Kupffer-cell depletion attenuates colonic and extracolonic granulomatous inflammation in chronic colitis

A hepatocyte-specific transcriptional program driven by Rela and Stat3 exacerbates experimental colitis in mice by modulating bile synthesis

Hepatic factors secreted by the liver promote homeostasis and are pivotal for maintaining the liver-gut axis. Bile acid metabolism is one such example wherein, bile acid synthesis occurs in the liver and its biotransformation happens in the intestine. Dysfunctional interactions between the liver and the intestine stimulate varied pathological outcomes through its bidirectional portal communication. Indeed, aberrant bile acid metabolism has been reported in inflammatory bowel disease (IBD). However, the molecular mechanisms underlying these crosstalks that perpetuate intestinal permeability and inflammation remain obscure. Here, we identify a novel hepatic gene program regulated by Rela and Stat3 that accentuates the inflammation in an acute experimental colitis model. Hepatocyte-specific ablation of Rela and Stat3 reduces the levels of primary bile acids in both the liver and the gut and shows a restricted colitogenic phenotype. On supplementation of chenodeoxycholic acid (CDCA), knock-out mice exhibit enhanced colitis-induced alterations. This study provides persuasive evidence for the development of multi-organ strategies for treating IBD and identifies a hepatocyte-specific Rela-Stat3 network as a promising therapeutic target.

Protective Effect of Spirulina platensis Extract against Dextran-Sulfate-Sodium-Induced Ulcerative Colitis in Rats

Inflammatory bowel disease is a multifactorial inflammatory condition. This study aimed to test the protective effects of Spirulina platensis against ulcerative colitis (UC). UC was induced in thirty-six male Wistar rats by adding dextran sulfate sodium (DSS) to their drinking water, while a control group received only drinking water. UC rats were equally-divided into six groups that received a single oral daily dose of vehicle (DSS), sulfasalazine (SSZ, 50 mg/kg/day), chloroform or the hydroalcoholic extracts of Spirulina platensis (100 or 200 mg/kg/day) for 15 days, and then blood and colon samples were harvested for determination of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), erythrocyte sedimentation rate (ESR), myeloperoxidase (MPO), and histopathology. At the end of the study, compared to time-matched controls, UC rats showed increased TNF-α (1.64-fold), IL-6 (5.73-fold), ESR (3.18-fold), and MPO (1.61-fold), along with loss of body weight (24.73%) and disease activity index (1.767 ± 0.216 vs. 0 ± 0), p < 0.001. These effects were prevented by SSZ treatment (p < 0.001 vs. DSS). The hydroalcoholic extract of Spirulina platensis dose-dependently modulated all DSS-induced inflammatory changes. However, the chloroform extract significantly lowered only IL-6 and ESR, but not TNF-α or MPO levels. The protective effects of the hydroalcoholic extract of Spirulina platensis against experimental UC involved mitigation of DSS-induced inflammation.

Gadolinium chloride attenuates acetic acid-evoked colitis in mice by reducing neutrophil infiltration and pro-oxidative enzyme activity

This study investigated the potential of gadolinium chloride (GdCl₃), an inhibitor of kupffer cells on the myeloperoxidase (MPO) function, both in vivo on colon inflammation model and in vitro on thioglycollate-elicited peritoneal neutrophils. Colon inflammation was induced in mice (n = 7) by 4% acetic acid (AA) enema. GdCl₃ (10 mg/kg) treatment was given 24 h before AA challenge. Clinical changes during the protocol were scored. Colons were segmented into distal and proximal parts for histological and biochemical assessment. Furthermore, myeloperoxidase (MPO) enzymes were extracted and analyzed by western blot. Short-term GdCl₃ treatment inhibited dose-dependently superoxide anion (O₂^·-), alkaline phosphatase (ALP), and MPO release and promoted neutrophil apoptosis. In vivo, low-dose GdCl₃ improved colitis scores and inhibited acute phagocyte recruitment and colon damage within the mucosa as revealed by the decrease in MPO, nitric oxide (NO), and malondialdehyde (MDA) levels. At the same time, GdCl₃ restored catalase (CAT), superoxide dismutase (SOD) activities, and reduced glutathione (GSH) levels, thus reversing the MDA/GSH ratio in both distal and proximal colons. Compared to proximal, distal colon was more altered and displayed higher pathological manifestations. Lastly, the induction of apoptosis and regulation of the major nitrosative and oxidative functions of neutrophils by GdCl₃ suggests its consideration as a beneficial tool in attenuating colon inflammation.

