Assessment of Serum Level of CXCL9 and CXCL10 in Cutaneous versus Systemic Lupus Erythematosus

INTRODUCTION

Lupus erythematosus is a chronic autoimmune multisystem disorder¹ .The disease's severity ranges from little cutaneous involvement to severe, potentially lethal systemic disease. Skin is the second most frequent organ involved with varying morbidity. ²

Cutaneous Lupus erythematosus (CLE) is a disfiguring, chronic skin condition that has a great influence on patients' quality of life.  Cutaneous lesions are usually well-defined and present in areas that are exposed to the sun. Ultraviolet light can trigger or exacerbate the disease, which has a remitting and exacerbating course. ³

DLE is the most prevalent subtype of CCLE⁴. About 25% of SLE patients have DLE-like lesions. They are presented as well-defind, erythematous, discoid plaques, with adherent scales and follicular plugging. Healing occur with thin, white atrophic non-contractile scar with slightly raised or hyperpigmented border. ⁵ 

SLE  is a chronic inflammatory autoimmune disease⁶. Females are the ones that are most affected (∼90% of cases), and is more prevalent in people of African descent⁷. The etiology of SLE is multifactorial. The main Pathological features are: auto-antibodies overproduction secreted by overactive B lymphocytes, immune complexes deposition in target organs, increased pro-inflammatory cytokine production and T-lymphocyte defect. ^{8, 9, 10}

CXCL9 and CXCL10, which are members of the CXC chemokine family¹¹, were discovered to be overexpressed in the sera and/or tissues of patients with autoimmune disorders such as  SLE ¹². In patients with SLE, the CXCR3 ligands CXCL9 and CXCL10 were demonstrated to be the most significantly upregulated genes. ¹³

PATIENTS AND METHODS

This case control study comprised 45 patients who were split into two groups based on clinical characteristics: the DLE group (15 patients) and the SLE group (30 patients). A control group of forty age-and gender-matched, apparently healthy individuals was also included. All patients were recruited from the University Hospital's Dermatology and Venereology outpatient clinic between October 2018 and June 2019. Before participating in this study, the subjects gave their informed written consent. The faculty of medicine's research ethics committee approved the study.

The study participants were of both sexes, aged between 20-50 years. Patients of other co-morbidities (systemic or dermatological diseases), other autoimmune diseases, drug induced lupus or Pregnancy and lactation were excluded.

A full medical history was taken for all patients, a complete general examination to detect systemic manifestations of LE, a dermatological examination including distribution, morphology, extent and severity of skin lesions, and measuring disease activity using CLASI score in the DLE group Figure 1¹⁴ and SLEDAI score in SLE group.

Fig. 1:  Cutaneous Lupus Erythematosus Disease Area and Severity Index (CLASI).

Two scores make up the CLASI: one that describes the disease's activity and another that measures the disease's damage.  Dyspigmentation and scarring, as well as scarring alopecia, are used to assess damage¹⁴.

CLASI revealed that activity scores were significantly determined by the amount of erythema¹⁵. The total activity score is composed of the following components: redness degree (0–3) and scale (0–2), involvement of mucous membrane (0–1), recent loss of hair (0–1), and non- scarring alopecia (0–3). The total damage score consists of the following components: the dyspigmentation degree (0–2) and scarring (0–2), the dyspigmentation persistence for more than twelve months, double the dyspigmentation score, and scalp scarring (0, 3, 4, 5, 6)¹⁴.

SLEDAI is a list of 24 elements, 16 of which are clinical elements and 8 are laboratory data. The presence or absence of these symptoms in the preceding 10 days is used to score these items¹⁶.

Following the evaluation of each item, a score is computed by adding the scores assigned to every item, depending on its individual weights. The involvement of organs has been weighed as follows: pain in joints or renal disease is multiplied by four, whereas neurological involvement of the central nervous system is multiplied by eight. The ultimate score runs from 0 and 105.  The greater the score, the more significant the disease activity. Scores of 6 and higher are regarded to be indicative of active disease that necessitates treatment. Scores of more than 20 are, however, extremely rare. Clinically important changes include those with a score of 6 (improving) and 8 (worsening) ¹⁷.

Five to seven ml of blood was collected from all studied groups by venipuncture under aseptic condition. Samples were collected into a serum separator tube. Samples were centrifuged for 15 min after clot formation.  The serum has been removed, and the samples have been kept at 5 ~20 °C until analysis. CXCL9 and CXCLI0 serum concentrations were assayed via ELISA utilizing a commercially accessible kit (R & D Systems, Inc. 614 McKinley "Place NE, Minneapolis, MN 55413, USA. E-MAIL: info@RnDSystems.com).

Statistical Analysis

The Statistical Package for the Social Sciences (SPSS/version 2000) program has been utilized to analyze the data.

RESULTS

This case control study comprised forty five Egyptian patients who were split into two groups, the DLE group (15 patients) and the SLE group (30 patients). The DLE group age ranged from 20-49 years (mean 38.87±8.42 SD). They were 8 females (53.3%) and 7 male (46.7%). The SLE group age ranged from 20-49 years (mean 34.77±9.95 SD). They were 23 females (76.7%) and 7 males (23.3%). In addition, the study included forty healthy gender and age matched volunteers who acted as controls. Their ages ranged from 21 – 49 (mean of 32.83±7.41 SD) they were 29 females (71.5%) and 11 males (27.5%).

The mean disease duration in DLE patients was (13.00 ± 6.01 SD), ranging from 4 to 22 years. The mean onset age was 11.7 years (median 12.5 range 2-17). 7 patients (46.7 percent) had a positive family history, while 8 patients had a negative family history (53.3 percent). Five patients (33.3 percent) were DLE active and 10 patients (66.7 percent) were DLE inactive based on CLASI score.

The disease duration for SLE varied from 1 year to 23 years, with a mean of (9.97 ± 6.92 SD). The mean onset age was 16.7 years (median 15.5 range 13.2 – 18 y). 6 patients (20%) had a positive family history, whereas 24 (80%) had a negative one. Twenty patients (66.7 %) were SLE active and 10 patients (33.3 %) were SLE inactive based on SLEDAI score.

When it came to CXCL9 and CXCL10 serum levels, there were highly statistically significant differences between the DLE and control groups (p-value = 0.000) (Table 1).

There were also highly statistically significant differences in serum levels of CXCL9 and CXCL10 between the SLE and control groups (p-value = 0.000) (Table 2).

There were highly statistically significant differences in serum CXCL9 and CXCL10 levels between the DLE and SLE groups (p-value = 0.000) (Table 3).

In all cases, there was no significant connection between serum CXCL9 and CXCL10 levels, age, or disease duration (Table 4).

There was no statistically significant relation between serum CXCL9 and CXCL10 levels and disease activity in the DLE group (Table 5).

There were a highly statistically significant and statistically significant relations between serum level of CXCL9 and CXCL10, respectively in SLE group regarding disease activity with (P-value= 0.002 and p-value = 0.019) (Table 6).

Table 1: Comparison between the DLE group and the controls in terms of CXCL9 and CXCL10.

Table 2: Comparison between the SLE group and controls in terms of serum CXCL9 and CXCL10 levels.

Table 3: Comparison between the DLE group and the SLE group in terms of serum CXCL9 and CXCL10 levels.

Table 4: Connection between serum CXCL9 and CXCL10 levels with age and duration in all cases.

Table 5: Relation between serum CXCL9 and CXCL10 levels with disease activity and in DLE group.

Table 6: Relation of serum level of CXCL9 and CXCL10 with disease activity in SLE group.