A model of canine leukocyte telomere dynamics

Recent studies have found associations of leukocyte telomere length (TL) with diseases of aging and with longevity. However, it is unknown whether birth leukocyte TL or its age-dependent attrition--the two factors that determine leukocyte TL dynamics--explains these associations because acquiring this information entails monitoring individuals over their entire life course. We tested in dogs a model of leukocyte TL dynamics, based on the following premises: (i) TL is synchronized among somatic tissues; (ii) TL in skeletal muscle, which is largely postmitotic, is a measure of TL in early development; and (iii) the difference between TL in leukocytes and muscle (ΔLMTL) is the extent of leukocyte TL shortening since early development. Using this model, we observed in 83 dogs (ages, 4-42 months) no significant change with age in TLs of skeletal muscle and a shorter TL in leukocytes than in skeletal muscle (P<0.0001). Age explained 43% of the variation in ΔLMTL (P<0.00001), but only 6% of the variation in leukocyte TL (P=0.035) among dogs. Accordingly, muscle TL and ΔLMTL provide the two essential factors of leukocyte TL dynamics in the individual dog. When applied to humans, the partition of the contribution of leukocyte TL during early development vs. telomere shortening afterward might provide information about whether the individual's longevity is calibrated to either one or both factors that define leukocyte TL dynamics.     

Leukocyte telomere length in the Finnish Diabetes Prevention Study

Leukocyte telomere length (TL) is considered a biomarker for biological aging. Shortened TL has been observed in many complex diseases, including type 2 diabetes (T2DM). Lifestyle intervention studies, e.g. the Diabetes Prevention Study (DPS), have shown a decrease in the incidence of T2DM by promoting healthy lifestyles in individuals with impaired glucose tolerance (IGT). Our aim was to study in the DPS the influence of the lifestyle intervention on TL. TL was measured by quantitative PCR-based method at two time points (N = 334 and 343) on average 4.5 years apart during the active intervention and post-intervention follow-up. TL inversely correlated with age. Our main finding was that TL increased in about two thirds of the individuals both in the intervention and in the control groups during follow-up; TL increased most in individuals with the shortest TL at the first measurement. TL was not associated with development of T2DM, nor did lifestyle intervention have an effect on TL. No association between insulin secretion or insulin resistance indices and TL was observed. We did not detect an association between TL and development of T2DM in the DPS participants. It could be due to all participants being overweight and having IGT at baseline, both of which have been found to be independently associated with shorter leukocyte TL in some earlier studies. TL had no substantial role in worsening of glucose tolerance in people with IGT. Our study confirms that leukocyte TL can increase with time even in obese people with impaired glucose metabolism.     

Early osteological development of the fins in the hatchery-reared red porgy, Pagrus pagrus (L. 1758)

The present study was undertaken to establish the normal, healthy features of morphological structures at various developmental stages as achieved under well-defined environmental culture conditions (temperature between 16 and 21°C, salinity 36 ppt, pH around 7.6, and oxygen saturation over 95%) common in aquaculture of the species. The pectoral fin supports began to develop at 2.90 mm total length (TL), followed by those of dorsal fins at 5.5 mm TL, caudal fins at 5.6 mm TL, pelvic fins at 5.9 mm TL and anal fins at 6.0 mm TL. The pelvic fins appeared fully at 7.4 mm TL. Development of dorsal lepidotrichia was first observed at 6.9 mm TL, attaining their final number at 7.6 mm TL. The dorsal spines first appeared at 6.5 mm TL and were complete at 7.4 mm TL. The anal lepidotrichia appeared during the development phase from 6.8 to 8.6 mm TL. At 5.6 mm TL, the upward flexion of the urostyle was initiated. The caudal lepidotrichia formed within the primordial fin at 5.6 mm TL and reached the final count at 7.4 mm TL. The caudal dermatotrichia first appeared at 7.3 mm TL and all forms were observed by 15.5 mm TL. The development pattern of fin supports found in Pagrus pagrus is quite similar to that described for other Sparid species.     

