Anti-erythropoietin receptor antibodies in systemic lupus erythematosus patients with anemia

Association of the systemic immune-inflammation index with anemia: a population-based study

Background

Inflammation has been reported to be related to anemia. As a novel inflammatory marker, Systemic immune-inflammation index (SII) has not been studied with Anemia. The aim of this study was to investigate the possible relationship between SII and anemia.

Methods

This retrospective cross-sectional survey was conducted using data from the 2005-2018 National Health and Nutrition Examination Survey (NHANES) population. In total, 19851 American adults aged ≥18 years were included. SII was calculated as the platelet count×neutrophil count/lymphocyte count. Anemia was defined as hemoglobin (Hgb) levels of < 13 g/dL in males and < 12 g/dL in females. Logistic regression analyses, subgroup analyses and sensitivity analyses were performed to investigate the relationship between SII and anemia.

Results

Our study included a total of 19851 patients, of which 1501 (7.6%) had anemia. After adjusting for all covariates, the multivariate logistic regression analysis showed that a higher SII (In-transform) level was associated with increased likelihood of anemia (OR=1.51, 95% CI: 1.36-1.68, P<0.001). The association between SII and anemia exhibited a nonlinear manner. The positive correlation between SII and anemia was related to the severity of anemia. Subgroup analysis showed that there was no significant dependence on age, family income, body mass index, hypertension, kidney disease and cancer except gender on this positive association. Furthermore, sensitivity analyses confirmed the robustness of our results.

Conclusion

Our study demonstrated that SII was positively associated with anemia especially among female participants. And this positive correlation was related to the severity of anemia. Further large-scale prospective studies are still needed to analyze the role of SII in anemia.

Endogenous erythropoietin has immunoregulatory functions that limit the expression of autoimmune kidney disease in mice

Background

Administration of recombinant erythropoietin (EPO), a kidney-produced hormone with erythropoietic functions, has been shown to have multiple immunoregulatory effects in mice and humans, but whether physiological levels of EPO regulate immune function in vivo has not been previously evaluated.

Methods

We generated mice in which we could downregulate EPO production using a doxycycline (DOX)-inducible, EPO-specific silencing RNA (shEPOrtTA^POS), and we crossed them with B6.MRL-Fas^lpr/J mice that develop spontaneous lupus. We treated these B6.MRL/lpr shEPOrtTA^POS with DOX and serially measured anti-dsDNA antibodies, analyzed immune subsets by flow cytometry, and evaluated clinical signs of disease activity over 6 months of age in B6.MRL/lpr shEPOrtTA^POS and in congenic shEPOrtTA^NEG controls.

Results

In B6.MRL/lpr mice, Epo downregulation augmented anti-dsDNA autoantibody levels and increased disease severity and percentages of germinal center B cells compared with controls. It also increased intracellular levels of IL-6 and MCP-1 in macrophages.

Discussion

Our data in a murine model of lupus document that endogenous EPO reduces T- and B-cell activation and autoantibody production, supporting the conclusion that EPO physiologically acts as a counterregulatory mechanism to control immune homeostasis.

Immune Mechanisms in Inflammatory Anemia

Maintaining the correct number of healthy red blood cells (RBCs) is critical for proper oxygenation of tissues throughout the body. Therefore, RBC homeostasis is a tightly controlled balance between RBC production and RBC clearance, through the processes of erythropoiesis and macrophage hemophagocytosis, respectively. However, during the inflammation associated with infectious, autoimmune, or inflammatory diseases this homeostatic process is often dysregulated, leading to acute or chronic anemia. In each disease setting, multiple mechanisms typically contribute to the development of inflammatory anemia, impinging on both sides of the RBC production and RBC clearance equation. These mechanisms include both direct and indirect effects of inflammatory cytokines and innate sensing. Here, we focus on common innate and adaptive immune mechanisms that contribute to inflammatory anemias using examples from several diseases, including hemophagocytic lymphohistiocytosis/macrophage activation syndrome, severe malarial anemia during Plasmodium infection, and systemic lupus erythematosus, among others.

Hematologic manifestations of juvenile systemic lupus erythematosus: An emphasis on anemia

Objective

Anemia is common in patients with juvenile systemic lupus erythematosus (jSLE). While autoimmune hemolytic anemia (AIHA) is the only etiology included in the classification criteria, the etiology of anemia in jSLE may be diverse. We aimed to investigate the etiology of anemia in jSLE and the relationship between anemia and disease characteristics at onset and during the follow-up period.

