EDITORIAL - Psoriasis, psoriatic arthritis, or Psoriatic Disease?

[Guest guest]

Journal of Rheumatology

February 2006

Editorial

--------------------------------------------------------------------------------

In this issue of The Journal, Madland, et al report results of a 2 week

pilot study on a dietary supplementation with seal oil compared to soy oil

in patients with psoriatic polyarthritis1. Despite its short duration,

several results of this research are significant. Mainly, 4 weeks after the

treatment, subjects taking seal oil dietary supplementation reported

improvement in patient's global assessment of disease, with a trend of

decreased tender and swollen joint counts. In addition, after seal oil

treatment, patients showed a promising shift in serum fatty acid

composition, towards a putative antiinflammatory profile. Finally, over 20%

of patients had high levels of calprotectin in feces. This point confirms

the widespread occurrence of an asymptomatic colitis in patients with

psoriatic arthritis (PsA).

Additionally, the relevance of this study lies in the attempt to understand

PsA beyond the classic schemes, focusing discussion on the crucial role

played by diet and, indirectly, by the bowel in the development of rheumatic

diseases.

That environmental factors may play a triggering role in arthritis

development has been well described. Among these factors, diet may be

considered of primary importance. Ten years ago, a consistent

spondyloarthritic involvement was demonstrated in patients with celiac

disease, where the presence of gluten in the diet triggers an enteropathy

followed by a malabsorptive syndrome2. We know that during the course of

bowel inflammation patients with Crohn's disease or with ulcerative colitis

may experience articular complaints. In these 2 conditions the importance of

diet has already been stated.

On the other hand, in more than 30% of patients with psoriasis, we reported

the occurrence of arthritis3,4, which may be accompanied by microscopic

inflammatory changes of colonic mucosa, even in the absence of bowel

symptoms5. Inflammatory bowel changes consisted of idiopathic inflammatory

bowel disease only in a few cases. Indeed, we found in the majority of

patients, based on guidelines suggested by the British Society of

Gastroenterology6, an unclassified form of colitis completely different from

ulcerative colitis (psoriatic colitis?). On the other hand, both Crohn's

disease and ulcerative colitis or celiac disease can be complicated by skin

symptoms including pyoderma gangrenosum and dermatitis herpetiformis, as

well as psoriasis.

Based on the foregoing our hypothesis of a pathogenetic link between the

skin, joints, and gut in spondyloarthritic patients is reliable. It is

conceivable that in patients with psoriasis a unique disease exists that may

develop and involve, at the same time or in different sequential stages,

cutaneous, articular, and intestinal sites.

Psoriasis is a systemic condition with a profound impact on the quality of

the life of patients. It has a relapsing clinical trend regarding severity

and extent of skin involvement. Clinical evidence, therefore, may be widely

variable over time. In fact, there are patients with classical, distinctive

lesions and others with minimal active manifestations, as well as those with

only a medical history of a previous rash. This cutaneous variability does

not affect the clinical expression of joint disease, which is present in 30%

of cases, independently from the presence and/or the degree of expression of

a clinically evident rash. PsA may also be observed in patients without

psoriasis but with a family history positive for a psoriasis in first or

second-degree relatives. This last setting characterizes the so-called

subset of psoriatic arthritis " sine psoriasis " 7. In addition, it highlights

the importance of genetic factors, which surely play a non-marginal

pathogenetic role in the clinical expression of all manifestations of the

disease.

Recently, new lines of biological evidence may help to explain all molecular

manifestations of the disease. In psoriatic patients the immune system is

involved in both the skin and the joints. Despite uncertainty about the

factor(s) that either initiates or perpetuates this immune reaction,

considerable progress has been made in characterizing the steps of the

inflammatory cascade. Epidermal keratinocytes, dendritic antigen-presenting

cells, T lymphocytes, endothelial cells, and synoviocytes are the actors

directed by various soluble mediators, among which tumor necrosis factor

(TNF) plays a fundamental role. TNF induces the production of growth

factors, adhesion molecules, and chemotactic polypeptides, which contribute

to the recruitment of a cellular network colonizing skin8,9, joints10,11,

and other sites, such as the bowel12,13.

In 1999, we proposed in an editorial4 the schema shown in Figure 1. At

present, this schema could be modified as shown in Figure 2. TNF activates

the inflammatory process of psoriasis in the skin, joints, and into the

bowel.

As matters stand, we must pose the question: Is it still meaningful to speak

of psoriasis or PsA as 2 distinct clinical manifestations? We indeed believe

that it would be better to introduce the concept of " psoriatic disease, " a

condition that can be characterized by involvement of several different

anatomical sites in the same patient. This would prompt a dermatologist to

better consider the effect of arthritis, while a rheumatologist would be

able to appreciate the emotional and physical morbidity impact induced by

rash. Finally, both dermatologists and rheumatologists should consider the

occurrence of bowel inflammation.

We imagine today that, in a model psoriatic arthritis clinic, a project for

clinical research should include a dermatologist, a rheumatologist, and a

gastroenterologist. In Naples we have experience in this combined approach.

Patients are always evaluated by a clinical team utilizing their different

approaches. Results are discussed during common clinical rounds, which

allows for improvement in our clinical standards. In the past 2 decades we

should be aware that many changes have modified our understanding of

psoriatic arthritis.

http://www.jrheum.com/subscribers/06/02/210.html

Not an MD

I'll tell you where to go!

Mayo Clinic in Rochester

http://www.mayoclinic.org/rochester

s Hopkins Medicine

http://www.hopkinsmedicine.org