Effect of chronic administration of tacrolimus and cyclosporine on human gastrointestinal permeability

Local FK506 delivery induces osteogenesis in rat bone defect and rabbit spine fusion models

Bone grafting procedures are commonly used for the repair, regeneration, and fusion of bones in a wide range of orthopaedic surgeries, including large bone defects and spine fusion procedures. Autografts are the clinical gold standard, though recombinant human bone morphogenetic proteins (rhBMPs) are often used, particularly in difficult clinical situations. However, treatment with rhBMPs can have off-target effects and increase surgical costs, adding to patients' already high economic and mental burden. Recent studies have identified that FDA-approved immunosuppressant drug, FK506 (Tacrolimus), can also activate the BMP pathway by binding to its inhibitors. This study tested the hypothesis that FK506, as a standalone treatment, could induce osteogenic differentiation of human mesenchymal stromal cells (hMSCs), as well as functional bone formation in a rat segmental bone defect model and rabbit spinal fusion model. FK506 enhanced osteogenic differentiation and mineralization of hMSCs in vitro. Standalone treatment with FK506 delivered on a collagen sponge produced consistent bone bridging of a critically sized rat femoral defect with functional mechanical properties comparable to naïve bone. In a rabbit single level posterolateral spine fusion model, treatment with FK506 delivered on a collagen sponge successfully fused the L5-L6 vertebrae at rates comparable to rhBMP-2 treatment. These data demonstrate the ability of FK506 to induce bone formation in human cells and two challenging in vivo models, and indicate FK506 can be utilized to treat a variety of spine disorders.

Local FK506 delivery induces osteogenesis in in vivo rat bone defect and rabbit spine fusion models

Bone grafting procedures are commonly used for the repair, regeneration, and fusion of bones in in a wide range of orthopaedic surgeries, including large bone defects and spine fusion procedures. Autografts are the clinical gold standard, though recombinant human bone morphogenetic proteins (rhBMPs) are often used, particularly in difficult clinical situations. However, treatment with rhBMPs can have off-target effects and significantly increase surgical costs, adding to patients' already high economic and mental burden. Recent studies have identified that FDA-approved immunosuppressant drug, FK506 (Tacrolimus), can also activate the BMP pathway by binding to its inhibitors. This study tested the hypothesis that FK506, as a standalone treatment, could induce osteogenic differentiation of human mesenchymal stromal cells (hMSCs), as well as functional bone formation in a rat segmental bone defect model and rabbit spinal fusion model. FK506 potentiated the effect of low dose BMP-2 to enhance osteogenic differentiation and mineralization of hMSCs in vitro. Standalone treatment with FK506 delivered on a collagen sponge, produced consistent bone bridging of a rat critically-sized femoral defect with functional mechanical properties comparable to naïve bone. In a rabbit single level posterolateral spine fusion model, treatment with FK506 delivered on a collagen sponge successfully fused the L5-L6 vertebrae at rates comparable to rhBMP-2 treatment. These data demonstrate the ability of FK506 to induce bone formation in human cells and two challenging in vivo models, and indicate FK506 can be utilized either as a standalone treatment or in conjunction with rhBMP to treat a variety of spine disorders.

Intestinal Permeability in Patients Early after Kidney Transplantation Treated with Two Different Formulations of Once-Daily Tacrolimus

Adequate tacrolimus blood exposure is crucial in the early post-renal transplant period and a gut epithelial barrier integrity may play a role. We prospectively investigated several markers of intestinal permeability in recent kidney transplant recipients (KTRs) treated with different tacrolimus extended-release formulations. Within each of the 49 KTR pairs that received grafts from the same donor, an early randomized conversion was performed from twice-daily (Prograf) to once-daily tacrolimus formulation: Advagraf or Envarsus. Plasma zonulin, calprotectin, circulating lipopolysaccharide (LPS), LPS-binding protein (LBP), intestinal fatty acid binding protein (FABP-2), and CD-14 levels were measured. There was no difference in the recipient age, dialysis vintage, BMI, and residual diuresis between Advagraf and Envarsus groups. FABP-2 and LPS levels were significantly associated with tacrolimus trough level, 3-h level, and area under the curve (AUC) in the Envarsus but not in the Advagraf group. AUC was independently increased by LPS and decreased by age, FABP-2 concentration, and the use of Envarsus formulation as compared with Advagraf. Functional changes of gastrointestinal tract in patients treated with Envarsus may influence intestinal tacrolimus absorption to a greater extent than in Advagraf-treated KTRs and may lead to inadequate variability of tacrolimus exposure early after kidney transplantation.

