In-vitro cyclosporin sensitivity of proliferating lymphocytes is predictive of in-vivo therapeutic response in ulcerative colitis

Antigen delivery to dendritic cells shapes human CD4+ and CD8+ T cell memory responses to Staphylococcus aureus

Intracellular persistence of Staphylococcus aureus favors bacterial spread and chronic infections. Here, we provide evidence for the existence of human CD4⁺ and CD8⁺ T cell memory against staphylococcal antigens. Notably, the latter could provide a missing link in our understanding of immune control of intracellular S. aureus. The analyses showed that pulsing of monocyte-derived dendritic cells (MoDC) with native staphylococcal protein antigens induced release of Th2-associated cytokines and mediators linked to T regulatory cell development (G-CSF, IL-2 and IL-10) from both CD4⁺ and CD8⁺ T cells, thus revealing a state of tolerance predominantly arising from preformed memory T cells. Furthermore, G-CSF was identified as a suppressor of CD8⁺ T cell-derived IFNγ secretion, thus confirming a tolerogenic role of this cytokine in the regulation of T cell responses to S. aureus. Nevertheless, delivery of in vitro transcribed mRNA-encoded staphylococcal antigens triggered Th1-biased responses, e.g. IFNγ and TNF release from both naïve and memory T cells. Collectively, our data highlight the potential of mRNA-adjuvanted antigen presentation to enable inflammatory responses, thus overriding the existing Th2/Treg-biased memory T cell response to native S. aureus antigens.

Staphylococcus aureus is deemed one of the most important nosocomial pathogens but, to date, there are no safe and protective vaccines. In this study we investigate the nature of the preformed T cell response to S. aureus antigens in healthy donors. Our data reveal that CD4⁺ and—so far not described—CD8⁺ T cell memory responses against native staphylococcal antigens exist but are skewed towards minimizing inflammation and promoting tolerance. The T cell response to staphylococcal antigens is characterized by the secretion of typical Th2 cytokines such as IL-5 and IL-13 and mediators associated with formation of T regulatory cells. Most importantly, G-CSF suppresses IFNγ release from pre-existent memory T cells. However, our data reveal that the use of mRNA-encoded antigens to trigger S. aureus-specific T cell responses bears the potential to override the tolerogenic bias. It favors TNF- and IFNγ-releasing T cells and may, thus, represent an innovative tool in prophylactic and therapeutic vaccine development.

Value of colonoscopy for prediction of prognosis in patients with ulcerative colitis

Ulcerative colitis (UC) is a chronic inflammatory bowel disorder characterized by exacerbations and remissions. Some UC patients remain refractory to conventional medical treatment while, in others, the effectiveness of drugs is limited by side-effects. Recently, cyclosporine and leukocyte removal therapy have been used for refractory UC patients. To predict the efficacy of these therapies is important for appropriate selection of treatment options and for preparation for colectomy. Endoscopy is the cornerstone for diagnosis and evaluation of UC. Endoscopic parameters in patients with severe or refractory UC may predict a clinical response to therapies, such as cyclosporine or leukocyte removal therapy. As for the patients with quiescent UC, relapse of UC is difficult to predict by routine colonoscopy. Even when routine colonoscopy suggests remission and a normal mucosal appearance, microscopic abnormalities may persist and relapse may occur later. To more accurately identify disease activity and to predict exacerbations in UC patients with clinically inactive disease is important for deciding whether medical treatment should be maintained. Magnifying colonoscopy is useful for the evaluation of disease activity and for predicting relapse in patients with UC.

Medical management of severe ulcerative colitis

The medical management of patients with severe ulcerative colitis requires initial stabilization, careful and repeated evaluations to exclude confounding or coexisting diagnoses, and timely delivery of appropriate medications. Medical therapies for these patients are potent but may be toxic, and administration must be done by experienced medical professionals, with adequate access to appropriate laboratory, radiographic, endoscopic, and surgical facilities. Patients who fail to respond to high-dose intravenous corticosteroids in a timely basis should be evaluated for cyclosporin therapy, or proceed to surgery. The promise of newer, investigational therapies to induce and maintain remission must be borne out by large controlled trials.

Cyclosporin therapy in severe ulcerative colitis: is it worth the effort?

PURPOSE

Cyclosporin is advocated in the treatment of acute severe ulcerative colitis that has failed to respond to high-dose corticosteroid therapy. This approach is controversial, with critics highlighting the temporary nature of remissions and the potential for adverse effects. There have been few reports of the long-term outcome of those patients who do respond. The purpose of this study was to investigate the clinical outcome of all patients treated with cyclosporin at our institution over the past five years.

METHODS

We conducted a retrospective study of 46 patients who presented to a tertiary referral center. Initial responders were those who avoided colectomy; a sustained response was defined as a remission that lasted while the patient was taking oral cyclosporin and for three months after this therapy was discontinued.

RESULTS

Thirty-two (69 percent) of 46 patients had an initial response to therapy, and 50 percent met criteria for a sustained response. Eleven of 23 sustained responders subsequently relapsed. At a mean of 22 months' follow-up, 26 percent of patients remain well and have never relapsed. Serious infective complications occurred in two patients, possibly attributable to therapy. No factors predictive of a likely response were identifiable on retrospective analysis.

CONCLUSIONS

This study confirms the efficacy of cyclosporin in the management of severe ulcerative colitis. Although many initial responders subsequently relapse, such patients may benefit from having even a short time to adjust to the need for surgery. A substantial minority (26 percent) of all patients treated remain in long-term remission.