Intercellular Adhesion Molecule-1 Deficiency Attenuates the Development of Skin Fibrosis in Tight-Skin Mice

The tight-skin (TSK/+) mouse, a genetic model for systemic sclerosis, develops cutaneous fibrosis. Although a fibrillin 1 gene mutation and immunological abnormalities have been demonstrated, the roles of adhesion molecules have not been investigated. To directly assess roles of adhesion molecules in skin fibrosis, TSK/+ mice lacking L-selectin and/or ICAM-1 were generated. The deficiency of ICAM-1, but not L-selectin, significantly suppressed ( approximately 48%) the development of skin sclerosis in TSK/+ mice. Similarly, ICAM-1 antisense oligonucleotides inhibited skin fibrosis in TSK/+ mice. Although T cell infiltration was modest into the skin of TSK/+ mice, ICAM-1 deficiency down-regulated this migration, which is consistent with the established roles of endothelial ICAM-1 in leukocyte infiltration. In addition, altered phenotype or function of skin fibroblasts was remarkable and dependent on ICAM-1 expression in TSK/+ mice. ICAM-1 expression was augmented on TSK/+ dermal fibroblasts stimulated with IL-4. Although growth or collagen synthesis of TSK/+ fibroblasts cultured with IL-4 was up-regulated, it was suppressed by the loss or blocking of ICAM-1. Collagen expression was dependent on the strain of fibroblasts, but not on the strain of cocultured T cells. Thus, our findings indicate that ICAM-1 expression contributes to the development of skin fibrosis in TSK/+ mice, especially via ICAM-1 expressed on skin fibroblasts.

Krüppel-Like Factor 2 Controls T Cell Trafficking by Activating L-Selectin (CD62L) and Sphingosine-1-Phosphate Receptor 1 Transcription

Krüppel-like factor 2 (KLF2) is a member of zinc-finger transcription factors. Based on its expression in naive and memory T cells and the activated phenotype of few T cells in mice lacking KLF2 in the lymphoid lineage, KLF2 is postulated to regulate T cell homeostasis by promoting cell quiescence. In this study, we show that in reporter gene assays KLF2 directly activates the promoters of both CD62L and sphingosine-1-phosphate receptor 1 (S1P1), whose expression is critical for T cell egress from the thymus and homing to the lymph nodes. Correspondingly, exogenous KLF2 expression in primary T cells significantly up-regulates both CD62L and S1P1. Following adoptive transfer, KLF2-transduced T cells are much more efficient in homing to lymphoid organs than nontransduced T cells. These findings suggest that KLF2 regulates T cell homeostasis at least partly by controlling CD62L and S1P1 expression, and therefore T cell egress from the thymus and circulation in the periphery.

T cell-associated CD18 but not CD62L, ICAM-1, or PSGL-1 is required for the induction of chronic colitis

The induction and perpetuation of chronic colitis are thought to involve a complex set of adhesive interactions between T cells and endothelial cells located on the vasculature within secondary lymphoid tissue and the intestine. The objective of this study was to assess the roles of T cell-associated CD18, CD62L (L-selectin), ICAM-1, and P-selectin glycoprotein ligand-1 (PSGL-1) in the induction of chronic colitis in mice. CD4(+)CD25(-) T cells derived from either wild-type (WT), CD18-deficient [CD18 knockout (KO)], CD62L KO, ICAM-1 KO, or PSGL-1 KO mice were adoptively transferred into recombinase activating gene-1 (RAG-1)-deficient mice (RAG KO mice) to assess the potential of these T cells to induce chronic colitis. At 8-10 wk following T cell transfer, we observed moderate to severe colitis as assessed by increases in colon weight-to-length ratios and by blinded histopathological analysis. In contrast, we found that transfer of CD18 KO T cells into RAG KO recipients resulted in the significant attenuation of colonic inflammation in these mice. Furthermore, we observed fewer infiltrating CD4(+) T cells in the colonic lamina propria in the CD18 KO-->RAG KO group compared with the WT-->RAG KO group. Finally, message levels of colonic TNF-alpha, IL-1beta, and IFN-gamma were significantly reduced in CD18 KO-->RAG KO mice compared with colitic control animals. We conclude that T cell-associated CD18, but not CD62L, ICAM-1, or PSGL-1, is required for the development of chronic colitis.