Intestinal permeability in patients with IgA nephropathy and other glomerular diseases: an observational study

BACKGROUND

A dysregulated 'gut-kidney axis' may contribute to immunoglobulin A nephropathy (IgAN). We studied whether IgAN patients have disturbed intestinal permeability.

METHODS

In a prospective, cross sectional, pilot study we assessed intestinal permeability in 35 IgAN patients, 18 patients with non-IgAN glomerulonephritides (GNs) and 19 healthy controls. After an overnight fast, trial participants ingested a multi-sugar solution and samples were obtained from 0 to 2, 2 to 5- and 5 to 24-h urine portions. Urinary sugar concentrations were quantified using isocratic ion-exchange high performance liquid chromatography. Indices of small intestinal permeability (0-2-h lactulose/L-rhamnose (L/R) ratio), distal small intestinal and proximal colonic permeability (2-5-h sucralose/erythritol (S/E) ratio) and colonic permeability (5-24-h sucralose/erythritol (S/E) ratio) were evaluated. Associations between groups and indices of intestinal permeability were investigated by a linear mixed model.

RESULTS

Small intestinal permeability (0-2 h L/R-ratio) was significantly increased in patients with glomerular diseases versus healthy controls. More precisely, increased small intestinal permeability was exclusively noted in non-IgAN GN patients, whereas IgAN patients exhibited a trend towards elevated small intestinal permeability. In total, 54% of patients with IgAN and 67% of non-IgAN GN patients had increased small intestinal permeability. Neither distal small intestinal and proximal colonic permeability nor colonic gut permeability indices (i.e., 2-5 h and 5-24 h S/E ratios) were significantly different between controls and any of the GN patient groups.

CONCLUSION

The present single center pilot study suggests that disturbed intestinal permeability is common in patients with glomerular diseases and is not specific for IgAN.

TRIAL REGISTRATION NUMBER

German Clinical Trials Register DRKS00021533, Date: 24.04.2020.

A decrease in functional microbiomes represented as Faecalibacterium affects immune homeostasis in long-term stable liver transplant patients

LT, liver transplantation; HCC, hepatocellular carcinoma; IS, immunosuppressants; DC, dendritic cells; Treg, regulatory T; Th17, T helper 17; AST, aspartate transaminase; ALT, alanine transaminase; OUT, operational taxonomic unit; LEfSe, linear discriminant analysis effect size; LDA, linear discriminant analysis; IL, interleukin; TGF, transforming growth factor; GM-CSF, granulocyte-macrophage colony-stimulating factor; IFN, interferon; TNF-α, tumor necrosis factor-α; MIP-1α, macrophage inflammatory protein-1α; IP-10, interferon γ-induced protein; MCP-1, monocyte chemoattractant protein-1; ACR, acute cellular rejection; NF-κB, nuclear factor κB; PT INR, prothrombin time; QC, quality check; PBMC, peripheral blood mononuclear cells; PBS, phosphate-buffered saline; ELISA, enzyme-linked immunosorbent assay.

Interactions between human microbiome, liver diseases, and immunosuppression after liver transplant

In liver transplant patients, solid tumors and post-transplant lymphoproliferative disorders have emerged as significant long-term mortality causes. In addition, it is assumed that de novo malignancy after liver transplantation (LT) is the second-leading cause of death after cardiovascular complications. Well-established risk factors for post-transplant lymphoproliferative disorders and solid tumors are calcineurin inhibitors, tacrolimus, and cyclosporine, the cornerstones of all immunosuppressive therapies used after LT. The loss of immunocompetence facilitated by the host immune system due to prolonged immunosuppressive therapy leads to cancer development, including LT patients. Furthermore, various mechanisms such as bacterial dysbiosis, activation through microbe-associated molecular patterns, leaky gut, and bacterial metabolites can drive cancer-promoting liver inflammation, fibrosis, and genotoxicity. Therefore, changes in human microbiota composition may contribute further to de novo carcinogenesis associated with the severe immunosuppression after LT.

