In the course of this research, complement activation and antiphospholipid antibody (aPL) levels were investigated in individuals suffering from lupus nephritis. In this study, a retrospective analysis was performed on individuals who had kidney biopsies that were positive for LN. For the purpose of determining the levels of anticardiolipin antibodies (aCLs) and anti-β2-glycoprotein I (anti-β2-GPI) antibodies belonging to the IgM, IgA, and IgG classes, thorough research was carried out. Concurrent with the kidney biopsy, information on clinical symptoms and pathology was also collected. Nearly half (45.8% to be exact) of the forty people with LN who participated in the study tested positive for antiphospholipid antibodies (aPLs). “Individuals who were diagnosed with LN and did not possess any antiphospholipid antibodies (aPLs) displayed elevated levels of glomerulus C1q, decreased levels of serum complement proteins C3 and C4, increased levels of hematuria, and higher scores on the SLEDAI (P<0.05). It was shown that there was an inverse association between the levels of C3 and C4 in the blood and the IgG-aCL (r=-0.31, P=0.007; r=-0.36, P=0.028). It was shown that there is a significant link between the levels of IgG-aCL and the deposits of glomerulus C4 (r=0.31, P=0.043).” This connection turned out to be essential. The findings presented here indicate that IgG-aCLs have the potential to exacerbate LN and activate complement pathways.
A large group of antibodies, known as antiphospholipid antibodies (aPLs), target phospholipids and the proteins that attach to them [1,2]. Anticardiolipin antibodies (aCLs) and anti-β2-glycoprotein I (anti-β2GPI) are two noteworthy components. Cell membranes include phospholipids like cardiolipin, which may be selectively bound by antibodies that are directed against it [3]. Conversely, immunoglobulins that target β2GPI linked up with the cardiolipin-binding protein [4]. Antiphospholipid syndromes (APS) have a robust association with thrombosis and pregnancy-related problems, according to the evidence [5]. This occurs when APS are utilized. Systemic lupus erythematosus (SLE) is often the underlying pathology that leads to the development of APS, while it can occasionally manifest as a primary illness on its own [6–9]. Compared to those without APLs, persons with SLE who have APLs are far more likely to experience thrombotic events, complications during pregnancy, thrombocytopenia, pulmonary hypertension, valvular disease, and renal abnormalities [6, 7]. Organ damage caused by APLs can be attributed to many pathogenic pathways, including complement activation, inflammation, and alterations of the fibrinolytic and anticoagulant systems [8]. In contrast, individuals suffering from systemic lupus erythematosus were most strongly linked to thrombosis by the IgG-anti-β2GPI antibody. In contrast, there was a stronger correlation between deep venous thrombosis and stroke and the IgA-anti-β2GPI antibody [1,3]. Research has shown that aPLs increase the likelihood of renal problems in SLE patients, but how exactly aPLs cause complement activation in people with lupus nephritis (LN) or systemic lupus erythematosus (SLE) is still unclear. This study set out to examine the connection between complement activation and aPLs in the setting of LN patients.
Prior to commencing the present inquiry, approval was sought from the relevant institutional ethics committee. at particular, the study was place at the Burla, Odisha, medical department of VIMSAR. Laboratory tests and demographic information were retrieved from medical records. All data was anonymised and kept anonymous during the whole procedure, according to the authors of the present study. The following details were carefully documented: the patient's demographics; the duration of the nephropathy; hematuria; albumin, eGFR, hemoglobin, white blood cells, platelet counts; C3 and C4 antibodies; anti-dsDNA antibodies; IgM, IgA, and IgG antibodies against cystic leukemia; and anti-β2-glycoprotein I antibodies. Concurrently, Thermo Fisher Scientific Laboratories created ELISA kits to identify IgM, IgA, and IgG antibodies that are anti-β2GPI antibodies. Anti-β2GPI antibody concentrations more than 20 U/mL for IgA or IgG isotypes and 17 U/mL for IgM isotype for aCLs were considered significant based on the positive criterion. It was concluded that the antibodies were positive when the anti-β2GPI antibody concentration exceeded 20 U/mL. With nephelometry, the complement components C3 and C4 were examined.
Statistical analysis:
We summarized the variables by presenting them in the form of means, standard deviations, or proportions. This was accomplished through the utilization of descriptive statistics. Using either the chi-square or the t-test, a comparison was made between the LN groups that had aPLs and those that did not have them. In order to determine whether or not there is a connection between kidney complement deposits, serum complement levels, and blood phospholipid levels, correlation tests such as Pearson's or Spearman's testing were utilized. The implementation of binary logistic regression allowed for the identification of the independent factors that were linked with aPL. The statistical analysis was conducted using SPSS 22 (IBM, USA) with a significance threshold of P<0.05. This was done for each and every statistical analysis.
LN patients with negative aPLs exhibited higher levels of hematuria, SLEDAI, hemoglobin, white blood cell count, and serum C3 and C4 (P = 0.046, P = 0.021, P = 0.004, P = 0.028, P = 0.004, P = 0.004). These factors were statistically significant in all cases. These findings supported the hypothesis, according to statistical analysis. No clinical parameter, such as age, gender, duration of sickness, estimated glomerular filtration rate (eGFR), urine protein/creatinine ratio, or any other clinical characteristic, was different between the two groups.