[Association of L-selectin gene polymorphism with susceptibility to coronary heart disease]

OBJECTIVE

To investigate the possible association between L-selectin gene P213S polymorphism and coronary heart disease (CHD) in Chinese population.

METHODS

In total 212 CHD patients diagnosed by angiography and 230 healthy controls were studied. The genotype and allele frequencies of L-selectin gene polymorphism were assayed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).

RESULTS

The frequency of the L-selectin gene 213P allele in CHD patients was significantly higher than that in the control group (77.59% vs 69.35%, P=0.006). Compared with the SS genotype, PP homozygote had a significantly increased CHD risk (OR=2.70 and OR=2.15 using unadjusted and adjusted Logistic regression models, respectively). No association was found between the severity of CHD and the Lselectin gene P213S polymorphism

CONCLUSION

Our findings suggest that L-selectin gene 213P mutant allele might contribute to susceptibility of Chinese individuals to contract CHD.

Molecular cloning of a cDNA encoding the feline CD62L

We cloned a cDNA fragment encoding a feline homologue of L-selectin (CD62L). The extracellular region of the feline CD62L fragment contained a calcium-dependent (C-type) lectin domain, an epidermal growth factor-like domain, and two Sushi/CCP/SCR domains. The flow cytometric analysis confirmed that the feline CD62L molecule, which was expressed 293T cells, retained an epitope recognized by an anti-human CD62L monoclonal antibody (Leu-8).

CD25+CD4+ regulatory T cell migration requires L-selectin expression: L-selectin transcriptional regulation balances constitutive receptor turnover

The molecular mechanisms controlling regulatory CD25(+)Foxp3(+)CD4(+) T cell (T(reg)) migration are central to in vivo immune responses. T(reg) cell subsets differentially express L-selectin, an adhesion molecule mediating lymphocyte migration to peripheral LNs (PLNs) and leukocyte rolling during inflammation. In this study, L-selectin was essential for T(reg) cell migration and normal tissue distribution. Specifically, there was a 90% reduction in PLN T(reg) cells in L-selectin(-/-) mice with a compensatory increase in spleen T(reg) cell numbers. Unexpectedly, however, 40% of the CD4(+) T cells remaining within PLNs of L-selectin(-/-) mice were T(reg) cells. The migratory properties of T(reg) cells were nonetheless markedly different from those of naive CD4(+) T cells, with 3- to 9-fold lower migration of T(reg) cells into PLNs and approximately 2-fold lower migration into the spleen. T(reg) cells also turned over cell surface L-selectin at a faster rate than CD25(-)CD4(+) T cells, but maintained physiologically appropriate L-selectin densities for optimal migration. Specifically, T(reg) cells expressed 30-40% more cell surface L-selectin when its endoproteolytic cleavage was blocked genetically, which resulted in a 2-fold increase in T(reg) cell migration into PLNs. However, increased L-selectin cleavage by T(reg) cells in wild-type mice was accompanied by 2-fold higher L-selectin mRNA levels, which resulted in equivalent cell surface L-selectin densities on T(reg) and naive T cells. Thus, T(reg) cells and CD25(-)CD4(+) T cells share similar requirements for L-selectin expression during migration, although additional molecular mechanisms constrain T(reg) cell migration beyond what is required for naive CD4(+) T cell migration.

Alpha 2,3-sialyltransferase-IV is essential for L-selectin ligand function in inflammation

