Iron deficiency and anaemia in bariatric surgical patients: causes, diagnosis and proper management

Obesity-induced chronic inflammation leads to activation of the immune system that causes alterations of iron homeostasis including hypoferraemia, iron-restricted erythropoiesis, and finally mild-to-moderate anaemia. Thus, preoperative anaemia and iron deficiency are common among obese patients scheduled for bariatric surgery (BS). Assessment of patients should include a complete haematological and biochemical laboratory work-up, including measurement of iron stores, vitamin B12 and folate. In addition, gastrointestinal evaluation is recommended for most patients with iron-deficiency anaemia. On the other hand, BS is a long-lasting inflammatory stimulus in itself and entails a reduction of the gastric capacity and/or exclusion from the gastrointestinal tract which impair nutrients absorption, including dietary iron. Chronic gastrointestinal blood loss and iron-losingenteropathy may also contribute to iron deficiency after BS. Perioperative anaemia has been linked to increased postoperative morbidity and mortality and decreased quality of life after major surgery, whereas treatment of perioperative anaemia, and even haematinic deficiency without anaemia, has been shown to improve patient outcomes and quality of life. However, long-term follow-up data in regard to prevalence, severity, and causes of anaemia after BS are mostly absent. Iron supplements should be administered to patients after BS, but compliance with oral iron is no good. In addition, once iron deficiency has developed, it may prove refractory to oral treatment. In these situations, IV iron (which can circumvent the iron blockade at enterocytes and macrophages) has emerged as a safe and effective alternative for perioperative anaemia management. Monitoring should continue indefinitely even after the initial iron repletion and anaemia resolution, and maintenance IV iron treatment should be provided as required. New IV preparations, such ferric carboxymaltose, are safe, easy to use and up to 1000 mg can be given in a single session, thus providing an excellent tool to avoid or treat iron deficiency in this patient population.

VEGF gene expression in adult human thymus fat: a correlative study with hypoxic induced factor and cyclooxygenase-2.

It is well known that the adult human thymus degenerates into fat tissue; however, it has never been considered as a potential source of angiogenic factors. Recently, we have described that this fat (TAT) produces angiogenic factors and induces human endothelial cell proliferation and migration, indicating its potential angiogenic properties. DESIGN Adult thymus fat and subcutaneous adipose tissue specimens were obtained from 28 patients undergoing cardiac surgery, making this tissue readily available as a prime source of adipose tissue. We focused our investigation on determining VEGF gene expression and characterizing the different genes, mediators of inflammation and adipogenesis, and which are known to play a relevant role in angiogenesis regulation. RESULTS We found that VEGF-A was the isoform most expressed in TAT. This expression was accompanied by an upregulation of HIF-1alpha, COX-2 and HO-1 proteins, and by increased HIF-1 DNA binding activity, compared to SAT. Furthermore, we observed that TAT contains a high percentage of mature adipocytes, 0.25% of macrophage cells, 15% of endothelial cells and a very low percentage of thymocyte cells, suggesting the cellular variability of TAT, which could explain the differences in gene expression observed in TAT. Subsequently, we showed that the expression of genes known as adipogenic mediators, including PPARgamma1/gamma2, FABP-4 and adiponectin was similar in both TAT and SAT. Moreover the expression of these latter genes presented a significantly positive correlation with VEGF, suggesting the potential association between VEGF and the generation of adipose tissue in adult thymus. CONCLUSION Here we suggest that this fat has a potential angiogenic function related to ongoing adipogenesis, which substitutes immune functions within the adult thymus. The expression of VEGF seems to be associated with COX-2, HO-1 and adipogenesis related genes, suggesting the importance that this new fat has acquired in research in relation to adipogenesis and angiogenesis.

Breast cancer 1 (BrCa1) may be behind decreased lipogenesis in adipose tissue from obese subjects.