Functional signaling of membrane-bound TL1A induces IFN-γ expression

TL1A, a TNF member implicated in autoimmune diseases, is a transmembrane protein that is processed to release soluble TL1A (TL1A-S). TL1A-S induces a Th1 response, although the functional significance of membrane-bound TL1A (TL1A-M) remains unknown. We generated TL1A-M expression in HEK-293 cells capable of binding DR3-Fc. Co-incubating IL-12/IL-18-primed CD4⁺ T cells with HEK-293 cells expressing TL1A-M induced 3-fold increase in IFN-γ that was blocked by anti-TL1A Ab. These results demonstrate that TL1A-M can bind death domain receptor 3 (DR3) through cell-cell contact to induce downstream IFN-γ secretion enhancement. Anti-TL1A antibodies designed to treat immune diseases should be verified to block both endogenous TL1A forms.     

Trypanosoma lewisi: stage-specific surface antigens and exoantigens recognized by monoclonal antibodies

The stage-specific expression of surface antigens by Trypanosoma lewisi was investigated using monoclonal antibodies directed against this parasite. Hybridomas secreting monoclonal antibodies were produced by the fusion of SP2/0-Ag 14 mouse plasmacytomas with spleen cells from rats infected previously with the Taliaferro strain of T. lewisi. Additivity enzyme-linked immunosorbent assays and indirect immunofluorescent antibody tests indicated the determinant recognized by monoclonal antibody TL40.3 (IgM) was different from those recognized by monoclonal antibodies TL40.1 (IgA), TL40.2 (IgM), and TL40.6 (IgG2 alpha). Monoclonal antibody TL40.3 agglutinated trypanosomes collected 3 days after parasite inoculation while monoclonal antibodies TL40.1, TL40.2, and TL40.6 agglutinated trypanosomes collected 6 days after inoculation. Since agglutinin titers against trypanosomes from irradiated (700 rad from a 60Co source) and nonirradiated rats were similar, expression of the antigens recognized by the monoclonal antibodies appeared to be independent of the immunological state of the host and the morphology of the parasite. The reproduction of T. lewisi in in vitro trypanostatic assays was inhibited only when the monoclonal antibodies were present in concentrations greater than or equal to those needed to agglutinate the trypanosomes. Monoclonal antibodies TL40.1 and TL40.3, but not TL40.2 and TL40.6, agglutinated erythrocytes collected later in the infection from irradiated, infected rats. None of the monoclonal antibodies agglutinated erythrocytes from nonirradiated, infected rats, from irradiated, noninfected rats or from nonirradiated, noninfected rats. This suggests that immunocompetent rats may make blocking antibodies against the exoantigens recognized by monoclonal antibodies TL40.1 and TL40.3.     

The effect of specific antiserum on the metabolism of three membrane-associated antigens of ASL-1 x LM(TK)- hybrid cells.

Fusion of ASL-1 cells, a murine leukemia forming thymus leukemia (TL) antigens, with LM(TK)- cells, a TL(--) murine cell line, resulted in a stable hybrid forming TL antigens. The hybrids failed to undergo modulation, the reversible dissappearance of TL antigens from the surfaces of the cells, stimulated by TL antiserum. Unlike ASL-1 cells, the rate of disappearance of the antigens from modulation negative hydrid cells was unaffected by TL antiserum. The t 1/2 of TL antigens of the hybrid was approximately 30 h. The t 1/2 of TL antigens of ASL-1 cells was 10 h in the presence of TL antiserum, 18 h in the absence of TL antiserum. The rate of metabolism of a putative tumor-associated antigen of ASL-1 cells formed by the hybrid was unaffected by exposure to specific antiserum, as was the metabolism of H-2 antigens formed by the cell types.     