L-selectin belongs to the C-type lectin family of glycoproteins and is constitutively expressed on most leukocytes. L-selectin mediates leukocyte rolling in inflamed microvessels and high endothelial venules (HEV) via binding to specific carbohydrate structures on selectin ligands. Previous studies using sialidase treatment suggested a role of sialic acid residues in L-selectin-dependent rolling. To investigate the role of the alpha2,3-sialyltransferase (ST3Gal)-IV on L-selectin ligand activity in vivo, we studied leukocyte rolling in inflamed venules of the cremaster muscle and in Peyer's patch HEV of ST3Gal-IV-deficient mice and littermate control mice. In cremaster muscle venules with or without TNF-alpha treatment, L-selectin-dependent rolling was almost completely abolished in ST3Gal-IV(-/-) mice. In both models, L-selectin interacts with P-selectin glycoprotein ligand-1 (PSGL-1) presented by adherent leukocytes and leukocyte fragments, but not with endothelial L-selectin ligands. In contrast, L-selectin-dependent rolling in Peyer's patch HEV, which is mediated by unknown endothelial L-selectin ligands, was not impaired in the absence of ST3Gal-IV. Our in vivo data show that PSGL-1, the molecule responsible for L-selectin-mediated leukocyte interactions in inflammation, is dependent on ST3Gal-IV, while alpha2,3-sialylation by ST3Gal-IV is not necessary for L-selectin ligand activity on high endothelial cells of Peyer's patch HEV.

Superior antitumor in vitro responses of allogeneic matched sibling compared with autologous patient CD8+ T cells

Allogeneic cell therapy as a means to break immunotolerance to solid tumors is increasingly used for cancer treatment. To investigate cellular alloimmune responses in a human tumor model, primary cultures were established from renal cell carcinoma (RCC) tissues of 56 patients. In three patients with stable RCC line and human leukocyte antigen (HLA)-identical sibling donor available, allogeneic and autologous RCC reactivities were compared using mixed lymphocyte/tumor cell cultures (MLTC). Responding lymphocytes were exclusively CD8(+) T cells, whereas CD4(+) T cells or natural killer cells were never observed. Sibling MLTC populations showed higher proliferative and cytolytic antitumor responses compared with their autologous counterparts. The allo-MLTC responders originated from the CD8(+) CD62L(high)(+) peripheral blood subpopulation containing naive precursor and central memory T cells. Limiting dilution cloning failed to establish CTL clones from autologous MLTCs or tumor-infiltrating lymphocytes. In contrast, a broad panel of RCC-reactive CTL clones was expanded from each allogeneic MLTC. These sibling CTL clones either recognized exclusively the original RCC tumor line or cross-reacted with nonmalignant kidney cells of patient origin. A minority of CTL clones also recognized patient-derived hematopoietic cells or other allogeneic tumor targets. The MHC-restricting alleles for RCC-reactive sibling CTL clones included HLA-A2, HLA-A3, HLA-A11, HLA-A24, and HLA-B7. In one sibling donor-RCC pair, strongly proliferative CD3(+)CD16(+)CD57(+) CTL clones with non-HLA-restricted antitumor reactivity were established. Our results show superior tumor-reactive CD8 responses of matched allogeneic compared with autologous T cells. These data encourage the generation of antitumor T-cell products from HLA-identical siblings and their potential use in adoptive immunotherapy of metastatic RCC patients.

Alterations in neutrophil surface expression of L-selectin (CD62L) and soluble L-selectin (sL-selectin) in hemodialysis patients: relation to HCV

High levels of L-selectin (CD62L) are a strong indicator of endothelial dysfunction, and atherosclerosis. Atherosclerosis is the leading cause of mortality and morbidity in hemodialysis (HD) patients. Whether HCV infection (highly prevalent in HD patients and also associated with alterations in adhesion molecules) would affect the leukocytic expression and/or the soluble form of L-selectin in hemodialysis patients is unknown. Seventy-two HD patients, HCV-positive (n=48) and HCV-negative (n=24) and 10 normal control were studied. Blood samples were obtained just prior to the start of the dialysis session (predialysis) and at the end of 15 min. of dialysis (intradialysis). The following tests were performed on all patients: HCV-RNA by RT-nested PCR, quantitative determination of sL-selectin by ELISA and neutrophil surface expression of L-selectin (CD62L) by flowcytometry. Both CD62L and sL-selectin were found to be significantly higher in HD patients as compared to normal controls irrespective to HCV. Fifteen minutes after start of the dialysis session both CD62L and absolute neutrophil count decreased significantly [CD62L, p < 0.0001 (HCV-positive), p= 0.03 in (HCV-negative), [neutrophil count, p < 0.0001 each], while sL-selectin showed a significant increase [p = 0.004 (HCV-positive), p = 0.006 (HCV-negative)]. These changes were unrelated to HCV status. A significant increase in CD62L in HCV-positive patients compared to HCV-negative ones in both pre and intradialysis samples was noted (p = 0.007, p = 0.02 respectively). However, no difference was observed in either sL-selectin or absolute neutrophil count between the two groups in the two tested time points. In conclusions, the increased levels of neutrophil-expressed and soluble forms of L-selectin in HD patients, and the intradialysis increase in sL-selectin and decrease in CD62L and neutrophil count are unrelated to HCV viremia. The association between HCV positivity and neutrophil expression of pre andintradialysis L-selectin point to a possible role of HCV that needs further studies.

