Outcomes Following Treatment with FOLFOX for Patients with Resectable or Potentially Resectable Metastatic Colorectal Cancer: A Population-based Cohort Study.

AIMS: To evaluate the safety and effectiveness of oxaliplatin-based combination chemotherapy for patients with metastatic colorectal cancer (mCRC) to extrahepatic sites. MATERIALS AND METHODS: We conducted a population-based retrospective study examining the safety and effectiveness of perioperative oxaliplatin for resectable or potentially resectable colorectal metastases in Ontario, Canada. Outcomes were also compared with patients with liver-only metastases. Patients received oxaliplatin for mCRC between 1 January 2013 and 30 June 2020. RESULTS: In total, 192 patients had extrahepatic metastases. Seventy per cent had R0 metastasectomy. The 3-year disease-free survival and overall survival were 62% and 79%, respectively; <4% of patients died within 60 days of metastasectomy and 74-90% of patients received treatment according to recommendations from a multidisciplinary setting. Compared with liver-only controls (n = 1306), patients had mCRC to the lung only (n = 115), lung and liver (n = 55) and liver with non-pulmonary site (n = 22). Extrahepatic metastases were more likely to be found for patients whose primary colorectal resection had positive margins (14% versus 7%, P = 0.005) and primary tumours located in the rectum [odds ratio 4.01 (2.31-6.97)]. After adjustment, there was no difference in overall survival between liver-only controls and patients with lung-only [hazard ratio 0.82 (0.59-1.15)] or liver and lung metastases [hazard ratio 1.26 (0.85-1.87)] (P = 0.24). In total, 79/115 (69%) of patients with lung-only metastases had a metastasectomy compared with 645/1306 (49%) and 15/55 (27%) of patients with liver-only and liver and lung metastases, respectively. Hospital visits were similar between patients with liver-only and extrahepatic metastases. CONCLUSION: Oxaliplatin-based chemotherapy for patients with resectable or potentially resectable mCRC with extrahepatic metastases was safe and resulted in similar outcomes in appropriately selected patients when compared with patients with liver-only metastases.

Redox Homeostasis in Ocular Tissues: Circadian Regulation of Glutathione in the Lens?

Accumulating evidence in tissues suggests an interconnection between circadian clocks and redox regulation. Diurnal variations in antioxidant levels, circadian rhythms of antioxidant enzyme activity, and differences in oxidative stress markers at different times of the day all indicate that oxidative stress responses follow a circadian rhythm. Disruptions of circadian rhythms are linked to a number of age-related diseases, including those in the eye. Typically, ocular tissues contain a robust antioxidant defence system to maintain redox balance and minimise oxidative stress and damage. The lens, in particular, contains remarkably high levels of the antioxidant glutathione (GSH). However, with advancing age, GSH levels deplete, initiating a chain of biochemical events that ultimately result in protein aggregation, light scattering, and age-related cataracts. While there is evidence that the lens exhibits circadian rhythms in the synthesis and release of melatonin, little is known about the regulation or function of timekeeping mechanisms in the lens. Since circadian rhythms are disrupted with age, and the depletion of GSH in the lens is a known initiating factor in the development of age-related cataracts, understanding the mechanisms involved in regulating GSH levels may lead to the future development of approaches to manipulate the clock to restore GSH levels and redox balance in the lens, and protect the lens from cataracts.

[Effect of body mass index on the assisted reproductive outcome of frozen-thawed embryo transfer in patients with polycystic ovary syndrome].

