Watchful Waiting After Radiological Guided Drainage of Intra-abdominal Abscess in Patients With Crohn's Disease Might Be Associated With Increased Rates of Stoma Construction.

Background: Management of spontaneous intra-abdominal abscess (IAA) in patients with Crohn's disease (CD) with radiologically guided percutaneous drainage (PD) was debated. Methods: This is a secondary analysis from a multicenter, retrospective cohort study of all the patients with CD who underwent PD followed by surgery at 19 international tertiary centers. Results: Seventeen patients (4.8%) who did not undergo surgery after PD were compared to those who had PD followed by surgical intervention 335/352 (95.2%). Patients who had PD without surgery were those with longer disease duration, more frequently had previous surgery for CD (laparotomies/laparoscopies), enteric fistula, on steroid treatment before and continue to have it after PD. Patients who had PD without subsequent surgical resection had a higher risk of stoma construction at later stages 8/17 (47.1%) versus 90/326 (27.6%) (P < .01). Patients with PD with no subsequent surgery had numerically higher rates of abscess recurrence 5/17 (29.4%) compared to those who had PD followed by surgery 45/335 (13.4%) the difference was not statistically significant (P = .07). Conclusions: Even with the low number of patients enrolled in this study who had PD of IAA without subsequent surgery, the findings indicate a markedly worse prognosis in terms of recurrence, length of stay, readmission, and stoma construction. Watchful waiting after PD to treat patients with spontaneous IAA might be indicated in selected patients with poor health status or poor prognostic factors.

Balance between activating NKG2D, DNAM-1, NKp44 and NKp46 and inhibitory CD94/NKG2A receptors determine natural killer degranulation towards rheumatoid arthritis synovial fibroblasts.

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation and synovial hyperplasia leading to progressive joint destruction. Fibroblast-like synoviocytes (FLS) are central components of the aggressive, tumour-like synovial structure termed pannus, which invades the joint space and cartilage. A distinct natural killer (NK) cell subset expressing the inhibitory CD94/NKG2A receptor is present in RA synovial fluid. Little is known about possible cellular interactions between RA-FLS and NK cells. We used cultured RA-FLS and the human NK cell line Nishi, of which the latter expresses an NK receptor repertoire similar to that of NK cells in RA synovial fluid, as an in vitro model system of RA-FLS/NK cell cross-talk. We show that RA-FLS express numerous ligands for both activating and inhibitory NK cell receptors, and stimulate degranulation of Nishi cells. We found that NKG2D, DNAM-1, NKp46 and NKp44 are the key activating receptors involved in Nishi cell degranulation towards RA-FLS. Moreover, blockade of the interaction between CD94/NKG2A and its ligand HLA-E expressed on RA-FLS further enhanced Nishi cell degranulation in co-culture with RA-FLS. Using cultured RA-FLS and the human NK cell line Nishi as an in vitro model system of RA-FLS/NK cell cross-talk, our results suggest that cell-mediated cytotoxicity of RA-FLS may be one mechanism by which NK cells influence local joint inflammation in RA.

Cytotoxicity of CD56(bright) NK cells towards autologous activated CD4+ T cells is mediated through NKG2D, LFA-1 and TRAIL and dampened via CD94/NKG2A.

In mouse models of chronic inflammatory diseases, Natural Killer (NK) cells can play an immunoregulatory role by eliminating chronically activated leukocytes. Indirect evidence suggests that NK cells may also be immunoregulatory in humans. Two subsets of human NK cells can be phenotypically distinguished as CD16(+)CD56(dim) and CD16(dim/-)CD56(bright). An expansion in the CD56(bright) NK cell subset has been associated with clinical responses to therapy in various autoimmune diseases, suggesting an immunoregulatory role for this subset in vivo. Here we compared the regulation of activated human CD4(+) T cells by CD56(dim) and CD56(bright) autologous NK cells in vitro. Both subsets efficiently killed activated, but not resting, CD4(+) T cells. The activating receptor NKG2D, as well as the integrin LFA-1 and the TRAIL pathway, played important roles in this process. Degranulation by NK cells towards activated CD4(+) T cells was enhanced by IL-2, IL-15, IL-12+IL-18 and IFN-α. Interestingly, IL-7 and IL-21 stimulated degranulation by CD56(bright) NK cells but not by CD56(dim) NK cells. NK cell killing of activated CD4(+) T cells was suppressed by HLA-E on CD4(+) T cells, as blocking the interaction between HLA-E and the inhibitory CD94/NKG2A NK cell receptor enhanced NK cell degranulation. This study provides new insight into CD56(dim) and CD56(bright) NK cell-mediated elimination of activated autologous CD4(+) T cells, which potentially may provide an opportunity for therapeutic treatment of chronic inflammation.