Efficacy and safety of mirror therapy for post-stroke aphasia: A systematic review and meta-analysis protocol.

BACKGROUND: Aphasia is one of the most common complications of stroke. Mirror therapy (MT) is promising rehabilitation measure for the treatment of post-stroke aphasia. Although some studies suggested that MT is effective and safe for aphasia, the effects and safety remain uncertain due to lacking strong evidence, such as the relevant systematic review and meta- analysis. METHODS: This study will search PubMed, Web of Science, Cochrane Library, EMBASE, Medline, China Knowledge Network (CNKI), WANFANG, China Biomedical Literature Database (CBM), from inception to 1th May 2023 to identify any eligible study. No language or date of publication shall be limited. We will only include randomised controlled trials of MT in the Treatment of poststroke aphasia. Two investigators will work separately on the study selection, data extraction, and study quality assessment. The western aphasia battery (WAB) and aphasia quotient (AQ) will be included as the main outcomes. Boston diagnostic aphasia examination method (BDAE), Chinese standard aphasia examination (CRRCAE) will be included as the secondary outcomes. The statistical analysis will be conducted by RevMan V.5.4 software. The risk of bias of included studies will be assessed by the Cochrane 'Risk of bias' tool. The quality of proof of the results will be evaluated by using the Grading of Recommendations Assessment, Development and Evaluation guidelines. RESULTS: The finding will be presented in a journal or related conferences. CONCLUSION: This study will provide a basis for whether mirror therapy (MT) is effective and safe in the treatment of post-stroke aphasia. TRIAL REGISTRATION: Systematic review registration INPLASY registration number: INPLASY 202340054.

Age-different BMSCs-derived exosomes accelerate tendon-bone interface healing in rotator cuff tears model.

BACKGROUND: Rotator cuff tears (RCTs) are culprit of shoulder pain and dysfunction. Tendon-bone interface (TBI) mal-healing is an essential contributor to retear after RCTs. Consequently, present project was conducted to investigate the role of bone marrow mesenchymal stem cells (BMSCs)-derived exosomes on TBI healing. METHOD: Young BMSCs (Y-BMSCs) and Aged BMSCs (A-BMSCs) were isolated from Young (3-month-old) and old (24-month-old) SD rats, and their-derived exosomes (A-BMSCs-exo and Y-BMSCs-exo) were identified. RCTs model was established, and A-BMSCs-exo and Y-BMSCs-exo were injected at the rotator cuff using hydrogel as a vehicle. Pathological changes of TBI were observed by HE, Sirius Red and Oil Red O staining. Western blotting and RT-qPCR were applied to assess the expression of extracellular matrix (ECM)-, tendon cell (TCs)-, osteogenic-, tendon-derived stem cell (TDSCs)- and angiogenic-associated proteins and mRNAs in TBI. RESULT: Y-BMSCs exhibited increased activity, osteogenic and lipogenic abilities than A-BMSCs. After A-BMSCs-exo and Y-BMSCs-exo treatment, TBI displayed massive sharpey's fibers growing along the tendon longitudinally, and a collagen fiber-chondrocyte migration zone forming a typical tendon-noncalcified fibrocartilage-calcified fibrocartilage-bone structure. A-BMSCs-exo and Y-BMSCs-exo significantly upregulated the expression of collagen Col I/II/III, Aggrecan, TNMD, SCX, Runx2, OPN, CD45, Sox2, CD31 and VEGFR2 in TBI. In vitro, A-BMSCs-exo and Y-BMSCs-exo significantly enhanced the activity of TCs and TDSCs, TDSCs stemness, and reduced the osteogenic and lipogenic capacity of TDSCs. The effect of Y-BMSCs-exo was significantly stronger than that of A-BMSCs-exo. CONCLUSION: BMSCs-derived exosomes facilitate ECM remodeling, osteogenic differentiation, angiogenesis, and stemness of TDSCs, thereby accelerating TBI healing in RCTs, with better outcomes using young individual-derived BMSCs.

