Sudanese and Swedish patients with systemic lupus erythematosus: immunological and clinical comparisons

Clinical and laboratory profiles of systemic lupus erythematosus patients in a new rheumatology clinic in southwestern Nigeria

Introduction

The aims were to study the sociodemographic characteristics of patients presenting to the clinic and to study the clinical and serological pattern of systemic lupus erythematosus (SLE) in a new rheumatology clinic of a predominantly Yoruba population.

Material and methods

This was a retrospective, cross-sectional study conducted over 7 years (January 2017 - December 2023). Patients who satisfied the 1997 American College of Rheumatology (ACR) and/or the 2012 Systemic Lupus International Collaborating Clinics (SLICC) classification criteria were enrolled using their medical records. Patients with overlap syndromes and other inflammatory or noninflammatory rheumatic diseases were excluded from the study. Their sociodemographic, clinical, laboratory, and treatment data were retrieved from their medical records and analysed using IBM SPSS version 23.0 software.

Results

A total of 65 patients were diagnosed with SLE with a frequency of 15.8%. The mean age ±SD of the patients at presentation was 33.85 years ±11.01 and the female to male ratio was 9.8 : 1. The median (IQR) duration of symptoms at presentation was 7.0 months (3-24). The common clinical presentations included synovitis (86.2%), acute cutaneous rash (53.8%), oral ulcers (52.3%), nonscarring alopecia (50.8%), and serositis (47.7%). Proteinuria was seen in 37.7% of the patients and the predominant renal histopathological feature was Class IV. Antinuclear antibody was 100% positive with 50.94% of the patients having a titre of 1 : 5,120 and above. Anti-double-stranded deoxyribonucleic acid and anti-Smith antibodies each had 50% prevalence. Dyslipidaemia was found in 76.7% of the patients.

Conclusions

The study's findings are largely consistent with similar studies done in Africa. Further prospective multi-centred studies are needed to further determine the epidemiological characteristics of the disease in Nigeria with a multi-ethnic population.

Pattern of systemic lupus erythematosus in NIGERIA: a multicentre descriptive hospital-based study

INTRODUCTION

Systemic lupus erythematosus (SLE) is a chronic autoimmune inflammatory disease with manifestations ranging from mild to life-threatening organ dysfunction. There is wide variability in the reported incidence and prevalence rate globally, particularly in low and middle-income countries. Nigeria had very few isolated reports of SLE from private and public hospitals Therefore, we conducted this large multi-center descriptive study to determine the sociodemographic, clinical profile, laboratory patterns, and treatment among Nigerian lupus patients.

METHODS

A retrospective hospital-based study of all SLE patients seen over 4 years (January 2017 to December 2020) was conducted at 20 rheumatology clinics spread across the 6 geopolitical zones of Nigeria. All patients 18 years and above satisfying the American College of Rheumatology (ACR) 1997 and/or the Systemic Lupus International Collaboration Clinics (SLICC) 2012 classification criteria for SLE were enrolled. Patients with other Rheumatic and Musculoskeletal Diseases (RMDs) not in keeping with SLE and Patients with incomplete data were excluded. Data was analysed using SPSS version 23.0 software.

RESULTS

A total of 896 patients with SLE were included in the final analysis with a mean age ± SD of 34.47 ± 11 and a female to male ratio of 8.1:1. Synovitis was reported by 61.6% of patients, while 51%, 19.9% and11.4% patients reported acute, sub-acute and chronic lupus rashes respectively. ANA was positive in 98.0% with titers ranging from 1:80 to 1:64,000.

CONCLUSION

SLE is not rare in Nigeria. Most patients were female in their 3rd to 4th decades of life. There is a delayed presentation to a rheumatology facility. Arthritis and mucocutaneous manifestations were the most frequent presentation. Key Points •This study presents the first national data on SLE in Nigeria •This study showed that SLE is not rare in Nigeria in contrast to previous reports •There appear to be ethnic disparity in the frequency of lupus among Nigerians •Nigerians with lupus have very high titer of ANA.

