Biology subjects

Joseph, J. P.

Publications and source records attributed to Joseph, J. P..

3 recordsLinked to original sources

bioRxiv2026

Comparative analysis of immunomodulatory effects of Artemisinin and Parthenolide on activation of immune cells and their roles in Salmonella Typhimurium infection

Plant-derived immunomodulators are of immense therapeutic interest, of which sesquiterpene lactones (SLs) are a promising source. Artemisinin and Parthenolide are two structurally related SLs that are known to inhibit NF-{kappa}B. However, whether this mechanism produces comparable immunomodulatory outcomes has not been directly examined. In this study, we compared the effects of Artemisinin and Parthenolide across different in vitro and in vivo inflammatory contexts: T-cell activation, macrophage activation, and Salmonella Typhimurium infection. Parthenolide inhibited mouse T-cell activation more effectively than Artemisinin in terms of cell cycling, IL-2 production, and induction of activation markers, CD69 and CD44. In addition, Parthenolide suppressed production of LPS-induced nitrite and pro-inflammatory cytokines in primary thioglycolate (TG)-elicited macrophages as well as RAW 264.7 cells. It also reduced ROS production across all tested conditions. In contrast, Artemisinin exhibited comparatively modest effects, although it increased IL-6 in LPS-activated RAW 264.7 cells. Neither compound reduced bacterial burden in an in vitro model of S. Typhimurium infection; however, Parthenolide, but not Artemisinin, lowered TNF- amounts. Together, these findings demonstrate that Parthenolide is a broader and more consistent immunomodulator than Artemisinin. These observations led us to investigate the effects of Parthenolide in an in vivo model of mice orally fed with S. Typhimurium. Parthenolide-treated mice showed higher survival accompanied with lower sera amounts of IL-6 and TNF-, indicating that its protective effects operate by limiting host immunopathology. The implications of these observations on the use of compounds that lower host inflammatory responses during infections are discussed.

immunology↗

bioRxiv2024

High intracellular calcium amounts inhibit activation-induced proliferation of mouse T cells

Optimal T cell activation is critical to orchestrate adaptive immune responses. Calcium is critical for T cell activation and integrates signaling pathways necessary to activate key transcription factors. In fact, patients with calcium channelopathies are immunodeficient. Here, we investigated the effects of different concentrations of intracellular calcium on activation of mouse T cells. High intracellular calcium amounts inhibited in vitro T cell proliferation as evidenced by a decreased cell cycling-to-hypodiploidy ratio in two models of activation: the combination of phorbol 12-myristate 13-acetate (PMA) and Ionomycin (an ionophore)/Thapsigargin (a SERCA inhibitor) or plate bound anti-CD3 and anti-CD28. High intracellular calcium amounts increased the production of reactive oxygen species (ROS) in T cells activated with PMA and Ionomycin and scavenging excess ROS using N-acetyl cysteine (NAC) or PEGylated superoxide dismutase (PEG-SOD) rescued the decrease in cycling-to-hypodiploidy ratio. To test the universality of our observations, we studied the effects of tert-Butylhydroquinone (tBHQ), a SERCA inhibitor and Nrf2 activator. tBHQ alone did not increase intracellular calcium amounts but increase was observed along with PMA. Also, tBHQ inhibited T cell activation in a dose-dependent manner in both in vitro models of T cell activation. Importantly, intraperitoneal injection of tBHQ ameliorated Dextran Sodium Sulfate (DSS)-induced colitis in mice as evidenced by rescue of colon length shortening and lower disease activity index. Overall, this study identifies high calcium amounts as a potential target to lower T cell activation. The implications of these observations are discussed as this strategy may be important in treatment of some autoimmune diseases.

immunology↗

bioRxiv2023

Functional loss of rffG and rfbB, encoding dTDP-glucose 4,6-dehydratase, changes colony morphology, cell shape, motility and virulence in Salmonella Typhimurium

Lipopolysaccharide (LPS) O-antigen and enterobacterial common antigen (ECA) play crucial roles in maintaining the structural integrity of the outer membrane in Gram-negative bacteria. Previous studies conducted with either LPS or ECA mutants have highlighted the importance of these cell surface polysaccharides in the physiology of Salmonella enterica serovar Typhimurium (S. Typhimurium). However, the functional consequences resulting from the abrogation of both O-antigen and ECA synthesis in S. Typhimurium are not well studied. In the present study, we generated single and double gene-deleted mutants of rffG and rfbB, which are paralogs, encoding dTDP-glucose 4,6-dehydratase that catalyze steps in the synthesis of both O-antigen and ECA. The functional loss of both rffG and rfbB ({Delta}rffG{Delta}rfbB), but not in single gene-deleted strains, results in a round cell morphology, smaller colony formation and altered LPS profile. In addition, the {Delta}rffG{Delta}rfbB strain displays defects in outer membrane permeability, causing hypersensitivity to bile and cell wall targeting antibiotics, e.g., meropenem and polymyxin B. Transcriptomic analysis identified flagellar and SPI-1 pathway to be highly down-regulated in the {Delta}rffG{Delta}rfbB strain which leads to impaired swimming and swarming motility and lower adhesion and invasion of HeLa cells. Importantly, the {Delta}rffG{Delta}rfbB strain is less proficient in colonizing Peyers patches, spleen and liver, is unable to induce pro-inflammatory cytokines and is attenuated in both the oral and intra-peritoneal models of S. Typhimurium infection in mice. Overall, this study highlights the importance of rffG and rfbB in maintaining cell wall integrity, colony and cellular morphology, motility and virulence in S. Typhimurium.

microbiology↗