Enhancement of the anti‐inflammatory activity of temporin‐1Tl‐derived antimicrobial peptides by tryptophan,arginine and lysine substitutions

Temporin‐1Tl (TL) is a 13‐residue frog antimicrobial peptide (AMP) exhibiting potent antimicrobial and anti‐inflammatory activity. To develop novel AMP with improved anti‐inflammatory activity and antimicrobial selectivity, we designed and synthesized a series of TL analogs by substituting Trp, Arg and Lys at selected positions. Except for Escherichia coli and Staphylococcus epidermidis, all TL analogs exhibited retained or increased antimicrobial activity against seven bacterial strains including three methicillin‐resistant Staphylococcus aureus strains compared with TL. TL‐1 and TL‐4 showed a little increase in antimicrobial selectivity, while TL‐2 and TL‐3 displayed slightly decreased antimicrobial selectivity because of their about twofold increased hemolytic activity. All TL analogs demonstrated greatly increased anti‐inflammatory activity, evident by their higher inhibition of the production tumor necrosis factor‐α (TNF‐α) and nitric oxide and the mRNA expression of inducible nitric oxide synthase and TNF‐α in lipopolysaccharide (LPS)‐stimulated RAW264.7 macrophage cells, compared with TL. Taken together, the peptide anti‐inflammatory activity is as follows: TL‐2 ≈ TL‐3 ≈ TL‐4 > TL‐1 > TL. In addition, LPS binding ability of the peptides corresponded with their anti‐inflammatory activity. These results apparently suggest that the anti‐inflammatory activity of TL analogs is associated with the direct binding ability between these peptides and LPS. Collectively, our designed TL analogs possess improved anti‐inflammatory activity and retain antimicrobial activity without a significant increase in hemolysis. Therefore, it is evident that our TL analogs constitute promising candidates for the development of peptide therapeutics for gram‐negative bacterial infection. Copyright © 2015 European Peptide Society and John Wiley & Sons, Ltd.     

Murine leukemia cell hybrids: The quantity of TL antigens expressed by parental and hybrid cells fails to correlate with their sensitivity to TL antibody and complement

The quantity of thymus-leukemia (TL) antigens expressed by murine leukemia cells is significantly greater than that expressed by somatic hybrids of such cells. Based upon the results of ¹²⁵I-lactoperoxidase labeling and antibody absorption procedures, and corrected for size differences between the two cell types, the quantity of TL antigens expressed by RADA-1 cells, a radiation-induced murine leukemia cell line of strain A/J mice, is approximately 5.0 times greater than that of somatic hybrids of RADA-1 and LM(TK)^? cells. LM(TK)^? cells are a thymidine kinase-deficient TL(-) mouse fibroblast cell line. The quantity of TL antigens expressed is related only in part to their susceptibility to lysis by TL antibodies and guinea pig complement (GPC). RADA-1 cells resist lysis. The quantity of TL antigens expressed by RADA-1 cells is analogous to that formed by nonneoplastic thymocytes obtained from F₁ hybrids of two strains of TL(+) and TL(-) mice; cells from both strains are sensitive to TL antiserum and GPC. ASL-1 cells, a spontaneously occurring leukemia cell line of A/J mice, express TL antigens in significantly higher quantities than any of the cell types examined. Exposed to TL antisera, the quantity of TL antigens of ASL-1 cells, but not that of hybrid cells, gradually diminishes. ASL-1 cells convert over a 6-h period of exposure to antibody and guinea pig complement (GPC) resistance; hybrid cells remain sensitive. However, ASL-1 cells converted to TL antibody and GPC resistance continue for a time to express TL antigens in quantities similar to that of sensitive F₁ thymocytes and resistant RADA-1 cells. RADA-1 X LM(TK)^? hybrid cells, which are sensitive to TL antibodies and GPC, express the lowest quantities of TL antigens of any of the cell types examined. It is likely that differences in the quantities of TL antigens expressed by different cell lines reflect genetic mechanisms controlling TL antigen expression. The failure of TL antisera to affect the quantities of TL antigens expressed by hybrid cells is taken as an indication that genetic controls governing antigen expression may be distinguished from those involved in regulating responsiveness to specific antiserum.     