Objective: To investigate the effect of body mass index (BMI) on clinical pregnancy and neonatal outcomes in patients with polycystic ovary syndrome (PCOS) during frozen-thawed embryo transfer. Methods: A total of 650 patients with PCOS who received routine in vitro fertilization or intracytoplasmic sperm injection treatment for frozen-thawed embryo transfer from June 2014 to June 2019 in Tianjin Central Hospital of Gynecology Obstetrics were retrospectively analyzed. According to BMI, PCOS patients were divided into group A (18.5≤BMI<23 kg/m2, n=253), group B (23≤BMI<25 kg/m2, n=167), and group C (BMI≥25 kg/m2, n=230). The general information, clinical pregnancy outcomes, pregnancy complications, the incidence of macrosomia and low-birth-weight infants were compared in the three groups, and the influencing factors of neonatal birth weight were analyzed. Results: The embryo implantation rate, clinical pregnancy rate, and ongoing pregnancy rate all showed downward trend with the increase of BMI, but the differences were not statistically significant (all P>0.05). The live birth rate in group C [47.0% (108/230)] was significantly lower than those in groups A and B, with statistical significance (χ²=7.43, P=0.024). The late miscarriage rate was higher in group C [9.4% (13/139)] than in groups A and B (χ²=7.66, P=0.022). The birth rates of macrosomia in groups B [22.2% (16/72)] and group C [21.1% (16/76)] were significantly higher than that in group A, and the difference was statistically significant (χ²=14.15, P=0.001). There was no statistically significant difference in the incidence of gestational diabetes between the three groups (χ²=3.81, P=0.149). The incidence of hypertension disorders complicating pregnancy increased with the increase of BMI, and the difference was not statistically significant (P>0.05). Regression analysis showed that macrosomia was significantly associated with maternal pre-pregnancy BMI and gestational weeks, and the risk of macrosomia increased by 15% (95%CI: 3%-28%) for every increase in maternal BMI. Conclusions: The embryo implantation rate, clinical pregnancy rate, and ongoing pregnancy rate of PCOS patients in frozen-thawed embryo transfer cycles show downward trend with the increase of BMI. Obese patients with PCOS have a significant increase in late miscarriage rate and a significant decrease in live birth rate. The incidence of hypertension disorders complicating pregnancy in PCOS patients in the obese group has an increasing trend, and the birth rate of macrosomia has increased significantly. Therefore, it is recommended that obese women with PCOS lose weight scientifically before pregnancy to improve pregnancy and neonatal outcomes.

[Impact of previous cesarean delivery on pregnancy outcomes of in vitro fertilization and frozen-thawed embryo transfer].

Objective: To investigate the impact of a previous cesarean delivery on pregnancy outcomes of in vitro fertilization and frozen-thawed embryo transfer (FET). Methods: The clinical data of 1 179 patients who received in vitro fertilization and FET in Tianjin Central Hospital of Gynecology Obstetrics from January 2014 to May 2019 and had a history of the previous delivery were retrospectively analyzed. The patients were divided into four groups according to different previous delivery history and the number of embryo transferred: group A (single embryo transfer group with cesarean delivery history, n=338), group B (single embryo transfer group with vaginal delivery history, n=78), group C (double embryo transfer group with cesarean delivery history, n=444), and group D (double embryo transfer group with vaginal delivery history, n=319). The 1∶1 propensity score based on age, body mass index (BMI), infertility duration, basal FSH, basal LH, number of oocytes retrieved and high-quality embryo rate was used to match group A and B (caliper value=0.15), group C and D (caliper value=0.05), and group A and C (caliper value=0.01) respectively to reduce the influence of selection bias. The clinical pregnancy outcomes of patients were compared. Results: (1) Group A and group B were single embryo transfer groups with a total of 77 pairs of matched patients. There were no statistically significant differences in clinical pregnancy rate [42.9% (33/77) vs 45.5% (35/77)], miscarriage rate, preterm birth rate, and neonatal birth weight (all P>0.05). (2) Group C and group D were double embryo transfer groups with a total of 304 pairs of matched patients. The clinical pregnancy rate [42.4% (129/304)] and twin pregnancy rate [9.5% (29/304)] of Group C were significantly lower than those of Group D [53.0% (161/304), 15.5% (47/304) respectively; both P<0.05). There were no statistically significant in miscarriage rate, preterm birth rate and neonatal birth weight between the two groups (all P>0.05). (3) Groups A and C matched 318 pairs of patients. The two groups had no statistical significances in clinical pregnancy rate [38.4% (122/318) vs 45.6% (145/318)], miscarriage rate and preterm birth rate (all P>0.05), but the twin pregnancy rate in group C was significantly higher than that of group A [11.3% (36/318) vs 0.3% (1/318), P<0.01). (4) The occurrence of the low-birth-weight infant were related to gestational age (OR=0.41, 95%CI: 0.32-0.54) and twin pregnancy (OR=4.44, 95%CI: 1.93-10.21), and the occurrence of macrosomia was related to BMI (OR=1.18, 95%CI: 1.06-1.32). Moreover, the previous delivery method was not related to the neonatal birth weight (P>0.05). Conclusions: Patients with different delivery histories receive FET therapy, the pregnancy outcomes of single embryo transfer are not significantly different, and the success rate of double embryo transfer in patients with a cesarean delivery history is low. The neonatal birth weight is not related to the history of the cesarean section. It is recommended that patients with a cesarean delivery history choose elective single embryo transfer to ensure the success rate and to reduce the risk.

