Memory T cell–mediated rejection is mitigated by FcγRIIB expression on CD8+ T cells

Donor‐reactive memory T cells generated via heterologous immunity represent a potent barrier to long‐term graft survival following transplantation because of their increased precursor frequency, rapid effector function, altered trafficking patterns, and reduced reliance on costimulation signals for activation. Thus, the identification of pathways that control memory T cell survival and secondary recall potential may provide new opportunities for therapeutic intervention. Here, we discovered that donor‐specific effector/memory CD8⁺ T cell populations generated via exposure to acute vs latent vs chronic infections contain differential frequencies of CD8⁺ T cells expressing the inhibitory Fc receptor FcγRIIB. Results indicated that frequencies of FcγRIIB‐expressing CD8⁺ donor‐reactive memory T cells inversely correlated with allograft rejection. Furthermore, adoptive T cell transfer of Fcgr2b^?/? CD8⁺ T cells resulted in an accumulation of donor‐specific CD8⁺ memory T cells and enhanced recall responses, indicating that FcγRIIB functions intrinsically to limit T cell CD8⁺ survival in vivo. Lastly, we show that deletion of FcγRIIB on donor‐specific CD8⁺ memory T cells precipitated costimulation blockade‐resistant rejection. These data therefore identify a novel cell‐intrinsic inhibitory pathway that functions to limit the risk of memory T cell–mediated rejection following transplantation and suggest that therapeutic manipulation of this pathway could improve outcomes in sensitized patients.     

Live birth after cervical ectopic uterus transplantation in mice

An ideal animal model is a prerequisite for the basic research of uterus transplantation. This study aimed to develop a new cervical ectopic uterus transplantation mice model, which was established by vascular anastomosis of the right common iliac artery and vein of the donor with the right common carotid artery and external jugular vein of the recipient, respectively, using the cuff method. The survival status of the transplanted uterus was assessed by macroscopic observation and histological examination after surgery, and the function of the graft uterus was tested by verifying whether the pregnancy is possible. A total of 40 transplants were performed, of which only 1 failed due to donor hemorrhage. After 26 transplants, the total operation time reduced to 52.4 ± 3.8 minutes, of which the total ischemia time took 6.6 ± 1.1 minutes. Sixty days after transplantation, all the graft uteri had a good blood supply and spontaneous contraction. The histology showed no significant difference between the transplanted uterus and the native. Embryo transfer experiments have proven that the transplanted uterus has uterine function. In conclusion, this new model is an effective and simple mice model for the studies of the scientific issues related to uterus transplantation.     

Recombinant human ADAMTS13 treatment and anti‐NET strategies enhance skin allograft survival in mice

Enhancing skin allograft longevity lessens the need for new allografts before optimal intervention is available. Reduced activity of ADAMTS13 (an enzyme that cleaves the pro‐thrombotic and proinflammatory von Willebrand factor) and presence of neutrophil extracellular traps (NETs) have been implicated in liver and lung allograft failures. The effect of ADAMTS13 treatment and the impact of NETs on skin allografts, however, remain unexplored. Here, we adopted a murine model of complete mismatch full‐thickness skin transplant by grafting dorsal skin from BALB/c mice to C57BL/6J background mice. Recombinant human ADAMTS13 (rhADAMTS13) treatment of graft recipients increased allograft survival. Western blot and immunofluorescence microscopy revealed the presence of NETs in allografts of vehicle, but surprisingly, not in rhADAMTS13‐treated mice, 3 days after surgery. Recapitulating the observations in mice, NETs were also observed in all the examined allografts from burn patients. Intriguingly, knocking out peptidylarginine deiminase 4 (PAD4, a key enzyme for NET formation) or DNase 1 treatment (which cleaves NETs) also prolonged allograft survival. In summary, rhADAMTS13 lessens inflammation in allografts by reducing NET burden, resulting in enhanced allograft survival. RhADAMTS13 and anti‐NET treatments could be new therapeutic strategies to promote skin allograft longevity and, hence, the survival of patients with severe burns.     