IL-15 and dermal fibroblasts induce proliferation of natural regulatory T cells isolated from human skin

Regulatory T cells (Tregs) are crucial for the induction and maintenance of self-tolerance and are present in peripheral tissues such as skin and gut under normal, noninflamed conditions. We report isolation and expansion of the Treg population resident in normal human skin. Cutaneous Tregs expressed high levels of CD25, L-selectin, GITR, FOXP3, and intracellular CTLA-4, low levels of CD69, and high levels of the skin-homing addressins CLA, CCR4, and CCR6. Skin Tregs suppressed the proliferation of CD25(lo) T cells from the same skin sample in response to CD3 and CD28 antibodies. Suppression was dependent on cell contact and not affected by neutralizing antibodies to interleukin-10 (IL-10) and transforming growth factor-beta (TGF-beta). Surprisingly, cutaneous Tregs proliferated in an antigen-independent manner when cultured in contact with dermal fibroblasts and IL-15, conditions similar to those found in chronically inflamed skin. We hypothesize that local proliferation of Tregs may occur within inflamed skin and could serve as a brake for cutaneous inflammation as well as a mechanism for the homeostatic proliferation of natural Tregs that has been observed within intact organisms.

Generation of peripheral B cells occurs via two spatially and temporally distinct pathways

We have identified a population of newly formed bone marrow (BM) B cells that shares multiple characteristics with late transitional B cells in the spleen. Both late splenic transitional B cells and cells within this uncharacterized BM population expressed the cell-surface phenotype AA4(+) CD23(+), yet the developmental kinetics and the renewal rate of AA4(+) CD23(+) BM B cells mirrored recently formed BM B cells. Further, unlike the least mature B cells in the BM and spleen, AA4(+) CD23(+) BM B cells expressed the homing receptor CD62L, were dependent on the antiapoptotic cytokine receptor BR3 and the tec family kinase Btk, and proliferated in response to IL-4 plus CD40 stimulation. Finally, frequencies of lambda light chain-positive B cells declined among AA4(+) CD23(+) B cells in both the BM and spleen, suggesting that V-gene selection events correlate with CD23 expression in both compartments. These observations indicate that the first step in B-cell maturation occurs in both the BM and the periphery and suggest that recently formed B cells exit the BM as a heterogeneous pool of immature and semimature B cells.

Selectin polymorphisms and perinatal morbidity in low-birthweight infants

BACKGROUND

Studies have shown an association between altered expression of selectins and premature birth, early sepsis and bronchopulmonary dysplasia.

AIM

To investigate the possible link between functional polymorphisms of the E-, P- and L-selectin genes and perinatal morbidity.

METHODS

We compared the genotype distribution of the E-selectin Ser128Arg, P-selectin Thr715Pro and L-selectin Pro213Ser polymorphisms in 125 low-birthweight singleton infants with those of 156 healthy term neonates. We also analysed the association of genotype with risk of sepsis and bronchopulmonary dysplasia.

RESULTS

We found no association between E-selectin or P-selectin polymorphisms and premature birth, nor did we find any association between E-selectin or P-selectin and early postnatal sepsis or bronchopulmonary dysplasia. Carriers of the 213Ser L-selectin allele were found to be more prevalent in low-birthweight infants, particularly in those with bronchopulmonary dysplasia. We found no association between the L-selectin polymorphism and early postnatal sepsis.

