Elucidation of the protein kinase C-dependent apoptosis pathway in distinct subsets of T lymphocytes in MRL-lpr/lpr mice

MRL-lpr mice are severely impaired in the Fas pathway of apoptosis induction. We here evaluate another pathway of apoptosis induction in MRL-lpr mice which is protein kinase C (PKC) dependent. Despite the defect of the Fas pathway, apoptosis developed during culture in vitro in splenic T lymphocytes from MRL-lpr mice more extensively than in T lymphocytes from MRL-+/+ mice. Apoptosis induction in the former cells was then found to be greatly promoted by PKC inhibitor H-7, and partially prevented by PKC activator phorbol 12-myristate 13-acetate (PMA). High sensitivity to H-7, but not to PKA inhibitor HA 1004, of these cells for apoptosis induction was confirmed by detailed time course and dose-dependency experiments of the drug effect. Population analysis showed that both CD4⁺ T lymphocytes and CD8⁺ T lymphocytes from MRL-lpr mice were highly sensitive to H-7, whereas CD8⁺ T lymphocytes, but not CD4⁺ T lymphocytes, from MRL-+/+ mice were susceptible to the reagent. Interestingly, B220⁺Thy-1⁺CD4^?CD8^? T lymphocytes from MRL-lpr mice were most sensitive to H-7 for apoptosis induction. Correspondingly, the membrane-translocated activated PKC-α level in splenic T lymphocytes from MRL-lpr was more extensively up-regulated by PMA than in splenic T lymphocytes from MRL-+/+. These results suggest that some signal consistently activates PKC in MRL-lpr T lymphocytes, and this event is needed for survival of these cells. On the other hand, CD4⁺CD8⁺ thymocytes were deleted by apoptosis in culture with PMA, whether these thymocytes were from MRL-lpr mice or MRL-+/+ mice. This finding suggested that the apoptosis induction pathway linked to PKC activation is intact in CD4⁺ CD8⁺ thymocytes from the Fas-defective MRL-lpr mice. We conclude from these results that the PKC-dependent signal pathways for either cell death or cell activation are intact or even accelerated in lpr mice, which could both compensate for the loss of the Fas pathway and promote the generation of autoreactive T lymphocytes.     

Fas-FasL Interaction Involved in Pathogenesis of Ocular Toxoplasmosis in Mice

Ocular toxoplasmosis is a potentially blinding intraocular inflammation. The intent of this study was to investigate the role of Fas-FasL interaction in a murine model of acquired ocular toxoplasmosis induced by intracameral inoculation of Toxoplasma gondii. Intraocular inflammation, Fas and FasL expression on lymphocytes and on ocular tissues, the occurrence of apoptosis, and the frequency of CD8⁺ and CD4⁺ T cells in the infected eyes were analyzed in C57BL/6 (B6) mice. Susceptibility to parasite-induced intraocular inflammation was observed in Fas-deficient (B6-lpr) and FasL-deficient (B6-gld) mice. Inoculation of 5,000 T. gondii tachyzoites induced significant intraocular inflammation associated with increase of Fas and FasL expression in the inoculated eyes of wild-type B6 mice. Flow cytometry demonstrated a significant increase of Fas and FasL expression on the splenocytes from naive mice incubated in vitro with the parasite and on the splenocytes harvested from the infected mice at day 8 after parasite inoculation. Apoptosis of inflammatory cells and cells in ocular tissues was seen, and a greater frequency of CD8⁺ than CD4⁺ T cells was observed in the infected eyes. The intensity of intraocular inflammation was greater in B6-lpr and B6-gld mice than in wild-type B6 mice (P < 0.05). The results suggest that Fas-FasL interaction associated with apoptosis is involved in the pathogenesis of acquired ocular toxoplasmosis in mice.     

