Hematopoietic SCT modulates gut inflammation in experimental inflammatory bowel disease

mRNA-engineered mesenchymal stromal cells expressing CXCR2 enhances cell migration and improves recovery in IBD

Mesenchymal stromal cells (MSCs) have shown significant heterogeneity in terms of therapeutic efficacy for inflammatory bowel disease (IBD) treatment, which may be due to an insufficient number of MSCs homing to the damaged tissue of the colon. Engineering MSCs with specific chemokine receptors can enhance the homing ability by lentiviral transduction. However, the unclear specific chemokine profile related to IBD and the safety concerns of viral-based gene delivery limit its application. Thus, a new strategy to modify MSCs to express specific chemokine receptors using mRNA engineering is developed to evaluate the homing ability of MSCs and its therapeutic effects for IBD. We found that CXCL2 and CXCL5 were highly expressed in the inflammatory colon, while MSCs minimally expressed the corresponding receptor CXCR2. Transient expression of CXCR2 in MSC was constructed and exhibited significantly enhanced migration to the inflamed colons, leading to a robust anti-inflammatory effect and high efficacy. Furthermore, the high expression of semaphorins7A on MSCs were found to induce the macrophages to produce IL-10, which may play a critical therapeutic role. This study demonstrated that the specific chemokine receptor CXCR2 mRNA-engineered MSCs not only improves the therapeutic efficacy of IBD but also provides an efficient and safe MSC modification strategy.

Medical, ethical, and legal aspects of hematopoietic stem cell transplantation for Crohn’s disease in Brazil

Crohn's disease (CD) is a chronic inflammatory bowel disease that can affect any part of the gastrointestinal tract. The etiology of CD is unknown; however, genetic, epigenetic, environmental, and lifestyle factors could play an essential role in the onset and establishment of the disease. CD results from immune dysregulation due to loss of the healthy symbiotic relationship between host and intestinal flora and or its antigens. It affects both sexes equally with a male to female ratio of 1.0, and its onset can occur at any age, but the diagnosis is most commonly observed in the range of 20 to 40 years of age. CD diminishes quality of life, interferes with social activities, traumatizes due to the stigma of incontinence, fistulae, strictures, and colostomies, and in severe cases, affects survival when compared to the general population. Symptoms fluctuate between periods of remission and activity in which complications such as fistulas, strictures, and the need for bowel resection, surgery, and colostomy implantation make up the most severe aspects of the disease. CD can be progressive and the complications recurrent despite treatment with anti-inflammatory drugs, corticosteroids, immunosuppressants, and biological agents. However, over time many patients become refractory without treatment alternatives, and in this scenario, hematopoietic stem cell transplantation (HSCT) has emerged as a potential treatment option. The rationale for the use of HSCT for CD is anchored in animal studies and human clinical trials where HSCT could reset a patient's immune system by eliminating disease-causing effector cells and upon immune recovery increase regulatory and suppressive immune cells. Autologous HSCT using a non-myeloablative regimen of cyclophosphamide and anti-thymocyte globulin without CD34+ selection has been to date the most common transplant conditioning regimen adopted. In this review we will address the current situation regarding CD treatment with HSCT and emphasize the medical, ethical, and legal aspects that permeate the procedure in Brazil.

A single administration of human adipose tissue-derived mesenchymal stromal cells (MSC) induces durable and sustained long-term regulation of inflammatory response in experimental colitis

Current therapies for inflammatory bowel diseases (IBD) are aimed at controlling the exacerbated response in the gut, but no treatment is fully effective for many refractory patients. Mesenchymal stromal cells (MSC) are multi-potent cells with regulatory immunosuppressive activity that may control inflammatory diseases. In this study, we investigated the short- and especially the long-term protective effects of MSC on experimental colitis. We show that MSC elicited protection to acute intestinal inflammation with gain of weight, improvement in the clinical disease score and expressive reduction in the mortality rate of treated mice. MSC changed the population of neutrophils, eosinophils and augmented the frequency of CD4 T lymphocytes in the gut-draining lymph nodes, together with reduced accumulation of these cells in the colon intraepithelial compartment. Interestingly, there were increased levels of programmed death 1 (PD-1) and glucocorticoid-induced tumour necrosis factor receptor family-related receptor (GITR) in the spleen regulatory T cells of mice that received MSC treatment, which also presented a reversal in the pattern of immune response in the gut, with diminished inflammatory, T helper type 1 (Th1) and Th17 profile, in contrast to augmented Th2 responses. Most strikingly, this balanced response elicited by a single administration of MSC during the acute colitis persisted long-term, with restored goblet cells, eosinophils and maintenance of elevated gut interleukin (IL)-4, besides increased CD4⁺ CD25⁺ PD-1⁺ cells in the spleen and reduced Th17 response in mesenteric lymph nodes (MLN) of treated mice on day 60. Taken together, our findings provided a significant contribution to translational immunology by pointing human adipose tissue-derived MSC as a novel therapeutic approach with long-term beneficial regulatory effects in experimental colitis.