CONCLUSION

Our results underline the importance of L-selectin in perinatal pathology, but further studies are needed to evaluate the alteration of L-selectin levels in carriers of the 213Ser allele and their possible contribution to premature birth and bronchopulmonary dysplasia.

Expression of CD44 and L-selectin in the innate immune system is required for severe joint inflammation in the proteoglycan-induced murine model of rheumatoid arthritis

Proteoglycan (PG)-induced arthritis, a murine model of rheumatoid arthritis, is characterized by autoimmunity against mouse cartilage PG and chronic joint inflammation. L-selectin (CD62L) and CD44 are major adhesion molecules on leukocytes that regulate their homing to lymph nodes and entry into inflamed tissues. In the present study, we studied the requirement for CD44 and CD62L expression for mediating lymphocyte homing, thus permitting the development of autoimmunity vs mediating the entry of leukocytes into the joints, thus allowing inflammation in PG-induced arthritis. We immunized wild-type, CD44 knockout (KO), CD62L KO, and double (CD44/CD62L) KO BALB/c mice with PG and monitored the effects of gene deficiencies on PG-specific immunity, arthritis severity, leukocyte trafficking, and the ability of lymphocytes to adoptively transfer disease to syngeneic SCID mice. Single and double KO mice demonstrated reduced PG-specific spleen cell proliferation, but the production of Th cytokines and autoantibodies was comparable in KO and wild-type mice. KO leukocytes had reduced ability to adhere tightly to the synovial endothelium in arthritic joints. This diminished leukocyte adhesion correlated with the magnitude of granulocyte (neutrophil) influx and the severity of inflammation, which were both reduced in the joints of KO mice. However, transfer of spleen cells from mildly arthritic KO donors to SCID hosts resulted in development of severe arthritis. Our results indicate that CD44 and CD62L expression in the cells of the innate immune system (granulocytes) is important for their efficient influx into the joints and also suggest that granulocytes play a crucial role in arthritis progression.

Polymorphism in L-Selectin, E-Selectin and ICAM-1 Genes in Asian Indian Pediatric Patients With Celiac Disease

Celiac disease (CD) follows an autoimmune course in which both genetic and environmental factors contribute to its development. A strong association with HLA class II molecules, predominantly HLA-DQ2, has been reported in most ethnic groups with CD. The aim of this study was to determine if genetic polymorphisms in L-selectin, E-selectin, and intercellular adhesion molecule-1 (ICAM-1) have any correlation with CD. We investigated 5 mutations, namely F206L in L-selectin, S128R and L554F in E-selectin, and G241R and K469E in ICAM-1, in 37 North Indian pediatric patients with CD. A significant increase in allele frequencies of 128R of E-selectin and the associated genotype SR was observed in patients. No significant differences were observed in the F206L polymorphism of L-selectin, or the G241R and E469K polymorphisms in the ICAM-1 gene in CD. This study illustrates that selectin gene polymorphism might contribute to the genetic background of CD and invites further investigation relevant to understanding the mechanisms underlying the immunopathogenesis of this autoimmune disease.

Lymphocyte recruitment into the aortic wall before and during development of atherosclerosis is partially L-selectin dependent

Atherosclerosis is an inflammatory disease of large arteries. Flow cytometry of aortic cell suspensions showed that B and T lymphocytes and some macrophages and dendritic cells are already present in the adventitia of normal/noninflamed mouse aortas. Adoptively transferred lymphocytes constitutively homed to the aorta and resided within the adventitia up to 7 d after transfer. Lymphocyte trafficking into normal/noninflamed or atherosclerosis-prone aortas was partially L-selectin dependent. Antigen-activated dendritic cells induced increased T lymphocyte proliferation within the aorta 72 h after adoptive transfer. During progression of atherosclerosis in apolipoprotein-E-deficient mice, the total number of macrophages, T cells, and dendritic cells, but not B cells, increased significantly. This alteration in immune cell composition was accompanied by the formation of tertiary lymphoid tissue in the adventitia of atherosclerotic aortas. These results demonstrate that lymphocytes already reside within the normal/noninflamed aorta before the onset atherosclerosis as a consequence of constitutive trafficking. Atherosclerosis induces the recruitment of macrophages and dendritic cells that support antigen presentation.