CONTEXT Expression and activity of the main lipogenic enzymes is paradoxically decreased in obesity, but the mechanisms behind these findings are poorly known. Breast Cancer 1 (BrCa1) interacts with acetyl-CoA carboxylase (ACC) reducing the rate of fatty acid biosynthesis. In this study, we aimed to evaluate BrCa1 in human adipose tissue according to obesity and insulin resistance, and in vitro cultured adipocytes. RESEARCH DESIGN AND METHODS BrCa1 gene expression, total and phosphorylated (P-) BrCa1, and ACC were analyzed in adipose tissue samples obtained from a total sample of 133 subjects. BrCa1 expression was also evaluated during in vitro differentiation of human adipocytes and 3T3-L1 cells. RESULTS BrCa1 gene expression was significantly up-regulated in both omental (OM; 1.36-fold, p = 0.002) and subcutaneous (SC; 1.49-fold, p = 0.001) adipose tissue from obese subjects. In parallel with increased BrCa1 mRNA, P-ACC was also up-regulated in SC (p = 0.007) as well as in OM (p = 0.010) fat from obese subjects. Consistent with its role limiting fatty acid biosynthesis, both BrCa1 mRNA (3.5-fold, p<0.0001) and protein (1.2-fold, p = 0.001) were increased in pre-adipocytes, and decreased during in vitro adipogenesis, while P-ACC decreased during differentiation of human adipocytes (p = 0.005) allowing lipid biosynthesis. Interestingly, BrCa1 gene expression in mature adipocytes was restored by inflammatory stimuli (macrophage conditioned medium), whereas lipogenic genes significantly decreased. CONCLUSIONS The specular findings of BrCa1 and lipogenic enzymes in adipose tissue and adipocytes reported here suggest that BrCa1 might help to control fatty acid biosynthesis in adipocytes and adipose tissue from obese subjects.

Tumor necrosis-like weak inducer of apoptosis as a proinflammatory cytokine in human adipocyte cells: up-regulation in severe obesity is mediated by inflammation but not hypoxia.

CONTEXT Adipose tissue hypoxia and endoplasmic reticulum (ER) stress may link the presence of chronic inflammation and macrophage infiltration in severely obese subjects. We previously reported the up-regulation of TNF-like weak inducer of apoptosis (TWEAK)/fibroblast growth factor-inducible 14 (Fn14) axis in adipose tissue of severely obese type 2 diabetic subjects. OBJECTIVES The objective of the study was to examine TWEAK and Fn14 adipose tissue expression in obesity, severe obesity, and type 2 diabetes in relation to hypoxia and ER stress. DESIGN In the obesity study, 19 lean, 28 overweight, and 15 obese nondiabetic subjects were studied. In the severe obesity study, 23 severely obese and 35 control subjects were studied. In the type 2 diabetes study, 11 type 2 diabetic and 36 control subjects were studied. The expression levels of the following genes were analyzed in paired samples of sc and visceral adipose tissue: Fn14, TWEAK, VISFATIN, HYOU1, FIAF, HIF-1a, VEGF, GLUT-1, GRP78, and XBP-1. The effect of hypoxia, inflammation, and ER stress on the expression of TWEAK and Fn14 was examined in human adipocyte and macrophage cell lines. RESULTS Up-regulation of TWEAK/Fn14 and hypoxia and ER stress surrogate gene expression was observed in sc and visceral adipose tissue only in our severely obese cohort. Hypoxia modulates TWEAK or Fn14 expression in neither adipocytes nor macrophages. On the contrary, inflammation up-regulated TWEAK in macrophages and Fn14 expression in adipocytes. Moreover, TWEAK had a proinflammatory effect in adipocytes mediated by the nuclear factor-kappaB and ERK but not JNK signaling pathways. CONCLUSIONS Our data suggest that TWEAK acts as a pro-inflammatory cytokine in the adipose tissue and that inflammation, but not hypoxia, may be behind its up-regulation in severe obesity.

Clinicopathologic correlations of renal microthrombosis and inflammatory markers in proliferative lupus nephritis.

INTRODUCTION Microthrombosis is often observed in lupus nephritis (LN) lesions, but its clinical significance is unknown. We evaluated the clinicopathologic correlations of renal microthrombosis and inflammatory markers in LN. METHODS Kidney biopsies from 58 patients with systemic lupus erythematosus (SLE) proliferative nephritis were analyzed with immunohistochemistry (IHC) for intravascular platelet aggregates (CD61), macrophagic infiltration (CD68), and activated complement deposition (C4d). Clinical data at the time of kidney biopsy and follow-up were analyzed with regard to pathologic IHC data. RESULTS Microthrombosis was present in 52% of the tissues. It was significantly more prevalent in patients with antiphospholipid antibodies (aPLs) (62% versus 42%). The presence of microthrombosis significantly correlated with higher macrophagic infiltration. Macrophagic infiltration but not microthrombosis was significantly correlated with C4d deposition. Only macrophagic infiltration showed a correlation with SLE and renal activity (proteinuria and active sediment), whereas neither the presence of CD61+ microthrombi nor the extent of C4d deposition correlated with LN severity or outcome. CONCLUSIONS Microthrombosis is associated with higher macrophagic infiltration in LN but does not seem to increase independently the severity of renal damage. Macrophagic infiltration was the best marker of SLE and renal activity in this LN series.