Methylphenidate causes cytotoxicity on photoreceptor cells via autophagy.

Methylphenidate (MPH) is used as the first-line treatment for attention-deficit hyperactivity disorder. However, there are concerns that this treatment may be associated with increased risk of retinal damage. This study was to investigate cytotoxicity of MPH on photoreceptor cells and explore its underlying mechanisms. MPH-caused cell toxicity was established in 661 W cells. Cytotoxicity was evaluated by 3-(4,5-dimethylthiazol)-2,5-diphenyltetrazolium-bromid and lactate dehydrogenase assays. Oxidative stress was measured by the markers: glutathione (GSH) reductase, catalase, and superoxide dismutase activities as well as GSH, reactive oxygen species, and malondialdehyde levels. Gene and protein expression was detected by real-time polymerase chain reaction (PCR) and western blot, respectively. Results showed that MPH decreased 661 W cell viability, increased caspase-3/9 activities, and induced oxidative stress. Furthermore, MPH treatment increased messenger RNA (mRNA) expression of Beclin-1 and microtubule-associated protein 1A/1B-light chain 3B (LC3B) protein expression in 661 W cells, suggesting autophagy was induced. MPH treatment also upregulated p-JAK1/p-STAT1 protein expression. These data demonstrated that MPH could increase oxidative stress in photoreceptor cells to cause cell toxicity via autophagy, providing the scientific rationale for the photoreceptor cell damage caused by the MPH administration.

[Multiple-factor analysis of serum allergen distribution of patients with allergic rhinitis and level of main allergen IgE in Shenyang area].

Objective:To discuss multiple-factor analysis of serum allergen distribution of patients with allergic rhinitis and level of main allergen IgE in Shenyang area, and to provide a scientific basis for the prevention of allergic rhinitis in this area.Method:Serum IgE was detected in 749 cases［501 cases of male (66.8%), and 248 cases of female (33.2%)］, with allergic rhinitis.The age range was from 3 to 65 years old, and they were divided into 5 groups based on age. A questionnaire survey was conducted to analyze the distribution of serum allergens and to carry out a multiple-factor analysis of level of the main allergen IgE in patients.Result:The primary allergen was house dust mite/dust mite in each age group, and the differences in the positive rate of elm, mold, cat/dog fur scurf, cockroach and ragweed among different groups were statistically significant（P<0.01 or P<0.05）.The ingested allergen sequencing for all age groups: the distribution of 7-14 years old group and 15-35 years old group were consistent with that of the whole, among the under 6 years old group, mango and pineapple was ranked 1st,beef and mutton was ranked 2nd,the occurrence rate of shrimp and crab rose to the 3rd place, among the 36-60 years old group, mango, pineapple and milk was ranked 1st, egg was ranked 2nd, and beef and mutton ranked 3rd, the differences in positive rate of mango and pineapple, beef and mutton, crab and nut among all groups were statistically significant(P<0.01 or P<0.05).The IgE level of cockroach was impacted by the allergic history, home cultivation of flowers and plants and animal domestication. The IgE level of mold was impacted by sex, allergy history, home rearing of pet and furniture updates. The IgE level of wormwood was impacted by allergy history and asthma history. The IgE level of peanut was impacted by age and allergy history. The IgE level of egg was impacted by history of food and drink allergy, home cultivation of flowers and plants and home rearing of pet. The IgE level of crab was impacted by the allergy history and home rearing of pet.Conclusion: The primary inhaled allergen in all groups is house dust mite/dust mite, and the ingested allergen varies in each group, which has provided a reference basis for prevention of ingested allergy.The varying influence factors for IgE level of primary allergens could be used to prevent the patients from contacting the allergen,and each risk factor has become a focus of prevention and control for patients, offering a major help to the prevention and treatment of allergic rhinitis.

