The roles of macrophage migration inhibitory factor in retinal diseases

Macrophage migration inhibitory factor(MIF),a multifunctional cytokine,is secreted by various cells and participates in inflammatory reactions,including innate and adaptive immunity.There are some evidences that MIF is involved in many vitreoretinal diseases.For example,MIF can exacerbate many types of uveitis;measurements of MIF levels can be used to monitor the effectiveness of uveitis treatment.MIF also alleviates trauma-induced and glaucoma-induced optic nerve damage.Furthermore,MIF is critical for retinal/choroidal neovascularization,especially complex neovascularization.MIF exacerbates retinal degeneration;thus,anti-MIF therapy may help to mitigate retinal degeneration.MIF protects uveal melanoma from attacks by natural killer cells.The mechanism underlying the effects of MIF in these diseases has been demonstrated:it binds to cluster of differentiation 74,inhibits the c-Jun N-terminal kinase pathway,and triggers mitogen-activated protein kinases,extracellular signal-regulated kinase-1/2,and the phosphoinositide-3-kinase/Akt pathway.MIF also upregulates Toll-like receptor 4 and activates the nuclear factor kappa-B signaling pathway.This review focuses on the structure and function of MIF and its receptors,including the effects of MIF on uveal inflammation,retinal degeneration,optic neuropathy,retinal/choroidal neovascularization,and uveal melanoma.

CD74 and macrophage migration inhibitory factor as therapeutic targets in gastric cancer

AIM:To investigate the relationship and molecular features of CD74/macrophage migration inhibitory factor(MIF)/Toll-like receptor 4(TLR4) in gastric cancer.METHODS:CD74,MIF and TLR4 expression in the paraffin-embedded sections of gastric cancer from 120 patients were detected by immunohistochemical staining.Knock down of CD74 expression in gastric cancer cell line MKN-45 was performed by lentivirus transduction and detected by Western blotting.MKN-45 cell proliferation assay under the stimulants was measured by the cell counting kit 8(CCK8) assay and MIF concentration in the culture medium was detected by enzymelinked immunosorbent assay.Surface staining of CD74 in the MKN-45 cell line under the stimulation of lipopolysaccharide(LPS) was measured by flow cytometry.MIF,CD74 and TLR4 co-localization in the MKN-45 cell line was performed by the immunoprecipitation.RESULTS:CD74,MIF and TLR4 were found to be expressed in gastric cancer and increased significantly in the advanced stage,and were also associated with lymph node metastasis.Correlation analysis revealed that CD74 was positively correlated with MIF(r = 0.2367,P < 0.01) and both proteins were also associated with TLR4(r = 0.4414,r = 0.5001,respectively,P < 0.01).LPS can significantly promote MKN-45 cell proliferation(3.027 ± 0.388 vs 4.201 ± 0.092,P < 0.05),induce MIF production(54.333 ± 2.906 pg/mL vs 29.667 ± 3.180 pg/mL,P < 0.01) and cell surface expression of CD74(75.6% ± 4.046%vs 9.4% ± 0.964%,P < 0.01) at LPS concentration of 1 μg/mL compared to medium control.Knockdown of CD74 or using antiCD74 and MIF antagonist ISO-1 significantly reduced LPS-induced MKN-45 cell proliferation(4.201 ± 0.092 vs 3.337 ± 0.087,4.534 ± 0.222 vs 3.368 ± 0.290,4.058 ± 0.292vs 2.934 ± 0.197,respectively,P < 0.01).MIF,CD74 and TLR4 could co-localize in the MKN-45 cell line.CONCLUSION:Upregulation of MIF,CD74 and TLR4 are associated with increasing clinical stage and provide an opportunity as novel gastric cancer chemoprevention and/or treatment strategy.

Novel SLA class I alleles of Chinese pig strains and their significance in xenotransplantation