Association between the Phe206Leu polymorphism of L-selectin and brucellosis

Brucellosis remains a major zoonosis worldwide; therefore, better understanding of its immunology is a priority for the development of new therapeutic and vaccination strategies. Genetic factors appear to have an important role in the pathogenesis of infectious diseases such as brucellosis. Adhesion molecules, such as members of the selectin family, participate in the interaction between leukocytes and the endothelium, as well as in inflammatory cell recruitment. The impact of L-selectin polymorphisms on brucellosis has not so far been investigated. The aim of this study was to assess an L-selectin Phe206Leu (F206L) polymorphism in patients with active brucellosis, and to analyse its possible relationship with disease progression. A case-control association study was carried out on 619 subjects, including 374 patients with brucellosis and 245 age- and sex-matched healthy controls. Genomic DNA was isolated, and amplification of L-selectin genomic regions was performed by PCR incorporating sequence-specific primers (PCR-SSP) to distinguish the genotypes. The frequencies of the F206L polymorphism were studied. A significant difference in F206L polymorphism was found between patients with brucellosis and controls. The 206Leu allele was more frequent in patients than in healthy individuals (36.6 versus 28 %, P=0.003). In addition, there was an association between the presence of the 206Leu allele and a relapse of brucellosis (odds ratio 6.53, 95 % confidence interval 1.5-28.8, P=0.005). The higher frequency of L-selectin genotypes in patients with brucellosis than in control individuals, as well as the association between the 206Leu allele and the occurrence of brucellosis relapse, suggest that the F206L polymorphism could make individuals more vulnerable to brucellosis.

Functional impact of IgA nephropathy-associated selectin gene haplotype on leukocyte-endothelial interaction

Previously, we discovered single-nucleotide polymorphisms (SNPs) associated with Immunoglobulin A (IgA) nephropathy in selectin genes, which were 712C>T(P238S) in L selectin, -642A>G in the promoter region of L selectin, and 1402C>T(H468Y) in E selectin. Interestingly, these SNPs were in nearly complete linkage disequilibrium, thus two haplotypes, disease-associated TGT and wild-type (Wt) CAC, were constructed. To investigate the functional significance of TGT haplotype, a stable CHO transfectant expressing a P238S-L-selectin variant (CHO-varL) and a recombinant adenovirus vector containing an H468Y-E-selectin variant (Ad-varE) were established and compared to their Wt counterparts. Under flow, CHO-varL exhibited significantly less adhesion over IL-1beta-activated HUVEC monolayers compared to CHO-wtL. Furthermore, a luciferase reporter construct, containing a promoter region of the L-selectin variant (luc-varL), exhibited significantly less transcription activity compared to Wt (luc-wtL). These results suggest that the adhesive interactions and expression level of L selectin in disease-associated haplotypes are significantly compromised, indicating a potential role of these SNPs in the pathogenesis of inflammatory diseases, including IgA nephropathy.

Secondary memory CD8+ T cells are more protective but slower to acquire a central-memory phenotype

The formation of memory CD8 T cells is an important goal of vaccination. However, although widespread use of booster immunizations in humans generates secondary and tertiary CD8 T cell memory, experimental data are limited to primary CD8 T cell memory. Here, we show that, compared with primary memory CD8 T cells, secondary memory CD8 T cells exhibit substantially delayed conversion to a central–memory phenotype, as determined by CD62L expression and interleukin (IL)-2 production. This delayed conversion to a central–memory phenotype correlates with reduced basal proliferation and responsiveness to IL-15, although in vitro coculture with a high concentration of IL-15 is capable of inducing proliferation and CD62L upregulation. Functionally, secondary memory CD8 T cells are more protective in vivo on a per cell basis, and this may be explained by sustained lytic ability. Additionally, secondary memory CD8 T cells are more permissive than primary memory CD8 T cells for new T cell priming in lymph nodes, possibly suggesting a mechanism of replacement for memory T cells. Thus, primary and secondary memory CD8 T cells are functionally distinct, and the number of encounters with antigen influences memory CD8 T cell function.

