| Abstract|| |
Renal involvement occurs in up to 60% of patients with systemic lupus erythematosus (SLE) and signifies a poor prognosis. The class of lupus nephritis (LN), determined on renal biopsy evaluation, guides the therapeutic management and has prognostic connotations. Our aim is to determine the clinicolaboratory features and histopathological patterns of LN at presentation in our local (South Indian) population. The study was conducted in a tertiary care hospital in South India between 2009 and 2014 on SLE patients with clinical evidence of LN. The renal biopsies were examined by light and immunofluorescence microscopy and were classified according to the International Society of Nephrology/Renal Pathology Society Classification of LN. A total of 46 patients were included, with age range of 12-60 years and a female to male ratio of 8.2:1. Arthritis, dermatological manifestations, and fever occurred, respectively, in 43.5%, 39.1%, and 30.4% of the cases. Class IV LN was present in 17 (37.1%), Class III LN in ten (21.7%), Class II LN in nine (19.5%), Class V LN in eight (17.4%), Class I LN in one (2.2%), and Class VI LN in one (2.2%) patients. Antinuclear antibody (ANA) and dsDNA positivity were present, respectively, in 82.6% and 65.2% of the patients. The most common pattern of LN was Class IV LN followed by Class III LN. Relatively higher proportions of ANA and anti-dsDNA positivity were present in proliferative LN, and there was a high frequency of arthritis at presentation in our LN patients.
|How to cite this article:|
Devadass CW, Mysorekar VV, Eshwarappa M, Mekala L, Siddaiah M G, Channabasappa K G. Clinical features and histological patterns of lupus nephritis in a single center of South India. Saudi J Kidney Dis Transpl 2016;27:1224-30
|How to cite this URL:|
Devadass CW, Mysorekar VV, Eshwarappa M, Mekala L, Siddaiah M G, Channabasappa K G. Clinical features and histological patterns of lupus nephritis in a single center of South India. Saudi J Kidney Dis Transpl [serial online] 2016 [cited 2020 Aug 9];27:1224-30. Available from: http://www.sjkdt.org/text.asp?2016/27/6/1224/194657
| Introduction|| |
Systemic lupus erythematosus (SLE) is a multi-system autoimmune disease exhibiting diverse clinicopathological manifestations.  Renal involvement [lupus nephritis (LN)] occurs in up to 60% of these patients during the course of the disease, accounting for a significant morbidity and mortality.  LN exhibits diverse clinical features with variable glomerular histopathological patterns. The class of LN discerned on renal biopsy evaluation highly correlates with prognosis and guides appropriate therapeutic management. , Prompt institution of immunosuppressive therapy, as determined by the renal pathologic lesion, results in favorable outcomes with high 10-year renal survival rates. ,,
The aim of the present study was to determine the clinicolaboratory features and histopathological patterns of LN at presentation in a single tertiary health-care center of South India.
| Materials and Methods|| |
The study was conducted in the Department of Pathology in collaboration with the Department of Nephrology, M. S. Ramaiah Medical College and Hospitals, Bengaluru, Karnataka, over a period of five years (between 2009 and 2014). Patients fulfilling the American College of Rheumatology Revised Criteria for Classification of SLE, exhibiting clinical evidence of LN with unexplained persistent proteinuria of ≥0.5 g/dL per day or hematuria (red blood cells >5/hpf) or leukocyturia (leucocytes >5/hpf) or cellular casts, who underwent percutaneous renal biopsy, were included in the study.  Examination of renal biopsy was done by light microscopy (hematoxylin and eosin, periodic acid-Schiff, Masson's trichrome, and Jones silver methenamine stains) and immunofluorescence microscopy using fluorescein isothiocyanate-conjugated rabbit antihuman immunoglobulin (Ig) G, IgM, IgA, andC3 from BioGenex. Clinical details and rele-vant investigations including age, sex, chief complaints, serum creatinine, 24 h proteinuria, urinalysis, complete blood counts, and serum complement levels (C3 and C4) were recorded. Antinuclear antibodies (ANAs) were detected by indirect immunofluorescence technique using commercial kits containing 5 × 2 BIOCHIPs coated with HEp-20-10 cells and primate liver [EUROIMMUN Medizinische labordiagnostika AG, D-23560 Lubek (Deutschland), Seekamp 31] on 1:100 serum dilutions as per the manufacturer's