Treatment with 3‐aminobenzamide during ex vivo lung perfusion of damaged rat lungs reduces graft injury and dysfunction after transplantation

Ex vivo lung perfusion (EVLP) with pharmacological reconditioning may increase donor lung utilization for transplantation (LTx). 3‐Aminobenzamide (3‐AB), an inhibitor of poly(ADP‐ribose) polymerase (PARP), reduces ex vivo lung injury in rat lungs damaged by warm ischemia (WI). Here we determined the effects of 3‐AB reconditioning on graft outcome after LTx. Three groups of donor lungs were studied: Control (Ctrl): 1 hour WI + 3 hours cold ischemia (CI) + LTx; EVLP: 1 hour WI + 3 hours EVLP + LTx; EVLP + 3‐AB: 1 hour WI + 3 hours EVLP + 3‐AB (1 mg^.mL^?1) + LTx. Two hours after LTx, we determined lung graft compliance, edema, histology, neutrophil counts in bronchoalveolar lavage (BAL), mRNA levels of adhesion molecules within the graft, as well as concentrations of interleukin‐6 and 10 (IL‐6, IL‐10) in BAL and plasma. 3‐AB reconditioning during EVLP improved compliance and reduced lung edema, neutrophil infiltration, and the expression of adhesion molecules within the transplanted lungs. 3‐AB also attenuated the IL‐6/IL‐10 ratio in BAL and plasma, supporting an improved balance between pro‐ and anti‐inflammatory mediators. Thus, 3‐AB reconditioning during EVLP of rat lung grafts damaged by WI markedly reduces inflammation, edema, and physiological deterioration after LTx, supporting the use of PARP inhibitors for the rehabilitation of damaged lungs during EVLP.     

Radiation and host retinoic acid signaling promote the induction of gut‐homing donor T cells after allogeneic hematopoietic stem cell transplantation

Intestinal graft‐versus‐host disease (GVHD) remains a devastating complication after allogeneic hematopoietic stem cell transplantation (HSCT). Although it has been well established that gut‐tropic donor T cells expressing integrin α4β7 are required to cause intestinal damage, the factors that control the induction of this pathogenic T cell population remain to be identified. Retinoic acid (RA) plays an important role in inducing α4β7 expression on T cells. In this study, we showed that gene expression of retinaldehyde dehydrogenase, the key enzyme involved in RA biosynthesis, is significantly increased in the spleen and mesenteric lymph nodes (MLNs) of irradiated mice. In a C57BL/6‐into‐B6D2F1 allogeneic HSCT model, irradiation significantly increased the induction of α4β7⁺‐donor T cells in mesenteric lymph nodes and spleen. Furthermore, we found that the RA pathway modulates the ability of dendritic cells to imprint gut‐homing specificity on alloreactive T cells. We also showed that host dendritic cell RA signaling influences GVHD risk. Our studies identified radiation and recipient RA signaling as 2 primary factors that dictate the magnitude of gut‐homing donor T cell induction after allogeneic HSCT. Attenuating radiation‐associated inflammation and modulating host RA signaling represent feasible strategies to mitigate intestinal GVHD by reducing gut‐seeking pathogenic donor T cells.     

Examination of murine antibody response to secondary hydatidosis using ELISA and immunoelectrophoresis

Summary Antibody responses in mice with up to 64 weeks of secondary Echinococcus granulosus hydatidosis were examined by ELISA using hydatid protoscolex antigen (Px), Antigen 5 (Ag5) and Antigen B (AgB), and by immunoelectrophoresis (IEP) using sheep hydatid cyst fluid (SHCF). Anti-Px IgG antibodies, evident from 3–5 days post infection (p.i.), increased steadily until 16 weeks and maintained a high level afterwards. Anti-Ag5 IgG antibodies were negligible up to two weeks, but they showed a small increase around 2–3 weeks which was followed by a big increase around 16 weeks p.i. The high level of anti-Ag5 IgG antibodies persisted to the end of experiment. The level of anti-AgB IgG antibodies remained relatively low throughout infection. Anti-Px IgM antibodies appeared in the early period of infection, but became insignificant as the infection proceeded. Specific IgM antibodies to Ag5 and AgB showed two waves of increase, one between 3 days to 4 weeks p.i. and the other between 16 weeks to 46 weeks p.i. The level of IgA antibodies to Ag5 and AgB was low and only a moderate amount of anti-Px IgA antibodies was detected. Generally, a higher level of serum antibodies are associated with a larger number of mature cysts. Serum samples from 5 of 8 mice harbouring hydatid cysts formed 1–3 bands with SHCF in IEP, including Arc 5, but a precipitation arc with AgB was not observed. Analysis of hydatid cyst fluid from the infected mice (MHCF) in IEP also failed to demonstrate AgB. Despite the high levels of antihydatid antibodies generated in the infected mice, protoscoleces appeared to be unhindered in their growth to mature cysts.     

