Fatigue in primary Sjögren's syndrome--a link to sickness behaviour in animals?
Interleukin-1beta (IL-1beta) is involved in the regulation of sickness behaviour in response to infection and inflammation in animals. Human fatigue can be considered an element of sickness behaviour and is a prominent and often disabling phenomenon in autoimmune diseases such as primary Sjögren's syndrome (PSS). The role of the IL-1 system in the fatigue of patients with PSS was explored. A cerebrospinal fluid (CSF) analysis of IL-1beta, IL-1Ra, and IL-1sRII was performed in 54 PSS patients and 53 control subjects. Fatigue was evaluated in the patients using the Fatigue Severity Scale (FSS) and a fatigue visual analogue scale (VAS); mood was evaluated using the Beck Depression Inventory (BDI). There were higher CSF levels of IL-1Ra pg/mL in PSS patients vs. controls (median 38.4: range 15.4-81.7 vs. 33.7: 7.3-163.1, p=0.026). Fatigue VAS scores were associated with increasing CSF levels of IL-1Ra in PSS patients (R(2)=0.11, p=0.015). In a subgroup analysis of the non-depressed PSS patients (N=37; 69%), the association between VAS scores and IL-1Ra was even stronger (R(2)=0.20, p=0.006). The positive association between VAS scores and IL-1Ra remained significant in a multiple regression analysis adjusting for age and BDI scores. Increased levels of IL-1Ra in the CSF are associated with increasing fatigue in PSS patients, indicating that the activated IL-1 system is a possible biological factor associated with fatigue.
Harboe
Erna
E
Clinical Immunology Unit, Department of Internal Medicine, Stavanger University Hospital, Norway. hare@sus.no
Tjensvoll
Anne Bolette
AB
Vefring
Hege K
HK
Gøransson
Lasse G
LG
Kvaløy
Jan Terje
JT
Omdal
Roald
R
D000328:Adult; D000368:Aged; D003863:Depression / Q000134:cerebrospinal fluid; D005221:Fatigue / Q000134:cerebrospinal fluid* / Q000150:complications; D005260:Female; D006801:Humans; D055809:Illness Behavior; D018836:Inflammation Mediators / Q000134:cerebrospinal fluid; D053590:Interleukin 1 Receptor Antagonist Protein / Q000134:cerebrospinal fluid*; D053583:Interleukin-1beta / Q000134:cerebrospinal fluid; D008297:Male; D008875:Middle Aged; D011788:Quality of Life; D053574:Receptors, Interleukin-1 Type II / Q000378:metabolism*; D012720:Severity of Illness Index; D012859:Sjogren's Syndrome / Q000134:cerebrospinal fluid* / Q000150:complications; D011795:Surveys and Questionnaires
D018836:Inflammation Mediators; D053590:Interleukin 1 Receptor Antagonist Protein; D053583:Interleukin-1beta; D053574:Receptors, Interleukin-1 Type II