Effects of Gut Metabolites and Microbiota in Healthy and Marginal Livers Submitted to Surgery

Microbiota is defined as the collection of microorganisms within the gastrointestinal ecosystem. These microbes are strongly implicated in the stimulation of immune responses. An unbalanced microbiota, termed dysbiosis, is related to the development of several liver diseases. The bidirectional relationship between the gut, its microbiota and the liver is referred to as the gut-liver axis. The translocation of bacterial products from the intestine to the liver induces inflammation in different cell types such as Kupffer cells, and a fibrotic response in hepatic stellate cells, resulting in deleterious effects on hepatocytes. Moreover, ischemia-reperfusion injury, a consequence of liver surgery, alters the microbiota profile, affecting inflammation, the immune response and even liver regeneration. Microbiota also seems to play an important role in post-operative outcomes (i.e., liver transplantation or liver resection). Nonetheless, studies to determine changes in the gut microbial populations produced during and after surgery, and affecting liver function and regeneration are scarce. In the present review we analyze and discuss the preclinical and clinical studies reported in the literature focused on the evaluation of alterations in microbiota and its products as well as their effects on post-operative outcomes in hepatic surgery.

Conversion from tacrolimus to sirolimus as a treatment modality in de novo allergies and immune-mediated disorders in pediatric liver transplant recipients

De novo PTAID may develop in pediatric solid organ transplant recipients, have a diverse spectrum, and are occasionally treatment resistant. Previous reports showed resolution of immune cytopenias in solid organ transplant recipients following replacement of the calcineurin inhibitor tacrolimus with the mTOR inhibitor sirolimus. Herein we describe a retrospective review (2000-2017) of subjects who developed PTAID in whom immunosuppression was changed to sirolimus. Eight recipients (6 males) of either liver (n = 7) or multivisceral transplant (n = 1) suffered from severe, treatment-resistant PTAID and were switched from tacrolimus to sirolimus. The median age at transplant was 1 year (range 0.5-2.4 years). Six (75%) recipients developed de novo allergy and 2 immune-mediated diseases. The median age at presentation of PTAID was 2.7 (1.4-9) years at a median of 1.3 (0.25-8) years after transplantation. The median time from PTAID presentation to conversion to sirolimus was 1.8 (0.45-10) years. Complete resolution of symptoms was seen in 4 (50%) patients after a median of 12 (range 4-24) months including 2 patients with immune-mediated disease, 1 eczema, and 1 with eosinophilic colitis. One patient with multiple food allergies had a partial response and 3 (38%) had no response. None of the 8 recipients developed sirolimus-attributed adverse events or acute rejection during a median follow-up of 5 (0.6-8) years after the conversion. Immunosuppression conversion from tacrolimus to sirolimus can be an effective therapy in patients suffering severe or treatment-resistant PTAID, suggesting a potential role for tacrolimus in the pathogenesis of PTAID.

Effect of liver transplantation on intestinal permeability and correlation with infection episodes

Background

Liver cirrhosis has been known to be associated with increased intestinal permeability (IP); however, little is known about the modification of IP after liver transplantation (LT). The present study was aimed to assess IP after LT and evaluated its association with laboratory tests and clinical parameters, as well as with the development of infections.

Methods

LT recipients were consecutively enrolled and compared with an equal number of patients with liver cirrhosis and healthy subjects. IP was assessed by urinary excretion of chromium-51 ethylenediaminetetraacetic acid (⁵¹Cr-EDTA).

Results

The median ⁵¹Cr-EDTA excretion was found to be higher in 35 LT recipients as compared with that in the healthy controls [4.77% (2.79–6.03) vs. 2.07% (1.57–2.42), p<0.0001], and comparable to that in the cirrhotic patients [3.69% (2.34–6.57), p = 0.445]. ⁵¹Cr-EDTA excretion was not associated with clinical variables, the type of immunosuppressive therapy, donor-related factors, comorbidities and incidence of infections [infection/no infection: 4.97% (3.14–7.03) vs 4.62% (2.79–5.82), p = 0.938].

Conclusion

LT recipients show an increased IP, similar to that in patients with liver cirrhosis. However, it is not associated with a high risk of infections. Further investigations into the pathogenesis of this persistent impairment of the intestinal barrier are warranted.

