Influence of hepatic fibrosis and inflammation: Correlation between histopathological changes and Gd-EOB-DTPA-enhanced MR imaging

Objective

To evaluate the influence of an active inflammatory process in the liver on Gd-EOB-DTPA-enhanced MR imaging in patients with different degrees of fibrosis/cirrhosis.

Material and methods

Overall, a number of 91 patients (61 men and 30 women; mean age 58 years) were included in this retrospective study. The inclusion criteria for this study were Gd-EOB-DTPA-enhanced MRI of the liver and histopathological evaluation of fibrotic and inflammatory changes. T1-weighted VIBE sequences of the liver with fat suppression were evaluated to determine the relative signal change (RE) between native and hepatobiliary phase (20min). In simple and multiple linear regression analyses, the influence of liver fibrosis/cirrhosis (Ishak score) and the histopathological degree of hepatitis (Modified Hepatic Activity Index, mHAI) on RE were evaluated.

Results

RE decreased significantly with increasing liver fibrosis/cirrhosis (p < 0.001) and inflammation (mHAI, p = 0.004). In particular, a correlation between RE and periportal or periseptal boundary zone hepatitis (moth feeding necrosis, mHAI A, p = 0.001) and portal inflammation (mHAI D, p < 0.001) was observed. In multiple linear regression analysis, both the degree of inflammation and the degree of fibrosis were significant predictors for RE (p < 0.01).

Conclusion

The results of this study suggest that the MR-based hepatic enhancement index RE is not only influenced by the degree of fibrosis, but also by the degree of inflammation.

Basophils Trigger Fibroblast Activation in Cardiac Allograft Fibrosis Development

Fibrosis is a major component of chronic cardiac allograft rejection. Although several cell types are able to produce collagen, resident (donor-derived) fibroblasts are mainly responsible for excessive production of extracellular matrix proteins. It is currently unclear which cells regulate production of connective tissue elements in allograft fibrosis and how basophils, as potential producers of profibrotic cytokines, are involved this process. We studied this question in a fully MHC-mismatched model of heart transplantation with transient depletion of CD4(+) T cells to largely prevent acute rejection. The model is characterized by myocardial infiltration of leukocytes and development of interstitial fibrosis and allograft vasculopathy. Using depletion of basophils, IL-4-deficient recipients and IL-4 receptor-deficient grafts, we showed that basophils and IL-4 play crucial roles in activation of fibroblasts and development of fibrotic organ remodeling. In the absence of CD4(+) T cells, basophils are the predominant source of IL-4 in the graft and contribute to expansion of myofibroblasts, interstitial deposition of collagen and development of allograft vasculopathy. Our results indicated that basophils trigger the production of various connective tissue elements by myofibroblasts. Basophil-derived IL-4 may be an attractive target for treatment of chronic allograft rejection.

Acute administration of antibiotics modulates intestinal capillary perfusion and leukocyte adherence during experimental sepsis

Antibiotic treatment represents a mainstay of therapy for clinical sepsis. Distinct from their antimicrobial effects, antibiotics may impact the inflammatory process in sepsis, e.g. within the intestinal microcirculation. The impact of seven antibiotics relevant to clinical sepsis on intestinal leukocyte recruitment and capillary perfusion was studied in rats with colon ascendens stent peritonitis (CASP)-induced sepsis or after endotoxin [lipopolysaccharide (LPS)] challenge. The following antibiotics were included: daptomycin; erythromycin; imipenem; linezolid; tigecycline; tobramycin; and vancomycin. The number of rolling and adherent leukocytes in intestinal submucosal venules and the functional capillary density (FCD) in three layers of the intestinal wall were assessed using intravital microscopy. CASP-induced sepsis reduces the intestinal FCD by 30-50%. Single administration of daptomycin, tigecycline or linezolid increased the intestinal FCD. CASP sepsis increased the number of rolling leukocytes by 4.5-fold, which was reduced by erythromycin but increased by vancomycin. The number of adherent leukocytes increased 3-fold in rats with CASP sepsis. It was reduced following administration of daptomycin, tigecycline (in V1 and V3 venules), erythromycin and linezolid (in V1 venules). However, following tobramycin and vancomycin, leukocyte adhesion was further enhanced. Administration of tigecycline and linezolid reduced the LPS-induced increase in the number of adherent leukocytes by 50%. However, imipenem did not affect leukocyte adherence. In conclusion, this work highlights the beneficial impact of the antibiotics daptomycin, tigecycline, erythromycin and linezolid in that they improve intestinal capillary perfusion and/or reduce leukocyte recruitment, whilst the antibiotics imipenem, tobramycin and vancomycin do not exert these properties.