In Vivo Remodeling of Altered Autophagy-Lysosomal Pathway by a Phosphopeptide in Lupus

Abstract

The phosphopeptide P140/Lupuzor, which improves the course of lupus disease in mice and patients, targets chaperone-mediated autophagy (CMA), a selective form of autophagy that is abnormally upregulated in lupus-prone MRL/lpr mice. Administered intravenously to diseased mice, P140 reduces the expression level of two major protein players of CMA, LAMP2A and HSPA8, and inhibits CMA in vitro in a cell line that stably expresses a CMA reporter. Here, we aimed to demonstrate that P140 also affects CMA in vivo and to unravel the precise cellular mechanism of how P140 interacts with the CMA process. MRL/lpr mice and CBA/J mice used as control received P140 or control peptides intravenously. Lysosome-enriched fractions of spleen or liver were prepared to examine lysosomal function. Highly purified lysosomes were further isolated and left to incubate with the CMA substrate to study at which cellular step P140 interacts with the CMA process. The data show that P140 effectively regulates CMA in vivo in MRL/lpr mice at the step of substrate lysosomal uptake and restores some alterations of defective lysosomes. For the first time, it is demonstrated that by occluding the intralysosome uptake of CMA substrates, a therapeutic molecule can attenuate excessive CMA activity in a pathological pro-inflammatory context and protect against hyperinflammation. This recovery effect of P140 on hyperactivated CMA is not only important for lupus therapy but potentially also for treating other (auto)inflammatory diseases, including neurologic and metabolic disorders, where CMA modulation would be highly beneficial.

B Cell Metabolism and Autophagy in Autoimmunity

“…While some of the therapeutic effects of rapamycin and metformin may derive from targeting B cell autophagy, this process is affected more clearly by rigerimod ( 111 ). Rigerimod disrupts chaperone–mediated autophagy, likely affecting the MHC–II–restricted presentation of endogenous antigens to autoreactive T cells ( 112 , 137 ). In mice, rigerimod suppresses autoimmune responses without compromising anti–viral immunity ( 138 , 139 ).…”

Interplay between mesenchymal stromal cells and immune system: clinical applications in immune-related diseases

“…In this direction, the immunosuppressive properties exerted by MSCs can be proven useful to halt the B cell proliferation and differentiation (Table 3). Previous studies have demonstrated that SLE patients are characterized by autophagy-activated CD4+ T helper and CD8+ cytotoxic T cells [118,119]. Specifically, CD4+ and CD8+ T cell subsets are characterized by defective mitochondria, mitochondrial hyperpolarization, ATP depletion and increased apoptosis [118,119].…”

“…Previous studies have demonstrated that SLE patients are characterized by autophagy-activated CD4+ T helper and CD8+ cytotoxic T cells [118,119]. Specifically, CD4+ and CD8+ T cell subsets are characterized by defective mitochondria, mitochondrial hyperpolarization, ATP depletion and increased apoptosis [118,119]. MSCs can effectively rescue the T cells from apoptosis using tunneling nanotubes to transfer their mitochondria.…”

Potential for Antigen-Specific Tolerizing Immunotherapy in Systematic Lupus Erythematosus

“…This promiscuous peptide sequence was identified using ex vivo peptide screening techniques (143). This epitope is recognized by IgG antibodies and CD4+ T cells from H-2 k MRL/lpr and H-2 d/z (NZB × NZW)F1 lupus-prone mice (143,144). With i.v.…”

“…A 70K-U1RNP 131-151 T helper epitope was identified in NZBxNZW F1 and MRL/ Fas(lpr) mice, which led to further identification of SmD1 and hnRNP A2/B1 epitopes in each strain. Of interest the SmD 95-119 epitope recognized by anti-Sm antibodies is homologous to an Epstein-Barr virus EBNA I peptide, suggesting a mechanism for epitope spreading through bystander T helper cells (144,175). Certain nuclear antigens tend to induce epitope spreading to related other nuclear antigens in mouse models (Table 2).…”