Stage-dependent detection of CD14+ and CD16+ cells in the human heart after myocardial infarction

Monocytes are critically involved in cardiovascular wound healing processes. Human monocytes can be classified into two subsets based on the expression of CD14 and CD16. Here, we examined the temporal and spatial distribution of CD14⁺ and CD16⁺ cells after myocardial infarction (MI) in human heart and spleen tissue and correlated it with markers of cardiac repair. Heart samples obtained at autopsy were histologically classified into acute (AMI; n?=?11), subacute (SAMI; n?=?10) and old (OMI; n?=?16) MI, or control myocardium (CONTR; n?=?8). Histochemical analyses revealed marked fibrosis in OMI (p?<?0.001 vs. CONTR). The adhesion molecule CD56 was also strongly expressed in OMI (p?<?0.01 vs. CONTR) and found to correlate with fibrosis (p?<?0.001). The number of capillaries was reduced in OMI (p?<?0.01 vs. CONTR; p?<?0.05 vs. AMI), whereas the hypoxia indicator carbonic anhydrase IX was predominantly expressed in AMI (p?<?0.01 vs. OMI and CONTR) and SAMI (p?<?0.05 vs. OMI and CONTR). The monocyte chemoattractrant osteopontin was also more highly expressed in hearts of SAMI patients (p?<?0.01 vs. CONTR). Numbers of CD14⁺ monocytes were found to correlate with CD16⁺ cells (p?<?0.05) and inversely with fibrosis (p?<?0.05). Regarding a MI-associated release of monocytes from spleen reservoirs, a non-significant reduction of splenic CD14⁺ and CD16⁺ cells was detected in subjects with AMI. In conclusion, disease stage-specific alterations in CD14⁺ and CD16⁺ cells in human heart may contribute to cardiac repair processes following MI.     

Increased serum IL-10 in lupus patients promotes apoptosis of T cell subsets via the caspase 8 pathway initiated by Fas signaling

We sought to investigate the expression of Fas and FasL on T cell surface and caspase 8 involvement in T cell apoptosis promoted by serum IL-10 in systemic lupus erythematosus(SLE) patients.Cells and sera were obtained from 35 SLE patients.Apoptosis of T cells in patients with SLE was increased and associated with the SLE disease activity index(SLEDAI).Elevated expression of Fas and FasL on T cell surface contributed to increased apoptosis of T cells.Increased IL-10 in the sera of SLE patients was capable of inducing Fas and FasL expression on CD4~+T cell surface,promoting apoptosis of this cell subset.Decreased IL-10 serum levels and low expression of Fas were found in 5 patients of the first follow-up group after 2-month treatment.In another group with one-year treatment,the SLEDAI declined to inactive scores.Serum IL-10 was decreased significantly,and expression of Fas and FasL on T cells was also reduced.Declined apoptosis was predominant only in CD4~+T cell subset.When sera with high level of IL-10 were used to culture PBMCs from healthy controls,activated caspase 8 was elevated in CD3~+T,CD4~+T and CD8~+T cells.The study showed that serum IL-10 induced apoptosis of T cell subsets via the caspase8 pathway initiated by Fas signaling.Increased apoptosis of T cells contributes to autoantigen burden,which is pathogenic in the development of SLE.     

Distinct different sensitivity of Treg and Th17 cells to Fas-mediated apoptosis signaling in patients with acute coronary syndrome