First-in-human phase I/Ib study of QL1706 (PSB205), a bifunctional PD1/CTLA4 dual blocker, in patients with advanced solid tumors.

BACKGROUND: QL1706 (PSB205) is a single bifunctional MabPair (a novel technical platform) product consisting of two engineered monoclonal antibodies (anti-PD-1 IgG4 and anti-CTLA-4 IgG1), with a shorter elimination half-life (t1/2) for CTLA-4. We report results from a phase I/Ib study of QL1706 in patients with advanced solid tumors who failed standard therapies. METHODS: In the phase I study, QL1706 was administered intravenously once every 3 weeks at one of five doses ranging from 0.3 to 10 mg/kg, and the maximum tolerated dose, recommended phase 2 dose (RP2D), safety, pharmacokinetics (PK), and pharmacodynamics (PD) of QL1706 were investigated. In the phase Ib study, QL1706 was administered at the RP2D intravenously every 3 weeks, and the preliminary efficacies in non-small cell lung cancer (NSCLC), nasopharyngeal carcinoma (NPC), cervical cancer (CC), and other solid tumors were evaluated. RESULTS: Between March 2020 and July 2021, 518 patients with advanced solid tumors were enrolled (phase I, n = 99; phase Ib, n = 419). For all patients, the three most common treatment-related adverse events (TRAEs) were rash (19.7%), hypothyroidism (13.5%), and pruritus (13.3%). The TRAEs and immune-related adverse events (irAEs) of grade ≥ 3 occurred in 16.0% and 8.1% of patients, respectively. In phase I, 2 of 6 patients in the 10mg/kg group experienced dose-limiting toxicities (DLTs) (grade 3 thrombocytopenia and grade 4 immune-mediated nephritis), so the maximum tolerated dose (MTD) was reached at 10 mg/kg. The RP2D was determined to be 5 mg/kg based on comprehensive analysis of tolerability, PK/PD, and efficacy. For all patients who received QL1706 at the RP2D, the objective response rate (ORR) and median duration of response were 16.9% (79/468) and 11.7 months (8.3-not reached [NR]), respectively; and the ORRs were 14.0% (17/121) in NSCLC, 24.5% (27/110) in NPC, 27.3% (15/55) in CC, 7.4% (2/27) in colorectal cancer, 23.1% (6/26) in small cell lung cancer. For immunotherapy-naive patients, QL1706 exhibited promising antitumor activities, especially in NSCLC, NPC, and CC, with ORRs of 24.2%, 38.7%, and 28.3%, respectively. CONCLUSIONS: QL1706 was well tolerated and demonstrated promising antitumor activity in solid tumors, especially in NSCLC, NPC, and CC patients. It is currently being evaluated in randomized phase II (NCT05576272, NCT05179317) and phase III (NCT05446883, NCT05487391) trials. Trial Registration ClinicalTrials.gov Identifier: NCT04296994 and NCT05171790.

Complement Deficiencies Result in Surrogate Pathways of Complement Activation in Novel Polygenic Lupus-like Models of Kidney Injury.

Lupus nephritis (LN) is a major contributor to morbidity and mortality in lupus patients, but the mechanisms of kidney damage remain unclear. In this study, we introduce, to our knowledge, novel models of LN designed to resemble the polygenic nature of human lupus by embodying three key genetic alterations: the Sle1 interval leading to anti-chromatin autoantibodies; Mfge8-/- , leading to defective clearance of apoptotic cells; and either C1q-/- or C3-/- , leading to low complement levels. We report that proliferative glomerulonephritis arose only in the presence of all three abnormalities (i.e., in Sle1.Mfge8 -/- C1q -/- and Sle1.Mfge8 -/- C3 -/- triple-mutant [TM] strains [C1q -/-TM and C3-/- TM, respectively]), with structural kidney changes resembling those in LN patients. Unexpectedly, both TM strains had significant increases in autoantibody titers, Ag spread, and IgG deposition in the kidneys. Despite the early complement component deficiencies, we observed assembly of the pathogenic terminal complement membrane attack complex in both TM strains. In C1q-/- TM mice, colocalization of MASP-2 and C3 in both the glomeruli and tubules indicated that the lectin pathway likely contributed to complement activation and tissue injury in this strain. Interestingly, enhanced thrombin activation in C3-/- TM mice and reduction of kidney injury following attenuation of thrombin generation by argatroban in a serum-transfer nephrotoxic model identified thrombin as a surrogate pathway for complement activation in C3-deficient mice. These novel mouse models of human lupus inform the requirements for nephritis and provide targets for intervention.