instructions. Antibodies to dsDNA were detected using EUROLINE test kits containing immunoblot strips coated with highly purified, native dsDNA isolated from salmon testes [EUROIMMUN Medizinische labordiagnostika AG, D-23560 Lubek (Deutschland), Seekamp 31]. The histology slides were interpreted independently and blindly by two nephropathologists, and classification was done according to the International Society of Nephrology/Renal Pathology Society Classification of LN as follows: Class I (minimal mesangial LN), Class II (mesangial proliferative LN), Class III (focal LN), Class IV (diffuse LN), Class V (membranous LN), and Class VI (advanced sclerotic LN). , As Class V LN with concurrent Class III LN (V + III) and Class V LN with concurrent Class IV (V + IV) assume the behavior of proliferative LN (i.e., Classes III and IV), these were included in the Class III and Class IV groups, respectively. For each biopsy, the activity (endocapillary hypercellularity, leukocyte infiltration, wire loops - subendothelial hyaline deposits and hyaline thrombi, fibrinoid necrosis/karyorrhexis, cellular crescents, and interstitial inflammation) and chronicity (glomerular sclerosis, fibrous crescents, tubular atrophy, and interstitial fibrosis) indices were computed. ,
The National Institutes of Health regimen was followed for the treatment of proliferative LN (Class III and Class IV), which included induction with intermittent intravenous cyclophosphamide (0.5-1 g/m 2 ) for six months, followed by maintenance with cyclophosphamide pulses or azathioprine (2-3 mg/day). Mycophenolate mofetil (2 mg/day) was used for induction in some patients. All patients received prednisolone (1 mg/kg/day) for at least four weeks, which was tapered gradually to 5-10 mg/day by 6-9 months. Diuretics, angiotensin-converting enzyme inhibitors, and antihypertensive drugs were administered when required.
Class II patients with proteinuria of more than 1 g/day were treated with prednisolone for 4-12 weeks with subsequent taper.
Class V patients were also treated with prednisolone with subsequent taper with or without azathioprine.
The patients were followed up monthly until complete remission (proteinuria <0.2 g/day, no active sediments, and normal serum creatinine) and subsequently for every four to six months.
| Statistical Analysis|| |
All the continuous parameters were expressed as mean and standard deviation, and all qualitative variables such as immunological investigations as proportions. Fisher's exact test was used to compare the difference in proportions of classes of LN with renal functions, complement levels, and immunological investigations. Data were analyzed using Microsoft Excel. P <0.05 was considered statistically significant.
| Results|| |
A total of 46 patients with biopsy-proven LN were included in the study. There were 41 (89.1%) females and 5 (10.9%) males with a female:male ratio of 8.2:1. Mean age at initial presentation was 29.4 for females (age range: 12-60 years) and 28 years for males (age range: 14-41 years).
The age distribution is depicted in [Figure 1]. Peak incidence of LN occurred in the third decade of life (34.8%) followed by the fourth (21.7%) and second decades (19.6%). Nearly 54.3% of the patients were aged <30 years.
The initial clinical manifestations are shown in [Table 1]. The most common presenting symptoms were arthritis (43.5%), dermatological manifestations (39.1%), and fever (30.4%). Apart from arthritis, the other musculoskeletal manifestation was myalgia (8.7%).
Hematological manifestations included anemia (52.2%) (hemoglobin concentration <11 g/dL), thrombocytopenia (17.4%) (platelets <1.5 lakhs/μL), and leukopenia (15.2%) (white blood cell <4 × 10 3 /μL). Pancytopenia was present in five (10.8%) patients. Lymphoreticular involvement was present in eight (17.4%) patients and comprised hepatosplenomegaly in 13% and lymphadenopathy in 4.4% of the patients.
Hypertension, edema, and oliguria were, respectively, present in 41.35%, 28.3%, and 8.7% of the patients.
Renal function, complement levels, and immunological investigations
The mean serum creatinine at presentation was 1.69 mg/dL (range: 0.6-7.9 mg/dL). The mean serum creatinine in Class IV LN was 1.96 mg/dL [standard deviation (SD) ±2.29], 1.93 mg/dL (SD ±1.97) in Class III LN, 1.47 mg/dL in Class V LN (SD ±0.73), and 0.81 mg/dL in Class II LN (SD ±0.21). Elevated serum creatinine (>1.5 mg/dL) was present in 17.4% of the patients.