Objective: An imbalance in CD4⁺CD25⁺ regulatory T (Treg) cells and Th17 cells has been found to correlate to occurrence of acute coronary syndrome [ACS, including unstable angina (UA) and acute myocardial infarction (AMI)]. However, the mechanisms of Th17/Treg imbalance in ACS patients are still unclear. The purpose of this study is to investigate the possibility of differences in sensitivity of Th17 and Tregs to Fas-mediated apoptosis which could lead to Th17/Treg imbalance in ACS patients. Methods: We examined the apoptosis of Th17 and Treg cells, apoptosis-related Fas/Fas ligand(FasL) pathway, and inflammatory markers in patients with AMI, UA, stable angina (SA) and controls by Flow cytometry and ELISA. Then we analysed the correlation of inflammatory markers and sFasL to Treg apoptosis, and the effect of anti-FasL antibody on Treg apoptois in vitro. Results: Our study demonstrated that apoptotic Tregs, Fas and FasL expression, Caspase-3 activity of Tregs were significantly higher in ACS patients than those in NCA and SA patients (all P < 0.05). The percentage of apoptotic Tregs is positively correlated with the levels of inflammatory markers and sFasL. In vitro incubation of peripheral blood mononuclear cells from ACS patients with anti-FasL antibody resulted in a markedly reduction of apoptotic Treg cells. However, there were no significant differences in apoptotic Th17 cells and in Fas and FasL expression for Th17 cells between the four groups (all P >0.05). Conclusions: Tregs, but not Th17 cells, become apoptotic through Fas/FasL pathway, which contributed to reduction of Tregs leading to an imbalance between Th17 and Treg cells. This could be the mechanism underlying Th17/Treg imbalance and occurrence of ACS.     

Switch from perforin-expressing to perforin-deficient CD8+ T cells accounts for two distinct types of effector cytotoxic T lymphocytes in vivo

Although CD8⁺ cytotoxic T lymphocytes (CTL) exhibit both Fas ligand (FasL) -based and perforin-based lytic activities, the accepted hallmark of a fully active CTL remains its perforin killing machinery. Yet the origin, rationale for possessing both a slow-acting (FasL) and a fast-acting (perforin) killing mechanism has remained enigmatic. Here we have investigated perforin expression in CTL directly involved in acute tumour (i.e. leukaemias EL4 and L1210) allograft rejection occurring within the peritoneal cavity. We show that at the height of the immune response, the majority of conjugate-forming CD8⁺ CTL express high levels of perforin messenger RNA and protein, and kill essentially via perforin. Later however, coinciding with complete rejection, fully cytocidal CTL emerge which exhibit a stark decrease in perforin and now kill preferentially via constitutively expressed FasL. Although late in emergence, and persistent, these powerful CTL are neither effector-memory nor memory CTL. This finding has implications for the monitoring of anti-transplant responses in clinical settings, based on assessing perforin expression in graft infiltrating CD8⁺ T cells. The results show that as the immune response progresses in vivo, targeted cellular suicide mainly prunes high perforin-expressing CD8⁺ cells, resulting in the gradual switch in effector CTL, from mostly perforin-based to largely Fas/FasL-based killers. Hence, two kinds of CD8⁺ CTL have two killing strategies.     

FasL Expression on Human Nucleus Pulposus Cells Contributes to the Immune Privilege of Intervertebral Disc by Interacting with Immunocytes

The mechanisms of immune privilege in human nucleus pulposus (NP) remain unclear. Accumulating evidence indicates that Fas ligand (FasL) might play an important role in the immune privilege of the disc. We aimed for addressing the role of FasL expression in human intervertebral disc degeneration (IDD) and immune privilege in terms of the interaction between NP cells and immunocytes via the FasL-Fas machinery. We collected NP specimens from 20 patients with IDD as degenerative group and 8 normal cadaveric donors as control. FasL expression was detected by qRT-PCR, western blotting and flow cytometry (FCM). We also collected macrophages and CD8⁺ T cells from the peripheral blood of patients with IDD for co-cultures with NP cells. And macrophages and CD8⁺ T cells were harvested for apoptosis analysis by FCM after 2 days of co-cultures. We found that FasL expression in mRNA, protein and cellular resolutions demonstrated a significant decrease in degenerative group compared with normal control (p<0.05). FCM analysis found that human NP cells with increased FasL expression resulted in significantly increased apoptosis ratio of macrophages and CD8⁺ T cells. Our study demonstrated that FasL expression tends to decrease in degenerated discs and FasL plays an important role in human disc immune privilege, which might provide a novel target for the treatment strategies for IDD.     