Review: Neurodegenerative processes in temporal lobe epilepsy with hippocampal sclerosis: Clinical, pathological and neuroimaging evidence.

Cognitive decline is increasingly described as a co-morbidity of temporal lobe epilepsy (TLE). Mechanisms underlying cognitive impairment are not fully understood despite examining clinical factors, such as seizure frequency, and cellular mechanisms of excitotoxicity. We review the neuropsychometry evidence for progressive cognitive decline and examine the pathology and neuroimaging evidence supporting a neurodegenerative process in hippocampal sclerosis (HS)-related TLE. Accelerated cognitive decline is described in groups of adult HS-related TLE patients. Large childhood studies show early onset of seizures result in poor development of verbal memory and a hindrance in achieving cognitive potential. We discuss HS classification according to different patterns of neuronal loss and correlation to post-temporal lobectomy cognitive outcomes in refractory TLE patients. Factors such as lateralization of HS pathology, neuronal density and subtype have correlated to cognitive outcomes with varying significance between different studies. Furthermore, alterations in neuronal maturity, regenerative capacity and aberrant connectivity appear to affect cognitive performance post-operatively suggesting a complex multifactorial process. More recent studies have identified tau pathology being present in HS-related TLE and correlated to post-operative cognitive decline in some patients. A traumatic head injury-related or novel tauopathy has been hypothesized as an underlying process. We discuss the value of prospective and cross-sectional imaging in assessing cognition and review volumetric magnetic resonance studies with progressive ipsilateral hippocampal atrophy identified to correlate with seizure frequency. Finally, we consider the use of positron emission tomography biomarkers, such as tau tracers, and connectivity studies that may examine in vivo pathways and further explore cognitive decline in TLE.

Contact lens--related corneal ulcer: a two-year review.

To create a national registry of contact-lens related corneal ulcers (CLRCU) patients in Malaysia with the aim of detecting outbreaks, identifying pattern of causative organisms, determining patient demography, risk factors, wearing patterns and monitoring outcome of treatment. The CLRCU registry is an ongoing patient registry established in 2007 as a surveillance tool used by Malaysian Ministry of Health ophthalmology departments. Notification of patients clinically suspected of CLRCU was performed online through the National Eye Database (NED). Data collected included patient demography, contact lens type, causative organism and treatment outcome. During 2007-2008, a total of 202 patients were notified to the CLRCU registry with a mean age of 26.7 years (71.8% female). All registered patients wore soft contact lens and monthly disposable lenses were the most popular (83.5%). The majority of patients had bacterial CLRCU and the most common causative organism was Pseudomonas (79.7% of bacterial cases). No epidemics were identified during the period of data examination. Use of contact lenses, which is increasing during modern times, may lead to CLRCU as a severe complication. The CLRCU registry is an effective tool which uses a web-based notification system that allows quick and up to date reports of CLRCU cases. This provides the ability to monitor outbreaks of disease and identify important causative and associated factors of the disease which may be used to reduce future incidence.

Maturation versus death of developing double-positive thymocytes reflects competing effects on Bcl-2 expression and can be regulated by the intensity of CD28 costimulation.