To lay background for studying rejection mechanisms in xenotransplantation and developing the strategies for intervention, class I genes of swine leukocyte antigens (SLA) of three Chinese pig strains Bm, Gz and Yn were cloned and sequenced. The cDNA of the class I loci P1 and P14 were amplified by RT-PCR and subjected to insert into sequencing vectors. All six allelic sequences we examined, each two for one Chinese strain, are not identical to those reported, which allows these novel sequences receiving their accession numbers AY102467- AY102472 from GenBank. This study further reveals that the homologies of MHC class I genes in their primary structures and the deduced amino acids between Chinese pigs (SLA) and human (HLA-A*0201) are better than those between pigs and mice (H-2Db/H-2Kb). The comparison also indicates that the amino acid residues critical for recognition by human KIRs are altered in the swine class I molecules. The amino acids responsible for binding human CD8 coreceptor are largely conserved although there are two critical residues substituted. A functional test indicated that the human T cells specific for the prokaryotically expressed SLA Plprotein could respond quite well in vitro to the class I-positive swine chon-drocytes and PBMCs in presence of human APCs. This implies that, due to the substitution of two critical residues, the inaccessibility of human CD8 coreceptor to swine class I molecule might be contributable to the indirect pathway that the human T cells have to use for recognizing the SLA class I xenogeneic antigens.

Distribution of paired immunoglobulin-like receptor B in the nervous system related to regeneration difficulties after unilateral lumbar spinal cord injury

Paired immunoglobulin-like receptor B（Pir B） is a functional receptor of myelin-associated inhibitors for axonal regeneration and synaptic plasticity in the central nervous system, and thus suppresses nerve regeneration. The regulatory effect of Pir B on injured nerves has received a lot of attention. To better understand nerve regeneration inability after spinal cord injury, this study aimed to investigate the distribution of Pir B（via immunofluorescence） in the central nervous system and peripheral nervous system 10 days after injury. Immunoreactivity for Pir B increased in the dorsal root ganglia, sciatic nerves, and spinal cord segments. In the dorsal root ganglia and sciatic nerves, Pir B was mainly distributed along neuronal and axonal membranes. Pir B was found to exhibit a diffuse, intricate distribution in the dorsal and ventral regions. Immunoreactivity for Pir B was enhanced in some cortical neurons located in the bilateral precentral gyri. Overall, the findings suggest a pattern of Pir B immunoreactivity in the nervous system after unilateral spinal transection injury, and also indicate that Pir B may suppress repair after injury.

BTLA,a New Inhibitory B7 Family Receptor with a TNFR Family Ligand

B and T lymphocyte attenuator （BTLA）, identified as an immune inhibitory receptor recently, plays widespread roles on T and B cells. Emerging evidence has generated plentiful information on the mechanisms which BTLA mediates negative regulation in immune responses and involves in a variety of physiological and pathological processes. The exploration of the biological mechanisms and regulation of BTLA will open possibilities on novel therapeutic strategies in immune-related diseases. Cellular ＆ Molecular Immunology. 2005;2（6）：427-432.

Glycogen synthase kinase 3 controls T-cell exhaustion by regulating NFAT activation

Cellular immunity mediated by CD8+T cells plays an indispensable role in bacterial and viral clearance and cancers.However,persistent antigen stimulation of CD8+T cells leads to an exhausted or dysfunctional cellular state characterized by the loss of effector function and high expression of inhibitory receptors during chronic viral infection and in tumors.Numerous studies have shown that glycogen synthase kinase 3(GSK3)controls the function and development of immune cells,but whether GSK3 affects CD8+T cells is not clearly elucidated.Here,we demonstrate that mice with deletion of Gsk3αand Gsk3βin activated CD8+T cells(DKO)exhibited decreased CTL differentiation and effector function during acute and chronic viral infection.In addition,DKO mice failed to control tumor growth due to the upregulated expression of inhibitory receptors and augmented T-cell exhaustion in tumor-infiltrating CD8+T cells.Strikingly,anti-PD-1 immunotherapy substantially restored tumor rejection in DKO mice.Mechanistically,GSK3 regulates T-cell exhaustion by suppressing TCR-induced nuclear import of NFAT,thereby in turn dampening NFAT-mediated exhaustion-related gene expression,including TOX/TOX2 and PD-1.Thus,we uncovered the molecular mechanisms underlying GSK3 regulation of CTL differentiation and T-cell exhaustion in anti-tumor immune responses.