Intestinal permeability in the pathogenesis of liver damage: From non-alcoholic fatty liver disease to liver transplantation

The intimate connection and the strict mutual cooperation between the gut and the liver realizes a functional entity called gut-liver axis. The integrity of intestinal barrier is crucial for the maintenance of liver homeostasis. In this mutual relationship, the liver acts as a second firewall towards potentially harmful substances translocated from the gut, and is, in turn, is implicated in the regulation of the barrier. Increasing evidence has highlighted the relevance of increased intestinal permeability and consequent bacterial translocation in the development of liver damage. In particular, in patients with non-alcoholic fatty liver disease recent hypotheses are considering intestinal permeability impairment, diet and gut dysbiosis as the primary pathogenic trigger. In advanced liver disease, intestinal permeability is enhanced by portal hypertension. The clinical consequence is an increased bacterial translocation that further worsens liver damage. Furthermore, this pathogenic mechanism is implicated in most of liver cirrhosis complications, such as spontaneous bacterial peritonitis, hepatorenal syndrome, portal vein thrombosis, hepatic encephalopathy, and hepatocellular carcinoma. After liver transplantation, the decrease in portal pressure should determine beneficial effects on the gut-liver axis, although are incompletely understood data on the modifications of the intestinal permeability and gut microbiota composition are still lacking. How the modulation of the intestinal permeability could prevent the initiation and progression of liver disease is still an uncovered area, which deserves further attention.

Fecal Microbiome Data Distinguish Liver Recipients With Normal and Abnormal Liver Function From Healthy Controls

Emerging evidence suggests that altered intestinal microbiota plays an important role in the pathogenesis of many liver diseases, mainly by promoting inflammation via the “intestinal microbiota-immunity-liver” axis. We aimed to investigate the fecal microbiome of liver recipients with abnormal/normal liver function using 16S rRNA gene sequencing. Fecal samples were collected from 90 liver recipients [42 with abnormal liver function (Group LT_A) and 48 with normal liver function (Group LT_N)] and 61 age- and gender-matched healthy controls (HCs). Fecal microbiomes were analyzed for comparative composition, diversity, and richness of microbial communities. Principal coordinates analysis successfully distinguished the fecal microbiomes of recipients in Group LT_A from healthy subjects, with the significant decrease of fecal microbiome diversity in recipients in Group LT_A. Other than a higher relative abundance of opportunistic pathogens such as Klebsiella and Escherichia/Shigella in all liver recipients, the main difference in gut microbiome composition between liver recipients and HC was the lower relative abundance of beneficial butyrate-producing bacteria in the recipients. Importantly, we established a fecal microbiome index (specific alterations in Staphylococcus and Prevotella) that could be used to distinguish Group LT_A from Group LT_N, with an area under the receiver operating characteristic curve value of 0.801 and sensitivity and specificity values of 0.771 and 0.786, respectively. These findings revealed unique gut microbial characteristics of liver recipients with abnormal and normal liver functions, and identified fecal microbial risk indicators of abnormal liver function in liver recipients.

Effects of medicines used to treat gastrointestinal diseases on the pharmacokinetics of coadministered drugs: a PEARRL Review

Objectives

Drugs used to treat gastrointestinal diseases (GI drugs) are widely used either as prescription or over-the-counter (OTC) medications and belong to both the 10 most prescribed and 10 most sold OTC medications worldwide. The objective of this review article is to discuss the most frequent interactions between GI and other drugs, including identification of the mechanisms behind these interactions, where possible.

Key findings

Current clinical practice shows that in many cases, these drugs are administered concomitantly with other drug products. Due to their metabolic properties and mechanisms of action, the drugs used to treat gastrointestinal diseases can change the pharmacokinetics of some coadministered drugs. In certain cases, these interactions can lead to failure of treatment or to the occurrence of serious adverse events. The mechanism of interaction depends highly on drug properties and differs among therapeutic categories. Understanding these interactions is essential to providing recommendations for optimal drug therapy.

Summary

Interactions with GI drugs are numerous and can be highly significant clinically in some cases. While alterations in bioavailability due to changes in solubility, dissolution rate, GI transit and metabolic interactions can be (for the most part) easily identified, interactions that are mediated through other mechanisms, such as permeability or microbiota, are less well-understood. Future work should focus on characterising these aspects.

Microbiota and the liver

The gut microbiome outnumbers the human genome by 150-fold and plays important roles in metabolism, immune system education, tolerance development, and prevention of pathogen colonization. Dysbiosis has been associated with nonalcoholic fatty liver disease (NAFLD), nonalcoholic steatohepatitis (NASH), and alcoholic liver disease (ALD) as well as cirrhosis and complications. This article provides an overview of this relationship. Liver Transplantation 24 539-550 2018 AASLD.