Immature double-positive (DP) thymocytes mature into CD4(+)CD8(-) cells in response to coengagement of TCR with any of a variety of cell surface "coinducer" receptors, including CD2. In contrast, DP thymocytes are signaled to undergo apoptosis by coengagement of TCR with CD28 costimulatory receptors, but the molecular basis for DP thymocyte apoptosis by TCR plus CD28 coengagement is not known. In the present study, we report that TCR plus CD28 coengagement does not invariably induce DP thymocyte apoptosis but, depending on the intensity of CD28 costimulation, can induce DP thymocyte maturation. We demonstrate that distinct but interacting signal transduction pathways mediate DP thymocyte maturation signals and DP thymocyte apoptotic signals. Specifically, DP maturation signals are transduced by the extracellular signal-related kinase (ERK)/mitogen-activated protein kinase (MAPK) pathway and up-regulate expression of the antiapoptotic protein Bcl-2. In contrast, the apoptotic response stimulated by CD28 costimulatory signals is mediated by ERK/MAPK-independent pathways. Importantly, when TCR-activated thymocytes are simultaneously coengaged by both CD28 and CD2 receptors, CD28 signals can inhibit ERK/MAPK-dependent Bcl-2 protein up-regulation. Thus, there is cross-talk between the signal transduction pathways that transduce apoptotic and maturation responses, enabling CD28-initiated signal transduction pathways to both stimulate DP thymocyte apoptosis and also negatively regulate maturation responses initiated by TCR plus CD2 coengagement.

Prevalence of Eperythrozoon spp. infection and congenital eperythrozoonosis in humans in Inner Mongolia, China.

Eperythrozoon is an obligate parasitic bacteria found in many species of animals. A large scale investigation of the prevalence of Eperythrozoon spp. in humans, was conducted in a developing country using light, electron microscope and animal inoculation. Samples were collected in undeveloped areas of Inner Mongolia in China over a 2-year period of 1994-6. Of the 1529 investigated samples, 35.3% were found to be Eperythrozoon spp. positive. The prevalence of infection was associated with occupation and seasonal variations. The infections were mainly mild, in 89.6% of cases (excluding pregnant women and their children). Of 74 pregnant women tested in the areas of high prevalence, 44 were confirmed Eperythrozoon spp. positive. Similarly, eperythrozoa were found in all 44 umbilical cords tested and in the neonatal peripheral blood samples taken at birth. These data suggest that eperythrozoa can be transmitted via the placenta.

Response to RAG-mediated VDJ cleavage by NBS1 and gamma-H2AX.

Genetic disorders affecting cellular responses to DNA damage are characterized by high rates of translocations involving antigen receptor loci and increased susceptibility to lymphoid malignancies. We report that the Nijmegen breakage syndrome protein (NBS1) and histone gamma-H2AX, which associate with irradiation-induced DNA double-strand breaks (DSBs), are also found at sites of VDJ (variable, diversity, joining) recombination-induced DSBs. In developing thymocytes, NBS1 and gamma-H2AX form nuclear foci that colocalize with the T cell receptor alpha locus in response to recombination activating gene (RAG) protein-mediated VDJ cleavage. Our results suggest that surveillance of T cell receptor recombination intermediates by NBS1 and gamma-H2AX may be important for preventing oncogenic translocations.

Non-CD28 costimulatory molecules present in T cell rafts induce T cell costimulation by enhancing the association of TCR with rafts.

While CD28 functions as the major T cell costimulatory receptor, a number of other T cell molecules have also been described to induce T cell costimulation. Here, we investigated the mechanisms by which costimulatory molecules other than CD28 contribute to T cell activation. Non-CD28 costimulatory molecules such as CD5, CD9, CD2, and CD44 were present in the detergent-insoluble glycolipid-enriched (DIG) fraction/raft of the T cell surface, which is rich in TCR signaling molecules and generates a TCR signal upon recruitment of the TCR complex. Compared with CD3 ligation, coligation of CD3 and CD5 as an example of DIG-resident costimulatory molecules led to an enhanced association of CD3 and DIG. Such a DIG redistribution markedly up-regulated TCR signaling as observed by ZAP-70/LAT activation and Ca2+ influx. Disruption of DIG structure using an agent capable of altering cholesterol organization potently diminished Ca2+ mobilization induced by the coligation of CD3 and CD5. This was associated with the inhibition of the redistribution of DIG although the association of CD3 and CD5 was not affected. Thus, the DIG-resident costimulatory molecules exert their costimulatory effects by contributing to an enhanced association of TCR/CD3 and DIG.

