Bringing together several pathologies of the immune system, connectivitis are diseases that affect all connective tissues and collagen, and several organs at the same time. Autoimmune diseases, they are characterized by the production of auto-antibodies directed against the body of the patient himself. 

Connectivity is a group of diseases that have in common a diffuse, inflammatory and chronic damage to the connective tissue and collagen of the body. Connective tissue and collagen are found in the space between cells in a body tissue (muscles, tendons, organs, etc.). 

Connectivity was once called collagenosis. Several diseases are found in the group of connectivitis:

• systemic lupus erythematosus (SLE) which affects all of the connective tissue of the organism and manifests itself in particular by a redness of the face like a “butterfly wing” on either side of the nose;
• rheumatoid arthritis (PR) which focuses primarily on small joints, those of the fingers for example and is part of chronic inflammatory rheumatism;
• lhas ankylosing spondylitis which concerns the joints, the vertebrae in particular and causes them to stiffen;
• the sarcoïdose which particularly affects the lungs with inflammation of the pulmonary alveoli which can lead to fibrosis of the lungs;
• type 1 diabetes, diabetes which occurs in childhood, a disease in which the pancreas is affected and no longer secretes enough insulin to regulate the level of sugar in the blood;
• lthe periarteritis noueuse which affects the walls of the body’s large arteries which thicken and slow down the flow of blood inside;
• Horton’s disease which also affects the large arteries, but rather those of the head such as the temporal arteries;
• Kawasaki’s maladie which is a childhood disease affecting the skin, lymph nodes and mucous membranes with involvement of the small and medium arteries;
• the Gougerot-Sjögren syndrome with damage to the lacrimal and salivary glands and a reduction in their secretions;
• le Raynaud’s syndrome, which manifests as a blood circulation disorder in the extremities (most often the fingers which are cold and purplish).

All these pathologies are autoimmune diseases that affect several organs and tissues and are expressed by very varied symptoms. For reasons most often unknown, it is about the action of auto-antibodies which are directed against the organism of the patient itself and cause inflammation and destruction of the affected tissues. Checking the blood for these antibodies is one of the important tests to make a diagnosis.

The frequency of these autoimmune diseases is difficult to determine, but for many of them, they mainly affect women (RA 75% of women, SLE 70% of women).

Genetic factors predispose to these diseases with familial forms of autoimmune diseases (8% in SLE for example). But there are also environmental causes such as the presence of infections (virus, infectious mononucleosis), involved in the occurrence of these autoimmune diseases.

Sex hormones 

They also play a role in the onset of autoimmune diseases, especially during pregnancy or ovulation inducing treatments (treatment of infertility) which can worsen SLE. Generally speaking, estrogen is involved in triggering autoimmunity.

Ultraviolet rays 

They would also have a responsibility in the occurrence of an autoimmune disease in particular for the photosensitive SLE with rash.

Some drugs

Certain drugs that modulate immunity, such as interferon alpha in the treatment of viral hepatitis, are sometimes involved in the outbreak of an autoimmune disease.

Toxic substances 

Finally, occupational exposure to toxic substances has also been implicated in the occurrence of scleroderma. This concerns exposure to silica, vinyl chloride used in the manufacture of PVC plastic and other chemicals.

But often no cause can be found

The symptomatology of connectivitis is very varied as is the diversity of the diseases grouped under this label. By their very definition, they have the particularity of affecting several organs and regions of the body at the same time. Skin lesions can be found in LEP, joint damage in RA or ankylosing spondylitis, damage to the tissues of the kidney (glomeruli).

An inflammatory syndrome is very generally found (but not always), objectified by blood markers (speed of sedimentation, C reactive protein). This inflammatory syndrome can be used as a guide to evaluate the effectiveness of a treatment when it decreases.

Fatigue is also widely shared in these various pathologies grouped together under the term “connectivitis”.

The intestine is also often affected with intestinal transit obstruction syndrome and malabsorption syndrome which can lead to undernutrition and weight loss.

More specific symptoms can be found depending on the diseases concerned such as for example severe headaches in Horton’s disease, dry eyes and dry mouth in Gougerot-Sjögren syndrome, progressive stiffness of the back in ankylosing spondylitis.

Treatments will depend on the type of connectivity diagnosed. But corticosteroid treatment (corticosteroid therapy) is most often used as a first-line treatment. Sometimes a drug that modulates immunity (immunosuppressant or biotherapy) is added or in LEP, an anti-malarial treatment (hydroxychloroquine).

The side effects of these treatments

These treatments have side effects and sometimes severe complications such as the occurrence of infections or increased risk of lymphoma-type cancers, as well as cardiovascular accidents. This involves regular monitoring of the treatment to give the lowest dose of medicine needed.

These treatments, some of which are new such as biotherapies, now make it possible to better control the progression of these diseases and thus improve the prognosis.