Lu Zhou

Impact of Human Granulocyte and Monocyte Isolation Procedures on Functional Studies

ABSTRACT One of the first lines of defense against infection is the activation of the innate immune system. It is becoming clear that autoimmune diseases, such as rheumatoid arthritis and Crohns disease, may be caused by disturbed innate immunity, and relating granulocyte and monocyte functions to the patient genotype has become an important part of contemporary research. Although it is essential to move this field forward, a systematic study comparing the efficacy and suitability for functional studies of the various available protocols for the isolation of these immune cells has not been performed. Here, we compare human granulocyte functionality under three enrichment protocols: (i) Ficoll density gradient centrifugation, (ii) anti-CD15 antibody-conjugated microbeads (positive selection), and (iii) Polymorphoprep. Primary monocytes were isolated in parallel using (i) anti-CD14 magnetic microbeads, (ii) non-monocyte depletion by antibody-conjugated magnetic microbeads (negative selection), (iii) RosetteSep antibody cocktail, and (iv) the classical adherence protocol. The best results in terms of purity and cell functionality were obtained with positive selection by magnetic microbeads for both human granulocytes and monocytes. Whereas phagocytosis of Escherichia coli bacteria was identical in all isolation procedures tested, the granulocyte respiratory burst was higher in positively selected cells. In addition, different granulocyte enrichment procedures affect cell surface receptor expression to different extents. In toto, we propose that positive selection of granulocytes and monocytes be adopted as the procedure of choice for studies of human granulocyte and monocyte functions but caution investigators to be aware of possible alterations in cell phenotypes with different isolation procedures.

The ubiquitin-proteasome pathway mediates gelsolin protein downregulation in pancreatic cancer

A well-known observation with respect to cancer biology is that transformed cells display a disturbed cytoskeleton. The underlying mechanisms, however, remain only partly understood. In an effort to identify possible mechanisms, we compared the proteome of pancreatic cancer with matched normal pancreas and observed diminished protein levels of gelsolin—an actin filament severing and capping protein of crucial importance for maintaining cytoskeletal integrity—in pancreatic cancer. Additionally, pancreatic ductal adenocarcinomas displayed substantially decreased levels of gelsolin as judged by Western blot and immunohistochemical analyses of tissue micoarrays, when compared with cancerous and untransformed tissue from the same patients (P < 0.05). Importantly, no marked downregulation of gelsolin mRNA was observed (P > 0.05), suggesting that posttranscriptional mechanisms mediate low gelsolin protein levels. In apparent agreement, high activity ubiquitin-proteasome pathway in both patient samples and the BxPC-3 pancreatic cancer cell line was detected, and inhibition of the 26s proteasome system quickly restored gelsolin protein levels in the latter cell line. The status of ubiquitinated gelsolin is related to lymph node metastasis of pancreatic cancer. In conclusion, gelsolin levels are actively downregulated in pancreatic cancer and enhanced targeting of gelsolin to the ubiquitin-proteasome pathway is an important contributing factor for this effect.

Monocytes and their pathophysiological role in Crohn’s disease

Abstract.Our immune system shows a stringent dichotomy, on the one hand displaying tolerance towards commensal bacteria, but on the other hand vigorously combating pathogens. Under normal conditions the balance between flora tolerance and active immunity is maintained via a plethora of dynamic feedback mechanisms. If, however, the balancing act goes faulty, an inappropriate immune reaction towards an otherwise harmless intestinal flora causes disease, Crohn’s disease for example. Recent developments in the immunology and genetics of mucosal diseases suggest that monocytes and their derivative cells play an important role in the pathophysiology of Crohn’s disease. In our review, we summarize the recent studies to discuss the dual function of monocytes - on the one hand the impaired monocyte function initiating Crohn’s disease, and on the other hand the overactivation of monocytes and adaptive immunity maintaining the disease. With a view to developing new therapies, both aspects of monocyte functions need to be taken into account.

Acute stress elicited by bungee jumping suppresses human innate immunity.

Although a relation between diminished human immunity and stress is well recognized both within the general public and the scientific literature, the molecular mechanisms by which stress alters immunity remain poorly understood. We explored a novel model for acute human stress involving volunteers performing a first-time bungee jump from an altitude of 60 m and exploited this model to characterize the effects of acute stress in the peripheral blood compartment. Twenty volunteers were included in the study; half of this group was pretreated for 3 d with the β-receptor blocking agent propranolol. Blood was drawn 2 h before, right before, immediately after and 2 h after the jump. Plasma catecholamine and cortisol levels increased significantly during jumping, which was accompanied by significantly reduced ex vivo inducibility of proinflammatory cytokines as well as activation of coagulation and vascular endothelium. Kinome profiles obtained from the peripheral blood leukocyte fraction contained a strong noncanonical glucocorticoid receptor signal transduction signature after jumping. In apparent agreement, jumping down-regulated Lck/Fyn and cellular innate immune effector function (phagocytosis). Pretreatment of volunteers with propranolol abolished the effects of jumping on coagulation and endothelial activation but left the inhibitory effects on innate immune function intact. Taken together, these results indicate that bungee jumping leads to a catecholamine-independent immune suppressive phenotype and implicate noncanonical glucocorticoid receptor signal transduction as a major pathway linking human stress to impaired functioning of the human innate immune system.