CD5 costimulation up-regulates the signaling to extracellular signal-regulated kinase activation in CD4+CD8+ thymocytes and supports their differentiation to the CD4 lineage.

CD5 positively costimulates TCR-stimulated mature T cells, whereas this molecule has been suggested to negatively regulate the activation of TCR-triggered thymocytes. We investigated the effect of CD5 costimulation on the differentiation of CD4+CD8+ thymocytes. Coligation of thymocytes with anti-CD3 and anti-CD5 induced enhanced tyrosine phosphorylation of LAT (linker for activation of T cells) and phospholipase C-gamma (PLC-gamma) compared with ligation with anti-CD3 alone. Despite increased phosphorylation of PLC-gamma, this treatment down-regulated Ca2+ influx. In contrast, the phosphorylation of LAT and enhanced association with Grb2 led to activation of extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase. When CD3 and CD5 on CD4+CD8+ thymocytes in culture were coligated, they lost CD8, down-regulated CD4 expression, and induced CD69 expression, yielding a CD4+(dull)CD8-CD69+ population. An ERK inhibitor, PD98059, inhibited the generation of this population. The reduction of generation of CD4+CD8- cells resulted from decreased survival of these differentiating thymocytes. Consistent with this, PD98059 inhibited the anti-CD3/CD5-mediated Bcl-2 induction. These results indicate that CD5 down-regulates a branch of TCR signaling, whereas this molecule functions to support the differentiation of CD4+CD8+ thymocytes by up-regulating another branch of TCR signaling that leads to ERK activation.

Association of a tetraspanin CD9 with CD5 on the T cell surface: role of particular transmembrane domains in the association.

CD9 is a member of the tetraspanin superfamily which is characterized by four transmembrane (TM) domains and associates with other surface molecules. This tetraspanin was recently found to be expressed on mature T cells. Here, we investigated which molecules associate with CD9 on T cells and which CD9 domains are required for the association. Immunoprecipitation of T cell lysates with anti-CD9 mAb followed by immunoblotting with mAb against various T cell molecules showed the association of CD9 with CD3, CD4, CD5, CD2, CD29 and CD44. Because association with CD5 was most prominent, we determined the role of CD9 TM or extracellular (EC) domains in the association with CD5. CD9 mutant genes lacking each domain were constructed and introduced into EL4 thymoma cells deficient in CD9 but expressing CD5. Among various types of stable EL4 transfectants, EL4 transfected with the mutant gene lacking TM domains (TM2/TM3) between two EC domains expressed a small amount of the relevant protein without showing association with CD5. CD9(-)CD5(-) monkey COS-7 cells transfected with this mutant gene and the CD5 gene expressed both transfected gene products, but the association of these was not detected. EL4 cells transfected with a CD9/CD81 chimera gene (the CD9 gene containing TM2/TM3 of CD81) expressed the chimeric protein on the cell surface and showed association with CD5. These results suggest an essential role of particular CD9 TM domains in the surface expression of the CD9 molecule as well as the association with CD5.

A caspase inhibitor protects thymocytes from diverse signal-mediated apoptosis but not from clonal deletion in fetal thymus organ culture.

A family of caspases has been implicated as an effector in various forms of apoptosis. The present study investigated whether this family of proteases is involved in the induction of intrathymic clonal deletion in comparison with apoptosis induced in the thymus by various signals. Potent apoptosis of thymocytes was induced in fetal thymus organ cultures (FTOC) when FTOC were treated with glucocorticoid, radiation, and anti-CD3 monoclonal antibody (mAb). As a model of negative selection based on apoptotic clonal deletion, the elimination of Vbeta8-expressing thymocytes was induced by inoculating Staphylococcal enterotoxin B (SEB) into FTOC. Addition of a peptide-based caspase inhibitor resulted in the protection of thymocytes from apoptosis induced by glucocorticoid, radiation, and anti-CD3 mAb. In contrast, the same treatment failed to prevent clonal deletion of Vbeta8high thymocytes. These results suggest that different pathways of cell death operate in the thymus that may be distinguished depending on the caspase/protease utilized in each pathway.

