Acute kidney injury after placement of an antibiotic-impregnated cement spacer during revision total knee arthroplasty.

We performed a retrospective cohort study of 84 patients to determine the incidence and predictors of acute kidney injury after antibiotic-impregnated cement spacer (ACS) placement for infected total knee arthroplasties. Acute kidney injury was defined as a more than 50% rise in serum creatinine from a preoperative baseline to a level greater than 1.4 mg/dL within 90 days postoperatively. Total incidence was 17% (n = 14; 95% confidence interval [CI], 10%-26%), and acute kidney injury was significantly associated with ACS tobramycin dose as both a dichotomous variable (>4.8 g; odds ratio, 5.87; 95% CI, 1.43-24.19; P = .01) and linear variable (odds ratio, 1.24 for every 1-g increase; 95% CI, 1.00-1.52; P = .049). Routine monitoring of serum creatinine and measurement of serum aminoglycoside levels in response to a threshold creatinine rise may be warranted after the placement of an aminoglycoside-containing ACS.

Regulation of gastric B cell recruitment is dependent on IL-17 receptor A signaling in a model of chronic bacterial infection.

Th17-driven immune responses contribute to the pathogenesis of many chronic inflammatory diseases. In this study, we investigated the role of IL-17 signaling in chronic gastric inflammation induced by Helicobacter pylori, a Gram-negative bacterium that persistently colonizes the human stomach. Wild-type C57BL/6 mice and mice lacking IL-17RA (IL-17RA(-/-)) were orogastrically infected with H. pylori. Differences in bacterial colonization density and gastric inflammation were not apparent at 1 mo postinfection, but by 3 mo postinfection, H. pylori colonization density was higher and mononuclear gastric inflammation more severe in infected IL-17RA(-/-) mice than in infected wild-type mice. A striking feature was a marked increase in gastric B cells, plasma cells, and lymphoid follicles, along with enhanced H. pylori-specific serum Ab responses, in infected IL-17RA(-/-) mice. Fewer gastric neutrophils and lower levels of neutrophil-recruiting chemokines were detected in infected IL-17RA(-/-) mice than in infected wild-type mice. Gastric IL-17a and IL-21 transcript levels were significantly higher in infected IL-17RA(-/-) mice than in infected wild-type mice or uninfected mice, which suggested that a negative feedback loop was impaired in the IL-17RA(-/-) mice. These results underscore an important role of IL-17RA signaling in regulating B cell recruitment. In contrast to many chronic inflammatory diseases in which IL-17RA signaling promotes an inflammatory response, IL-17RA signaling down-regulates the chronic mononuclear inflammation elicited by H. pylori infection.

Long-term outcomes of cytomegalovirus infection and disease after lung or heart-lung transplantation with a delayed ganciclovir regimen.

BACKGROUND: Information is limited on long-term outcomes after preemptive use of ganciclovir to control cytomegalovirus (CMV) infection in lung transplantation. METHODS: We studied 78 lung recipients who received antithymocyte globulin induction from 1994 to 2000. All patients received six months of oral acyclovir (800 mg TID). This was interrupted three wk post transplantation for a two-wk course of IV ganciclovir. Additional courses of ganciclovir were administered based on serial virological monitoring. CMV-mismatched patients (R-D+) also received four doses of CMV immunoglobulin between weeks 2 and 8. RESULTS: The one yr cumulative risk of CMV disease was 2% (1/61) in CMV seropositive (R+) patients, but was 37% (6/17) in R-D+ patients (p < 0.0001). Over 4.3 yr of follow-up, patients with CMV infection developed more chronic graft dysfunction caused by bronchiolitis obliterans or bronchiolitis obliterans syndrome than patients without CMV infection (p = 0.012). This effect was also apparent in the subgroup of R+ recipients (p = 0.043). Acute rejection and overall survival were not associated with CMV infection. CONCLUSIONS: The use of prophylactic acyclovir and short preemptive courses of ganciclovir effectively controlled CMV disease in R+ patients, but was a relative failure in R-D+ patients. CMV infection was significantly associated with chronic graft dysfunction, even in R+ recipients who had good control of CMV symptoms.

Cytomegalovirus ventriculoencephalitis in a peripheral blood stem cell transplant recipient.