Role of macrophages in the development of arteritis in MRL strains of mice with a deficit in Fas-mediated apoptosis

The lpr and gld genes have been shown to encode the Fas antigen deletion mutant and the Fas ligand (FasL) mutant, respectively. An MRL strain of mice bearing the gld gene was observed to spontaneously develop granulomatous arteritis, similar to that in mice bearing the lpr gene, indicating that arteritis in this strain is due to an inefficient Fas–FasL interaction resulting in an incapacity for Fas-mediated apoptosis. The arterial lesions in both strains were characterized by a remarkable perivascular accumulation of activated macrophages bearing Mac-2 antigen, following the infiltration of CD4⁺ cells, and this resulted in the destruction of the arterial wall. Almost all of these infiltrating cells were Fas-positive, as determined in MRL/gld mice. Macrophage colony-stimulating factor (M-CSF), which is present at increased levels in MRL/lpr mice, but not in MRL/Mp- +/+ (MRL/+) mice, induced the expression of Mac-2 antigen and Fas antigen on spleen adherent cells of MRL/+ mice. Moreover, continuous infusion of M-CSF into the peritoneal cavity or subcutis of MRL/+ mice induced the release of oxygen radicals of peritoneal macrophages or granuloma formation associated with the massive accumulation of Mac-2+ cells, respectively. These findings suggest that macrophages in these mice, which may be activated by M-CSF and may avoid Fas-mediated apoptosis, play a critical role as effector cells in the destruction of arterial wall.     

Activated cytotoxic lymphocytes promote tumor progression by increasing the ability of 3LL tumor cells to mediate MDSC chemoattraction via Fas signaling

The Fas/FasL system transmits intracellular apoptotic signaling, inducing cell apoptosis. However, Fas signaling also exerts non-apoptotic functions in addition to inducing tumor cell apoptosis. For example, Fas signaling induces lung cancer tumor cells to produce prostaglandin E2 (PGE2) and recruit myeloid-derived suppressor cells (MDSCs). Activated cytotoxic T lymphocytes (CTLs) induce and express high levels of FasL, but the effects of Fas activation initiated by FasL in CTLs on apoptosis-resistant tumor cells remain largely unclear. We purified activated CD8⁺ T cells from OT-1 mice, evaluated the regulatory effects of Fas activation on tumor cell escape and investigated the relevant mechanisms. We found that CTLs induced tumor cells to secrete PGE2 and increase tumor cell-mediated chemoattraction of MDSCs via Fas signaling, which was favorable to tumor growth. Our results indicate that CTLs may participate in the tumor immune evasion process. To the best of our knowledge, this is a novel mechanism by which CTLs play a role in tumor escape. Our findings implicate a strategy to enhance the antitumor immune response via reduction of negative immune responses to tumors promoted by CTLs through Fas signaling.     

Increased Fas antigen expression in murine retrovirus-induced immunodeficiency syndrome,MAIDS

The Fas antigen (Fas), which is a cell surface protein belonging to the tumor necrosis factor receptor family, mediates apoptosis. To assess the contribution of Fas to the pathogenesis of retrovirus-induced immunodeficiency, we examined the kinetics of Fas expression on the lymphocytes during the course of murine acquired immunodeficiency syndrome (MAIDS) induced by a defective LP-BM5 murine leukemia virus. The Fas-positive cells were increased in proportion both in αβ T cells and B cells with the progression of MAIDS. The appearance of Fas-positive cells in αβ T cells preceeded those in B cells during the course of MAIDS. Among αβ T cells, about half of the Thy1.2⁺ αβ T cells were positive for Fas, while almost all of Thy1.2^? CD4⁺ αβ T cells were of the Fas-positive phenotype. The Fas-positive cells in MAIDS mice, especially unique Thy1.2^?CD4⁺ αβ T cells, were easily rendered apoptotic by stimulation via Fas, indicating that Fas expressed on the lymphocytes is functional. Furthermore, concomitant infection with Mycobacterium avium in MAIDS mice caused a marked increase in Fas-positive cells accompanied by a severely impaired T cell reactivity to polyclonal stimuli. Taken together, these results suggest the possible participation of the Fas system in the pathogenesis of retrovirus-induced immunodeficiency.     