Structural identity of the TL antigen homologues derived from strain 2 and strain 13 guinea pigs

Strain 2 and strain 13 guinea pig thymocytes have been shown to bear a molecule that by several criteria appears to be a homologue of the murine TL antigen. The existence of a TL polymorphism in the mouse system as evidenced by TL- strains and various TL phenotypes in TL+ strains prompted a study to determine if a similar polymorphism could be demonstrated in the guinea pig system. By using two-dimensional gel electrophoresis, the thymocytes of a third inbred strain, DHCBA, were shown to bear a TL antigen, and the TL antigens of strains 2 and DHCBA were shown to give identical patterns of spots. A biochemical comparison of the strain 2 and strain 13 TL antigen heavy chains by tryptic and chymotryptic peptide mapping demonstrated that these molecules have identical peptides. Thus, no polymorphism could be demonstrated within the guinea pig TL system for the three inbred strains studied. Comparative tryptic peptide mapping of the guinea pig TL and class I B.1+S antigens demonstrated 43% homology, significantly higher than that reported for murine H-2 and TL antigens. These results provide suggestive evidence that the gene duplication giving rise to the genes determining the class I and TL antigens may have occurred more recently in the guinea pig than in the mouse.     

The T cell costimulator TL1A is induced by FcgammaR signaling in human monocytes and dendritic cells

The recently described TL1A/DR3 ligand/receptor pair mediates strong costimulation of Th1 cells. Activation of T and NK cells induces DR3 expression, permitting soluble recombinant TL1A to increase IFN-gamma production and proliferation of these cells. Gut T cells and macrophages express TL1A, especially in Crohn's disease (CD), and there is a strong association between CD and tl1a single nucleotide polymorphisms. Murine studies implicate TL1A in gut inflammation. To determine whether professional T cell-activating cells can express TL1A, fresh blood monocytes and monocyte-derived dendritic cells were stimulated with various activating ligands, including TLR agonists, IFN-gamma, and immune complexes. FcgammaR stimulation strongly induced TL1A mRNA in both cell types, which correlated with the detection of TL1A on the cell surface and in cell culture medium. TLR agonists capable of inducing IL-6 and TNF-alpha in monocytes and dendritic cells did not induce surface nor soluble TL1A. Furthermore, we demonstrate that TL1A production in monocytes leads to enhancement of T cell responses. The induction of TL1A on APCs via specific pathway stimulation suggests a role for TL1A in Th1 responses to pathogens, and in CD.     

Identification of cis-acting elements in the 3'-untranslated region of the dengue virus type 2 RNA that modulate translation and replication

Using the massively parallel genetic algorithm for RNA folding, we show that the core region of the 3'-untranslated region of the dengue virus (DENV) RNA can form two dumbbell structures (5'- and 3'-DBs) of unequal frequencies of occurrence. These structures have the propensity to form two potential pseudoknots between identical five-nucleotide terminal loops 1 and 2 (TL1 and TL2) and their complementary pseudoknot motifs, PK2 and PK1. Mutagenesis using a DENV2 replicon RNA encoding the Renilla luciferase reporter indicated that all four motifs and the conserved sequence 2 (CS2) element within the 3'-DB are important for replication. However, for translation, mutation of TL1 alone does not have any effect; TL2 mutation has only a modest effect in translation, but translation is reduced by ～60% in the TL1/TL2 double mutant, indicating that TL1 exhibits a cooperative synergy with TL2 in translation. Despite the variable contributions of individual TL and PK motifs in translation, WT levels are achieved when the complementarity between TL1/PK2 and TL2/PK1 is maintained even under conditions of inhibition of the translation initiation factor 4E function mediated by LY294002 via a noncanonical pathway. Taken together, our results indicate that the cis-acting RNA elements in the core region of DENV2 RNA that include two DB structures are required not only for RNA replication but also for optimal translation.     

