HSPB5 suppresses renal inflammation and protects lupus-prone NZB/W F1 mice from severe renal damage.

BACKGROUND: Lupus nephritis (LN) is an inflammatory disease of the kidneys affecting patients with systemic lupus erythematosus. Current immunosuppressive and cytotoxic therapies are associated with serious side effects and fail to protect 20-40% of LN patients from end-stage renal disease. In this study, we investigated whether a small heat shock protein, HSPB5, can reduce kidney inflammation and the clinical manifestations of the disease in NZB/W F1 mice. Furthermore, we investigated whether HSPB5 can enhance the effects of methylprednisolone, a standard-of-care drug in LN, in an endotoxemia mouse model. METHODS: NZB/W F1 mice were treated with HSPB5, methylprednisolone, or vehicle from 23 to 38 weeks of age. Disease progression was evaluated by weekly proteinuria scores. At the end of the study, the blood, urine, spleens, and kidneys were collected for the assessment of proteinuria, blood urea nitrogen, kidney histology, serum IL-6 and anti-dsDNA levels, immune cell populations, and their phenotypes, as well as the transcript levels of proinflammatory chemokine/cytokines in the kidneys. HSPB5 was also evaluated in combination with methylprednisolone in a lipopolysaccharide-induced endotoxemia mouse model; serum IL-6 levels were measured at 24 h post-endotoxemia induction. RESULTS: HSPB5 significantly reduced terminal proteinuria and BUN and substantially improved kidney pathology. Similar trends, although to a lower extent, were observed with methylprednisolone treatment. Serum IL-6 levels and kidney expression of BAFF, IL-6, IFNγ, MCP-1 (CCL2), and KIM-1 were reduced, whereas nephrin expression was significantly preserved compared to vehicle-treated mice. Lastly, splenic Tregs and Bregs were significantly induced with HSPB5 treatment. HSPB5 in combination with methylprednisolone also significantly reduced serum IL-6 levels in endotoxemia mice. CONCLUSIONS: HSPB5 treatment reduces kidney inflammation and injury, providing therapeutic benefits in NZB/W F1 mice. Given that HSPB5 enhances the anti-inflammatory effects of methylprednisolone, there is a strong interest to develop HSBP5 as a therapeutic for the treatment of LN.

The small heat shock protein HSPB5 attenuates the severity of lupus nephritis in lupus-prone mice.

Lupus nephritis (LN) is a common and serious complication of systemic lupus erythematosus. The current treatments for LN are accompanied with severe immunotoxicity and have limits of effectiveness. Since our in vitro experiments demonstrated that a small heat shock protein (HSP), alpha-B crystallin (HSPB5; CRYAB), selectively modulates myeloid cells towards anti-inflammatory and tolerogenic phenotypes, the aim of this study was to investigate whether HSPB5 can attenuate the severity of LN. MRL/lpr mice were treated intravenously with HSPB5 at 2.5 or 10 µg/dose twice per week after disease onset, from 11 to 21 weeks of age. Disease progression was monitored by weekly measurements of proteinuria, and sera, spleens, and kidneys were collected for assessment at the terminal time point. Treatment with 10 µg HSPB5 substantially reduced endocapillary proliferation and tubular atrophy, which significantly reduced proteinuria and blood urea nitrogen (BUN). Compared to vehicle, 10 µg HSPB5 treatment substantially decreased activation/proliferation of splenocytes, increased IL-10+ macrophages, T and B regulatory cells (Treg, Breg), increased serum IL-10, and lowered expression of IL-6 in kidneys, which correlated with improved kidney function and pathology. This study demonstrated the utility of exogenous human HSPB5 to attenuate severe nephropathy in MRL/lpr mice and provides evidence in favour of a novel therapeutic approach for lupus nephritis.

Knockdown of BNIP3L or SQSTM1 alters cellular response to mitochondria target drugs.

Macroautophagy/autophagy, a pathway by which cellular components are sequestered and degraded in response to homeostatic and cell stress-related signals, is required to preserve hematopoietic stem and progenitor cell function. Loss of chromosomal regions carrying autophagy genes and decreased autophagy gene expression are characteristic of acute myeloid leukemia (AML) cells. Deficiency of autophagy proteins is also linked to an altered AML metabolic profile; altered metabolism has recently emerged as a potential druggable target in AML. Here, we sought to understand the mitochondria-specific changes that occur in leukemia cells after knockdown of BNIP3L/Nix or SQSTM1/p62, which are two autophagy genes involved in mitochondrial clearance and are downregulated in primary AML cells. Mitochondrial function, as measured by changes in endogenous levels of reactive oxygen species (ROS) and mitochondrial membrane potential, was altered in leukemia cells deficient in these autophagy genes. Further, these AML cells were increasingly sensitive to mitochondria-targeting drugs while displaying little change in sensitivity to DNA-targeting agents. These findings suggest that BNIP3L or SQSTM1 may be useful prognostic markers to identify AML patients suitable for mitochondria-targeted therapies. Abbreviations: AML: acute myeloid leukemia; DHE: dihydroethidium; mtDNA: mitochondrial DNA; NAO: 10-N-nonyl acridine orange; PD: population doubling; R123: rhodamine 123; ROS: reactive oxygen species; TRC: transduced scramble controls.