The mean 24 h proteinuria at presentation was 2.8 g (range: 0.33-11.0 g). Mean protein excretion in Class IV LN was 4.27 g/24 h (SD ±2.31), 2.18 g/24 h in Class III LN (SD ±1.8), 3.51 g/24 h in Class V LN (SD ±2.31), and 0.78 g/dL in Class II LN (SD ±0.68). Nephrotic-range proteinuria (>3.5 g/24 h) and active urinary sediment (>5 red blood cells/hpf and/or cellular casts) were, respectively, present in overall 23.9% and 30.4% of the patients of LE.
ANA and ds-DNA positivity were present, respectively, in overall 82.6% and 65.2% of the patients of LE. One patient who had a history of abortion was positive for antiphospholipid antibodies.
Diffuse LN (Class IV) was the most common histological pattern and occurred in 17 (37.1%) patients. This included three cases of diffuse segmental proliferative LN [IV-S (A)], two cases of diffuse segmental proliferative and sclerosing LN [IV-S (A/C)], four cases of diffuse global proliferative and sclerosing LN [IV-G (A/C)], and eight cases of diffuse global proliferative LN [IV-G (A)]. In addition, one of the latter cases showed concurrent membranous LN.
This was followed by focal LN (Class III) which occurred in 10 (21.7%) patients and comprised four cases of focal proliferative [III - (A)] and six cases of focal proliferative and sclerosing LN [III (A/C)]. In addition, one of the former and two of the latter cases showed concurrent membranous LN.
Mesangial proliferative LN (Class II) was present in nine (19.5%), membranous LN (Class V) in 8 (17.4%), minimal mesangial LN (Class I) in 1 (2.2%), and advanced sclerosing LN (Class VI) in 1 (2.2%) patients.
[Table 2] shows the various classes of LN with renal functions, complement levels, and immunological investigations.
|Table 2: Various classes of LN with renal functions, complement levels, and immunological investigations.|
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IgG was positive in 80.4%, C3 in 71.7%, IgM in 60.9%, and IgA in 58.7% of the cases. Full-house pattern of glomerular immune deposits were present in 56.5% of the cases. The immune deposits were seen in the mesangium and/or glomerular basement membrane.
Complete records were available in 30 (65.2%) patients of which, at the end of one year, 19 (63%) achieved complete remission, six (20%) were in partial remission (proteinuria of 0.2-2 g/day, no active urine sediments, and normal serum creatinine), two (6.7%) still showed active renal disease (neither complete nor partial remission with normal serum creatinine), two (6.7%) progressed to chronic renal failure (serum creatinine >1.5 mg/dL for >3 months) and one (3.3%) died because of sepsis [Table 3].
| Discussion|| |
The younger age at initial presentation was comparable with many other studies. ,,, A North Indian study by Dhir et al revealed a mean age of 23.6 ± 10.5 years and a South Indian series showed a mean age of 25.6 ± 6.27. , In a study conducted in East Nepal, all the patients were females.  This female predilection is attributed to the influence of female sex hormones on the immune system. Further, it is known that higher antibody responses occur in female sex of mammalian species. ,,
Arthritis was the most common initial clinical manifestation, which is in synchrony with the study by Dhir et al.  However, the frequency in the latter study was higher (72.7%) compared to ours (43.5%). A high frequency (78.4%) was also reported in East Nepal. 
A statistically significant difference was observed between the different classes of LN and low-serum complement C3 levels (P = 0.029) [Table 2]. Complement C3 levels were reduced in Classes III and IV LN in contrast to Classes II and V, which showed normal complement levels.
Literature review reveals that reduced serum complement C3 levels are present in more than one-half of Class III LN and in two-thirds of Class IV LN cases. This is in synchrony with our study, which revealed low-complement C3 levels in 40% of Class III LN and 64% of Class IV LN. 
[Table 4] shows the comparison of renal functions, complement levels, and immunological investigations with other recently published studies in India and other countries. The frequency of LN patients with elevated serum creatinine levels, hypocomplementemia, and nephrotic-range proteinuria was significantly less compared to North Indian and Pakistanian series. , This could be explained by the relatively higher prevalence of proliferative (Class IV) LN in these regions, which commonly presents as nephritic/nephrotic syndrome or acute renal failure.  The same reason can explain the relatively less frequency of active urine sediment, compared to Pakistani study. 