Differential involvement of a Fas-CPP32-like protease pathway in apoptosis of TCR/CD9-costimulated, naive T cells and TCR-restimulated, activated T cells.

Our previous study showed that CD9 costimulation of TCR-triggered naive T cells elicits activation ([3H]TdR incorporation) that is similar to CD28 costimulation; however, unlike CD28 costimulation, CD9 costimulation results in apoptosis of these previously activated T cells. Here, we investigated whether the apoptosis occurring after TCR/CD9 stimulation is associated with a death pathway involving Fas stimulation and Fas-mediated caspase activation as observed in activation-induced cell death (AICD). In contrast to AICD, the apoptosis resulting from TCR/CD9 stimulation in C57BL/6 T cells was independent of Fas, because this form of apoptosis was not prevented by anti-Fas ligand mAb and was also induced in MRL/lpr T cells. AICD was observed at 12 h after the restimulation of activated T cells with anti-CD3 and reached a peak level at 24 h after this restimulation. CPP32-like protease activity was detected during AICD. Although TCR/CD9 stimulation-associated apoptosis was observed at 24 h after the stimulation of naive T cells and reached a peak level at 36 h after this stimulation, CPP32-like protease activity in these T cells was only marginal at all time points. Nevertheless, both forms of apoptosis were prevented similarly by two different peptide-based caspase inhibitors. These results indicate that the apoptosis that follows the T cell activation which is induced as a result of CD9 costimulation does not involve a Fas-CPP32-like protease pathway, but suggest that different caspase members are likely to be critical in this form of apoptosis.

A fundamental difference in the capacity to induce proliferation of naive T cells between CD28 and other co-stimulatory molecules.

T cell activation requires two signals: a signal from the TCR and a co-stimulatory signal provided by antigen-presenting cells (APC). In addition to CD28, multiple molecules on the T cell have been described to deliver co-stimulatory signals. Here, we investigated whether there exist quantitative or qualitative differences in the co-stimulatory capacity between CD28 and other molecules. Anti-CD28 monoclonal antibody (mAb) and mAb against CD5, CD9, CD2, CD44 or CD11a all induced activation of naive T cells in the absence of APC when co-immobilized with a submitogenic dose of anti-CD3 mAb. [3H]Thymidine incorporation determined 2 days after co-stimulation was all comparable. In contrast to progressive T cell proliferation induced by CD28 co-stimulation, co-stimulation by other T cell molecules led to a decrease in viable cell recovery along with the induction of apoptosis of once activated T cells. This was associated with a striking difference in IL-2 production; CD28 co-stimulation induced progressively increasing IL-2 production, whereas co-stimulation by other molecules produced limited amounts of IL-2. Addition of recombinant IL-2 to the latter cultures corrected the induction of apoptosis, resulting in levels of cellular proliferation comparable to those observed for CD28 co-stimulation. These results indicate that a fundamental difference exists in the nature of co-stimulation between CD28 and other molecules, which can be evaluated by the levels of IL-2 production, but not simply by [3H]thymidine incorporation.

Suppression of allograft responses induced by interleukin-6, which selectively modulates interferon-gamma but not interleukin-2 production.