Thermal transport of Josephson junction based on two-dimensional electron gas.

We study the phase-dependent thermal transport of a short temperature-biased Josephson junction based on two-dimensional electron gas (2DEG) with both Rashba and Dresselhaus couplings. Except for thermal equilibrium temperature T, characters of thermal transport can also be manipulated by interaction parameter h0 and the parameter [Formula: see text] . A larger value and a sharper switching behavior of thermal conductance can be obtained if h0 takes suitable values and [Formula: see text] is larger. Finally, we propose a possible experimental setup based on the discussed Josephson junction and find that the temperature of the right superconducting electrode TR is influenced by the same three parameters in a similar way with thermal conductance. This setup may provide a valid method to select moderately-doped 2DEG materials and superconducting electrodes to control the change of temperature and obtain an efficient temperature regulator.

B cell responses to apoptotic cells in MFG-E8-/- mice.

Defective clearance of apoptotic cells in MFG-E8 deficient mice results in lupus-like disease in the mixed B6x129, but not pure B6 background. The lack of overt autoimmunity in MFG-E8-/- B6 mice suggests that accumulation of apoptotic cells is not sufficient to break central tolerance. However, the delayed clearance of apoptotic cells in the follicles of MFG-E8-/- B6 mice provides an excellent opportunity to investigate how B cells respond to excessive apoptotic cells in the periphery under relatively non-inflammatory conditions. In MFG-E8-/- B6 mice, we found increased IgG2c production against apoptotic cells and oxidized LDL. Apoptotic cell induced antibody responses depended on MyD88 signal and T cell help. In addition, MFG-E8-/- B6 mice had enlarged MZ B cell compartments as well as an enhanced antibody response to NP-Ficoll. Moreover, a significant percentage of MZ B cells in aged MFG-E8-/- B6 mice migrated into follicles. Injecting apoptotic cells or oxidized LDL into wild type mice as well as physiological accumulation of LDL in ApoE-/- mice recapitulated the translocation of MZ B cells. To determine how MFG-E8 deficiency affects the functions of autoreactive B cells specific for nucleic acids in the periphery under non-inflammatory conditions, we utilized BCR transgenic mice to bypass central selection and compared the differentiation of TLR9 dependent anti-dsDNA 56R B cells and TLR7 dependent anti-ssRNA H564 B cells in MFG-E8-/- mice. In MFG-E8-/- 56R mice, anti-dsDNA specific 56R/Vκ38c B cells differentiated into MZ B cells but not AFCs. On the contrary, in MFG-E8-/-H564 mice, anti-ssRNA specific H564 B cells further differentiated into GC B cells and AFCs. Adoptive transfer of activated autoreactive B cells confirmed that H564 B cells were more sensitive to apoptotic cell antigens than 56R B cells. Our observations provide new insights about the MZ B cell translocation in lupus patients as well as the dichotomy of TLR9 and TLR7 signals in the pathogenesis of lupus.

Forced expression of IL-7R promotes CD8 T cell cytotoxicity to self antigen.