Methods

Patients diagnosed with jSLE who met the Systemic Lupus Erythematosus International Collaborating Clinics classification criteria between January 2012 and December 2020 were retrospectively analyzed.

Results

Hematologic involvement was observed in 70% of the patients. Anemia was the most common cytopenia among patients (60%). Anemia of chronic disease (ACD) and AIHA were the most common etiological factors, both observed in 23% of patients. Patients with anemia had a significantly higher rate of positive ds-DNA antibody and higher erythrocyte sedimentation rate (ESH) and Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) scores. ESH, serum ferritin, and SLEDAI scores negatively correlated with hemoglobin levels in patients with anemia. Iron deficiency was the sole etiology of new-onset anemia. Patients with new-onset anemia during the follow-up period had significantly lower hemoglobin values at onset and a higher rate of renal involvement.

Conclusion

Anemia in jSLE is mostly AIHA and ACD, but iron deficiency is not rare. The severity of inflammation is associated with the severity of anemia. During the follow-up period, iron deficiency was the predominant cause of anemia, especially in patients with lower hemoglobin concentrations at onset and renal involvement.

Association of the premature immunosenescence with the presence and severity of anemia among patients with systemic lupus erythematosus

INTRODUCTION

One of the possible mechanisms that contribute to the development of anemia in systemic lupus erythematosus (SLE) is the presence of premature immunosenescence in SLE. This study aimed to observe the correlation between immunosenescence with anemia in SLE.

METHODS

This research was a cross-sectional study with the subject was 60 women with SLE aged 16-45 years old. Subjects were recorded for the demographic and clinical data, complete blood counts, iron status (iron serum, total iron-binding capacity, and transferrin saturation), ferritin, inflammatory markers (erythrocyte sedimentation rate [ESR] and C-reactive protein [CRP]), and anti-dsDNA levels. Immunosenescence was observed by measuring the senescent T cells from peripheral blood mononuclear cells (PBMC) by flow cytometry, counted as CD4⁺CD57⁺ and CD8⁺CD57⁺ T cells. Serum IL-2 and IFNγ as the cytokines associated with immunosenescence were also measured from all subjects. Subjects were divided into anemic and non-anemic groups according to the classification of anemia from WHO (Hb < 12 gr/dl).

RESULTS

Anemic SLE patients had higher CD4⁺CD57⁺, CD8⁺CD57⁺, and IFNγ, while IL-2 was lower in SLE patients with anemia. Multivariate linear regression revealed that the decreasing levels of Hb were associated with the increase of CD8⁺CD57⁺ percentages and IFNγ levels. Anti-dsDNA, ESR, CRP, ferritin, iron serum, and transferrin saturation were correlated with CD8⁺CD57⁺. IFNγ level also correlated with the anti-dsDNA, iron serum, and ferritin levels. No correlation was found between the iron status and inflammatory markers with CD4⁺CD57⁺ percentages and IL-2 levels. Multivariate regression analysis showed that IFNγ was positively associated with anti-dsDNA and negatively associated with iron serum and transferrin saturation, while CD8⁺CD57⁺ percentages were positively associated with the ferritin levels.

CONCLUSION

Immunosenescence is associated with anemia by modulating the inflammatory response and causing iron dysregulation in SLE.

Erythropoietin in Lupus: Unanticipated Immune Modulating Effects of a Kidney Hormone

Systemic lupus erythematosus (SLE) is a multiorgan autoimmune disease with variable clinical presentation, typically characterized by a relapsing-remitting course. SLE has a multifactorial pathogenesis including genetic, environmental, and hormonal factors that lead to loss of tolerance against self-antigens and autoantibody production. Mortality in SLE patients remains significantly higher than in the general population, in part because of the limited efficacy of available treatments and the associated toxicities. Therefore, novel targeted therapies are urgently needed to improve the outcomes of affected individuals. Erythropoietin (EPO), a kidney-produced hormone that promotes red blood cell production in response to hypoxia, has lately been shown to also possess non-erythropoietic properties, including immunomodulatory effects. In various models of autoimmune diseases, EPO limits cell apoptosis and favors cell clearance, while reducing proinflammatory cytokines and promoting the induction of regulatory T cells. Notably, EPO has been shown to reduce autoimmune response and decrease disease severity in mouse models of SLE. Herein, we review EPO's non-erythropoietic effects, with a special focus on immune modulating effects in SLE and its potential clinical utility.