Severe Murine Typhus with Pulmonary System Involvement

We encountered a case of severe murine typhus complicated by acute respiratory distress syndrome. To determine worldwide prevalence of such cases, we reviewed the literature and found that respiratory symptoms occur in ≈30% of murine typhus patients. In disease-endemic areas, murine typhus should be considered for patients with respiratory symptoms and fever.     

Murine Typhus as a Cause of Cognitive Impairment: Case Report and a Review of the Literature

BackgroundMurine typhus is a systemic febrile illness caused by Rickettsia typhi, a gram-negative, obligate intracellular bacterium. It is found worldwide, including in the United States, where cases are concentrated in suburban areas of Texas and California. The disease manifests with fever, headache, and rash. Central nervous system involvement is rare in both adults and children. Aseptic meningitis and meningoencephalitis are the most common neurological presentations, occurring in 2% to 5% of cases. Neurological dysfunction, including memory impairment and behavioral alterations, can occur and usually are reversible. Long-term deficits are considered rare even in untreated cases and have not been described in the pediatric population.MethodsSingle case report.ResultsWe describe a previously healthy 17-year-old girl infected with R. typhi who developed meningoencephalitis that resulted in chronic cognitive impairment despite treatment.ConclusionMurine typhus should be considered in the differential diagnosis of aseptic meningitis and meningoencephalitis. Early diagnosis and treatment can prevent death and long-term morbidity.     

Protective effects of pharmacological therapies in animal models of multiple sclerosis: a review of studies 2014–2019

Multiple sclerosis(MS)is an inflammatory demyelinating disease of the central nervous system.The disability caused by inflammatory demyelination clinically dominates the early stages of relapsing-remitting MS and is reversible.Once there is considerable loss of axons,MS patients enter a secondary progressive stage.Disease-modifying drugs currently in use for MS suppress the immune system and reduce relapse rates but are not effective in the progressive stage.Various animal models of MS(mostly mouse and rat)have been established and proved useful in studying the disease process and response to therapy.The experimental autoimmune encephalomyelitis animal studies reviewed here showed that a chronic progressive disease can be induced by immunization with appropriate amounts of myelin oligodendrocyte glycoprotein together with mycobacterium tuberculosis and pertussis toxin in Freund's adjuvant.The clinical manifestations of autoimmune encephalomyelitis disease were prevented or reduced by treatment with certain pharmacological agents given prior to,at,or after peak disease,and the agents had protective effects as shown by inhibiting demyelination and damage to neurons,axons and oligodendrocytes.In the cuprizone-induced toxicity animal studies,the pharmacological agents tested were able to promote remyelination and increase the number of oligodendrocytes when administered therapeutically or prophylactically.A monoclonal IgM antibody protected axons in the spinal cord and preserved motor function in animals inoculated with Theiler's murine encephalomyelitis virus.In all these studies the pharmacological agents were administered singly.A combination therapy may be more effective,especially using agents that target neuroinflammation and neurodegeneration,as they may exert synergistic actions.     

Aqueous fraction of Sauropus androgynus might be responsible for bronchiolitis obliterans

Background and objective: Bronchiolitis obliterans (BO) has been reported to develop following ingestion of Sauropus androgynus (SA), a leafy shrub distributed in Southeast Asia. Little is known about direct effects of SA on airway resident cells or haematopoietic cells in vitro. Identification of the SA component responsible for the development of BO would be an important key to elucidate its mechanism. We sought to elucidate the direct effects of SA on airway resident cells or haematopoietic cells and identify the SA element responsible for the pathogenesis of BO. Methods: SA dry powder was partitioned into fractions by solvent extraction. Human and murine monocytic cells, epithelial cells and endothelial cells were cultured with SA solution or fractions eluted from SA. We also investigated the effect of SA in vivo using a murine BO syndrome (BOS) model. Results: The aqueous fraction of SA induced significant increases of inflammatory cytokine and chemokine production from monocytic lineage cells. This fraction also induced significant apoptosis of endothelial cells and enhanced intraluminal obstructive fibrosis in allogeneic trachea allograft in the murine BOS model. We found individual differences in tumour necrosis factor α (TNF‐α) production from monocytes of healthy controls stimulated by this aqueous fraction of SA, whereas it induced high‐level TNF‐α production from monocytes of patients with SA‐induced BO. Conclusions: These results suggest that an aqueous fraction of SA may be responsible for the pathogenesis of BO.