Adhesive mechanisms governing interferon-producing cell recruitment into lymph nodes

Natural interferon-producing cells (IPCs) are found in peripheral lymph nodes (PLNs), where they support NK cell, T cell, and B cell responses to pathogens. However, their route of entry and the adhesive mechanisms used to gain access to PLNs remain poorly defined. We report that IPCs can enter PLNs via a hematogenous route, which involves a multistep adhesive process, and that transmigration is enhanced by inflammation. Results indicate that L-selectin on IPCs is required for efficient attachment and rolling on high endothelial venules in vivo in both nonstimulated and inflamed PLNs. IPCs, however, also possess functional ligands for E-selectin that contribute to this process only in the latter case. In conjunction with selectin-mediated adhesion, both β₁- and β₂-integrins participate in IPC attachment to the inflamed vessel wall, whereas chemotaxis relies in part on the chemokine receptor CCR5. Identification of the adhesive machinery required for IPC trafficking into PLNs may provide opportunities to regulate immune responses reliant on the activity of these cells.

Association of the Phe206Leu Allele of the L-Selectin Gene with Coronary Artery Disease

BACKGROUND AND AIMS

The aim of this study was to assess the association between the L-selectin Phe206Leu polymorphism and coronary artery disease.

METHODS

A total of 322 patients (221 men and 101 women) with coronary artery disease in one or more vessels documented by angiography were studied; 157 subjects (85 men and 72 women) without atherosclerosis were included as controls. All subjects were genotyped for the L-selectin Phe206Leu gene polymorphism using polymerase chain reaction with sequence-specific primer (PCR-SSP). To assess disease severity, all patients were classified by numbers of coronary arteries with 50% stenosis.

RESULTS

A significantly increased frequency of the 206Leu mutant allele was observed in patients with coronary artery disease compared to the controls. The 206Leu allele frequency occurred in 42% of the patients with coronary artery disease compared to 30% of the controls (p<0.009). No association was found between the severity of coronary artery disease and the L-selectin Phe206Leu polymorphism.

CONCLUSION

Our findings suggest that carriage of L-selectin 206Leu mutant allele could contribute to susceptibility of Iranian individuals to contracting coronary artery disease.

L-selectin and intercellular adhesion molecule-1 regulate the development of Concanavalin A-induced liver injury

Concanavalin A (Con A)-induced hepatitis is a model for human T cell-mediated hepatitis. We evaluated the role of L-selectin and intercellular adhesion molecule-1 (ICAM-1) in this model by injecting Con A intravenously in mice lacking L-selectin (L-selectin-/-), ICAM-1 (ICAM-1-/-), or both (L-selectin/ICAM-1-/-). Blood and liver samples were collected 0, 8, 24, and 48 h after Con A treatment. Increases in plasma transaminase levels, which peaked 8 h after injection, were reduced significantly in L-selectin-/-, ICAM-1-/-, and L-selectin/ICAM-1-/- mice compared with wild-type mice. Liver necrosis was more strongly inhibited in ICAM-1-/- mice than in L-selectin-/- mice but was most prominently reduced in L-selectin/ICAM-1-/- mice, in parallel with decreased plasma transaminase levels. The reduced severity of hepatitis in the mutant mice correlated with decreases in numbers of liver CD4+ T cells but not numbers of CD8+ T cells or neutrophils. Following Con A treatment, L-selectin deficiency reduced liver mRNA expression of tumor necrosis factor-alpha, and ICAM-1 deficiency reduced expression of interleukin-4. By contrast, reductions in liver macrophage inhibitor protein-1alpha mRNA occurred in all mutant mice. These results indicate that L-selectin and ICAM-1 contribute cooperatively to the development of Con A-induced hepatitis by regulating leukocyte infiltration and subsequent cytokine production.

Impact of selectin gene polymorphisms on rapid progression to end-stage renal disease in patients with IgA nephropathy

OBJECTIVE

It is evident that leukocyte infiltration plays an important role in the pathogenesis of IgA nephropathy (IgAN). Selectin is one of the key adhesion molecules involved in leukocyte infiltration. Recent studies demonstrated a significant association between the selectin gene polymorphisms and susceptibility to IgAN. However, the impact of selectin gene polymorphisms on the progression to end-stage renal disease (ESRD) has not been studied.