Different patterns of renal illness are seen in those LN groups with aPLs and those without. According to the statistical analysis, glomerulus C1q deposits were significantly bigger in patients with LN with positive aPLs than in patients with negative aPLs (P = 0.049). When comparing the two patient groups, this was the situation. There was no discernible difference between the groups in the circumferential or C3 and C4 deposits, the ISN/RPS classification, the activity index, the chronicity index, or any other pathology data.
In order to determine which aPL subtypes had the most impact on complement activation, particularly in glomerular deposits, this correlation research investigated the associations between aPL subtypes and complement components. The purpose of the experiment was to determine which subtypes had the biggest impact. A favorable correlation between IgG- aCLs and glomerulus C4 deposit was demonstrated (r=0.31, P=0.043 over the research period). That's what the correlation coefficient showed. Conversely, a negative correlation was seen between the blood levels of C3 and C4 (r=-0.31, P=0.007 and r=-0.36, P=0.028, respectively). Furthermore, there was a significant link. Further evidence supporting this hypothesis came from the finding that the levels of IgM-aCL were negatively correlated with the blood concentrations of C3 and C4 (r=-0.21, P=0.044 and r=-0.33, P=0.048).
Within the framework of the logistic regression model, the only dependent variable for which clinical and pathological factors were not taken into consideration was APL. We initially planned to use serum C3 in our regression model, but we ended up changing it when we switched to IgG-aCL as our dependent variable. Based on the data, it was determined that serum C3 and IgG-aCL are independent variables (OR = 0.99, P = 0.026).
45.8% of LN patients were positive for aPLs in our investigation. It is especially remarkable because antibodies against β2-GPI, IgA-aCL, or IgA-anti-β2-GPI were not included in earlier studies. This is why our study's positive aPL % is consistent with data from previous studies including LN patients [9–11]. Evidence suggests that SLEDAI is a valid tool for tracking lupus disease development. The SLEDAI was significantly greater in participants in this research who tested positive for aPLs compared to those who tested negative. The study's results confirmed this to be true. This study's results corroborate those of previous studies [6,9] that found a correlation between illness severity and available aPLs. However, it should be mentioned that other studies [10] have shown conflicting results, which might be because different populations were tested or other kinds of aPLs were examined.
Our study found that group A was more prone to hematuria, a sign of proliferative lesions in the glomerulus, among those who tested positive for aPLs. In contrast to those in the aPLs-negative group, members in the aPLs-positive group had a lower chronicity score and a higher activity index. This was true even though there was little difference in the renal activity index between the two groups. This was seen both times, even though there was no statistically significant difference between the two groups. It was also demonstrated that the group who had positive findings for aPLs had a higher incidence of proliferative lesions, which are classified as belonging to classes III and IV. Even while other research has shown a connection between aPLs and kidney issues including glomerular microthrombosis, this connection is still not well accepted [11–13]. Findings suggest that aPLs may be a powerful tool for tracking LN activity, which is significant from the study.
Additionally, our findings demonstrated that aPL-positive patients had blood concentrations of C3 and C4 that were lower than those of aPL-negative patients. This restriction did not apply to patients whose aPL tests were negative. Serum C3 and C4 levels showed an inverse connection with the concentrations of various aPLs (IgG-aCL), but kidney complement deposition levels showed a positive correlation with aPL levels. Using logistic regression analysis, it was possible to determine an independent relationship between blood C3 and IgG-aCL. Given that immune complex deposits have been linked to complement activation in the glomerulus, it is important to note that these factors may contribute to lymph node (LN) disease [12]. A thorough investigation of the role of aPL in this process is still in progress, however it has been acknowledged that anti-ds DNA antibody might have contributed to this development [13]. Some research has suggested that APLs may play a role in complement activation and glomerular microthrombosis in the LNB [14,15]. Thrombosis has been associated to fetal loss and aPL-induced complement cascade activation in patients with main and secondary APS, which has led to questions about the idea that thrombosis is the sole mechanism causing tissue destruction in APS [16, 17].
Activation of the classical pathway by immune complex formation has been shown in diseases such systemic lupus erythematosus (SLE) and others related to immune complexes [18–20]. An example of a circulating immunological complex is an antiphospholipid antibody-antigen complex. Thrombotic events, pregnancy complications, or even lung rupture might result from this combination's ability to speed up the start of complement activation. Therefore, our results provide evidence that autoantigens and aPL may work together to promote complement activation. However, this study does have a few issues that must be resolved. A small sample size made it difficult to measure lupus anticoagulants because the test was not available at our hospital. Other limitations include an inadequate evaluation of complement activation factors, which made it difficult to determine the predominant complement activation pathway. Furthermore, the study only evaluated aPLs at a single time point, which limited our ability to understand their potential significance for prognosis or disease monitoring. Several shortcomings of the study are as follows. To solve this issue, larger cohort prospective studies in the future are required.
Ultimately, our findings offer compelling proof that aPLs could be a helpful indicator for monitoring LN activity. For whatever reason, IgG-aCLs have the ability to trigger the established complement pathways.