Involvement of the Fas (CD95) system in peripheral cell death and lymphoid organ development

Fas-mediated apoptosis is a form of cell death that operates through a Fas-Fas ligand (FasL) interaction. In this study we investigated the role of the Fas system during development of normal and Fas-mutated lymphocytes. Irradiated RAG2^–/– recipients were reconstituted with bone marrow cells from B6 and lpr mice (Fas defective) or from B6 and gld mice (FasL defective), and analyzed for long-term development. The results showed a primary role of the Fas system in peripheral cell death and thymic colonization. In the periphery, the interaction in vivo between Fas⁺ and Fas^– T cell populations indicated that cellular homeostasis was defective. Indeed, we observed a FasL-mediated cytotoxic effect on normal-derived T cells, explaining the dominance of lpr T cells in the mixed chimeras. The Fas mutation affected neither cell activation nor cell proliferation, as the effector (Fas^–) and target (Fas⁺) cells behaved similarly with regard to activation marker expression and cell cycle status. However, Fas^– T cells failed to seed the periphery and the thymus in the long term. We suggest that this could be due to the fact that FasL is involved in the structural organization of the lymphoid compartment.     

Protective effect of low-molecular-weight heparin on pancreatic encephalopathy in severe acute pancreatic rats

Background and aims

Pancreatic encephalopathy (PE) is a severe complication and significant cause of death in patients with severe acute pancreatitis (SAP). We have reported previously that low-molecular-weight heparin (LMWH) treatment could reduce incidence of PE in SAP patients. Our objective here was to investigate the protective effect of LMWH and its mechanism on PE in SAP rats.

Methods

SD rats were randomly divided into three groups: (1) Sham-operation (S) group, (2) SAP group, and (3) LMWH treatment (LMWH) group. LMWH was administrated 4?h after the SAP model conducted. The levels of serum amylase, myelin basic protein (MBP), tumor necrosis factor-alpha (TNF-α), interleukin 6 (IL-6), brain water content, occurrence of apoptosis, and pathological changes of pancreas and brain were measured at 1?day after models were set up in the SAP and S groups, and 1?day after LMWH treatment was administrated in the LMWH group.

Results

(1) The levels of serum amylase, TNF-α, and IL-6 in the SAP group were increased significantly more than those in the S and LMWH groups (all P?<?0.001), as were the levels of serum MBP in the SAP group compared to those in the S and LMWH groups (P?<?0.01, <0.05 respectively). However, while the level of serum amylase and IL-6 in the LMWH group were significantly increased compared to those in the S group (P?<?0.05, <0.001 respectively), the levels of TNF-α and MBP showed no significant difference between the LMWH and S groups (all P?>?0.05). (2) The brain water content in the SAP group was significantly increased compared to the S group and LMWH group (P?<?0.01, <0.05 respectively). (3) Neuronal apoptosis, demyelination, and mitochondrial vacuolation in neuronal cells were observed in the SAP group; in contrast, in the LMWH group, significantly lower rates of neuronal apoptosis, demyelination and mitochondrial edema were observed in neuronal cells.

Conclusions

The protective effect of LMWH on PE progression in SAP rats might result from inhibition of inflammatory activation and reduction of the occurrence of neuronal apoptosis.     

The effect of turtle (Trachemys scripta elegans) shell extract in normal and cyclophosphamide-treated mice

