In this study, we investigated for the first time the anti-inflammatory and immunomodulatory properties of crude polysaccharide (PSHT) extracted from green marine algae Halimeda tuna. PSHT exhibited anti-oxidant activity in vitro through scavenging 1, 1-diphenyl-2-picryl hydroxyl free radical, reducing Fe³⁺/ferricyanide complex, and inhibiting nitric oxide. PSHT maintained the erythrocyte membrane integrity and prevented hemolysis. Our results also showed that PSHT exerted a significant anti-edematic effect in vivo by decreasing advanced oxidation protein products and malondialdehyde levels and increasing the superoxide dismutase and glutathione peroxidase activities in rat’s paw model and erythrocytes. Interestingly, PSHT increased the viability of murine RAW264.7 macrophages and exerted an anti-inflammatory effect on lipopolysaccharide-stimulated cells by decreasing pro-inflammatory molecule levels, including nitric oxide, granulocyte-macrophage colony-stimulating factor (GM-CSF) and tumor necrosis factor-alpha (TNF-α). Our findings indicate that PSHT could be used as a potential immunomodulatory, anti-inflammatory, anti-hemolytic, and anti-oxidant agent. These results could be explained by the computational findings showing that polysaccharide building blocks bound both cyclooxygenase-2 (COX-2) and TNF-α with acceptable affinities.

The study of the tumor microenvironment (TME) has become an important part of colorectal cancer (CRC) research. Indeed, it is now accepted that the invasive character of a primary CRC is determined not only by the genotype of the tumor cells, but also by their interactions with the extracellular environment, which thereby orchestrates the development of the tumor. In fact, the TME cells are a double-edged sword as they play both pro- and anti-tumor roles. The interaction of the tumor-infiltrating cells (TIC) with the cancer cells induces the polarization of the TIC, exhibiting an antagonist phenotype. This polarization is controlled by a plethora of interconnected pro- and anti-oncogenic signaling pathways. The complexity of this interaction and the dual function of these different actors contribute to the failure of CRC control. Thus, a better understanding of such mechanisms is of great interest and provides new opportunities for the development of personalized and efficient therapies for CRC. In this review, we summarize the signaling pathways linked to CRC and their implication in the development or inhibition of the tumor initiation and progression. In the second part, we enlist the major components of the TME and discuss the complexity of their cells functions.

The development of non-toxic, novel anti-tumor alternatives that target key hallmark events of tumor progression is of a high priority for cancer therapy. Natural compounds, such as Essential oils (EOs) derived from plant extracts are a mixture of chemical components known for their diverse pharmacological properties, including anticancer potential. For this purpose, we investigated the antitumor activity of Eucalyptus globulus essential oil (EEO) and its major constituents against colorectal cancer cells in vitro. EEO significantly reduced the viability of colon cancer LS174 cells, induced caspase-dependent apoptosis and triggered cell cycle arrest by modulating the expression of several effectors involved in these processes. Mechanistically, EEO exhibited its activity by targeting p38, SAPK/JNK, ERK1/2, and AKT kinases in LS174 cells. Considering the pivotal role of p53 status in mediating the response to anticancer therapies, we further investigated the effects of Eucalyptol, 3-Cyclohexene-1-methanol, α-Pinene, and α-Terpineol, identified as major components of EEO, on the viability of human colon adenocarcinoma LS174 (wild type p53) and HT29 (mutant p53) cell lines. Interestingly, we highlighted for the first time that 3-Cyclohexene-1-methanol exhibited the most anti-proliferative activity against both tumor cells irrespective to their p53 status. It exerted its effect by inducing apoptotic cell death, disturbing cell cycle progression along with reducing the phosphorylation of key components of the proliferation and survival pathways p38, ERK1/2, and AKT kinases. Our results suggest that Eucalyptus essential oil and its component, 3-Cyclohexene-1-methanol represent promising multi-targeting candidates for colorectal cancer therapy.

Background: Vaccination constitutes the best strategy against COVID-19. In Tunisia, seven vaccines standing for the three main platforms, namely RNA, viral vector, and inactivated vaccines, have been used to vaccinate the population at a large scale. This study aimed to assess, in our setting, the kinetics of vaccine-induced anti-RBD IgG and IgA antibody responses. Methods: Using in-house developed and validated ELISA assays, we measured anti-RBD IgG and IgA serum antibodies in 186 vaccinated workers at the Institut Pasteur de Tunis over 12 months. Results: We showed that RNA vaccines were the most immunogenic vaccines, as compared to alum-adjuvanted inactivated and viral-vector vaccines, either in SARS-CoV-2-naïve or in SARS-CoV-2-experienced individuals. In addition to the IgG antibodies, the vaccination elicited RBD-specific IgAs. Vaccinated individuals with prior SARS-CoV-2 infection exhibited more robust IgG and IgA antibody responses, as compared to SARS-CoV-2-naïve individuals. Conclusions: After following up for 12 months post-immunization, we concluded that the hierarchy between the platforms for anti-RBD antibody-titer dynamics was RNA vaccines, followed by viral-vector and alum-adjuvanted inactivated vaccines.