What complications can lupus cause?

In the absence of treatment, lupus most often progresses gradually: the immune system remains abnormally active and maintains ongoing inflammation throughout the body. Over time, this inflammation can weaken certain organs, particularly the kidneys, the heart and its blood vessels, the lungs, and also the nervous system. Flare-ups then tend to become more frequent, while periods of remission become shorter, with a risk of long-lasting damage.

Conversely, when a treatment is introduced, the course of the disease is generally better controlled. The aim is not to make the disease disappear but to stabilise it: to reduce the intensity of flare-ups, protect the organs and maintain as consistent a quality of life as possible. Even in this context, lupus remains a condition that must be closely monitored, as it can become active again after a quiet phase and certain complications may develop in the long term.

The manifestations of lupus can vary greatly from one person to another. Some complications are common, while others are rarer but potentially serious.

Cutaneous complications of lupus

Lupus can cause permanent cutaneous complications that affect appearance and quality of life. These complications occur mainly after repeated or chronic lesions , and require particular attention for their prevention and monitoring.

Alopecia and scarring or depigmentation

Scarring alopecia corresponds to an irreversible loss of hair in certain areas, often following severe skin lesions. Scarring and depigmentation may also appear as a result of chronic eruptions or repeated inflammatory lesions. These complications arise from prolonged inflammation and the destruction of hair follicles or skin tissues by autoantibodies, often worsened by exposure to sunlight. Scarring alopecia affects around 5 to 15% of patients, while severe scarring or depigmentation occurs in 10 to 20% of patients with chronic cutaneous lesions. Once established, these lesions are difficult to reverse.

A longitudinal study conducted on 420 patients with lupus showed that scarring alopecia affected around 12% of patients over a 10‑year period. Severe cutaneous scarring and depigmentation occurred mainly in patients who had experienced chronic and recurrent skin lesions, confirming that persistent inflammation and untreated skin lesions are key factors in the development of these complications.

Squamous cell carcinoma.

Squamous cell carcinoma corresponds to a type of skin cancer that originates in the squamous cells of the epidermis. It generally develops as a result of repeated damage caused by UV radiation, particularly from sunlight, which alters the DNA of skin cells and promotes the emergence of mutations capable of triggering a cancerous process.

Individuals with fair skin, who are more sensitive to the effects of sunlight, are approximately 1.5 to 2 times more likely to develop this type of lesion than people with darker skin.

It is important to note that in patients with lupus, the risk of developing a squamous cell carcinoma is slightly increased. However, the disease on its own is not a decisive factor. Other elements play a role, such as excessive sun exposure, smoking, certain viral infections, and the presence of chronic skin conditions. Thus, even though particular vigilance is recommended in people with lupus, the overall level of risk remains moderate.

Infectious complications.

Complications related to infections represent one of the main causes of morbidity and mortality in patients with lupus. They arise both from the disease itself and from the treatments used to control it. From a biological perspective, lupus leads to an intrinsic alteration of the immune system. Specifically, there is dysfunction of B and T lymphocytes, an ineffectual production of protective antibodies, as well as utilisation of complement, which plays a key role in the elimination of pathogens. Added to this vulnerability is the effect of immunosuppressive treatments, corticosteroids or biotherapies, which reduce the body’s defensive capacities by dampening the immune response.

These mechanisms promote different types of infections. Bacterial infections are the most frequent, particularly respiratory and urinary infections. Viral infections, such as herpetic reactivations, and opportunistic infections (tuberculosis, fungal infections) occur more often in patients who are severely immunocompromised. Some studies report that nearly 50% of patients experience at least one significant infectious episode. Moreover, infections are involved in up to 30 to 50% of lupus-related deaths, particularly in the first few years following diagnosis.

Complications related to pregnancy.

Pregnancy in a patient with lupus represents a particular situation, in which immunological and hormonal changes can influence the course of the disease and lead to specific complications. The origin of these complications is based on a complex interaction between lupus activity, maternal autoantibodies and the physiological adaptations of pregnancy. Certain autoantibodies, especially antiphospholipid antibodies and anti-SSA/Ro and anti-SSB/La antibodies, can cross the placental barrier and interact with fetal tissues or the placental vascular system. In addition, the treatments used, particularly corticosteroids, can also play a role by increasing the risk of gestational diabetes, as they reduce the sensitivity of cells to insulin and stimulate glucose production by the liver, thereby leading to an increase in blood sugar levels.

From a mechanistic perspective, antiphospholipid antibodies promote the formation of microthromboses in the placenta, impairing exchanges between the mother and the fetus. This can lead to placental insufficiency. Anti-SSA/SSB antibodies, for their part, can target the fetal cardiac conduction system, resulting in rhythm disturbances. These mechanisms give rise to different types of complications. In the mother, there is an increased risk of lupus flares in approximately 25 to 50% of pregnancies, as well as arterial hypertension in 10 to 20% of patients and pre-eclampsia in 5 to 15%. On the fetal side, complications may include miscarriages in 15 to 25% of cases, intrauterine growth restriction in 10 to 20%, preterm birth in 20 to 30% of pregnancies and, more rarely, neonatal lupus with cardiac involvement.

Kidney disorders.

Renal involvement (nephropathy) is a common phenomenon in systemic lupus erythematosus (SLE), and has a significant impact on both functional and vital prognosis. Several types of lesions can occur in the kidney. The most frequent affect the glomeruli (the small filters of the kidneys), but other structures can also be involved. However, the most common manifestation remains lupus glomerulonephritis (GN). The intrarenal lesions observed are associated both with glomerular deposits of immunoglobulins and complement, and with infiltration of renal tissue by inflammatory cells, particularly activated macrophages. Anti-native DNA antibodies are associated with the occurrence of glomerular damage, but the autoantibodies that appear to be largely directly responsible for this renal condition are anti-nucleosome antibodies. The process may initially be silent, before becoming apparent through proteinuria, hypertension, or progressive renal failure.