Anti-phosphatidylserine/prothrombin antibodies and thrombosis associate positively with HLA-DRB1*13 and negatively with HLA-DRB1*03 in SLE

OBJECTIVES

Emerging evidence demonstrates that aPS-PT associate with thrombotic events. Genetic predisposition, including HLA-DRB1 alleles, is known to contribute to the occurrence of conventional aPL [anti-β2glycoprotein-I (anti-β2GPI) and aCL]. We investigated associations between aPS-PT and HLA-DRB1* alleles and thrombosis in SLE. Conventional aPL were included for comparison.

METHODS

We included 341 consecutive SLE patients, with information on general cardiovascular risk factors, including blood lipids, LA and thrombotic events. aPS/PT, anti-β2GPI and aCL of IgA/G/M isotypes and LA were quantified.

RESULTS

aPS/PT antibodies associated positively with HLA-DRB1*13 [odds ratio (OR) 2.7, P = 0.002], whereas anti-β2GPI and aCL antibodies associated primarily with HLA-DRB1*04 (OR 2.5, P = 0.0005). These associations remained after adjustment for age, gender and other HLA-DRB1* alleles. HLA-DRB1*13, but not DRB1*04, remained as an independent risk factor for thrombosis and APS after adjustment for aPL and cardiovascular risk factors. The association between DRB1*13 and thrombosis was mediated by aPS-PT positivity. HLA-DRB1*03, on the other hand, associated negatively with thrombotic events as well as all aPL using both uni- and multivariate analyses. HLA-DRB1*03 had a thrombo-protective effect in aPL-positive patients. Additionally, HLA-DRB1*03 was associated with a favourable lipid profile regarding high-density lipoprotein and triglycerides.

CONCLUSIONS

HLA-DRB1*13 confers risk for both aPS-PT and thrombotic events in lupus. The association between HLA-DRB1*13 and thrombosis is largely, but not totally, mediated through aPS-PT. HLA-DRB1*03 was negatively associated with aPL and positively with favourable lipid levels. Thus, HLA-DRB1*03 seems to identify a subgroup of SLE patients with reduced vascular risk.

Systemic Lupus Erythematosus Classification and Diagnosis

Since the European League Against Rheumatism/American College of Rheumatology 2019 classification criteria for systemic lupus erythematosus (SLE) were published, they were externally validated by groups worldwide. In particular, the new criteria worked well also in East Asian and pediatric cohorts. Antinuclear antibodies (ANA) as an entry criterion were critically discussed, but the group of ANA-negative patients is small (<5%) worldwide. Specificity of the criteria is dependent on correct attribution only of those criteria that are not better explained by other causes. Although the classification criteria should not be used for diagnosis, many novel aspects inform diagnostic considerations.

Associations with thrombosis are stronger for antiphosphatidylserine/prothrombin antibodies than for the Sydney criteria antiphospholipid antibody tests in SLE

Objectives

Antiphosphatidylserine/prothrombin complex antibodies (aPS/PT) are risk factors for thrombosis, yet further validation of their clinical relevance in different ethnic groups is required. We investigated the performance of aPS/PT of IgA/G/M isotypes among Sudanese and Swedish systemic lupus erythematosus (SLE) patients.

Methods

Consecutive SLE patients/matched controls from Sudan (n = 91/102) and Sweden (n = 332/163) were included. All patients fulfilled the 1982 ACR SLE classification criteria. IgA/G/M of aPS/PT, anti-cardiolipin and anti-β₂glycoprotein I (anti-β₂GPI) were tested in both cohorts, and lupus anticoagulant (LA) also in the Swedish cohort. Clinical antiphospholipid syndrome-related events and atherosclerosis, measured as carotid plaques were assessed for associations. Univariate and multivariate analyses adjusting for cardiovascular risk factors were performed.

Results

Sudanese SLE patients had higher levels of IgM aPS/PT, but using national cut-offs, the frequency of positivity was similar to Swedish patients for all isotypes. Among Swedish patients, all isotypes of aPS/PT associated with venous thromboembolism (VTE), while only IgA aPS/PT associated with arterial thrombosis (AT). aPS/PT antibodies associated strongly with LA and they were, independently, the best predictor for VTE. Double positivity for aPS/PT and anti-β₂GPI associated with higher VTE risk than the conventional triple positivity. Carotid plaques did not associate with any antiphospholipid antibody.