Antibodies specific to ferritin light chain polypeptide are frequently detected in patients with immune‑related pancytopenia

Immuno-related pancytopenia (IRP) is characterized by pancytopenia resulting from bone marrow suppression or destruction mediated by auto-antibodies. In our previous study, a K562 cDNA library was established, which was used to screen for seven possible auto-antigens produced by hematopoietic cells in patients with IRP, including ferritin light chain (FTL). In the present study, FTL was expressed and purified, and the levels of the auto-antibodies specific to FTL were measured. Through ELISA, it was shown that the titer of anti-FTL antibodies was higher in patients with IRP without treatment compared with those who had recovered from IRP, those with severe aplastic anemia (SAA), those with myelodysplastic syndrome (MDS) and the healthy controls. Furthermore, the expression levels of FTL-mRNA were upregulated in patients with IRP without treatment compared with those who had recovered from IRP, those with MDS and the normal controls. The results suggest that FTL antibody expression is upregulated in patients with IRP. Detecting FTL antibodies may therefore have certain clinical value in differentiating between IRP, SAA and MDS. Furthermore, in specific patients with IRP, FTL as an auto-antigen may induce immune attack on hematopoietic stem cells.

Erythropoietin inhibits SGK1-dependent TH17 induction and TH17-dependent kidney disease

IL-17-producing CD4+ cells (TH17) are pathogenically linked to autoimmunity including to autoimmune kidney disease. Erythropoietin's (EPO) newly recognized immunoregulatory functions and its predominant intra-renal source suggested that EPO physiologically regulates TH17 differentiation, thereby serving as a barrier to the development of autoimmune kidney disease. Using in vitro studies of human and murine cells and in vivo models, we show that EPO ligation of its receptor (EPO-R) on CD4+ T cells directly inhibits TH17 generation and promotes trans-differentiation of TH17 into IL-17-FOXP3+CD4+ T cells. Mechanistically, EPO/EPO-R ligation abrogates upregulation of SGK1 gene expression and blocks p38 activity to prevent SGK1 phosphorylation, thereby inhibiting RORC-mediated transcription of IL-17 and IL-23 receptor genes. In a murine model of TH17-dependent aristolochic acid (ArA)-induced, interstitial kidney disease associated with reduced renal EPO production, we demonstrate that transgenic EPO overexpression or recombinant EPO (rEPO) administration limits TH17 formation and clinical/histological disease expression. EPO/EPO-R ligations on CD4+ T cells abrogate, while absence of T cell-expressed EPO-R augments, TH17 induction and clinical/histological expression of pristane-induced glomerulonephritis (associated with decreased intrarenal EPO). rEPO prevents spontaneous glomerulonephritis and TH17 generation in MRL-lpr mice. Together, our findings indicate that EPO physiologically and therapeutically modulate TH17 cells to limit expression of TH17-associated autoimmune kidney disease.

Anti-IL-10 antibody in systemic lupus erythematosus

Purpose

IL-10 is a cytokine known to inhibit inflammatory cytokines. To determine its role in the pathogenesis of systemic lupus erythematosus (SLE), the presence of anti-IL-10 antibody is required to be examined. Although antibodies against cytokines are known to be present in SLE, no studies have determined the role of IL-10, particularly in Japanese patients. We assayed anti-IL-10 antibody in SLE and examined the clinical significance.

Patients and methods

We performed a retrospective study of 80 Japanese patients with SLE. Sixteen scleroderma patients, 19 rheumatoid arthritis (RA) patients, 23 Behcet’s disease patients, and 23 healthy subjects were selected as control groups. Clinical information was abstracted from medical records. Anti-IL-10 antibody level was determined with an ELISA.

Results

With the cutoff established as serum absorbance +2 SDs (OD 0.729) in healthy subjects, we defined any sample above this cutoff as anti-IL-10 antibody-positive. Fourteen patients with SLE (17.5%) were found to be anti-IL-10 antibody positive. Absorbance was significantly higher in serum from patients with SLE and RA than in healthy individuals. In SLE, patients with low complement values were significantly more common in the antibody-positive group. Serum IgG levels were significantly higher in the antibody-positive group. In multivariable analysis, high level of serum IgG is associated with anti-IL-10 antibody positive.

Conclusion

The present study found that anti-IL-10 antibody is present in SLE and related to clinical parameters. These results suggest that the presence of anti-IL-10 antibody was associated with high level of serum IgG, but is not associated with disease activity in patients with SLE.