Small intestinal mucosal abnormalities in relatives of patients with dermatitis herpetiformis

Celiac Disease and Neurological Manifestations: From Gluten to Neuroinflammation

Celiac disease (CD) is a complex multi-organ disease with a high prevalence of extra-intestinal involvement, including neurological and psychiatric manifestations, such as cerebellar ataxia, peripheral neuropathy, epilepsy, headache, cognitive impairment, and depression. However, the mechanisms behind the neurological involvement in CD remain controversial. Recent evidence shows these can be related to gluten-mediated pathogenesis, including antibody cross-reaction, deposition of immune-complex, direct neurotoxicity, and in severe cases, vitamins or nutrients deficiency. Here, we have summarized new evidence related to gut microbiota and the so-called "gut-liver-brain axis" involved in CD-related neurological manifestations. Additionally, there has yet to be an agreement on whether serological or neurophysiological findings can effectively early diagnose and properly monitor CD-associated neurological involvement; notably, most of them can revert to normal with a rigorous gluten-free diet. Moving from a molecular level to a symptom-based approach, clinical, serological, and neurophysiology data might help to disentangle the many-faceted interactions between the gut and brain in CD. Eventually, the identification of multimodal biomarkers might help diagnose, monitor, and improve the quality of life of patients with "neuroCD".

The pathology of malabsorption: current concepts

Intestinal malabsorption results from a wide variety of causes, which can most easily be organized into three groups. Maldigestion arises from problems with mixing or with digestive mediators, and includes post-gastrectomy patients and those with deficiencies of pancreatic or intestinal enzymes, or of bile salts. Mucosal and mural causes of malabsorption are abundant, and include gluten-sensitive enteropathy, tropical sprue, autoimmune enteropathy, and HIV/AIDS-related enteropathy, as well as mural conditions such as systemic sclerosis. Finally, microbial causes of malabsorption include bacterial overgrowth, Whipple's disease, and numerous infections or infestations that are most frequently seen in immunocompromised patients. An overview of the most common and interesting entities in each of these categories follows, along with a discussion of current concepts. Mucosal conditions and microbial causes of malabsorption are given special attention.

Dermatitis herpetiformis

Dermatitis herpetiformis (DH) is a relatively rare skin disorder with an estimated incidence of 1:10,000 in the UK. It is characterized by urticarial plaques and blisters on the elbows, buttocks, and knees, although other sites may also be involved. The eruption tends to be persistent: only 10-15% of patients have spontaneous remission over a 25-year study period. The disease is characterized by the presence of IgA deposits in the upper dermis of uninvolved skin and the diagnosis should not be made in the absence of these deposits. Two-thirds of patients have a small intestinal enteropathy with villous atrophy as seen in coeliac disease (CD). However, the remaining third also show evidence of a gluten sensitivity in the intestine, as judged by increased lymphocytic infiltration of the epithelium. Villous atrophy also ensues after gluten challenge in those patients with previous normal villous architecture. The initial treatment of the rash is with one of the following three drugs, dapsone, sulphapyridine or sulphamethoxypyridazine. However, the rash also clears with gluten withdrawal. It must be stressed, however, that the average time to achieve significant reduction in drug requirements is 6 months and it can be over 2 years before drugs are no longer required. On re-introduction of gluten the eruption recurs. Patients with DH have a high incidence of auto-immune disorders, thyroid disease, pernicious anaemia, and insulin-dependent diabetes, and should be screened for those diseases on a yearly basis. As with coeliac disease there is also an increased incidence of lymphoma and a gluten-free diet appears to protect patients from this complication. The mechanism by which gluten causes the skin lesions has still to be elucidated, but current investigations implicate lymphocytes and cytokines in the pathogenesis. The original hypothesis of an antigen-antibody reaction in the skin with complement activation causing the skin lesions, may not be correct.

Familial incidence of dermatitis herpetiformis

Dermatitis herpetiformis and gluten-sensitive enteropathy are diseases in which exposure to gluten results in an inflammatory response. Both diseases are associated with certain human lymphocyte antigen alleles, and gluten-sensitive enteropathy is well known to cluster in families. Gluten-sensitive enteropathy has also been reported in families of patients with dermatitis herpetiformis. Despite this evidence that dermatitis herpetiformis is a genetic disease, reports of the familial occurrence of dermatitis herpetiformis are rare. We have obtained family histories from 92 patients with dermatitis herpetiformis with 740 first-degree relatives. Six of these relatives have dermatitis herpetiformis. Comparison of these data with the expected prevalence of dermatitis herpetiformis shows this incidence to be highly significant (p less than 0.0001), strongly suggesting that dermatitis herpetiformis is a familial disease, presumably because of shared genetic factors but possibly because of a shared environment.

Dermatoglyphics in dermatitis herpetiformis

In a dermatoglyphic study of 101 patients with dermatitis herpetiformis, comparison was made with their normal relatives and several random normal series. The results of the several comparisons are quite consistent, considering the nature of the data, for the all point to an attenuation of qualitative and quantitative digital and palmar traits in the patients. It is argued that these differences are associated with the disease itself, and that some of the female relatives have an inherited tendency to the disorder, but do not express it. The findings suggest the involvement of genetic factors in the aetiology, and possibly intrauterine environmental influences as well.

Incidence of small-intestinal mucosal abnormalities and of clinical coeliac disease in the relatives of children with coeliac disease

Evidence is presented of a higher than normal incidence both of clinical coeliac disease and of small-intestinal mucosal abnormalities in relatives of children with coeliac disease. In such relatives the incidence of mucosal abnormality may differ from the incidence of clinical coeliac disease. The data show an absence of any simple Mendelian pattern of inheritance: in place of the hypothesis that inheritance is through a dominant gene of reduced penetrance, it is argued that the pathogenesis of coeliac disease is multifactorial, the genetic basis of susceptibility being polygenic and interacting with environmental factors. On this hypothesis the relative contributions of inheritance and environment to liability to the clinical condition are estimated, the genetic component being 45% +/- 9. Environmental factors appear more important in the development of mucosal abnormality.