E. Greco

Complement and autoimmunity

The complement system is a component of the innate immune system. Its main function was initially believed to be limited to the recognition and elimination of pathogens through direct killing or stimulation of phagocytosis. However, in recent years, the immunoregulatory functions of the complement system were demonstrated and it was determined that the complement proteins play an important role in modulating adaptive immunity and in bridging innate and adaptive responses. When the delicate mechanisms that regulate this sophisticated enzymatic system are unbalanced, the complement system may cause damage, mediating tissue inflammation. Dysregulation of the complement system has been involved in the pathogenesis and clinical manifestations of several autoimmune diseases, such as systemic lupus erythematosus, vasculitides, Sjögren’s syndrome, antiphospholipid syndrome, systemic sclerosis, dermatomyositis, and rheumatoid arthritis. Complement deficiencies have been associated with an increased risk to develop autoimmune disorders. Because of its functions, the complement system is an attractive therapeutic target for a wide range of diseases. Up to date, several compounds interfering with the complement cascade have been studied in experimental models for autoimmune diseases. The main therapeutic strategies are inhibition of complement activation components, inhibition of complement receptors, and inhibition of membrane attack complex. At present, none of the available agents was proven to be both safe and effective for treatment of autoimmune diseases in humans. Nonetheless, data from preclinical studies and initial clinical trials suggest that the modulation of the complement system could constitute a viable strategy for the treatment of autoimmune conditions in the decades to come.

Intravenous immunoglobulin therapy in pregnant patients affected with systemic lupus erythematosus and recurrent spontaneous abortion

OBJECTIVES We aimed to test the maternal and fetal outcome of SLE patients who suffered from recurrent spontaneous abortion (RSA) treated with intravenous immunoglobulin (IVIg) alone during pregnancy and whether the clinical response to IVIg treatment is accompanied by modifications of SLE-associated antibodies and of complement levels. METHODS Twelve SLE-RSA pregnant patients were treated with high-dose IVIg and compared with 12 SLE-RSA pregnant patients treated with prednisolone and NSAIDs. They were evaluated for the clinical response [lupus activity index-pregnancy (LAI-P) scale] and for ANA, anti-dsDNA, anti Ro/SS-A or La/SS-B, aCL, LAC, C4, C3 before and during pregnancy, and before and after each treatment course. Pregnancy outcome in the two groups was also evaluated. RESULTS The groups characteristics were homogeneous at the beginning of pregnancy. A beneficial clinical response following IVIg treatment was noted in all patients and mean LAI-P decreased from 0.72 +/- 0.43 at the beginning of pregnancy to 0.13 +/- 0.19 at the end of pregnancy (P < 0.0001). Antibodies and complement levels tended to normalize in most of the patients. These clinical and laboratory improvements were significant with respect to the control group. Pregnancy was successfully carried out in 12/12 (100%) SLE-RSA patients with a mean Apgar score of 8.92. Three patients in the control group got aborted (25%). CONCLUSIONS IVIg has a high response rate among SLE-RSA pregnant patients and may be considered safe and effective.

Anti-thyroid antibodies and antiphospholipid syndrome: evidence of reduced fecundity and of poor pregnancy outcome in recurrent spontaneous aborters.

Problem:  To determine the presence of anti‐thyroid antibodies in patients with primary antiphospholipid syndrome (APS) [antiphospholipid antibodies (aPL) + recurrent spontaneous abortion (RSA)], compare APS alone with APS and thyroid autoimmunity for fecundity and for pregnancy outcome.

Complement system and rheumatoid arthritis: relationships with autoantibodies, serological, clinical features, and anti-TNF treatment