BACKGROUND: Interferon (IFN)-gamma produced by activated T cells represents an important effector cytokine in mediating an inflammatory response. METHODS: The present study investigated the modulation of allograft responses by inhibiting IFN-gamma production. C57BL/6 (B6) lymph node cells were stimulated with class II H2-disparate B6-C-H-2bm12 (bm12) spleen cells. RESULTS: Addition of interleukin (IL)-6 to the primary B6 anti-bm12 mixed lymphocyte reaction (MLR) inhibited neither proliferative responses nor IL-2 production. However, IL-6 induced a dose-dependent suppression of IFN-gamma production in the same MLR cultures. B6 mice were engrafted with bm12 skin grafts, and IL-6 was given to bm12 skin graft recipients every other day. T cells from these recipient mice produced significantly less IFN-gamma in secondary B6 anti-bm12 MLR than those from bm12 skin graft recipients that had not received IL-6 injections. IFN-gamma production by these T cells was suppressed more strongly when the secondary MLR was conducted in the presence of IL-6. In addition to suppression of IFN-gamma expression, IL-6 injections resulted in prolongation of bm12 skin graft survival. The critical involvement of IFN-gamma in anti-bm12 rejection responses was substantiated by evidence that administration of anti-IFN-gamma monoclonal antibody strikingly prolonged bm12 skin graft survival. The prolongation of graft survival by in vivo treatment with either IL-6 or anti-IFN-gamma monoclonal antibody was found to be induced without blocking cellular infiltration of the grafts. CONCLUSIONS: These results indicate that IFN-gamma acts as a key cytokine in a B6 anti-bm12 allograft response and that IL-6 may down-regulate this response by inhibiting IFN-gamma production of alloreactive T cells.

CD9-mediated costimulation of TCR-triggered naive T cells leads to activation followed by apoptosis.

The induction of full activation or death in TCR-triggered T cells depends largely on whether appropriate costimulatory signals are provided. In this study, we show that the costimulation of CD9 on naive T cells during TCR stimulation results in transient, albeit potent, activation followed by apoptosis, rather than full activation. Anti-CD9 mAb synergized with suboptimal doses of anti-CD3 mAb in inducing T cell activation. [3H]TdR incorporation determined 2 days after CD9 costimulation was as potent as that induced by CD28 costimulation. In contrast to progressive T cell proliferation induced by CD28 costimulation, CD9 costimulation led to the induction of apoptosis of once-activated T cells. Although IL-2R expression was induced significantly earlier and to a greater degree after CD9 costimulation than after CD28 costimulation, CD9 costimulation only transiently produced a small amount of IL-2 and induced apparently low levels of bcl-xL compared with those observed in CD28 costimulation. Addition of rIL-2 to cultures of CD9 costimulation induced strikingly enhanced expression of bcl proteins, especially of bcl-xL, and protected TCR-stimulated T cells from apoptosis. These data indicate that CD9-mediated costimulation of TCR-triggered naive T cells leads to activation followed by apoptosis as the result of failure to generate a positive signal for sufficient levels of IL-2 production.

Synergy between CD28 and CD9 costimulation for naive T-cell activation.

Our previous study demonstrated that CD9 is expressed on most mature naive T-cells and delivers a potent costimulatory signal that functions independently of CD28. Here, we investigated whether this CD9-mediated signal is different from the CD28-mediated signal in the mode of costimulation and whether both signals function synergistically for T-cell activation. Anti-CD9 or anti-CD28 monoclonal antibody (mAb) increased [3H]TdR incorporation of naive T-cells in the absence of antigen-presenting cells (APC) when coimmobilized with submitogenic doses of anti-CD3 mAb. The levels of costimulation induced by ligation of CD9 and CD28 were comparable. However, the costimulatory effect differed between soluble anti-CD9 and CD28 mAb. A soluble form of anti-CD28 mAb could costimulate anti-CD3-triggered T-cells, whereas soluble anti-CD9 mAb failed to costimulate. Although anti-CD28 costimulated naive T-cells treated with phorbol myristate acetate (PMA) instead of anti-CD3 mAb, a combination of PMA plus anti-CD9 mAb could not induce T-cell activation. The combined costimulation of anti-CD3-triggered T-cells with anti-CD9 and anti-CD28 mAbs resulted in strikingly enhanced [3H]TdR uptake and lymphokine (IL-2 and IFN-gamma) production when compared to those induced by each costimulation. These results suggest that CD9 and CD28 induce T-cell costimulation using different signaling pathways, thereby inducing synergy in T-cell activation.