Comparing Factors Associated With Tubulointerstitial Inflammation in Lupus Nephritis

Routinely available serologic markers have no correlation with tubulointerstitial damage in patients with lupus nephritis (LN), underscoring a need to identify novel biomarkers and targeted therapies aimed at treating tubulointerstitial inflammation before the development of interstitial fibrosis and tubular atrophy (IF/TA), according to data published in Arthritis & Rheumatology.

The retrospective study, conducted at a community-based urban tertiary care center in Bronx, New York, is the largest study to date to compare a vast array of clinical and serologic factors associated with tubulointerstitial inflammation and IF/TA in patients with LN. The investigators identified patients with systemic lupus erythematosus who had had a renal biopsy that was consistent with LN between 2005 and 2017. Medical records were used to compile clinical data and multivariable logistic regression models were used to assess factors associated with tubulointerstitial inflammation and IF/TA.

A total of 203 patients with LN were included in this analysis. Results showed that 20% had moderate to severe tubulointerstitial inflammation, 22% had moderate to severe IF/TA, and 10% had both. Moderate to severe tubulointerstitial inflammation was associated with a shorter disease duration, black ethnicity, proliferative LN, and an estimated glomerular filtration rate (eGFR) of <60 mL/min/1.73m² at the time of biopsy. Moreover, the use of hydroxychloroquine (HCQ) was associated with significantly lower odds of moderate to severe tubulointerstitial inflammation (odds ratio, 0.27; 95% CI, 0.10-0.70; P =.008).

Factors associated with moderate to severe IF/TA included eGFR of <60 mL/min/1.73m² at the time of biopsy and proliferative LN. Furthermore, the presence of moderate to severe tubulointerstitial inflammation and older age was also linked to the presence of moderate to severe IF/TA. None of the routinely available serologic markers, including anti-dsDNA, anti-Ro/La antibodies, and low complement, was associated with tubulointerstitial damage.

The investigators concluded that the use of HCQ was strongly associated with less inflammation in patients with LN. In addition, the findings of tubulointerstitial inflammation, proliferative LN, and low eGFR levels were the major determinants of the presence of tubulointerstitial scarring. They indicated that the identification of modifiable factors is crucial for the development of enhanced preventive and therapeutic strategies to improve survival in patients with lupus-related renal disease.

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Reference

Londoño Jimenez A, Mowrey WB, Putterman C, Buyon J, Goilav B, Broder A. Tubulointerstitial damage in lupus nephritis: a comparison of the factors associated with tubulointerstitial inflammation and renal scarring [published online May 31, 2018]. Arthritis Rheumatol. doi:10.1002/art.40575