Lysosomotropic agents ameliorate macrophage dysfunction following the phagocytosis of IgG-coated erythrocytes: a role for lipid peroxidation

Lysosomotropic Features and Autophagy Modulators among Medical Drugs: Evaluation of Their Role in Pathologies

The concept of lysosomotropic agents significantly changed numerous aspects of cellular biochemistry, biochemical pharmacology, and clinical medicine. In the present review, we focused on numerous low-molecular and high-molecular lipophilic basic compounds and on the role of lipophagy and autophagy in experimental and clinical medicine. Attention was primarily focused on the most promising agents acting as autophagy inducers, which offer a new window for treatment and/or prophylaxis of various diseases, including type 2 diabetes mellitus, Parkinson's disease, and atherosclerosis. The present review summarizes current knowledge on the lysosomotropic features of medical drugs, as well as autophagy inducers, and their role in pathological processes.

Efficacy analysis of hydroxychloroquine therapy in systemic lupus erythematosus: a study on disease activity and immunological biomarkers

BACKGROUND

Hydroxychloroquine (HCQ) is a widely prescribed medication to patients with systemic lupus erythematosus (SLE), with potential anti-inflammatory effects. This study was performed to investigate the efficacy of HCQ therapy by serial assessment of disease activity and serum levels of proinflammatory cytokines in SLE patients.

METHODS

In this prospective cohort study, 41 newly diagnosed SLE patients receiving 400 mg HCQ per day were included. Patients requiring statins and immunosuppressive drugs except prednisolone at doses lower than 10 mg/day were excluded. Outcome measures were assessed before commencement of HCQ therapy (baseline visit) as well as in two follow-up visits (1 and 2 months after beginning the HCQ therapy). Serum samples of 41 age-matched healthy donors were used as controls.

RESULTS

Median levels of IL-1β (p < 0.001), IL-6 (p = 0.001), and TNF-α (p < 0.001) were significantly higher, whereas, median CH50 level was significantly lower (p < 0.001) in SLE patients compared with controls. Two-month treatment with HCQ resulted in significant decrease in SLEDAI-2K (p < 0.001), anti-dsDNA (p < 0.001), IL-1β (p = 0.003), IL-6 (p < 0.001) and TNF-α (p < 0.001) and a significant increase in CH50 levels (p = 0.012). The reductions in SLEDAI-2K and serum levels of IL-1β and TNF-α were significantly greater in the first month compared with the reductions in the second month.

CONCLUSION

HCQ therapy is effective on clinical improvement of SLE patients through interfering with inflammatory signaling pathways, reducing anti-DNA autoantibodies and normalizing the complement activity.

Oxidative stress and autophagy in the regulation of lysosome-dependent neuron death

Lysosomes critically regulate the pH-dependent catabolism of extracellular and intracellular macromolecules delivered from the endocytic/heterophagy and autophagy pathways, respectively. The importance of lysosomes to cell survival is underscored not only by their unique ability effectively to degrade metalloproteins and oxidatively damaged macromolecules, but also by the distinct potential for induction of both caspase-dependent and -independent cell death with a compromise in the integrity of lysosome function. Oxidative stress and free radical damage play a principal role in cell death induced by lysosome dysfunction and may be linked to several upstream and downstream stimuli, including alterations in the autophagy degradation pathway, inhibition of lysosome enzyme function, and lysosome membrane damage. Neurons are sensitive to lysosome dysfunction, and the contribution of oxidative stress and free radical damage to lysosome dysfunction may contribute to the etiology of neurodegenerative disease. This review provides a broad overview of lysosome function and explores the contribution of oxidative stress and autophagy to lysosome dysfunction-induced neuron death. Putative signaling pathways that either induce lysosome dysfunction or result from lysosome dysfunction or both, and the role of oxidative stress, free radical damage, and lysosome dysfunction in pediatric lysosomal storage disorders (neuronal ceroid lipofuscinoses or NCL/Batten disease) and in Alzheimer's disease are emphasized.

Antimalarials in cutaneous lupus erythematosus: mechanisms of therapeutic benefit

Antimalarials are arguably the best modality currently available for treating patients with cutaneous lupus erythematosus (LE). Although antimalarials have been used for decades in treating cutaneous LE, the precise mechanisms by which they provide therapeutic benefit are not well defined. The putative mechanisms by which antimalarials might provide therapeutic benefit to patients with cutaneous LE include a number of interrelated anti-inflammatory and immunosuppressive effects that include photoprotection, lysosomal stabilization, suppression of antigen presentation, and inhibition of prostaglandin and cytokine synthesis. If we had a more precise understanding of how antimalarials provide therapeutic benefit in cutaneous LE we might gain better insight into the pathogenic mechanisms of LE and ways of developing better therapies for afflicted patients.

Role of an oxidative stress in the macrophage dysfunction caused by erythrophagocytosis

A phagocytic challenge with immunoglobulin G (IgG)-coated erythrocytes (EIgGs) has been shown to cause a subsequent depression of macrophage respiratory burst capacity and phagocytic function. The present study evaluated the hypothesis that this macrophage dysfunction is caused by an oxidative stress. An oxidative stress induced by ferric ammonium citrate (FAC) plus cumene hydroperoxide (CHP) caused a depression of macrophage function that was attenuated by antioxidants and iron chelators. In contrast, the same antioxidants and iron chelators did not alter changes caused by a challenge with EIgGs. EIgG challenge caused an increase in lipid peroxidation but failed to deplete glutathione (GSH) or decrease the activity of glyceraldehyde-3-phosphate dehydrogenase (GA-3-PD), suggesting that there was only a slight oxidative stress. Inhibition of the Fc gamma receptor (Fc gammaR) stimulated respiratory burst by removing calcium during the challenge did not attenuate the changes caused by an EIgG challenge. A phagocytic challenge with nonerythrocyte particles, IgG-coated beads (BIgGs), did not depress the respiratory burst capacity but did depress phagocytic function. Fc gammaR expression was depressed following a phagocytic challenge but not an oxidative stress. Thus, an oxidative stress can depress macrophage function, but the dysfunction caused by a phagocytic challenge with EIgGs involves Fc gammaR depletion and the erythrocyte contents rather than an oxidative stress.