Cross-presentation of apoptotic cell associated antigens by immature dendritic cells prevents the activation of self reactive CD8 T cells. Tolerized self reactive CD8 T cells down-regulate IL-7R expression on their surface. Whether over-expression of IL-7R can reverse their fate and function has not been examined. In this paper, we showed forced expression of IL-7R in OT-I T cells by a transgene enhanced CD8 T cell mediated diabetes in the RIP-mOVA model. Although IL-7R Tg (transgenic) did not completely reverse the deletion of OT-I T cells, it provided a significant survival advantage over w.t OT-I T cells. Furthermore, IL7R Tg OT-I T cells isolated from diabetic pancreata displayed increased production of IFN-γ, higher expression of T-bet, and increased externalization of CD107a. We also found that immature DCs containing apoptotic cells expressed high levels of PDL-1 on their surface. Although IL-7R Tg did not change PD1 expression on activated OT-I cells in vivo, the transgene enabled a significantly lower number of OT-I T cells to induce diabetes in the absence of PDL-1. Our results demonstrated that forced expression of IL-7R not only improved the functionality of tolerized CD8 T cells, it also acted in synergy with PDL-1 deficiency to further promote CD8 T cell cytotoxicity to self antigens.

Nonlinear optical properties of sodium copper chlorophyllin in aqueous solution.

BACKGROUND: Sodium copper chlorophyllin (SCC), as one of the derivatives of chlorophyll - with its inherent green features; good stability for heat, light, acids and alkalies; unique antimicrobial capability; and particular deodori zation performance - is widely applied in some fields such as the food industry, medicine and health care, daily cosmetic industry etc. SCC, as one of the metal porphyrins, has attracted much attention because of its unique electronic band structure and photon conversion performance. To promote the application of SCC in materials science; energy research and photonics, such as fast optical communications; and its use in nonlinear optical materials, solar photovoltaic cells, all-optical switches, optical limiters and saturable absorbers, great efforts should be dedicated to studying its nonlinear optical (NLO) properties. METHODS: In this study, the absorption spectra and NLO properties of SCC in aqueous solution at different concentrations were measured. The Z-scan technique was used to determine NLO properties. RESULTS: The results indicated that the absorption spectra of SCC exhibit 2 characteristic absorption peaks located at the wavelengths 405 and 630 nm, and the values of the peaks increase with increasing SCC concentration. The results also showed that SCC exhibits reverse saturation absorption and negative nonlinear refraction (self-defocusing). CONCLUSIONS: It can be seen that SCC has good optical nonlinearity which will be convenient for applications in materials science, energy research and photonics.

Granulocyte/Macrophage Colony-stimulating Factor-dependent Dendritic Cells Restrain Lean Adipose Tissue Expansion.

The physiological roles of macrophages and dendritic cells (DCs) in lean white adipose tissue homeostasis have received little attention. Because DCs are generated from bone marrow progenitors in the presence of granulocyte/macrophage colony-stimulating factor (GM-CSF), we used GM-CSF-deficient (Csf2(-/-)) mice fed a low fat diet to test the hypothesis that adipose tissue DCs regulate the development of adipose tissue. At 4 weeks of age, Csf2(-/-) mice had 75% fewer CD45(+)Cd11b(+)Cd11c(+)MHCII(+) F4/80(-) DCs in white adipose tissue than did wild-type controls. Furthermore, the Csf2(-/-) mice showed a 30% increase in whole body adiposity, which persisted to adulthood. Adipocytes from Csf2(-/-) mice were 50% larger by volume and contained higher levels of adipogenesis gene transcripts, indicating enhanced adipocyte differentiation. In contrast, adipogenesis/adipocyte lipid accumulation was inhibited when preadipocytes were co-cultured with CD45(+)Cd11b(+)Cd11c(+)MHCII(+)F4/80(-) DCs. Medium conditioned by DCs, but not by macrophages, also inhibited adipocyte lipid accumulation. Proteomic analysis revealed that matrix metalloproteinase 12 and fibronectin 1 were greatly enriched in the medium conditioned by DCs compared with that conditioned by macrophages. Silencing fibronectin or genetic deletion of matrix metalloproteinase 12 in DCs partially reversed the inhibition of adipocyte lipid accumulation. Our observations indicate that DCs residing in adipose tissue play a critical role in suppressing normal adipose tissue expansion.

The antiepileptic effect of the glycolytic inhibitor 2-deoxy-D-glucose is mediated by upregulation of K(ATP) channel subunits Kir6.1 and Kir6.2.