Conclusions

IgA aPS/PT associated with AT, and the association of IgG/M aPS/PT with VTE outperforms LA and criteria antiphospholipid antibodies in Swedish SLE patients. Furthermore, double positivity for aPS/PT and anti-β₂GPI performed better than conventional triple positivity. Future studies need to address if aPS/PT can replace LA, as this would simplify clinical procedures.

Rheumatic diseases in Africa

Historically, rheumatic diseases have not received much attention in Africa, particularly in sub-Saharan Africa, possibly owing to a focus on the overwhelming incidence of infectious diseases and the decreased life span of the general population in this region. Global attention and support, together with better health policies and planning, have improved outcomes for many infectious diseases; thus, increasing attention is being turned to chronic non-communicable diseases. Rheumatic diseases were previously considered to be rare among Africans but there is now a growing interest in these conditions, particularly as the number of rheumatologists on the continent increases. This interest has resulted in a growing number of publications from Africa on the more commonly encountered rheumatic diseases, as well as case reports of rare diseases. Despite the limited amount of available data, some aspects of the epidemiology, genetics and clinical and laboratory features of rheumatic diseases in African populations are known, as is some detail on the use of therapeutics. Similarities and differences in these conditions can be seen across the multi-ethnic and genetically diverse African continent, and it is hoped that increased awareness of rheumatic diseases in Africa will lead to earlier diagnosis and better outcomes for patients.

The prevalence of rheumatic diseases is increasing in African countries, leading to an increased need for specialist rheumatologists and disease-modifying drugs. In this Review, the authors outline what is currently known about the state of rheumatic diseases in Africa.

In the past, there has been an emphasis on communicable diseases in Africa, but attention has now shifted towards non-communicable diseases such as rheumatic diseases.

Common rheumatic diseases are seen in Africa and are both comparable and different from presentations seen outside of Africa.

Diverse genetic and environmental factors affect the presentation of common rheumatic diseases among different African nations.

A shortage of appropriately trained staff, laboratory testing capacity and effective medications exists across the whole continent.

Advocacy and research are needed to increase awareness of the risk factors, presentations and management of rheumatic diseases in Africa.

Specialized treatment guidelines are needed for resource-poor countries in Africa.

New lupus criteria: a critical view

PURPOSE OF REVIEW

To review the validation of the European League Against Rheumatism (EULAR)/American College of Rheumatology (ACR) 2019 classification criteria for systemic lupus erythematosus (SLE).

RECENT FINDINGS

Positive antinuclear antibodies, which constitute the obligatory entry criterion of the EULAR/ACR criteria, were found in the vast majority of SLE patients worldwide, with 97% (94-100%) of patients antinuclear antibodies positive in studies investigating EULAR/ACR criteria performance. Combined over the publications, EULAR/ACR criteria sensitivity was 92% (range 85-97%). Specificity varied more relevantly, with the publications published after the EULAR/ACR 2019 criteria showing 93% (83-98%) specificity. Of particular relevance is the good performance of the EULAR/ACR criteria seen in pediatric SLE as well as in early SLE.

SUMMARY

The new classification criteria have been investigated in an impressive number of cohorts worldwide, adding to the data from the EULAR/ACR criteria project cohort. It is critical to strictly keep to the attribution rule, that items are only counted if there is no more likely alternative explanation than SLE, the domain structure, where only the highest weighted item in a domain counts, and the limitation to highly specific tests for antibodies to double-stranded DNA.