In the present study, the immune effect of turtle shell extract on normal and cyclophosphamide (CP)-treated mice was determined. Mice treated with the turtle shell extract and CP had significantly (p<0.05) elevated levels of serum IgG, ATL, ATS and CREA compared with CP-treated mice. The turtle shell extract-treated mice had significantly elevated serum IgG (p<0.001), reduced serum CREA level (p<0.05), but the serum ATL, ATS and BUN did not change significantly compared with normal mice. Treatment with the turtle shell extract significantly improved the CD3⁺, CD4⁺CD8^?, CD4^?CD8⁺ and CD4⁺CD8⁺ cells percentages (p<0.05) in normal mice, and also significantly improved CD3⁺ and CD4⁺CD8^? cells percentages in CP-treated mice (p<0.05). There was significant difference (p<0.001) in the proliferation rate of PHA-stimulated spleen lymphocyte in vitro between the turtle shell extract + CP-treated mice and CP-treated mice, and also between the turtle shell extract-treated mice and normal mice (p<0.05). These results demonstrate that the turtle shell extract can up-regulate the immune states of normal and CP-treated mice, and shows some protective effect on liver and kidney damage in CP-induced mice.     

Effect of Transgenic Overexpression of FLIP on Lymphocytes on Development and Resolution of Experimental Autoimmune Thyroiditis

In our previous studies, resolution of granulomatous experimental autoimmune thyroiditis (G-EAT) was promoted when thyroid epithelial cells were protected from Fas-mediated apoptosis due to transgenic overexpression of FLIP. We hypothesized that if FLIP were overexpressed on lymphocytes, CD4⁺ effector cells would be protected from Fas-mediated apoptosis, and resolution would be delayed. To test this hypothesis, we generated transgenic (Tg) mice overexpressing FLIP under the CD2 promoter. Transgenic FLIP was expressed on CD4⁺ and CD8⁺ T cells and B cells. Transgenic overexpression of FLIP protected cultured splenocytes from Fas-mediated, but not irradiation-induced, apoptosis in vitro. Unexpectedly, Tg⁺ donor cells transferred minimal G-EAT, which was partially overcome by depleting donor CD8⁺ T cells. When Tg⁺ and Tg⁻ donors transferred equivalent disease, G-EAT resolution was delayed in FLIP transgenic mice. However, CD2-FLIP Tg⁺ donors often transferred less severe G-EAT, even after depletion of CD8⁺ T cells. This influenced the rate of G-EAT resolution, resulting in little difference in G-EAT resolution between groups. Tg⁺ mice always had reduced anti-mouse thyroglobulin autoantibody responses, compared with Tg⁻ littermates, presumably because of FLIP overexpression on B cells. These results suggest that effects of transgenic FLIP on a particular autoimmune disease vary, depending on what cells express the transgene and whether those cells are effector cells or if they function to modulate disease.Experimental autoimmune thyroiditis (EAT) is a chronic inflammatory autoimmune disease that can be induced in genetically susceptible strains of mice by injecting mouse thyroglobulin (MTg) and adjuvant^1,2 or by transferring MTg-primed donor spleen cells activated with MTg in vitro.^2,3 A severe granulomatous form of EAT (G-EAT) is induced when MTg-sensitized donor spleen cells are activated in vitro with MTg and IL-12^4,5 or with MTg and IL-23 (unpublished data). Thyroid lesions in G-EAT are characterized by infiltration of inflammatory cells and destruction of thyroid epithelial cells.^4–7 DBA/1 and CBA/J mice, used in most G-EAT experiments in our laboratory, develop severe G-EAT when donor cells are activated with MTg and IL-12.^3–7 Thyroid lesions reach maximal severity 20 days after cell transfer, and inflammation either resolves or progresses to fibrosis at day 50 to day 60, depending on the extent of damage at day 20.^3–7 DBA/1 recipients typically develop very severe thyroid lesions (5+ severity score) by day 20, with few or no remaining intact follicles, and inflammation and fibrosis persist 60 days after cell transfer.^4–7 CBA/J recipients also develop very severe G-EAT, but there are usually some intact thyroid follicles, less neutrophil infiltration, and less fibrosis at day 20, compared with lesions in DBA/1 mice. Thyroid lesions in CBA/J mice usually resolve by 50 to 60 days after cell transfer.⁸ CD4⁺ T cells are the primary effector cells for G-EAT.⁴The Fas/FasL apoptotic pathway plays an important role in many human and murine autoimmune diseases, including Graves'' disease, Hashimoto''s thyroiditis, and EAT or G-EAT in mice.^9–17 The anti-apoptotic molecule FLIP (FLICE inhibitory protein FLIP; FLICE is the Fas-associated death domain-like IL-1β-converting enzyme) inhibits Fas-mediated apoptosis by blocking activation of caspase-8.^18,19 The Fas/FasL pathway can function to both induce autoimmune damage^13,14 and reduce autoimmune responses.^11,12,17Our previous studies showed that resolution of G-EAT involves apoptosis of CD4⁺ effector cells mediated, at least in part, through the Fas/FasL pathway by FasL expressing thyrocytes.¹⁷ Expression of transgenic FLIP on thyroid epithelial cells promotes earlier resolution of G-EAT by protecting thyroid epithelial cells from Fas-mediated apoptosis.^20,21 Because CD4⁺ T cells are the primary effector cells for G-EAT, we hypothesized that if transgenic FLIP were expressed on lymphocytes, CD4⁺ effectors would be protected from Fas-mediated apoptosis, and resolution would be inhibited, resulting in chronic inflammation. Transgenic (Tg) mice overexpressing FLIP under the CD2 promoter were generated to test this hypothesis.     