Antibodies to acetylcholine receptor and tetanus toxoid: in vitro synthesis by thymic lymphocytes

Thymic lymphocytes (TL) of patients with myasthenia gravis (MG) have been reported to synthesize antibodies to acetylcholine receptors (anti-AChR). Incubation of TL with pokeweed mitogen (PWM), a polyclonal T cell- and monocyte-dependent activator of B cell differentiation, was reported to inhibit TL in vitro synthesis of anti-AChR. We studied the TL of 16 patients with MG without thymoma. TL of 10 of 16 patients synthesized anti-AChR in vitro without stimulation. In the presence of PWM, the amount of anti-AChR synthesized by the TL of these 10 patients increased in five, decreased in three, and was unaffected in two. There was a correlation between serum anti-AChR titer and PWM-stimulated synthesis (r = 0.87), but not with unstimulated synthesis (r = 0.33) of anti-AChR by TL. There was no correlation between the amount of synthesized anti-AChR and the amount of secreted IgG or with the percentage of B cells (surface Ig+) in the TL suspensions. TL of three age-matched cardiac surgery controls failed to synthesize detectable anti-AChR, although two of three synthesized IgG. Four patients with MG were booster immunized with tetanus toxoid (TT) 3 to 4 wk prior to thymectomy. TL of three synthesized anti-TT in vitro, whereas TL of three nonboosted MG patients failed to synthesize anti-TT. Thus, we have shown that TL of some patients with MG are capable of anti-AChR synthesis, with evidence of heterogeneity of the in vitro response, and the B cell repertoire in the thymus may, in part, reflect recent systemic immune events of the host.     

Nestling telomere length does not predict longevity,but covaries with adult body size in wild barn swallows

Telomere length and dynamics are increasingly scrutinized as ultimate determinants of performance, including age-dependent mortality and fecundity. Few studies have investigated longevity in relation to telomere length (TL) in the wild and none has analysed longevity in relation to TL soon after hatching, despite the fact that telomere shortening may mostly occur early in life. We show that TL in nestling barn swallows (Hirundo rustica) in the wild does not predict longevity. However, TL positively covaries with body size, suggesting that individuals with large TL can afford to grow larger without paying the cost of reduced TL, and/or that benign rearing conditions ensure both large body size and low rates of telomere shortening. Overall, our study hints at a role of TL in developmental processes, but also indicates a need for further analyses to assess the expectation that TL in young individuals predicts longevity in the wild.     

Telomere length as a biological marker in malignancy

Telomere maintenance is important for tumor cell growth and survival. Telomere length (TL) is determined by the balance between positive and negative factors impacting telomere homeostasis. In the last decade, TL has emerged as a promising clinical marker for risk and prognosis prediction in patients with malignant disorders. Tumor TL, as well as TL in healthy tissues such as peripheral blood, may carry valuable information for future treatment strategies. Here we discuss the present status of TL as a biological marker in cancer patients.     

TL1A Increases Expression of CD25, LFA-1, CD134 and CD154, and Induces IL-22 and GM-CSF Production from Effector CD4 T-Cells