Classical and recent advances in the treatment of inflammatory bowel diseases

Crohn's disease (CD) and ulcerative colitis (UC) are intestinal disorders that comprise the inflammatory bowel diseases (IBD). These disorders have a significant effect on the quality of life of affected patients and the increasing number of IBD cases worldwide is a growing concern. Because of the overall burden of IBD and its multifactorial etiology, efforts have been made to improve the medical management of these inflammatory conditions. The classical therapeutic strategies aim to control the exacerbated host immune response with aminosalicylates, antibiotics, corticosteroids, thiopurines, methotrexate and anti-tumor necrosis factor (TNF) biological agents. Although successful in the treatment of several CD or UC conditions, these drugs have limited effectiveness, and variable responses may culminate in unpredictable outcomes. The ideal therapy should reduce inflammation without inducing immunosuppression, and remains a challenge to health care personnel. Recently, a number of additional approaches to IBD therapy, such as new target molecules for biological agents and cellular therapy, have shown promising results. A deeper understanding of IBD pathogenesis and the availability of novel therapies are needed to improve therapeutic success. This review describes the overall key features of therapies currently employed in clinical practice as well as novel and future alternative IBD treatment methods.

Bone marrow transplantation helps restore the intestinal mucosal barrier after total body irradiation in mice

Bone marrow transplantation (BMT) substantially improves 10-day survival after total body irradiation (TBI), consistent with an effect on intestinal radiation death. Total body irradiation, in addition to injuring the intestinal epithelium, also perturbs the mucosal immune system, the largest immune system in the body. This study focused on how transplanted bone marrow cells (BMCs) help restore mucosal immune cell populations after sublethal TBI (8.0 Gy). We further evaluated whether transplanted BMCs: (a) home to sites of radiation injury using green fluorescent protein labeled bone marrow; and (b) contribute to restoring the mucosal barrier in vivo. As expected, BMT accelerated recovery of peripheral blood (PB) cells. In the intestine, BMT was associated with significant early recovery of mucosal granulocytes (P = 0.005). Bone marrow transplantation did not affect mucosal macrophages or lymphocyte populations at early time points, but enhanced the recovery of these cells from day 14 onward (P = 0.03). Bone marrow transplantation also attenuated radiation-induced increase of intestinal CXCL1 and restored IL-10 levels (P = 0.001). Most importantly, BMT inhibited the post-radiation increase in intestinal permeability after 10 Gy TBI (P = 0.02) and modulated the expression of tight junction proteins (P = 0.01-0.05). Green fluorescent protein-positive leukocytes were observed both in intestinal tissue and in PB. These findings strongly suggest that BMT, in addition to enhancing general hematopoietic and immune system recovery, helps restore the intestinal immune system and enhances intestinal mucosal barrier function. These findings may be important in the development and understanding of strategies to alleviate or treat intestinal radiation toxicity.

Reappraisal of total body irradiation followed by bone marrow transplantation as a therapy for inflammatory bowel disease

The main current therapies for inflammatory bowel diseases (IBD) are aimed at controlling the exacerbated inflammation in the gut. Although these therapies have been successful, they are not curative and it is not possible to predict whether a beneficial response will occur or which patients will be refractory to the treatment. Total body irradiation (TBI) associated with chemotherapy is the first choice in the treatment of some hematological disorders and is an applicable option in the preparation of patients with hematologic diseases for hematopoietic stem cell transplantation. Then, in this study we investigated the association of TBI as immunosuppressive therapy and bone marrow cell (BMC) transplantation as a strategy to induce colitis recovery and immune reconstitution in the TNBS model of intestinal inflammation. TNBS mice treated with TBI associated with BMC transplantation presented elevated gain of weight and an overall better outcome of the disease when compared to those treated only with TBI. In addition, TBI associated or not with BMC reduced the frequency of inflammatory cells in the gut and restored the goblet cell counts. These results were accompanied by a down regulation in the production of inflammatory cytokines in the colon of mice treated with TBI alone or in association with BMC transplantation. The BMC infused were able to repopulate the ablated immune system and accumulate in the site of inflammation. However, although both treatments (TBI or TBI+BMC) were able to reduce gut inflammation, TBI alone was not enough to fully restore mice weight and these animals presented an extremely reduced survival rate when their immune system was not promptly reconstituted with BMC transplantation. Finally, these evidences suggest that the BMC transplantation is an efficient strategy to reduce the harmful effects of TBI in the colitis treatment, suggesting that radiotherapy may be an important immunosuppressive therapy in patients with IBD, by modulating the local inflammatory response.

Investigational new drugs in the treatment of inflammatory bowel disease: a review

The unraveling of the immuno-pathobiology of inflammatory bowel disease (IBD) in the past three decades has ushered in a new era of translational medicine. The biotechnology revolution has resulted in a paradigm shift in how clinicians view and treat IBD. Anti-tumor necrosis factor (TNF)-α strategies using infliximab and adalimumab currently dominate the therapeutic arena. Better understanding of how these biologicals work is driving the quest for loftier therapeutic goals of achieving mucosal healing, sustaining deep remission, and even modifying the natural history of IBD. However, not all patients respond to anti-TNF drugs. Immune-mediated adverse reactions and loss of efficacy with time also limit their use. There are many investigational drugs undergoing active clinical trials. Many have not fulfilled their early promises but some are potentially making the transition from bench to trial and to the bedside in the near future. Clinicians and investigators need to underpin our excitement with caution for the unknown long-term consequences of modulating cytokines and selective adhesion molecules in human. Here we provide an overview of investigational new drugs and other therapeutic strategies currently undergoing clinical trials in IBD.