Clinical significance of incidental colorectal wall thickening on computed tomography scan in African-American and Hispanic patients

We sought to assess the significance of an incidental finding of colorectal wall thickening (CRWT) on computed tomography (CT) scan in African-American and Hispanic patients. We retrospectively reviewed charts of African-American and Hispanic patients from January 1994 to December 2005. Those patients were included in whom the colonoscopy was performed due to incidental CRWT on CT scan. Patients with a history or a family history of colorectal malignancy, inflammatory bowel disease, or colorectal surgery, with an incomplete colonoscopic examination, or <18 years of age were excluded. Endoscopic and pathological findings were abstracted. Thirty-two patients met the criteria. Endoscopic examination was abnormal in 21 (65.6%). The positive predictive value of CRWT for abnormal endoscopic examination was 65.6%. Abnormal endoscopic examination revealed diverticulosis in 9 (43%), erythematous mucosa in 8 (38%), polyps in 6 (29%), mass in 2 (9%), thickened folds in 1 (5%), and diverticulitis in 1 (5%). Histopathological findings revealed colitis in 7 (33%), adenoma in 4 (19%), hyperplastic polyps in 4 (19%), adenocarcinoma in 2 (9%), lymphoid aggregates in 2 (9%), melanosis coli in 1 (5%), and normal in 1 (5%) in the abnormal examination group. Abnormal endoscopic examination was found in 65.6% of patients. The prevalence of colitis, adenomas, and malignancy was high, therefore abnormal CRWT warrants further endoscopic evaluation.

Importance of the liver in systemic complications associated with acute pancreatitis: the role of Kupffer cells

Although its exact nature is still unknown, acute pancreatitis progresses with a local production of inflammatory mediators, eventually leading to systemic inflammatory response syndrome. Knowing that almost all pancreatic mediators released from the pancreas to the bloodstream may pass through the liver before their dilution in the systemic circulation, it would be reasonable to assume a determinant role for this organ in the development of the inflammatory response associated with acute pancreatitis. Thus, recent studies have shown the involvement of the liver in the complex network of events triggering the multiorgan dysfunction associated with the disease. Once pancreatic mediators reach the liver, they strongly activate Kupffer cells, the resident macrophages, greatly amplifying the release of cytokines into the bloodstream and thus contributing to the systemic manifestations of acute pancreatitis. Altogether, these results show that the pancreas is not the only source of mediators that trigger the deleterious effects of acute pancreatitis, but that the liver may orchestrate the final outcome of the disease. The purpose of this review is to discuss progress in understanding the function of the liver in the early stages of the development of systemic organ dysfunction secondary to acute pancreatitis.

Influx of macrophages into livers of rats treated with hepatotoxicants (thioacetamide, allyl alcohol, D-galactosamine) induces expression of HSP25

Treatment of rats with a single dose of thioacetamide (TAA) provokes centrilobular inflammation and a significant expression of heat shock protein HSP25 in hepatocytes surrounding the area of inflammation. The HSP25 accumulation in hepatocytes adjacent to inflammatory regions was confirmed by identification of positive hepatocytes concentrated at periportal areas after treatment of rats with allyl alcohol (AA) or distributed diffusely throughout liver lobule after treatment with D-galactosamine (D-gal). In our model of TAA-treated rats the use of the anti-inflammatory drug-indomethacin, and the redox-regulating drug-N-acetylcysteine (NAC), significantly attenuated TAA-induced HSP25 expression and evoked morphological changes of recruited ED1+ macrophages. Treatment of rats with gadolinium chloride (GdCl(3)) decreased considerably the number of Kupffer cells (ED2+ macrophages) without affecting significantly the number and morphology of ED1+ macrophages as well as the expression pattern of TAA-induced HSP25. Our data shows for the first time that ED1+ macrophages recruited into the liver by treatment with TAA play a significant role in HSP25 induction in hepatocytes.

Folate-targeted immunotherapy effectively treats established adjuvant and collagen-induced arthritis

Activated macrophages express a cell surface receptor for the vitamin folic acid. Because this receptor is inaccessible or not measurably expressed on other normal cells, folic acid has been recently exploited to selectively deliver attached radio-emitters to sites of activated macrophage accumulation, allowing scintigraphic imaging of inflamed joints and organs of arthritic rats. We demonstrate here that folate-linked haptens can also be targeted to activated macrophages, decorating their cell surfaces with highly immunogenic molecules. Under conditions in which the rodent has already been immunized against keyhole limpet hemocyanine-(fluorescein isothiocyanate) FITC, activated macrophages are eliminated. Administration of folate-FITC conjugates to rodents with experimental arthritis attenuates (a) systemic and peri-articular inflammation, (b) bone and cartilage degradation, and (c) arthritis-related body weight loss. Treatment with folate-hapten conjugates is comparable to methotrexate, etanercept, anakinra, and celecoxib at alleviating the symptoms of arthritis. We conclude that reduction of activated macrophages by folate-targeted immunotherapy can ameliorate the symptoms of arthritis in two rodent models of the disease.

Role of hepatic STAT3 in brain-insulin action on hepatic glucose production

STAT3 regulates glucose homeostasis by suppressing the expression of gluconeogenic genes in the liver. The mechanism by which hepatic STAT3 is regulated by nutritional or hormonal status has remained unknown, however. Here, we show that an increase in the plasma insulin concentration, achieved either by glucose administration or by intravenous insulin infusion, stimulates tyrosine phosphorylation of STAT3 in the liver. This effect of insulin was mediated by the hormone's effects in the brain, and the increase in hepatic IL-6 induced by the brain-insulin action is essential for the activation of STAT3. The inhibition of hepatic glucose production and of expression of gluconeogenic genes induced by intracerebral ventricular insulin infusion was impaired in mice with liver-specific STAT3 deficiency or in mice with IL-6 deficiency. These results thus indicate that IL-6-STAT3 signaling in the liver contributes to insulin action in the brain, leading to the suppression of hepatic glucose production.