Accumulation of antinuclear associated antibodies in circulating immune complexes is more prominent in SLE patients from Sudan than Sweden

The role of anti-nuclear autoantibody (ANA) specificities in immune complexes (IC) formation has been studied to a limited extent in SLE, and not at all in African SLE patients. We compared ANA in IC from Sudanese and Swedish SLE patients. We included 93 Sudanese and 332 Swedish SLE patients fulfilling the 1982 ACR criteria. IC were captured using C1q-coated beads. ANA specificities were quantified in sera and IC. Results were related to modified SLEDAI. Whereas serum levels of anti-Sm, anti-dsDNA and anti-ribosomal P were higher in Swedish patients, IC levels of most ANA specificities were higher among Sudanese patients. This difference was especially prominent for anti-chromatin antibodies, which remained after adjustment for age, disease duration and treatment. Total levels of C1q-binding IC correlated with levels of specific ANA in IC, with highest correlations for anti-chromatin antibodies among Sudanese patients. Whereas occurrence of anti- SSA/Ro60, anti-histone and anti-U1RNP in both serum and IC associated with high SLEDAI score, anti-dsDNA in IC but not in serum associated with high SLEDAI. ANA, especially antibodies targeting chromatin, accumulate more in IC from Sudanese SLE patients. If the autoantibody fraction forming IC is pathogenically important, this might explain the generally described severe SLE in black populations.

New insights into the role of antinuclear antibodies in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease characterized by antinuclear antibodies (ANAs) that form immune complexes that mediate pathogenesis by tissue deposition or cytokine induction. Some ANAs bind DNA or associated nucleosome proteins, whereas other ANAs bind protein components of complexes of RNA and RNA-binding proteins (RBPs). Levels of anti-DNA antibodies can fluctuate widely, unlike those of anti-RBP antibodies, which tend to be stable. Because anti-DNA antibody levels can reflect disease activity, repeat testing is common; by contrast, a single anti-RBP antibody determination is thought to suffice for clinical purposes. Experience from clinical trials of novel therapies has provided a new perspective on ANA expression during disease, as many patients with SLE are ANA negative at screening despite previously testing positive. Because trial results suggest that patients who are ANA negative might not respond to certain agents, screening strategies now involve ANA and anti-DNA antibody testing to identify patients with so-called 'active, autoantibody-positive SLE'. Evidence suggests that ANA responses can decrease over time because of the natural history of disease or the effects of therapy. Together, these findings suggest that, during established disease, more regular serological testing could illuminate changes relevant to pathogenesis and disease status.

High IgA antiphospholipid autoantibodies in healthy Sudanese explain the increased prevalence among Sudanese compared to Swedish systemic lupus erythematosus patients

Objectives

IgA antiphospholipid antibodies (aPL) are prevalent in systemic lupus erythematosus (SLE) patients of African American, Afro-Caribbean and South African origin. Nevertheless, data from North Africa are lacking, and most studies use manufacturer-suggested cut-offs based on Caucasian controls. Therefore, we compared aPL isotypes in Sudanese and Swedish SLE patients using nation-based cut-offs.

Methods

Consecutive SLE patients and age- and sex-matched controls from Sudan (N = 115/106) and Sweden (N = 340/318) were included. All patients fulfilled the 1982 American College of Rheumatology SLE classification criteria. Antiphospholipid syndrome–related events were obtained from patients’ records. IgA/G/M anticardiolipin and anti-β₂ glycoprotein I (β₂GPI) were analysed with two independent assays. IgA anti-β₂GPI domain 1 (D1) was also investigated. Manufacturers’ cut-offs and the 95th and 99th percentile cut-offs based on national controls were used.

Results

Sudanese patients and controls had higher levels and were more often positive for IgA aPL than Swedes when using manufacturers’ cut-offs. In contrast, using national cut-offs, the increase in IgA aPL among Sudanese patients was lost. Occurrence of IgA anti-D1 did not differ between the countries. Venous thromboses were less common among Sudanese patients and did not associate with aPL. No clinical associations were observed with IgA anti-β₂GPI in Sudanese patients. Thromboses in Swedes were associated with IgG/M aPL. Fetal loss was associated with aPL in both cohorts.

Conclusions

IgA anti-β₂GPI prevalence was higher among Sudanese compared to Swedish patients when manufacturers’ cut-offs were used. This situation was reversed when applying national cut-offs. Anti-D1 was not increased in Sudanese patients. Previous studies on populations of African origin, which demonstrate a high prevalence of IgA aPL positivity, should be re-evaluated using a similar cut-off approach.