Metabolic modulation of neuronal excitability is becoming increasingly important as an antiepileptic therapy. It was reported that the glycolytic inhibitor 2-deoxy-D-glucose (2-DG) and the activation of the ATP-sensitive potassium ion channel (K(ATP) channel) had an antiepileptic effect in models of epilepsy. To explore whether 2-DG exerts an antiepileptic effect through upregulation of the K(ATP) channel subunits Kir6.1 and Kir6.2, the expression of these subunits in hippocampus of five groups of mice with pilocarpine-induced status epilepticus (SE) was evaluated. A seizure group with pilocarpine-kindling convulsions (EP) was compared to similar groups treated with high, medium, and low 2-DG concentrations (100-500 mg/kg) and a normal control group (Con). Kir6.1 and Kir6.2 mRNAs and proteins were analyzed at 4 h, 1 days (acute period), 7 days (latent period), 30, and 60 days (chronic period) following SE. In the seizure group (compared to the Con group), hippocampal expression of Kir6.1 and Kir6.2 increased dramatically at 1, 7, and 30 days, and was further increased after treatment with medium and high dose 2-DG (all P < 0.05). Our results suggest that 2-DG may exert an antiepileptic effect through up-regulation of mRNAs and protein levels of Kir6.1 and Kir6.2, which may therefore be used as molecular targets in the treatment of epilepsy with 2-DG.

The role of local field potential coupling in epileptic synchronization.

THIS REVIEW HOPES TO CLEARLY EXPLAIN THE FOLLOWING VIEWPOINTS: (1) Neuronal synchronization underlies brain functioning, and it seems possible that blocking excessive synchronization in an epileptic neural network could reduce or even control seizures. (2) Local field potential coupling is a very common phenomenon during synchronization in networks. Removal of neurons or neuronal networks that are coupled can significantly alter the extracellular field potential. Interventions of coupling mediated by local field potentials could result in desynchronization of epileptic seizures. (3) The synchronized electrical activity generated by neurons is sensitive to changes in the size of the extracellular space, which affects the efficiency of field potential transmission and the threshold of cell excitability. (4) Manipulations of the field potential fluctuations could help block synchronization at seizure onset.

[Analysis on the spectral properties of the stilbene 420 laser dye].

Stilbene 420 dye solution was prepared and the laser dye absorption spectrum was measured. Q-switched frequency-doubling Nd : YAG laser was used as the pumping source to realize the stilbene 420 dye laser and fluorescence spectra analysis. Laser spectroscopy reached the strongest peak at 425 nm and full width at half maximun (FWHM) is 1 nm. Spectral range was from 420 nm to 440 nm. Fluorescence spectrum peak was at 428.5 nm. Compared with the strongest peak laser, the wavelength difference was 3.5 nm. The highest dye conversion efficiency was 9.26%.

Unique proteomic signatures distinguish macrophages and dendritic cells.

Monocytes differentiate into heterogeneous populations of tissue macrophages and dendritic cells (DCs) that regulate inflammation and immunity. Identifying specific populations of myeloid cells in vivo is problematic, however, because only a limited number of proteins have been used to assign cellular phenotype. Using mass spectrometry and bone marrow-derived cells, we provided a global view of the proteomes of M-CSF-derived macrophages, classically and alternatively activated macrophages, and GM-CSF-derived DCs. Remarkably, the expression levels of half the plasma membrane proteins differed significantly in the various populations of cells derived in vitro. Moreover, the membrane proteomes of macrophages and DCs were more distinct than those of classically and alternatively activated macrophages. Hierarchical cluster and dual statistical analyses demonstrated that each cell type exhibited a robust proteomic signature that was unique. To interrogate the phenotype of myeloid cells in vivo, we subjected elicited peritoneal macrophages harvested from wild-type and GM-CSF-deficient mice to mass spectrometric and functional analysis. Unexpectedly, we found that peritoneal macrophages exhibited many features of the DCs generated in vitro. These findings demonstrate that global analysis of the membrane proteome can help define immune cell phenotypes in vivo.