NK cell receptor imbalance and NK cell dysfunction in HBV nfection and hepatocellular carcinoma

Hepatocellular carcinoma （HCC） is currently the third leading cause of cancer mortality and a common poor-prognosis malignancy due to postoperative recurrence and metastasis. There is a significant correlation between chronic hepatitis B virus （HBV） infection and hepatocarcinogenesis. As the first line of host defense against viral infections and tumors, natural killer （NK） cells express a large number of immune recognition receptors （NK receptors （NKRs）） to recognize ligands on hepatocytes, liver sinusoidal endothelial cells, stellate cells and Kupffer cells, which maintain the balance between immune response and immune tolerance of NK cells. Unfortunately, the percentage and absolute number of liver NK cells decrease significantly during the development and progression of HCC. The abnormal expression of NK cell receptors and dysfunction of liver NK cells contribute to the progression of chronic HBV infection and HCC and are significantly associated with poor prognosis for liver cancer. In this review, we focus on the role of NK cell receptors in anti-tumor immune responses in HCC, particularly HBV-related HCC. We discuss specifically how tumor cells evade attack from NK cells and how emerging understanding of NKRs may aid the development of novel treatments for HCC. Novel mono- and combination therapeutic strategies that target the NK cell receptor-ligand system may potentially lead to successful and effective immunotherapy in HCC.

Exhaustion and senescence: two crucial dysfunctional states of T cells in the tumor microenvironment

The failure of a massive influx of tumor-infiltrating T lymphocytes to eradicate tumor cells in the tumor microenvironment is mainly due to the dysfunction of T cells hyporesponsive to tumors.T-cell exhaustion and senescence induced by malignant tumors are two important dysfunctional states that coexist in cancer patients,hindering effective antitumor immunity and immunotherapy and sustaining the suppressive tumor microenvironment.Although exhausted and senescent T cells share a similar dysfunctional role in antitumor immunity,they are distinctly different in terms of generation,development,and metabolic and molecular regulation during tumor progression.Here,we discuss the unique phenotypic and functional characteristics of these two types of dysfunctional T cells and their roles in tumor development and progression.In addition,we further discuss the potential molecular and metabolic signaling pathways responsible for the control of T-cell exhaustion and senescence in the suppressive tumor microenvironment.Understanding these critical and fundamental features should facilitate rethinking the unresponsiveness to current immunotherapies in clinical patients and lead to further development of novel and effective strategies that target different types of dysfunctional T cells to enhance cancer immunotherapy.

LILRB4, an immune checkpoint on myeloid cells

Leukocyte immunoglobulin-like receptor B4(LILRB4)is an inhibitory receptor in the LILR family mainly expressed on normal and malignant human cells of myeloid origin.By binding to ligands,LILRB4 is activated and subsequently recruits adaptors to cytoplasmic immunoreceptor tyrosine inhibitory motifs to initiate different signaling cascades,thus playing an important role in physiological and pathological conditions,including autoimmune diseases,microbial infections,and cancers.In normal myeloid cells,LILRB4 regulates intrinsic cell activation and differentiation.In disease-associated or malignant myeloid cells,LILRB4 is significantly correlated with disease severity or patient survival and suppresses T cells,thereby participating in the pathogenesis of various diseases.In summary,LILRB4 functions as an immune checkpoint on myeloid cells and may be a promising therapeutic target for various human immune diseases,especially for cancer immunotherapy.

The number and cytotoxicity and the expression of cytotoxicity-related molecules in peripheral natural killer(NK)cells do not predict the repeated implantation failure(RIF)for the in vitro fertilization patients

Natural killer(NK)cells are thought to play a key role in the successful establishment of a pregnancy by facilitating immunological adaptation of the semi-allogeneic developing embryo.The aim of this study was to explore the cell number,immunophenotypic characteristics,and activities of peripheral blood NK cells in women with repeated implantation failure(RIF).Peripheral blood was obtained from 27 women with RIF and 11 healthy,fertile controls during the middle luteal phase of the menstrual cycle.CD3^-CD56^+NK cells were quantified and analyzed by flow cytometry for the expression of cytolytic molecules(granzyme B,granulysin,and perforin)as well as cell surface receptors responsible for NK cell activation or inhibition(NKG2D,NKp30,NKp46,CD158a,CD158b).NK cytotoxicity was measured at three effector-to-target cell ratios.Women with RIF and fertile controls did not differ significantly in the percentage of circulating CD3CD56t NK cells,or in the proportions of these cells that expressed granzyme B,granulysin,or perforin.The two groups also did not differ significantly in the proportions of NK cells expressing the receptors NKG2D,NKp30,NKp46,CD158a or CD158b.General linear model analysis showed that NK cytotoxicity increased with effector-to-target cell ratio.However,NK cytotoxicity did not differ significantly between patients with RIF and fertile controls.These results suggest that RIF is not associated with significant alterations in the number or function of peripheral blood NK cells.