Autoantibodies (rheumatoid factor, RF; anti-citrullinated-protein antibodies, ACPA) and complement system are involved in rheumatoid arthritis (RA). ACPA and anti-TNF agents are capable of in vitro modulating complement activity. We investigated the relationships between complement, autoantibodies, and anti-TNF treatment in vivo. One-hundred fourteen RA patients (89F/25M), diagnosed according to 1987 ACR criteria, and 30 healthy controls were enrolled. Serological analysis included ESR, CRP, complement C3, C4 and CH50, RF and ACPA (ELISA, cut-off>20U/ml). Split-products (SP) of C3 and B were studied by immunoelectrophoresis/counterimmunoelectrophoresis. Seventy-six patients started anti-TNF treatment and were studied at baseline and after 22 weeks. Disease activity was measured with DAS28 and response to therapy with EULAR criteria. At baseline, RA patients showed significantly higher levels of C3 and C4 than controls (C3 127.9±26.5 vs 110±25mg/dl, P=0.0012; C4 29.7±10.2 vs 22.7±8.3mg/dl, P=0.0003). No differences in C3, C4 and CH50 levels were observed between ACPA+ (n=76) and ACPA- (n=38) patients. After 22 weeks of anti-TNF, C3, C4 and RF were significantly reduced (P<0.003, <0.005 and <0.04, respectively) and RF changes showed negative correlation with CH50. SP of C3 and B were observed neither at baseline nor after 22 weeks. DAS28 significantly improved after 22 weeks. Patients showing higher baseline C3 or lower reduction of C3 levels after 22 weeks had a worse EULAR outcome (χ2=22.793, P<0.001). RF levels seem to correlate with complement CH50. The presence of high levels of C3 in RA patients may reflect a pro-inflammatory status and represent a negative prognostic factor for anti-TNF therapy.

Inhibition of the complement system by glutathione: molecular mechanisms and potential therapeutic implications.

Glutathione (GSH), a component of the antioxidant defence system, plays a role in autoimmunity and the complement system is often responsible for tissue damage in autoimmune diseases. The aim of this study is to evaluate the effects of GSH on the complement system. The complement system was examined in the normal human sera (NHS) of 30 healthy subjects. Increasing quantities of GSH (1, 2, 10, 20 mg) were incubated in 1 ml of each NHS. The mixtures were evaluated for complement activities (THC, CPA and APA) and for the presence of cleavage fragments of activation of C3 and B. GSH was also incubated with human complement in the presence of classical and alternative pathway activators. The results showed an inhibitory effect of GSH on the complement system starting from a dosage of GSH≥1 mg/ml. Indeed, when NHS was incubated with GSH at such dosage, a significant reduction of the complement activities THC, CPA, and APA was observed (P<0.0001, P<0.005, P=NS, respectively), and no cleavage fragments of C3 or B were found. Further analysis demonstrated that the inhibition was exerted on C3-9 and to a lower extent on classical and alternative pathway C3-convertases. Our results indicate that GSH is capable of inhibiting the complement system. These findings are relevant for the design of interventions aimed at modulation of GSH metabolism to inhibit complement-mediated damage in autoimmune diseases.

Recurrent Angioedema: Occurrence, Features, and Concomitant Diseases in an Italian Single-Center Study

Background: Angioedema (AE) is a potentially life-threatening condition with hereditary (HAE), acquired (AAE), or iatrogenic causes. A careful workup allows for the identification of the etiology of attacks and the appropriate management. In this cohort study, based on a clinical practice setting, we aimed at investigating clinical and laboratory findings concerning different features of patients with recurrent AE who were referred to a single, tertiary-level center for HAE. Methods: Clinical and laboratory data of patients fulfilling the criteria for C1-inhibitor-deficient HAE (C1-INH-HAE), C1-INH-AAE, angiotensin-converting enzyme inhibitor-related AE (ACEI-RA), and idiopathic AAE (I-AAE) were evaluated. Descriptive statistics were analyzed by means of the Mann-Whitney U test. The Fisher exact test was used for group comparisons. Results: Patients were diagnosed with type 1 HAE (n = 14), type 2 HAE (n = 1), C1-INH-AAE (n = 8), ACEI-RA (n = 16), or I-AAE (n = 26). We included only patients with concomitant autoimmune diseases from the I-AAE group (n = 8, aut-I-AAE). Age at disease onset and at diagnosis was younger in type 1 HAE than in all the other groups. The diagnostic delay was longer in type 1 HAE than in ACEI-RA. C4 and C1q levels were lower in C1-INH-AAE than in type 1 HAE, ACEI-RA, and aut-I-AAE. Both HAE and C1-INH-AAE showed lower C1-INH antigen and function compared to the other groups. Peripheral attacks were more frequent in type 1 HAE, while airway, abdominal, and oral attacks were prevalent in C1-INH-AAE. Conclusion: Investigating the clinical and laboratory features of recurrent AE without wheals represents a major topic for facilitating early diagnosis and improving treatment strategies for this heterogeneous and misdiagnosed condition.