Cytomegalovirus encephalitis occurs rarely in transplant recipients. We describe a patient with cytomegalovirus ventriculoencephalitis who had a very high CSF viral load but a low peripheral blood viral load. No resistance mutations were present in cerebrospinal fluid viral DNA, whereas DNA from blood showed a resistance mutation in the UL54 gene but not in the UL97 gene. Viral replication was intense in the brain ependyma and periventricular areas without evidence of peripheral cytomegalovirus disease. The data provide evidence for compartmentalization of cytomegalovirus infection. Levels of ganciclovir and foscarnet in the cerebrospinal fluid may be inadequate for treatment, even for some drug-susceptible strains, and, together with periventricular replication, may explain the disparity between cerebrospinal fluid viral load and peripheral blood viral load.

Alloimmunity in primate heart recipients with CD154 blockade: evidence for alternative costimulation mechanisms.

BACKGROUND: CD154 mediates key facets of humoral and cellular immunity to alloantigens, and is tolerogenic to influenza antigens in primates. Barriers to CD154-based tolerance induction for primate cardiac allografts have not previously been defined. METHODS: Heterotopic cardiac allograft outcomes in cynomolgus monkeys treated with a CD154 inhibitor, IDEC-131 (n=27), were compared to no treatment (n=4) or cyclosporine A (n=6). RESULTS: CD154 blockade significantly prolonged median allograft survival, from 6.2 (range 6, 7, n=4) days in untreated controls, to 39 (8,112, n=16) days with intensive monotherapy and 93 (>25, 386; n=3) days with added antithymocyte globulin (ATG), but did not yield tolerance. Alloantibody production was delayed but not prevented by IDEC-131 alone or with ATG, and was exacerbated by infusion of donor bone marrow (n=8). Expression of ICOS was prominent in graft infiltrating lymphocytes, and preceded elaboration of antidonor antibody and vasculopathy. CONCLUSION: CD154 monotherapy modulates primate cardiac alloimmunity, but does not readily induce tolerance. Targeting alternative costimulation pathways, including ICOS, may facilitate tolerance induction based on CD154 blockade.

Inhibition of Src kinases combined with CD40 ligand blockade prolongs murine cardiac allograft survival.

BACKGROUND: Members of the Src family of tyrosine kinases (SFKs) are requisite signaling molecules activated by multiple receptors during immune responses. Their expression and catalytic activity has not been characterized in allograft rejection in vivo. METHODS: We measured expression and catalytic activity of SFKs in MHC- mismatched murine cardiac allografts. We also examined the effects of a Src inhibitor (CGP77675) with or without anti-CD154 mAb on graft survival, histology, and expression and catalytic activity of SFKs within the grafts. RESULTS: In acutely rejecting allografts from untreated controls, total activity of Hck and Lyn increased 10-fold, predominantly reflecting increases in the amount of protein. Total activity of Lck increased only fourfold, reflecting small changes in both the amount of protein and specific activity. One dose of anti-CD154 plus CGP77675 markedly diminished cellular infiltration, but survival was only moderately prolonged despite inhibition of all SFKs in the rejected grafts. Two doses of anti-CD154 plus CGP77675 allowed permanent graft acceptance in 60% of recipients even after discontinuation of the inhibitor. Both rejected and long surviving grafts showed increased activity of all SFKs. Recipients that rejected their grafts showed serum alloantibody production, and grafts rejected during treatment demonstrated deposition of complement indicating the contribution of antibody to rejection. CONCLUSIONS: The myeloid and B cell Src family kinases, Hck and Lyn, rather than the T cell Src kinase Lck, show the greatest increase in expression and total activity in rejecting allografts. Both rejected and long-surviving grafts show significant increases in SFK expression and acitivity.

Successful management of an ABO-mismatched lung allograft using antigen-specific immunoadsorption, complement inhibition, and immunomodulatory therapy.