Elevated levels of the cytokine TL1A is associated with several autoimmune diseases e.g. rheumatoid arthritis and inflammatory bowel disease. However, the exact role of TL1A remains elusive. In this study, we investigated the function of TL1A in a pro-inflammatory setting. We show that TL1A together with IL-12, IL-15 and IL-18 increases expression of the co-stimulatory molecules CD154 (CD40 ligand) and CD134 (OX40) on previously activated CD4⁺ T cells. This indicates that TL1A functions as a co-stimulatory molecule, decreasing the activation threshold of T-cells. We have previously shown that TL1A co-stimulation strongly induces IL-6 in human healthy leukocytes. Interestingly, the cytokine-activated effector T-cells did not produce IL-6 in response to TL1A, indicating distinct effects of TL1A on different cell populations. We further show that this co-stimulation increases the expression of CD25 (IL-2Rα) and CD11a (α-chain of LFA-1) on CD4 T-cells, likely governing increased IL-2/IL-15 sensitivity and cell-cell contact. Along with this, TL1A co-stimulation caused a specific induction of IL-22 and GM-CSF from the activated T-cells. These results substantially contribute to the explanation of TL1A''s role in inflammation. Our results suggest that TL1A should be considered as a target for immunotherapeutic treatment of rheumatoid arthritis and inflammatory bowel disease.     

Early development of the endangered freshwater goby, Rhinogobius sp. BI (Gobiidae)

The early development of the endangered freshwater goby, Rhinogobius sp. BI (ogasawara-yoshinobori in Japanese), was described in the course of a serial rearing experiment over generations as ex situ preservation. The eggs, measuring 2.0 mm in long diameter and 0.7 mm in short diameter, were elliptical with a colorless transparent chorion, a slightly yellowish yolk, and some oil globules. Hatching occurred naturally at 6 to 7 days after spawning at 24.0°C. Newly hatched larvae, measuring 3.2–3.4 mm in total length (TL), had opened mouth and a globular yolk sac. The yolk was completely absorbed at 3.5 mm TL (5 days after hatching). Notochord flexion initiated at 5.7 mm TL (18 days) and finished at <9.1 mm TL (30 days). First dorsal fin began to form in postflexion larvae at 10.0 mm TL (40 days), and a full complement was attained at 11.6 mm TL (45 days). Second dorsal fin emerged at 5.7 mm TL (18 days); full count was attained and segmentation initiated at 9.1 mm TL (30 days). Anal fin anlage appeared at 5.7 mm TL (18 days); its ray count was completed and segmentation initiated at 9.1 mm TL (30 days), and branching at 15.6 mm TL (60 days). Caudal fin support appeared at 4.5 mm TL (15 days); segmentation initiated at 6.0 mm TL (24 days) and branching at 10.0 mm TL (40 days). Fanlike pectoral fin present in newly hatched larvae. Pectoral fin rays appeared at 10.0 mm TL (40 days), and its ray count completed at 15.6 mm TL (60 days). Pelvic fin projected at 9.1 mm TL (30 days), and a sucking disc partially formed at 11.6 mm TL (45 days). Aggregate numbers of all fin rays were completed at 15.6 mm TL in 60 days after hatching. Pelagic period continued for about 40 days, and settlement was completed in postflexion larvae at 45 days.     

A change in a single gene of Salmonella typhimurium can dramatically change its buoyant density.

The growth rates and buoyant densities of a Salmonella typhimurium mutant, TL126 (proB74A+), with enhanced osmotolerance caused by proline overproduction were measured and compared with the growth rates and buoyant densities of an isogenic (wild-type) strain, TL128 (proB+ A+), with normal control of proline production. Growth rates were determined in a rich medium (Luria broth) with added NaCl to produce various osmotic strengths ranging from 300 to 2,000 mosM. At low concentrations of NaCl, there was little variation in doubling times between the two strains. However, as the osmotic strength of the medium approached and exceeded 1,300 mosM, the doubling times of TL126 (osmotolerant) were 1.5 to 2 times faster than those of TL128 (wild type), confirming the osmotolerance of TL126. Buoyant densities were determined by equilibrium sedimentation in a Percoll gradient of osmotic strength equal to that of the growth medium. The osmolarity of the Percoll gradient was adjusted by the addition of NaCl. At low osmolarities (300 to 500 mosM), the buoyant density of TL126 (osmotolerant) was slightly but consistently lower than that of TL128 (wild type). As the osmotic strength was increased, the buoyant density of TL126 (osmotolerant) increased in proportion to the osmotic strength. In contrast, the buoyant density of strain TL128 (wild type) did not increase as much. At high osmolarities (1,600 to 2,000 mosM), the buoyant density of TL126 (osmotolerant) was consistently higher than that of TL128 (wild type). These results suggest that the intracellular accumulation of proline by TL126, the osmotolerant strain, increases both the growth rates and buoyant densities at osmolarities of 1,300 mosM and above.     