ANA is an important initial screening test for lupus, and anti-dsDNA antibodies are highly specific for lupus. Literature review reveals that approximately 98% of the cases have ANA positivity and 50%-70% of the patients have anti-dsDNA antibodies.  The relatively lower ANA positivity in our study (82.6%), East Nepal series, and Pakistani study partly could be attributed to cases with ANAnegative lupus and technical factors. ,,,
A strong association between high-titer ANA and anti-dsDNA antibodies with proliferative LN has been demonstrated.  The latter antibodies have significant nephritogenic potential and exhibit cross-reactivity to glomerular constituents, especially heparin sulfate and type IV collagen of the basement membrane. Many studies in different populations have recognized that anti-dsDNA titers rise and fall, correlating with the activity of the disease.  In our series, although there was an increase in the proportion of anti-dsDNA positivity in proliferative LN (Classes III and IV) compared to Classes II and V (70% in Class III and 82.4% in Class IV vs. 55.6% in Class II and 37.5% in Class V), this difference was not statistically significant.
Similar to North Indian and Pakistani series, Class IV LN was the most common histological subtype, followed by Class III LN. , However, Class II LN was reported as the most common subtype in East Nepal.  These differences could be due to racial factors and genetic variability, geographic differences in populations, methods of case identification, diagnostic criteria, variability of renal lesions, and expertise of the pathologist in recognizing histological differences and distinguishing between classes.
Class I LN generally accounts for a small fraction of LN cases. These cases may not have any clinical renal symptoms or may present with minimal urinary abnormalities such as mild subnephrotic proteinuria or microscopic hematuria. , In our study, only one case (2.2%) of Class I LN, with clinical manifestation of subnephrotic proteinuria was present. Class II LN cases generally do not have renal insufficiency and up to 60% of these patients present with subnephrotic proteinuria, asymptomatic hematuria, or both. , In our study, subnephrotic proteinuria was present in 77.8% of the cases and none of the patients had renal insufficiency (elevated serum creatinine). Many studies have revealed that proteinuria does not exceed 1 g/24 h, which is in synchrony with our study (mean 24 h proteinuria = 0.78 g/dL).  Literature review reveals that Class III LN cases have a heterogeneous clinical presentation with active urinary sediment, nephroticrange proteinuria, and renal insufficiency occurring, respectively, in 50%, 33.3%, and 10-25% of the cases, which is very similar to our observations. ,
Class IV cases have the most active and severe clinical renal symptoms with 50% presenting with nephrotic-range proteinuria and renal insufficiency occurring in more than 50% of the cases.  In our study, nephroticrange proteinuria and renal insufficiency with elevated serum creatinine were, respectively, present in 35.3% and 29.4% of the cases. Further, 47.1% of our cases presented with active urinary sediment.
Renal insufficiency is uncommon in Class V LN, with 59-70% of these cases having nephrotic-range proteinuria.  In synchrony with the above findings, none of our Class V LN cases had renal insufficiency, and only 37.5% of our cases had nephrotic-range proteinuria.
Class VI LN cases represent a late stage of LN and clinically present as severe renal insufficiency. , We had only one case of Class VI LN presenting with elevated serum creatinine levels.
With the standard immunosuppressive regimen, 83.3% of our patients achieved remission (complete or partial) at one year. This is very similar to a study conducted by Dhir et al in Asian Indians, where 84.6% had achieved remission.  However, our figures may not reflect the true treatment outcome, as 34.8% of our patients had either incomplete records or were lost to follow-up.
In conclusion, a wide range of histological glomerular changes can occur in LN, with the most common, in our population, being Class IV LN followed by Class III LN. Relatively higher proportions of ANA and anti-dsDNA positivity are present in proliferative LN. Lowcomplement C3 levels are characteristically present in Classes III and IV LN. There is a high frequency of arthritis at presentation in our LN patients. Although the frequency and patterns of different classes of LN vary among the populations, the clinical renal manifesttation within each class is relatively homogeneous.
Conflict of interest: None declared.
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Clement Wilfred Devadass
Department of Pathology, M. S. Ramaiah Medical College and Hospitals, Bengaluru - 560 060, Karnataka
[Table 1], [Table 2], [Table 3], [Table 4]