Apoptosis in labial salivary glands from Sjögren's syndrome (SS) patients: comparison with human T lymphotropic virus-I (HTLV-I)-seronegative and -seropositive SS patients

Apoptosis is a type of cell death that occurs during morphogenesis and development of the immune system. One of the mechanisms is mediated through the Fas and Fas ligand (FasL) pathway. To determine the possible involvement of Fas and its ligand in salivary gland destruction, we analysed the appearance of nuclei with DNA fragmentation by using nick end labelling (TUNEL) and the expression of Fas and FasL by immunohistochemistry in labial salivary glands. Furthermore, we compared the features of apoptosis in labial salivary glands between HTLV-I^? and HTLV-I⁺ SS. When the frozen sections of 10 primary SS patients in the absence of anti-HTLV-I antibody were examined, several apoptotic cells were found in the acinar and ductal epithelial cells as well as infiltrated mononuclear cells. Both Fas and FasL were detected in the infiltrated mononuclear cells. Acinar epithelial cells, which are surrounded by FasL⁺ mononuclear cells, were also double-positive with Fas and FasL, although the expression of FasL was localized at their apical border, suggesting that apoptosis of mononuclear cells was achieved by activation-induced mechanisms through Fas/FasL pathways, and that of acinar epithelial cells was mediated by FasL derived from either acinar epithelial cells themselves or infiltrated mononuclear cells. Interestingly, Fas expression in ductal epithelial cells was localized around the lumen side of the ducts, indicating that FasL secreted from acinar epithelial cells may induce Fas-mediated apoptosis of ductal epithelial cells. We also studied the labial salivary glands from nine SS patients with anti-HTLV-I antibodies. There was no significant difference in the occurrence of apoptotic cells or in the expression of Fas and FasL between HTLV-I⁺ and HTLV-I^? SS patients. It was of note that neither the expression of Fas and FasL nor the presence of apoptotic cells were determined in labial salivary glands from subjects without SS. These findings indicate that Fas-mediated apoptosis in salivary glands could be involved in the pathological manifestations of SS, irrespective of HTLV-I seropositivity.     

TcR-α/β CD4CD8 T Cells in Humans with the Autoimmune Lymphoproliferative Syndrome Express a Novel CD45 Isoform That Is Analogous to Murine B220 and Represents a Marker of Altered O-Glycan Biosynthesis