Autoimmunity in MFG-E8-deficient mice is associated with altered trafficking and enhanced cross-presentation of apoptotic cell antigens.

Apoptotic cells must be rapidly cleared, as defects in this process can lead to autoimmunity. Milk fat globule EGF factor 8 (MFG-E8) binds to apoptotic cells and facilitates their removal through interaction with phagocytes. Mice deficient in MFG-E8 develop lupus-like autoimmunity associated with accumulation of apoptotic cells in vivo. Here, we have shown that MFG-E8 controls phagocytic ingestion of cell fragments as well as their intracellular processing into MHC-antigen complexes. Older Mfge8-/- mice spontaneously developed dermatitis associated with CD8+ T cell infiltration and striking activation of effector memory CD8+ T cells. CD8+ T cell responses to both exogenous and endogenous apoptotic cell-associated antigens were enhanced in Mfge8-/- mice. MFG-E8 deficiency accelerated the onset of disease in a mouse model of autoimmune diabetes. Enhanced CD8+ T cell responses were attributed to increased cross-presentation by DCs along with increased detection of antigen-MHCI complexes. Intracellular trafficking analysis revealed that intact apoptotic cells ingested by wild-type DCs rapidly fused with lysosomes, whereas smaller fragments persisted in Mfge8-/- DC endosomal compartments for 24 hours. These observations suggest that MFG-E8 deficiency promotes immune responses to self antigens not only by delaying the clearance of dying cells but also by altering intracellular processing, leading to enhanced self-antigen presentation.

Ly6C(low) monocytes differentiate into dendritic cells and cross-tolerize T cells through PDL-1.

Monocyte-derived dendritic cells are active participants during the immune response against infection, but whether they play a role in maintaining self-tolerance under steady-state conditions is not known. Here we investigated the differentiation of monocytes, their ability to ingest apoptotic cells, and their potential functionality in vivo. We observed that Ly6C (Gr-1)(low) mature monocytes up-regulate their MHC II level in the spleen, express high levels of PDL-1 (programmed death ligand 1), and are more efficient than Ly6C(high) immature monocytes in the ingestion of apoptotic cells in vivo. Sorted circulating Ly6C(low) monocytes were able to cross-present both apoptotic cell-associated OVA and soluble OVA protein. Monocytes containing apoptotic cells can further differentiate into CD11c(+)CD8alpha(-)MHC II(+) splenic dendritic cells that maintained high expression of PDL-1. Since wild-type but not PDL-1-deficient peripheral blood monocytes containing apoptotic cell-associated OVA suppressed the response to OVA immunization, PDL-1 expression was required for monocyte-mediated T cell tolerance. These observations demonstrate that Ly6C(low) mature monocytes can promote tolerance to self Ag contained in apoptotic cells through a PDL-1-dependent mechanism.

Transforming growth factor-beta suppresses the activation of CD8+ T-cells when naive but promotes their survival and function once antigen experienced: a two-faced impact on autoimmunity.

OBJECTIVE: Transforming growth factor-beta (TGF-beta) can exhibit strong immune suppression but has also been shown to promote T-cell growth. We investigated the differential effect of this cytokine on CD8(+) T-cells in autoimmunity and antiviral immunity. RESEARCH DESIGN AND METHODS: We used mouse models for virally induced type 1 diabetes in conjunction with transgenic systems enabling manipulation of TGF-beta expression or signaling in vivo. RESULTS: Surprisingly, when expressed selectively in the pancreas, TGF-beta reduced apoptosis of differentiated autoreactive CD8(+) T-cells, favoring their expansion and infiltration of the islets. These results pointed to drastically opposite roles of TGF-beta on naïve compared with antigen-experienced/memory CD8(+) T-cells. Indeed, in the absence of functional TGF-beta signaling in T-cells, fast-onset type 1 diabetes caused by activation of naïve CD8(+) T-cells occurred faster, whereas slow-onset disease depending on accumulation and activation of antigen-experienced/memory CD8(+) T-cells was decreased. TGF-beta receptor-deficient CD8(+) T-cells showed enhanced activation and expansion after lymphocytic choriomeningitis virus infection in vivo but were more prone to apoptosis once antigen experienced and failed to survive as functional memory cells. In vitro, TGF-beta suppressed naïve CD8(+) T-cell activation and gamma-interferon production, whereas memory CD8(+) T-cells stimulated in the presence of TGF-beta showed enhanced survival and increased production of interleukin-17 in conjunction with gamma-interferon. CONCLUSIONS: The effect of TGF-beta on CD8(+) T-cells is dependent on their differentiation status and activation history. These results highlight a novel aspect of the pleiotropic nature of TGF-beta and have implications for the design of immune therapies involving this cytokine.

