Higher APOB is associated with poor renal outcome in lupus nephritis

AIMS: Lupus nephritis is a common and severe complication of SLE, significantly affecting patient morbidity and mortality. It is quite meaningful to identify some non-invasive predictors related to the progression of LN. Early intervention of these factors may delay the development to ESRD. METHODS AND RESULTS: This study included 462 LN patients at The Affiliated Hospital of Southwest Medical University from January 2018 to September 2023. The participants were divided into two groups: high APOB group (serum APOB > 0.8 g/L, n = 264) and the low APOB group (serum APOB ≤ 0.8 g/L, n = 198) according to the median baseline serum APOB concentration. The results demonstrated that LN patients in the high APOB group had significantly higher lipid metabolism-related indicators (P < 0.001), higher levels of urea, SUA, and SCr (P < 0.01), and a higher proportion of patients with CKD stages 3-4 (P = 0.011). The Kaplan-Meier survival curve showed that the high APOB group patients had worse renal prognosis (HR = 3.292, 95%CI: 1.835-5.907, P < 0.001). To investigate the impact of long-term APOB exposure, this study also collected various APOB exposure metrics in the cumAPOB cohort which included 286 LN patients. The statistical results showed that compared with the low cumAPOB group, the lipid metabolism-related indexes (P < 0.001) and the proportion of patients who reached endpoints (P = 0.001) in the high cumAPOB group were significantly higher. And the cumAPOB was a risk factor for poor renal prognosis in patients with LN. When the high APOB exposure time reached 3 years, the risk of endpoint events was approximately 15 times that of the control group (OR = 15.08, 95%CI 2.159-105.3, P = 0.006). CONCLUSION: Serum APOB level may be positively associated with the poor renal progression of LN. Key Points • Renal biopsy plays a key role in the evaluation and management of lupus nephritis (LN). However, some patients may not accept this detection for its invasive procedure. Therefore, it is quite meaningful to identify risk factors related to the progression of LN in some non-invasive method. • With the prolonged high-exposure duration of APOB, the risk of endpoint events in LN patients within the cohort gradually increased. • The impact of APOB on the renal prognosis of LN patients was not instantaneous, but results from long-term high-level cumulative exposure - a slow process of quantitative to qualitative change. • APOB was an independent risk factor for LN patients, with a cumulative effect.