Liver transplant modulates gut microbial dysbiosis and cognitive function in cirrhosis

Liver transplantation (LT) improves daily function and cognition in patients with cirrhosis, but a subset of patients can remain impaired. Unfavorable microbiota or dysbiosis is observed in patients with cirrhosis, but the effect of LT on microbial composition, especially with poor post-LT cognition, is unclear. The aims were to determine the effect of LT on gut microbiota and to determine whether gut microbiota are associated with cognitive dysfunction after LT. We enrolled outpatient patients with cirrhosis on the LT list and followed them until 6 months after LT. Cognition (Psychometric Hepatic Encephalopathy score [PHES]), health-related quality of life (HRQOL), and stool microbiota (multitagged sequencing for diversity and taxa) tests were performed at both visits. Persistent cognitive impairment was defined as a stable/worsening PHES. Both pre-/post-LT data were compared with age-matched healthy controls. We enrolled 45 patients (56 ± 7 years, Model for End-Stage Liver Disease score 26 ± 8). They received LT 6 ± 3 months after enrollment and were re-evaluated 7 ± 2 months after LT with a stable course. A significantly improved HRQOL, PHES, with increase in microbial diversity, increase in autochthonous, and decrease in potentially pathogenic taxa were seen after LT compared with baseline. However, there was continued dysbiosis and HRQOL/cognitive impairment after LT compared with controls in 29% who did not improve PHES after LT. In these, Proteobacteria relative abundance was significantly higher and Firmicutes were lower after LT, whereas the reverse occurred in the group that improved. Delta PHES was negatively correlated with delta Proteobacteria and positively with delta Firmicutes. In conclusion, LT improves gut microbiota diversity and dysbiosis compared with pre-LT baseline but residual dysbiosis remains compared with controls. There is cognitive and HRQOL enhancement in general after LT, but a higher Proteobacteria relative abundance change is associated with posttransplant cognitive impairment. Liver Transplantation 23 907-914 2017 AASLD.

Impact of environmental factors on alloimmunity and transplant fate

Although gene-environment interactions have been investigated for many years to understand people's susceptibility to autoimmune diseases or cancer, a role for environmental factors in modulating alloimmune responses and transplant outcomes is only now beginning to emerge. New data suggest that diet, hyperlipidemia, pollutants, commensal microbes, and pathogenic infections can all affect T cell activation, differentiation, and the kinetics of graft rejection. These observations reveal opportunities for novel therapeutic interventions to improve graft outcomes as well as for noninvasive biomarker discovery to predict or diagnose graft deterioration before it becomes irreversible. In this Review, we will focus on the impact of these environmental factors on immune function and, when known, on alloimmune function, as well as on transplant fate.

The Intestinal Microbiome and the Liver Transplant Recipient: What We Know and What We Need to Know

The intestinal microbiome and immune system are in close symbiotic relationship in health. Gut microbiota plays a role in many chronic liver diseases and cirrhosis. However, alterations in the gut microbiome after liver transplantation and the implications for liver transplant recipients are not well understood and rely mainly on experimental animal studies. Recent advances in molecular techniques have identified that increased intestinal permeability, decreased beneficial bacteria, and increased pathogenic species may play important roles in the early posttransplant period. The associations between microbiota perturbation and postliver transplant infections and acute rejection are evolving. The link with metabolic syndrome, obesity, and cardiac disease in the general population require translation into the transplant recipient. This review focuses on our current knowledge of the known and potential interaction of the microbiome in the liver transplant recipient. Future human studies focused on microbiota changes in liver transplant patients are warranted and expected.

Food allergies developing after solid organ transplant

The development of food allergy is an increasingly recognized form of morbidity after solid organ transplant. It occurs more commonly in liver transplant recipients, although it has also been reported in heart, lung, kidney, and intestinal transplants. Pediatric transplant recipients are more likely to develop symptoms compared to adults, and reports of frequency vary widely from 5% to 38% in pediatric liver transplant recipients. Multiple mechanisms have been proposed in the literature, although no single mechanism can yet account for all reported observations. As food allergy can have at worst potentially fatal consequences, and at best require lifestyle adjustment through food avoidance, it is important for recipients to be aware of the donor's food allergies and particularly in pediatrics, the possibility of completely de novo allergies. This review explores the recent reports surrounding food allergy after solid organ transplant, including epidemiology, proposed mechanisms, and implications for practice.