Innate and adaptive immune response to apoptotic cells.

The immune system is constantly exposed to dying cells, most of which arise during central tolerance and from effete circulating immune cells. Under homeostatic conditions, phagocytes (predominantly macrophages and dendritic cells) belonging to the innate immune system, rapidly ingest cells and their debris. Apoptotic cell removal requires recognition of altered self on the apoptotic membrane, a process which is facilitated by natural antibodies and serum opsonins. Recognition, may be site and context specific. Uptake and ingestion of apoptotic cells promotes an immunosuppressive environment that avoids inflammatory responses to self-antigens. However, it does not preclude a T cell response and it is likely that constant exposure to self-antigen, particularly by immature dendritic cells, leads to T cell tolerance. Tolerance occurs by several different mechanisms including anergy and deletion (for CD8+T cells) and induction of T regulatory cells (for CD4+T cells). Failed apoptotic cell clearance promotes immune responses to self-antigens, especially when the cellular contents are leaked from the cell (necrosis). Inflammatory responses may be induced by nucleic acid stimulation of Toll like receptors and other immune sensors, specific intracellular proteins and non-protein (uric acid) stimulation of inflammasomes.

IGM is required for efficient complement mediated phagocytosis of apoptotic cells in vivo.

A variety of complement components have been detected on apoptotic cells and proposed to facilitate recognition and/or ingestion by phagocytes. The triggers for complement activation remain uncertain. To determine the role of IgM in classical pathway activation and clearance of apoptotic cells in vitro and in vivo, we quantified these parameters in mice deficient in serum IgM (sIgM). Phagocytosis by bone marrow-derived macrophages of apoptotic cells incubated with serum deficient in sIgM was markedly reduced, similar to apoptotic cells incubated with C1q deficient serum in vitro. Similarly, intraperitoneal clearance of apoptotic cells and cellular C3 deposition were significantly reduced in mice deficient in sIgM compared to wild-type mice. Clearance and C3 deposition were reconstituted by addback of IgM. In mice deficient in both sIgM and Clq, addback of both serum factors was required for restoration of clearance. These findings indicate that, on a quantitative basis, sIgM is a potent factor required for intraperitoneal phagocytosis of apoptotic cells, and further demonstrate that IgM and C1q work in concert to activate complement, resulting in C3 deposition on the apoptotic cell surface and ultimately, efficient clearance of the apoptotic cell by macrophages.

The role of IgM antibodies in the recognition and clearance of apoptotic cells.

Apoptotic cells not only translocate phosphatidylserine to the outside of the membrane, they activate phospholipases that remodel their membranes resulting in the exposure and diffusion of altered phospholipids. These altered phospholipids include lysophosphotidylcholine (LPC) that is a ligand for CRP and is also antigenic for natural IgM antibodies. Furthermore, soluble LPC acts as a "find me" signal to attract phagocytes to migrate toward apoptotic cells. IgM mediated opsonization of apoptotic cells with complement accelerates their clearance by phagocytic cells. Failure to rapidly remove apoptotic cells on the other hand, allows dying cells to undergo post-apoptotic necrosis and inflammation. Natural antibodies therefore provide a previously unrecognized role in prevention of autoimmunity.