PATIENTS AND METHODS

To evaluate the influence of the selectin gene polymorphisms on the progression of IgAN, we designed specific primers for PCR genotyping and analyzed the association of selectin gene polymorphisms with the declining rate in renal function to its ESRD.

RESULTS

A total of 61 hemodialysis patients were enrolled in the study. The mean age at renal biopsy was 33.0+/-13.3 years old, and the mean age at the start of hemodialysis was 41.2+/-13.8 years old. The mean interval between the time points of renal biopsy and the start of hemodialysis was 8.2+/-6.5 years (ranging from 0 to 33 years). The interval was significantly longer in IgAN patients with a homoallele of C in C1402T, C1402/C1402, of the E-selectin gene, or a homoallele of C in C712T, C712/C712, of the L-selectin gene compared to others. The haplotype, which is a combination of C1402/C1402 and C712/C712, is able to distinguish the group that is at least a better prognosis than the severest prognostic one.

CONCLUSION

This study provides a possible association between the selectin gene polymorphisms and the rapid progression to ESRD in IgAN patients.

R5 variants of human immunodeficiency virus type 1 preferentially infect CD62L- CD4+ T cells and are potentially resistant to nucleoside reverse transcriptase inhibitors

The persistence of human immunodeficiency virus type 1 (HIV-1) in memory CD4+ T cells is a major obstacle to the eradication of the virus with current antiretroviral therapy. Here, we investigated the effect of the activation status of CD4+ T cells on the predominance of R5 and X4 HIV-1 variants in different subsets of CD4+ T cells in ex vivo-infected human lymphoid tissues and peripheral blood mononuclear cells (PBMCs). In these cell systems, we examined the sensitivity of HIV replication to reverse transcriptase inhibitors. We demonstrate that R5 HIV-1 variants preferentially produced productive infection in HLA-DR- CD62L- CD4+ T cells. These cells were mostly in the G1b phase of the cell cycle, divided slowly, and expressed high levels of CCR5. In contrast, X4 HIV-1 variants preferentially produced productive infection in activated HLA-DR+ CD62L+ CD4+ T cells, which expressed high levels of CXCR4. The abilities of the nucleoside reverse transcriptase inhibitors (NRTI) zidovudine and lamivudine to stop HIV-1 replication were 20 times greater in activated T cells than in slowly dividing HLA-DR- CD62L- CD4+ T cells. This result, demonstrated both in a highly physiologically relevant ex vivo lymphoid tissue model and in PBMCs, correlated with higher levels of thymidine kinase mRNA in activated than in slowly dividing HLA-DR- CD62L- CD4+ T cells. The non-NRTI nevirapine was equally efficient in both cell subsets. The lymphoid tissue and PBMC-derived cell systems represent well-defined models which could be used as new tools for the study of the mechanism of resistance to HIV-1 inhibitors in HLA-DR- CD62L- CD4+ T cells.

Cutting edge: activation of the aryl hydrocarbon receptor by 2,3,7,8-tetrachlorodibenzo-p-dioxin generates a population of CD4+ CD25+ cells with characteristics of regulatory T cells

Activation of the aryl hydrocarbon receptor (AhR) by its most potent ligand, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), leads to immune suppression in mice. Although the underlying mechanisms responsible for AhR-mediated immune suppression are not known, previous studies have shown that activation of the AhR must occur within the first 3 days of an immune response and that CD4+ T cells are primary targets. Using the B6-into-B6D2F1 model of an acute graft-vs-host response, we show that activation of AhR in donor T cells leads to the generation of a subpopulation of CD4+ T cells that expresses high levels of CD25, along with CD62L(low), CTLA-4, and glucocorticoid-induced TNFR. These donor-derived CD4+ CD25+ cells also display functional characteristics of regulatory T cells in vitro. These findings suggest a novel role for AhR in the induction of regulatory T cells and provide a new perspective on the mechanisms that underlie the profound immune suppression induced by exposure to TCDD.