Autoimmune lymphoproliferative syndrome (ALPS), caused by inherited defects in apoptosis secondary to mutations in genes encoding Fas/CD95/APO-1 and Fas ligand (Fasl)/CD95L, is characterized by nonmalignant lymphadenopathy and splenomegaly, increased T cell receptor α/β⁺ CD4⁻CD8⁻ T cells (α/β⁺ double-negative T cells [α/β⁺-DNT cells]), autoimmunity, hypergammaglobulinemia, and cytokine abnormalities. The α/β⁺-DNT cells are immunophenotypically and functionally similar to α/β⁺-DNT cells that accumulate in lpr and gld mice, which bear genetic mutations in Fas and FasL. In these mice, α/β⁺-DNT cells express the B-cell-specific CD45R isoform B220. We show that α/β⁺-DNT cells of ALPS patients, with either Fas or FasL mutations, also express B220. In addition, also similar to LPR/gLD mice, they have an unusual population of B220-positive CD4⁺ T cells. B220 expression, together with our finding of characteristic lectin binding profiles, demonstrates that cell surface O-linked glycoproteins have undergone specific modifications, which may have consequences for lymphocyte trafficking, cell–cell interactions, and access to alternative apoptosis pathways.     

Alteration of T cell subtypes in spleen and antibodies of serum in mice infected with Angiostrongylus cantonensis

The immune responses of Angiostrongylus cantonensis infection are closely relevant to the host’s self-protection and the nematode’s pathogenesis. In the present study, BALB/c mice were randomly divided into uninfected control group, infection group 1, and infection group 2. The infection group 1 and infection group 2 were infected with 20 and 40 third-stage larvae of A. cantonensis per mouse, respectively. The splenocytes from the mice were collected and cultured on the 19th and 25th days post-infection; the subtypes of T cells in splenocytes were detected by flow cytometry with fluorescence staining method, and the cytokines in cultured supernatants of splenocytes were assayed by the method of ELISA. The specific IgG and IgE antibodies in sera of the mice were periodically detected by ELISA. The results showed that the percentages of CD4⁺ and CD4⁺ IL-4⁺ T cells in splenocytes of infected mice were much higher (P?<?0.05) than those in control mice; however, the percentages of CD4⁺ IL-17⁺ and CD4⁺ IFN-γ⁺ T cell were much lower(P?<?0.01) after the infection. The levels of CD8⁺ T cells in infected mice also rose, but differences between control mice and infected mice were not significant. In comparison with control mice, the concentration of IL-4 in the cultured supernatants of splenocytes in infected mice increased significantly (P?<?0.05), but that of IL-17 decreased significantly (P?<?0.01). In addition, the number of larvae infected and days after infection may influence levels of the T cell subtypes and the cytokines in spleen, too (P?>?0.05). On humoral immunity, the levels of specific IgG antibodies in sera rose a bit at the fifth day post-infection, and reached a peak at the 20th day post-infection; the specific IgE antibodies gradually heightened during first 10 days post-infection; then, it showed a downward trend during the 15th to 25th days post-infection. It is evident that the percentages of CD4⁺ T lymphocytes of spleen in the mice infected with A. cantonensis markedly increase and polarize to Th2 phenotypes, and the function of Th17 cells is inhibited. In addition, the elevation of specific IgG antibodies in sera of the infected mice is more significant than that of specific IgE antibodies.     

Cartilage-Hair Hypoplasia Syndrome: Increased Apoptosis of T Lymphocytes Is Associated with Altered Expression of Fas (CD95), FasL (CD95L), IAP,Bax, and Bcl2

Cartilage-hair hypoplasia (CHH) is a rare autosomal recessive short-limbed dwarfism associated with thin and sparse hair and cell mediated or combined immunodeficiency. However, the basis of immune deficiency in CHH is unclear. In this study, we investigated a role of apoptosis in immunodeficiency in a patient with CHH. An increased apoptosis of both CD4⁺ and CD8⁺ T cells, as determined by TUNEL assay, was observed in CHH compared to an age-matched healthy dwarf control. Increased apoptosis in CHH was associated with increased expression of Fas (CD95), CD95L, and Bax and decreased expression of Bcl-2 and inhibitor of apoptosis protein (IAP) compared to the control. These data suggest that lymphopenia and immunodeficiency in CHH may be, at least in part, due to increased apoptosis of T cells, possibly through the Fas/ FasL signaling pathway.