Without treatment, persistent inflammation can lead to irreversible fibrosis of the kidney.

Data from longitudinal cohorts indicate that approximately 10% of patients with lupus nephritis progress to end-stage renal failure. Furthermore, numerous studies have shown that the intensity of immune complex deposition and complement activation are directly related to renal prognosis, confirming the central role of these mechanisms in disease progression.

There are several forms of lupus nephritis, classified from I to IV according to their severity, ranging from mild forms to severe involvement that can lead to renal failure.

Cardiovascular disorders.

Cardiovascular complications related to lupus arise from a persistent state of chronic inflammation. This inflammation, which is characteristic of the disease, gradually damages the vascular endothelium, the thin layer of cells lining the inside of blood vessels and representing the starting point for cardiovascular abnormalities. Several mechanisms account for these complications.

The production of autoantibodies and the formation of immune complexes lead to activation of the complement system and secretion of pro‑inflammatory molecules. This sequence promotes endothelial dysfunction, which is the first step towards atherosclerosis. Similarly, certain autoantibodies, such as antiphospholipid antibodies, induce a prothrombotic state. This disrupts coagulation mechanisms, which increases the risk of clot formation.

These processes lead to various forms of cardiovascular involvement. On the one hand, there are direct inflammatory conditions, such as pericarditis or myocarditis, and on the other, vascular complications related to atherosclerosis, including myocardial infarction and stroke. Added to this are thromboembolic events, which are particularly common in patients with an associated antiphospholipid syndrome.

Cardiovascular risk is influenced by several patient profiles. It is higher in young individuals with active lupus, in patients with kidney involvement, and in those exposed to corticosteroids over a prolonged period, as these promote hypertension, lipid disorders and diabetes.

Work in vascular immunology has furthermore confirmed that chronic inflammation and complement activation accelerate arterial ageing, a phenomenon sometimes described as premature atherosclerosis. These findings highlight the central role of systemic inflammation in the development of cardiovascular complications in lupus and explain why their prevention depends as much on controlling disease activity as on managing associated risk factors.

Pulmonary involvement.

Pulmonary complications are diverse and include pleural disorders, interstitial lung diseases, vasculitides, pulmonary embolism, pulmonary hypertension, upper airway disorders, pulmonary shrinkage syndrome, as well as infections. Clinical presentations may range from an absence of symptoms, as seen in mild pleural effusion or obstructive airway disease, to potentially life-threatening conditions, such as acute lupus pneumonitis or diffuse alveolar haemorrhage. Interstitial lung diseases and lupus-associated pulmonary hypertension tend to be milder and are associated with a relatively favourable prognosis.

Although, overall, pulmonary involvement is common in lupus, the heterogeneity of this disease and the rarity of individual complications make the conduct of clinical trials difficult. Consequently, treatment generally relies on case series and anecdotal reports involving various immunosuppressive agents. Some of these immunosuppressive drugs, such as azathioprine, methotrexate and cyclophosphamide, have also been associated with drug-induced lung injury.

Neurological disorders.

Neurological manifestations of lupus are among the most heterogeneous. They may result from several mechanisms, notably inflammation of cerebral blood vessels, the formation of microthromboses linked to antiphospholipid antibodies, or the direct action of autoantibodies on neurones. These mechanisms may lead to cognitive impairment, seizures, or strokes. Neurological forms affect a minority of patients; nevertheless, they can be severe.

The diagnosis of neurological involvement is complicated by non-specific and variable symptoms, requiring a thorough neurological examination, brain imaging, characterisation of autoantibodies, and analysis of the cerebrospinal fluid. Current therapeutic approaches include corticosteroids, immunosuppressants, and novel biological treatments that target specific immune pathways. The management of neuropsychiatric symptoms, epileptic seizures, and neuropathic pain remains a particularly challenging aspect of care.

Studies suggest that certain autoantibodies, particularly those directed against neuronal receptors, can directly alter synaptic transmission. Other work has highlighted a link between disease activity and abnormalities observed on brain imaging, suggesting a relationship between systemic inflammation and neurological involvement.

Haematological complications.

Haematological complications of lupus are among the earliest manifestations of the disease. They may appear within the first years, sometimes even before the diagnosis is confirmed, which suggests that they may represent an early sign of the disease. These abnormalities result from dysregulation of the immune system leading to the production of autoantibodies directed against blood cells. These autoantibodies bind to red blood cells, white blood cells, or platelets, causing their premature destruction, mainly in the spleen and the reticuloendothelial system. In addition, in some cases, there is involvement of the bone marrow, disrupting the normal production of blood cells.

Several types of involvement may be observed. Anaemia is the most frequent, whether inflammatory or autoimmune haemolytic. Leukopenia, particularly lymphopenia, indicates impairment of the immune system itself, while immune thrombocytopenia carries a risk of haemorrhage. Conversely, some patients may present a prothrombotic state, especially if they have antiphospholipid antibodies, creating a paradox between the risk of bleeding and that of thrombosis. These abnormalities are more common in patients with significant systemic involvement or certain early severe forms.

The data from the literature confirm this dynamic. Several longitudinal studies have shown that haematological abnormalities are not only frequent but also correlated with disease activity, making them an indirect marker of severity. Furthermore, work in immunohaematology has highlighted the central role of autoantibodies and complement activation in cell destruction, supporting the hypothesis of a direct immune mechanism underlying these complications.

Lupus can have very different consequences depending on its form and how it progresses. Some complications are common and now well controlled, while others remain more serious. Nevertheless, early, regular and appropriate management can significantly reduce these risks and improve the long-term prognosis.

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