Runt‐related transcription factor 3 is associated with ulcerative colitis and shows epistasis with solute carrier family 22, members 4 and 5

Background: Inflammatory bowel disease (IBD), comprising Crohns disease (CD) and ulcerative colitis (UC), are intestinal inflammatory disorders with a complex genetic background. Mice deficient for the runt‐domain‐transcription‐factor3 (Runx3) develop spontaneous colitis. Human RUNX3 resides in an IBD‐susceptibility locus. We studied the association of RUNX3 in a cohort of IBD patients and analyzed the interaction with SLC22A4/5. RUNX3 and OCTN1 mRNA expression was assessed in inflamed and noninflamed mucosa from patients and controls. Methods: 543 IBD patients (309 CD / 234 UC) and 296 controls were included. Four single nucleotide polymorphisms (SNPs) and 4 microsatellite markers were studied for RUNX3. Five SNPs (including SNP‐207G→C and SNP1672C→T) were analyzed for SLC22A4/5. RUNX3, and OCTN1 expression in mucosal tissue from 30 patients (14 UC / 16 CD) and 6 controls were determined by quantitative polymerase chain reaction. Results: A significant association between RUNX3‐SNP rs2236851 and UC (OR 1.61; 95% confidence interval [CI] 1.11–2.32, P = 0.020) was found. Carriership is associated with pancolitis (odds ratio [OR] 1.86; 95% CI 1.08–3.21). SLC22A4/5‐SNPs rs272893 and rs273900 are associated with CD (OR 2.16; 95% CI 1.21–3.59 and OR 2.40; 95% CI 1.43–4.05). We found epistasis for carriership of a risk‐associated allele in RUNX3 and SLC22A4/5 for UC patients versus CD patients (OR 3.83; 95% CI 1.26–11.67). RUNX3 mRNA expression is increased (P = 0.01) in inflamed colonic mucosa of UC patients compared to noninflamed mucosa and controls. Conclusions: We provide evidence for the genetic association of RUNX3 with UC and for CD with the IBD5 locus including SLC22A4/5. An epistatic effect of RUNX3 and SLC22A4 was associated with an increased risk for UC. Our data suggest a role for RUNX3 in UC susceptibility.

Suppression of p21Rac Signaling and Increased Innate Immunity Mediate Remission in Crohn’s Disease

Overactivation of p21Rac1 is a rate-limiting step for innate immune function in Crohn’s disease and prevents remission. Crohn’s Disease on the Rac Crohn’s disease is a type of inflammatory bowel disease (IBD), wherein the body’s immune system attacks the gastrointestinal tract. In patients with Crohn’s, there are areas of apparently healthy tissue right next to damaged intestine, but it remains unclear what differentiates healthy and inflamed regions. Now, Parikh et al. examine signal transduction differences in healthy and inflamed tissue to find targets that may be protective in Crohn’s. The authors performed a comparative kinome profile in healthy controls as well as healthy and inflamed tissues from Crohn’s patients. They found that p21Rac1 GTPase signaling is suppressed in noninflamed tissue. What’s more, blocking p21Rac1 correlated with clinical improvement of IBD, potentially by boosting innate immune responses. These data suggest that blocking p21Rac1 may be protective for IBD. In inflammatory bowel disease (IBD), large areas of apparently healthy mucosa lie adjacent to ulcerated intestine. Knowledge of the mechanisms that maintain remission in an otherwise inflamed intestine could provide important clues to the pathogenesis of this disease and provide rationale for clinical treatment strategies. We used kinome profiling to generate comprehensive descriptions of signal transduction pathways in inflamed and noninflamed colonic mucosa in a cohort of IBD patients, and compared the results to non-IBD controls. We observed that p21Rac1 guanosine triphosphatase (GTPase) signaling was strongly suppressed in noninflamed colonic mucosa in IBD. This suppression was due to both reduced guanine nucleotide exchange factor activity and increased intrinsic GTPase activity. Pharmacological p21Rac1 inhibition correlated with clinical improvement in IBD, and mechanistically unrelated pharmacological p21Rac1 inhibitors increased innate immune functions such as phagocytosis, bacterial killing, and interleukin-8 production in healthy controls and patients. Thus, suppression of p21Rac activity assists innate immunity in bactericidal activity and may induce remission in IBD.

Haplotype‐based analysis of ulcerative colitis risk loci identifies both IL2 and IL21 as susceptibility genes in Han Chinese

Background: The incidence of ulcerative colitis (UC) varies between Western and Eastern ethnicities. A distinct genetic background may play a role in the differences. Until now, very little was known of the UC genetics in Asian populations. Here we performed a haplotype‐based analysis of six known UC susceptibility loci in Han Chinese patients. Methods: In all, 245 UC patients and 300 healthy controls of Han Chinese descent were genotyped for 27 single nucleotide polymorphisms (SNPs), which cover the major haplotypes of the chromosome regions containing IL10, IL2/IL21, MYO9B, ECM1, MST1, and IL23R in Han Chinese. Results: In contrast to the tight linkage disequilibrium (LD) block of the IL2/IL21 region in Caucasians, IL2 and IL21 reside in two independent LD blocks in Han Chinese. The IL2 SNP rs2069762 (P = 7.0 × 10−4, odds ratio [OR] = 1.54, 95% confidence interval [CI] 1.20–1.99) and the IL21 SNP rs2055979 (P = 1.2 × 10−4, OR = 1.50, 95% CI 1.17–1.92) were independently associated with UC. We identified one risk haplotype in IL2 and another independent risk haplotype in IL21. In addition to the IL2/IL21 locus, we observed association of the TT genotype of SNP rs1545620 in MYO9B with UC (P = 0.0169; OR = 0.29, 95% CI 0.11–0.78) and association of rs17375018 in IL23R with pancolitis in Chinese UC patients (P = 0.002; OR = 2.38, 95% CI 1.41–4.02). Conclusions: Our study confirmed the association of the IL2/IL21 region with UC in Han Chinese patients, and further implied both IL2 and IL21 as genetic risk factors for UC. Han Chinese UC patients share part of their genetic susceptibility with Caucasian patients.