Elevated expressions of GRP78/CHOP in lupus nephritis: their diagnostic value and association with PERK/IRE1α pathway-mediated renal cell apoptosis

doi:10.12122/j.issn.1673-4254.2025.10.01

Abstract

Abstract:

Objective To examine the changes in serum levels of endoplasmic reticulum stress (ERS) proteins GRP78/CHOP in patients with lupus nephritis (LN) and analyze their diagnostic value and association with renal pathological features. Methods From a sample bank established based on a multicenter cohort study of systemic lupus erythematosus (SLE), 60 LN patients and 35 SLE patients without renal involvement were randomly selected. ELISA was used to detect serum levels of GRP78 and CHOP in the patients to analyze their correlation with clinical features and their diagnostic ability for LN and active LN. MRL/lpr mice were used as an animal model of LN to examine their serum levels of GRP78 and CHOP expression and renal expressions of endoplasmic reticulum apoptosis-related proteins. Results Serum GRP78 and CHOP levels were significantly higher in LN patients than in SLE patients without renal involvement (P<0.05), and were also higher in active LN patients than in patients in the stable phase (P<0.05). Correlation analysis indicated that serum GRP78 and CHOP levels were positively correlated with SLEDAI scores and 24-h urinary protein. ROC analysis showed that CHOP had a high diagnostic ability for LN (AUC=0.762) and active LN (AUC=0.933). Consistent with the clinical findings, serum GRP78 and CHOP levels were elevated in LN mice, and the expressions of PERK and IRE1α pathway proteins were also increased in the kidneys of the mice. TUNEL staining showed increased renal cell apoptosis and elevated renal expressions of apoptosis-related proteins in LN mice. Conclusion Serum levels of GRP78/CHOP are increased in LN patients possibly in association with ERS-induced apoptosis mediated by the PERK/IRE1α dual pathway.

Key words: lupus nephritis, endoplasmic reticulum stress pathway, apoptosis, GRP78, CHOP, PERK/IRE1α

Yihan WANG, Weiqing ZHANG, Ting FANG, Zhimin XIE, Yongsheng FAN, Xinchang WANG. Elevated expressions of GRP78/CHOP in lupus nephritis: their diagnostic value and association with PERK/IRE1α pathway-mediated renal cell apoptosis[J]. Journal of Southern Medical University, 2025, 45(10): 2055-2061.

Figures/Tables 8

Tab.1 Comparison of general clinical data between the patients in LN group and SLE group

Item	LN (n=60)	SLE (n=35)	P
Age (year, Mean±SD)	41.31±2.08	38.24±2.73	0.28
Female [n (%)]	56 (93.33%)	33 (94.29%)	0.85
BMI (kg/m²)	21.84±0.60	22.99±0.98	0.35
SLEDAI	8.14±0.74	5.25±0.58	0.05
Illness duration (year)	8.18±1.33	8.90±1.90	0.57
24 h UTP (g/d)	1192.82±243.66	119.17±24.58	0.00
Anti-dsDNA[+(%)]	24 (40%)	11 (31.43%)	0.40
Anti-Sm[+(%)]	13 (21.67%)	8 (22.86%)	0.89
Hb (g/L)	115.25±3.04	123.04±5.66	0.10
PLT (10⁹/L)	188.19±10.36	213.90±13.08	0.31
WBC (10¹²/L)	5.81±0.50	5.68±0.49	0.63
C3 (g/L)	0.70±0.04	0.74±0.04	0.80
C4 (g/L)	0.14±0.02	0.12±0.02	0.20

Fig.1 Level of serum GRP78 and CHOP in LN and SLE patients. A: Serum level of GRP78 in LN and SLE patients. B: Serum level of CHOP in LN and SLE patients. C: Serum level of GRP78 in LN patients in active and remission phase. D: Serum level of CHOP in LN patients in active and remission phase. **P<0.01, ***P<0.001.

Fig.2 Correlation of GRP78 and CHOP with clinical parameters in LN patients. *P<0.05, **P<0.01.

Fig.3 Diagnostic capabilities of GRP78 and CHOP for LN. A: ROC curves of peripheral blood GRP78 and CHOP for diagnosing LN. B: ROC curves of GRP78 and CHOP for diagnosis of LN in the active phase.

Fig.4 Disease characteristics in the mouse models of LN. A: Serum level of IL-6 in LN and control groups. B: Serum level of TNF-α in LN and control groups. C: Serum level of anti-dsDNA in LN and control groups. D: Renal HE staining, PAS staining and IgG staining showing mesangial cell proliferation (blue arrow), lymphocytes infiltration (green arrow), and basement membrane thickening (red arrow) (scale bar=50 μm). **P<0.01, ***P<0.001.

Fig.5 Serum levels of GRP78 and CHOP in mouse models of LN. A: Serum levels of GRP78 in LN and control groups. B: Serum levels of CHOP in LN and control groups. **P<0.01.

Fig.6 Renal apoptosis is increased in mouse models of LN. A: Kidney TUNEL staining in LN and control groups (scale bar=50 μm). B: Expression of apoptosis-related proteins in LN and control groups. C: Relative expression levels of apoptosis-related proteins in the two groups. *P<0.05, **P<0.01.

Fig.7 Expressions of proteins related to endoplasmic reticulum stress apoptosis in the kidney of LN mice. A: Protein bands in Western blotting of endoplasmic reticulum stress-related proteins. B-I: Relative PERK phosphorylation level and relative expression levels of PERK, ATF4, CHOP, IREα, IREα, phosphorylated JNK, and JNK, respectively. *P<0.05, **P<0.01, ***P<0.001.

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