Sulfasalazine

Rational: Intracellular bacterial survival is a major factor causing chronic or recurrent infection, leading to the failure of both host defense and/or antibiotic treatment. However, the elimination of intracellular bacteria is challenging as they are protected from antibiotics and host immune attack. Recent studies have indicated that iron helps macrophages against intracellular bacteria, contradictory to traditional "nutritional immunity", in which iron is considered a key nutrient for bacterial survival in host cells. However, how iron facilitates intracellular bacterial death has not been fully clarified. In this study, we found that ferroptotic stress can help macrophages suppress intracellular bacteria by reversing the importation of ferrous iron into bacterial vacuoles via ferroportin and thereby inducing in situ ferroptosis-like bacterial death. Methods: A macrophage model of bacterial invasion was established to monitor dynamic changes in ferroptotic hallmarks, including ferrous iron and lipid peroxidation. Ferroptosis inducers and inhibitors were added to the model to evaluate the relationship between ferroptotic stress and intracellular bacterial survival. We then determined the spatiotemporal distributions of ferroportin, ferrous iron, and lipid peroxidation in macrophages and intracellular bacteria. A bacterial infection mouse model was established to evaluate the therapeutic effects of drugs that regulate ferroptotic stress. Results: Ferrous iron and lipid peroxidation increased sharply in the early stage of bacterial infection in the macrophages, then decreased to normal levels in the late stage of infection. The addition of ferroptosis inducers (ras-selective lethal small molecule 3, sulfasalazine, and acetaminophen) in macrophages promoted intracellular bacterial suppression. Further studies revealed that ferrous iron could be delivered to the intracellular bacterial compartment via inward ferroportin transportation, where ferrous iron induced ferroptosis-like death of bacteria. In addition, ferroptotic stress declined to normal levels in the late stage of infection by regulating iron-related pathways in the macrophages. Importantly, we found that enhancing ferroptotic stress with a ferroptosis inducer (sulfasalazine) successfully suppressed bacteria in the mouse infection models. Conclusions: Our study suggests that the spatiotemporal response to ferroptosis stress is an efficient pathway for macrophage defense against bacterial invasion, and targeting ferroptosis may achieve therapeutic targets for infectious diseases challenged by intracellular pathogens.

The glutamate transporter xCT (SCL7a11, system Xc-, SXC) is an emerging key player in glutamate/cysteine/glutathione homeostasis in the brain and in cancer. xCT expression correlates with the grade of malignancy. Here, we report on the use of the U.S. Food and Drug Administration and EMA-approved xCT inhibitor, sulfasalazine (SAS) in gliomas. SAS does not affect cell viability in gliomas at concentrations below 200 µM. At higher concentrations SAS becomes gliomatoxic. Mechanistically SAS inhibits xCT and induces ferroptotic cell death in glioma cells. There is no evidence for impact on autophagic flux following SAS application. However, SAS can potentiate the efficacy of the standard chemotherapeutic and autophagy-inducing agent temozolomide (Temcat, Temodal or Temodar®). We also investigated SAS in non-transformed cellular constituents of the brain. Neurons and brain tissue are almost non-responding to SAS whereas isolated astrocytes are less sensitive towards SAS toxicity compared to gliomas. In vivo SAS treatment does not affect experimental tumor growth and treated animals revealed comparable tumor volume as untreated controls. However, SAS treatment resulted in reduced glioma-derived edema and, hence, total tumor volume burden as revealed by T2-weighted magnetic resonance imaging. Altogether, we show that SAS can be utilized for targeting the glutamate antiporter xCT activity as a tumor microenvironment-normalizing drug, while crucial cytotoxic effects in brain tumors are minor.

The sodium-independent cystine-glutamate antiporter plays an important role in extracellular cystine uptake. It comprises the transmembrane protein, xCT and its chaperone, CD98. Because glutathione is only weakly cell membrane permeable, cellular uptake of its precursor, cystine, is known to be a key step in glutathione synthesis. Moreover, it has been reported that xCT expression affects the progression of tumors and their resistance to therapy. Sulfasalazine is an inhibitor of xCT that is known to increase cellular oxidative stress, giving it anti-tumor potential. Here, we describe a radio-sensitizing effect of sulfasalazine using a B16F10 melanoma model. Sulfasalazine decreased glutathione concentrations and resistance to H2O2 in B16F10 melanoma cells, but not in mouse embryonic fibroblasts. It synergistically enhanced the cyto-killing effect of X-irradiation in B16F10 cells. It inhibited cellular DNA damage repair and prolonged cell cycle arrest after X-irradiation. Furthermore, in an in vivo transplanted melanoma model, sulfasalazine decreased intratumoral glutathione content, leading to enhanced susceptibility to radiation therapy. These results suggest the possibility of using SAS to augment the treatment of radio-resistant cancers.

BackgroundRheumatoid arthritis is indeed a constant, progressive autoimmune disease that acts on the synovial membrane, distinguished by joint pain, swelling, and tenderness. Sulfasalazine belongs to BCS Class IV having low solubility and low permeability. To overcome the issue and provide a localized effect Cubosomes were chosen for the transdermal drug delivery system.ObjectivesThe primary objective of this investigation was to pass on sulfasalazine-loaded cubosomes over the skin to treat rheumatoid arthritis. On the way to overcome this issue of oral sulfasalazine and provide localized effect, Cubosomes were chosen for the transdermal drug delivery system.MethodsSulfasalazine-loaded cubosomes were prepared by the top-down method using GMO and Poloxamer 407. Different concentrations of lipid and surfactant were used in the formulation using 32 full factorial designs. The prepared formulations were assessed for p.s, z,p, %EE, FTIR, SEM, in-vitro release, ex-vivo permeation, and deposition studies with pH 7.4 phosphate buffer saline.ResultsThe particle size varies between 65 nm to 129 nm, while the negative zeta potential ranged from - 18.8 mV to -24.8 mV. The entrapment efficiency was between 87% and 95%. The formulations' in-vitro drug release was carried out for 12 hours. The optimized formulation showed a controlled release of sulfasalazine and better ex-vivo permeation and deposition properties than sulfasalazine suspension.ConclusionOverall study findings support the possibility of applying transdermal sulfasalazineloaded cubosomes to alleviate rheumatoid arthritis.