumors. Hydrogels with rapid thermogelling properties can achieve localized and controlled release of LPS, thus retaining the anti-cancer effect of LPS and avoiding a robust inflammatory storm. LPS/PPP promoted M1 macrophage polarization, TLR4 expression, and phagocytosis in tumors. The combination of PGA and LPS/PPP (PGA_LPS) notably repressed CT26 tumor growth and the inhibition rate reached 67.6 %. PGA_LPS triggered the recruitment of helper and cytotoxic T cells, IFN-γ level, decreased the proportion of immunosuppressive regulatory T cells. PGA_LPS also restored the beta-diversity of gut microbiota and increased short chain fatty acids abundance (butyric acid, 608.93 % vs. model group, P < 0.01). PGA_LPS followed by αPD-L1 resulted in obvious inhibition of both CT26 and 4T1 tumor growth, promoted cleaved-caspase 3 and Bax expression, T cell responses and the rescue of T cells exhaustion. These results confirmed that PGA_LPS reinforced the anticancer effect of αPD-L1, probably by reshaping the tumor microenvironment and intestinal flora, which sheds light on the combination approach to intensify the effect of immune checkpoint inhibitors.

Diversity, Complexity, and Specificity of Bacterial Lipopolysaccharide (LPS) Structures Impacting Their Detection and Quantification

Endotoxins are toxic lipopolysaccharides (LPSs), extending from the outer membrane of Gram-negative bacteria and notorious for their toxicity and deleterious effects. The comparison of different LPSs, isolated from various Gram-negative bacteria, shows a global similar architecture corresponding to a glycolipid lipid A moiety, a core oligosaccharide, and outermost long O-chain polysaccharides with molecular weights from 2 to 20 kDa. LPSs display high diversity and specificity among genera and species, and each bacterium contains a unique set of LPS structures, constituting its protective external barrier. Some LPSs are not toxic due to their particular structures. Different, well-characterized, and highly purified LPSs were used in this work to determine endotoxin detection rules and identify their impact on the host. Endotoxin detection is a major task to ensure the safety of human health, especially in the pharma and food sectors. Here, we describe the impact of different LPS structures obtained under different bacterial growth conditions on selective LPS detection methods such as LAL, HEK-blue TLR-4, LC-MS2, and MALDI-MS. In these various assays, LPSs were shown to respond differently, mainly attributable to their lipid A structures, their fatty acid numbers and chain lengths, the presence of phosphate groups, and their possible substitutions.

A TLR4 Agonist Induces Osteosarcoma Regression by Inducing an Antitumor Immune Response and Reprogramming M2 Macrophages to M1 Macrophages

Osteosarcoma (OsA) has limited treatment options and stagnant 5-year survival rates. Its immune microenvironment is characterized by a predominance of tumor-associated macrophages (TAMs), whose role in OsA progression remain unclear. Nevertheless, immunotherapies aiming to modulate macrophages activation and polarization could be of interest for OsA treatment. In this study, the antitumor effect of a liposome-encapsulated chemically detoxified lipopolysaccharide (Lipo-MP-LPS) was evaluated as a therapeutic approach for OsA. Lipo-MP-LPS is a toll-like receptor 4 (TLR4) agonist sufficiently safe and soluble to be IV administered at effective doses. Lipo-MP-LPS exhibited a significant antitumor response, with tumor regression in 50% of treated animals and delayed tumor progression in the remaining 50%. The agent inhibited tumor growth by 75%, surpassing the efficacy of other immunotherapies tested in OsA. Lipo-MP-LPS modulated OsA's immune microenvironment by favoring the transition of M2 macrophages to M1 phenotype, creating a proinflammatory milieu and facilitating T-cell recruitment and antitumor immune response. Overall, the study demonstrates the potent antitumor effect of Lipo-MP-LPS as monotherapy in an OsA immunocompetent model. Reprogramming macrophages and altering the immune microenvironment likely contribute to the observed tumor control. These findings support the concept of immunomodulatory approaches for the treatment of highly resistant tumors like OsA.