BACKGROUND: Successful management of an ABO-mismatched lung allograft recipient has not previously been described. METHODS: Because of a clerical error, a 67-year-old blood type B patient with idiopathic pulmonary fibrosis received a left single-lung allograft from a blood type A donor. Cyclophosphamide was added to immunosuppression with anti-thymocyte globulin induction, cyclosporine, mycophenolate mofetil, and prednisone. When increasing anti-A antibody titers were detected, antigen-specific immunoadsorption, anti-CD20 monoclonal antibody, and recombinant soluble complement receptor type 1 (TP10) were administered. RESULTS: Rising anti-A antibody titers were reduced acutely by immunoadsorption, and remained low during long-term follow-up. Humoral injury to the graft was not detected. Acute cellular rejection and multiple complications were successfully managed. Three years after transplantation the patient is clinically well on stable maintenance immunosuppression and prophylactic photochemotherapy. CONCLUSIONS: Modulation of anti-A antibody, preserved graft function, and a favorable patient outcome can be achieved for an ABO-mismatched lung allograft.

Inactivation of a Helicobacter pylori DNA methyltransferase alters dnaK operon expression following host-cell adherence.

The Helicobacter pylori hpyIM gene encodes a type II DNA methyltransferase that is highly conserved among strains. To investigate the potential role of M.HpyI methyltransferase activity in controlling gene expression in H. pylori, we analyzed gene transcription profiles in wild-type strain J166 and an isogenic hpyIM mutant strain using gene arrays. This analysis showed that the expression of a majority of genes was unaffected by hpyIM mutation, especially in exponential phase cultures. However, in stationary phase cultures and in cells adherent to AGS gastric epithelial cells in vitro, loss of hpyIM function altered the expression of the stress-responsive dnaK operon. Complementation of the hpyIM mutation using a shuttle plasmid encoding a wild-type copy of the gene re-established the wild-type pattern of dnaK operon expression. These data suggested that hpyIM, encoding a DNA methyltransferase, may have a role in H. pylori physiology that supersedes its original function in a type II restriction-modification system.

Endoplasmic reticulum stress in alveolar epithelial cells is prominent in IPF: association with altered surfactant protein processing and herpesvirus infection.

Recent evidence suggests that dysfunctional type II alveolar epithelial cells (AECs) contribute to the pathogenesis of idiopathic pulmonary fibrosis (IPF). Based on the hypothesis that disease-causing mutations in surfactant protein C (SFTPC) provide an important paradigm for studying IPF, we investigated a potential mechanism of AEC dysfunction suggested to result from mutant SFTPC expression: induction of endoplasmic reticulum (ER) stress and the unfolded protein response (UPR). We evaluated biopsies from 23 IPF patients (including 3 family members with L188Q SFTPC mutations, 10 individuals with familial interstitial pneumonia without SFTPC mutations, and 10 individuals with sporadic IPF) and sections from 10 control lungs. After demonstrating UPR activation in cultured A549 cells expressing mutant SFTPC, we identified prominent expression of UPR markers in AECs in the lungs of patients with SFTPC mutation-associated fibrosis. In individuals with familial interstitial pneumonia without SFTPC mutations and patients with sporadic IPF, we also found UPR activation selectively in AECs lining areas of fibrotic remodeling. Because herpesviruses are found frequently in IPF lungs and can induce ER stress, we investigated expression of viral proteins in lung biopsies. Herpesvirus protein expression was found in AECs from 15/23 IPF patients and colocalized with UPR markers in AECs from these patients. ER stress and UPR activation are found in the alveolar epithelium in patients with IPF and could contribute to disease progression. Activation of these pathways may result from altered surfactant protein processing or chronic herpesvirus infection.

Serum sickness following rabbit antithymocyte-globulin induction in a liver transplant recipient: case report and literature review.

Thymoglobulin (Genzyme, Cambridge, MA) is an antithymocyte globulin preparation used for induction immunosuppression therapy in solid organ transplantation. It is being utilized with increasing frequency in orthotopic liver transplantation (OLT) in an effort to minimize or delay the use of calcineurin inhibitors due to their inherent nephrotoxicity. Experience with thymoglobulin in OLT remains limited. We report a case of serum sickness in a patient who received thymoglobulin following OLT. The patient experienced intermittent fevers, polyarthralgia, and acute renal failure 9 days after completion of thymoglobulin administration. The patient's symptoms resolved rapidly and completely with a course of intravenous steroids. We review a set of diagnostic criteria for serum sickness and emphasize the importance of early recognition of the process. Early treatment of serum sickness with steroids or plasmapheresis is highly effective and can reduce unnecessary morbidity from this unusual sequela of induction immunosuppression with antithymocyte globulin.