Thermoluminescence dating tests of Pleistocene sediments from uplifted marine shorelines along the southwest coastline of the Calabrian Peninsula (southern Italy)

This paper presents TL age estimates of Pleistocene raised marine terraces from southern Calabria (southern Italy). It focuses on the dating of last interglacial shallow-marine sand deposits, including several Tyrrhenian key reference deposits whose stratigraphic assignment is based on biostratigraphic evidence (presence of a Strombus bubonius fauna) and geochronometric data (amino-acid data calibrated with U/Th dates on coral). The TL age estimates are obtained on alkali feldspar coarse grains using their blue TL emission. They are in good agreement with the IR-OSL age estimates obtained on the same feldspar samples. Our feldspar TL method is tested on two Tyrrhenian key reference sites, Ravagnese and Bovetto, in the Reggio di Calabria area. Their measured TL age estimates (97 ± 11 ka and 100 ± 10 ka) are lower than their estimated geological age (i.e. Oxygen Isotope Substage 5e). The correction for long-term fading suggested by Mejdahl (1988), is tested on these two samples using a lifetime of 446 ka as estimated from both Calabrian and Miocene sand collected within the same area. This correction would yield preliminary TL ages (116 ± 13 ka and 116 ± 12 ka) that are in better agreement with the expected geological age. The application of our TL method to paleoshorelines lying below the Tyrrhenian reference shoreline of Ravagnese-Bovetto, yields stratigraphically consistent TL age estimates. The TL method is also applied to two supposedly pre-last interglacial paleoshorelines which are geomorphologically older than the Tyrrhenian reference shorelines. They remain however chronologically undifferentiated, both by the TL and the amino-acid methods. Finally, the preliminary feldspar TL results obtained on the Miocene and the Calabrian sand deposits (> 1 Ma), suggest that our feldspar TL method is limited, in the SW Calabrian area, to about 200 ka.     

An anti-TL1A antibody for the treatment of asthma and inflammatory bowel disease

TL1A is an attractive therapeutic target for the treatment of mucosal inflammation associated with inflammatory bowel disease (IBD) and asthma. Blockade of the TL1A pathway has been shown to reduce inflammatory responses while leaving baseline immunity intact, and to be beneficial in animal models of colitis and asthma. Given the therapeutic potential of blocking this pathway in IBD and asthma, we developed C03V, a human antibody that binds with high affinity to soluble and membrane-bound TL1A. In an assay measuring apoptosis induced by exogenous TL1A, C03V was 43-fold more potent than the next most potent anti-TL1A antibody analyzed. C03V also potently inhibited endogenous TL1A activity in a primary cell-based assay. This potency was linked to the C03V-binding epitope on TL1A, encompassing the residue R32. This residue is critical for the binding of TL1A to its signaling receptor DR3 but not to its decoy receptor DcR3, and explains why C03V inhibited TL1A-DR3 binding to a much greater extent than TL1A-DcR3 binding. This characteristic may be advantageous to preserve some of the homeostatic functions of DcR3, such as TL1A antagonism. In colitis models, C03V significantly ameliorated microscopic, macroscopic and clinical aspects of disease pathology, and in an asthma model it significantly reduced airways inflammation. Notable in both types of disease model was the reduction in fibrosis observed after C03V treatment. C03V has the potential to address unmet medical needs in asthma and IBD.