CCR5 blockade modulates inflammation and alloimmunity in primates.

Pharmacologic antagonism of CCR5, a chemokine receptor expressed on macrophages and activated T cells, is an effective antiviral therapy in patients with macrophage-tropic HIV infection, but its efficacy in modulating inflammation and immunity is only just beginning to be investigated. In this regard, the recruitment of CCR5-bearing cells into clinical allografts is a hallmark of acute rejection and may anticipate chronic rejection, whereas conventionally immunosuppressed renal transplant patients homozygous for a nonfunctional Delta32 CCR5 receptor rarely exhibit late graft loss. Therefore, we explored the effects of a potent, highly selective CCR5 antagonist, Merck's compound 167 (CMPD 167), in an established cynomolgus monkey cardiac allograft model. Although perioperative stress responses (fever, diminished activity) and the recruitment of CCR5-bearing leukocytes into the graft were markedly attenuated, anti-CCR5 monotherapy only marginally prolonged allograft survival. In contrast, relative to cyclosporine A monotherapy, CMPD 167 with cyclosporine A delayed alloantibody production, suppressed cardiac allograft vasculopathy, and tended to further prolong graft survival. CCR5 therefore represents an attractive therapeutic target for attenuating postsurgical stress responses and favorably modulating pathogenic alloimmunity in primates, including man.

Humoral immunity to vimentin is associated with cardiac allograft injury in nonhuman primates.

Immunity to autologous protein has not previously been described following nonhuman primate cardiac transplant. Native hearts and cardiac allografts from cynomolgus monkeys were assessed by immunohistology for vimentin, a highly conserved intermediate filament protein. IgM and IgG to vimentin were measured in serial sera from untreated (n = 4) or cyclosporine (CsA)-treated (n = 8, 2 with ATG) cardiac allograft recipients, and in groups treated with anti-CD154 antibody with (n = 6) or without ATG (n = 28). IgM or IgG reactive with vimentin was elaborated within 30 days with unmodified acute rejection (3/4) or in CsA-treated animals (5/6). CD154 blockade did not prevent anti-vimentin IgM (14/28) but tended to delay the IgG response during therapy (anti-CD154: 8/28, p = 0.10 vs. CsA; anti-CD154+ATG: 2/6). CAV and alloantibody were seen in 25 of 26 animals with grafts surviving over 30 days, including seven animals without increasing anti-vimentin antibody. Anti-vimentin antibodies and vascular complement deposition were found in rejected hearts. Acute and chronic alloimmunity disrupt modulation of autoreactivity to vimentin through pathways, which are resistant to CsA, but may be partially regulated by CD154.

c-Src regulation of fibroblast growth factor-induced proliferation in murine embryonic fibroblasts.

Activated fibroblast growth factor receptor 1 (FGFR1) propagates FGF signals through multiple intracellular pathways via intermediates FRS2, PLCgamma, and Ras. Conflicting reports exist concerning the interaction between FGFR1 and Src family kinases. To address the role of c-Src in FGFR1 signaling, we compared proliferative responses of murine embryonic fibroblasts (MEF) deficient in c-Src, Yes, and Fyn to MEF expressing either endogenous levels or overexpressing c-Src. MEF with endogenous c-Src had significantly greater FGF-induced DNA synthesis and proliferation than cells lacking or overexpressing c-Src. This was related directly to c-Src expression by analysis of c-Src-deficient cells transfected with and sorted for varying levels of a c-Src expression vector. This suggests an "optimal" quantity of c-Src expression for FGF-induced proliferation. To determine if this was a general phenomenon for growth factor signaling pathways utilizing c-Src, responses to epidermal growth factor (EGF), platelet-derived growth factor (PDGF), and lysophosphatidic acid (LPA) were examined. As for FGF, responses to EGF were clearly inhibited when c-Src was absent or overexpressed. In contrast, varying levels of c-Src had little effect on responses to PDGF or LPA. The data show that mitogenic pathways activated by FGF-1 and EGF are regulated by c-Src protein levels and appear to differ significantly from those activated by PDGF and LPA.

Characterization of expression of a functionally conserved Helicobacter pylori methyltransferase-encoding gene within inflamed mucosa and during in vitro growth.

Methylation of bacterial DNA can regulate microbial growth and virulence. Expression of hpyIM, a conserved methyltransferase of the gastric pathogen Helicobacter pylori, was quantitated in gastric biopsy specimens from 41 H. pylori-infected patients and during growth in vitro, by quantitative reverse transcriptase-polymerase chain reaction and/or RNA slot-blot analysis, to determine whether levels of transcription were associated with pathologic outcome, as based on both severity of gastritis and inflammatory cytokine levels, or were regulated by bacterial growth phase. The effects that hpyIM inactivation has on bacterial morphology were determined by electron microscopy. Expression of hpyIM varied dramatically within colonized gastric tissue, and levels were not related to either colonization density, severity of inflammation, mucosal IL-8 concentrations, or clinical disease. In vitro, hpyIM expression was higher during log-phase growth and was required for normal bacterial morphology, suggesting that hpyIM expression may be growth-phase regulated within the gastric niche.

Differential expression of the IFN-gamma-inducible CXCR3-binding chemokines, IFN-inducible protein 10, monokine induced by IFN, and IFN-inducible T cell alpha chemoattractant in human cardiac allografts: association with cardiac allograft vasculopathy and acute rejection.

CXCR3 chemokines exert potent biological effects on both immune and vascular cells. The dual targets suggest their important roles in cardiac allograft vasculopathy (CAV) and rejection. Therefore, we investigated expression of IFN-inducible protein 10 (IP-10), IFN-inducible T cell alpha chemoattractant (I-TAC), monokine induced by IFN (Mig), and their receptor CXCR3 in consecutive endomyocardial biopsies (n = 133) from human cardiac allografts and corresponding normal donor hearts (n = 11) before transplantation. Allografts, but not normal hearts, contained IP-10, Mig, and I-TAC mRNA. Persistent elevation of IP-10 and I-TAC was associated with CAV. Allografts with CAV had an IP-10-GAPDH ratio 3.7 +/- 0.8 compared with 0.8 +/- 0.2 in those without CAV (p = 0.004). Similarly, I-TAC mRNA levels were persistently elevated in allografts with CAV (6.7 +/- 1.9 in allografts with vs 1.5 +/- 0.3 in those without CAV, p = 0.01). In contrast, Mig mRNA was induced only during rejection (2.4 +/- 0.9 with vs 0.6 +/- 0.2 without rejection, p = 0.015). In addition, IP-10 mRNA increased above baseline during rejection (4.1 +/- 2.3 in rejecting vs 1.8 +/- 1.2 in nonrejecting biopsies, p = 0.038). I-TAC did not defer significantly with rejection. CXCR3 mRNA persistently elevated after cardiac transplantation. Double immunohistochemistry revealed differential cellular distribution of CXCR3 chemokines. Intragraft vascular cells expressed high levels of IP-10 and I-TAC, while Mig localized predominantly in infiltrating macrophages. CXCR3 was localized in vascular and infiltrating cells. CXCR3 chemokines are induced in cardiac allografts and differentially associated with CAV and rejection. Differential cellular distribution of these chemokines in allografts indicates their central roles in multiple pathways involving CAV and rejection. This chemokine pathway may serve as a monitor and target for novel therapies to prevent CAV and rejection.

CD154 regulates primate humoral immunity to influenza.

Current methods of immunosuppression for the purposes of allowing solid organ transplantation in humans are broadly inhibitory and thus are associated with an increased risk of opportunistic infections and neoplasia. We have shown previously that a selective blockade of CD40-CD154 interactions during heart transplantation in cynomolgus macaques significantly delays immune-mediated graft injury. Here, we determined the effect of anti-CD154 mAb therapy on primate serologic responses to immunization with influenza virus hemagglutinin (HA), a T-cell-dependent Ag. We found that CD154 blockade attenuated primary and secondary serum Ab responses of IgM and IgG isotypes to influenza, even when anti-CD154 treatment was discontinued prior to reimmunization. These findings show that in primates CD40-CD154 interactions are necessary for both primary and secondary Ab responses to viral Ags. Furthermore, the data suggest that viral Ag stimulation of primates in the absence of CD154 stimulation may have a tolerizing effect on that Ag.