An Anti-C1s Monoclonal, TNT003, Inhibits Complement Activation Induced by Antibodies Against HLA.

Antibody-mediated rejection (AMR) of solid organ transplants (SOT) is characterized by damage triggered by donor-specific antibodies (DSA) binding donor Class I and II HLA (HLA-I and HLA-II) expressed on endothelial cells. While F(ab')2 portions of DSA cause cellular activation and proliferation, Fc regions activate the classical complement cascade, resulting in complement deposition and leukocyte recruitment, both hallmark features of AMR. We characterized the ability of an anti-C1s monoclonal antibody, TNT003, to inhibit HLA antibody (HLA-Ab)-induced complement activation. Complement deposition induced by HLA-Ab was evaluated using novel cell- and bead-based assays. Human aortic endothelial cells (HAEC) were cultured with HLA-Ab and human complement; production of activated complement proteins was measured by flow cytometry. Additionally, C3d deposition was measured on single antigen beads (SAB) mixed with HLA-Ab and human complement. TNT003 inhibited HLA-Ab mediated complement deposition on HAEC in a concentration-dependent manner; C3a, C4a and C5a anaphylatoxin production was also diminished by TNT003. Finally, TNT003 blocked C3d deposition induced by Class I (HLAI-Ab)- and Class II (HLAII-Ab)-specific antibodies on SAB. These data suggest TNT003 may be useful for modulating the effects of DSA, as TNT003 inhibits complement deposition and split product formation generated by HLA-I/II-Ab in vitro

"Suboptimal" kidney donors: The experience with tacrolimus-based immunosuppression

Female, pediatric, and older donors have been associated with inferior graft survival after renal transplantation. We analyzed these three subgroups in 397 patients receiving tacrolimus-based immunosuppression. There were no differences in recipient age, incidence of retransplantation, or percentage of sensitized patients. Female donors, compared with male donors, were associated with comparable 1- and 3-year patient survival rates (96% and 93% vs. 95% and 92%, respectively) and comparable 1- and 3-year graft survival rates (90% and 80% vs. 88% and 81%, respectively). Renal function was also similar. Recipients of pediatric en bloc kidneys, when compared with recipients of other cadaveric kidneys, also had comparable 1- and 3-year patient survival rates (94% and 94% vs. 95% and 91%, respectively) and comparable 1- and 3-year graft survival rates (84% and 84% vs. 89% and 79%, respectively). Renal function was better in recipients of en bloc kidneys, with a mean serum creatinine level of 1.4±1.8 mg/dl vs. 2.0±1.5 mg/dl (P=0.01). In contrast to the first two subgroups, donors over 60 years of age, when compared with donors under 60 years of age, were associated with worse 1- and 3-year patient survival rates (88% and 80% vs. 96% and 94%, respectively; P<0.03) and worse 1- and 3-year graft survival rates (74% and 62% vs. 91% and 83%, respectively; P<0.0001). Renal function was worse in the older donor group, with a serum creatinine level of 2.7±1.2 mg/ml vs. 1.9±1.5 mg/dl (P=0.01). We conclude that, under tacrolimus-based immunosuppression, kidneys from female or very young pediatric donors are not associated with adverse outcomes, whereas kidneys from donors over 60 years of age are associated with inferior outcomes

HLA and cross-reactive antigen group matching for cadaver kidney allocation

Background. Allocation of cadaver kidneys by graded human leukocyte antigen (HLA) compatibility scoring arguably has had little effect on overall survival while prejudicing the transplant candidacy of African-American and other hard to match populations. Consequently, matching has been proposed of deduced amino acid residues of the individual HLA molecules shared by cross- reactive antigen groups (CREGs). We have examined the circumstances under which compatibility with either method impacted graft survival. Methods. Using Cox proportional hazards regression modeling, we studied the relationship between levels of conventional HLA mismatch and other donor and recipient factors on primary cadaver kidney survival between 1981 and 1995 at the University of Pittsburgh (n=1,780) and in the United Network for Organ Sharing (UNOS) Scientific Registry during 1991-1995 (n=31,291). The results were compared with those obtained by the matching of amino acid residues that identified CREG-compatible cases with as many as four (but not five and six) HLA mismatches. Results. With more than one HLA mismatch (>85% of patients in both series), most of the survival advantage of a zero mismatch was lost. None of the HLA loci were 'weak.' In the UNOS (but not Pittsburgh) category of one-HLA mismatch (n=1334), a subgroup of CREG-matched recipients (35.3%) had better graft survival than the remaining 64.7%, who were CREG-mismatched. There was no advantage of a CREG match in the two- to four-HLA incompatibility tiers. Better graft survival with tacrolimus was observed in both the Pittsburgh and UNOS series. Conclusions. Obligatory national sharing of cadaver kidneys is justifiable only for zero-HLA-mismatched kidneys. The potential value of CREG matching observed in the one-HLA-mismatched recipients of the UNOS (but not the Pittsburgh) experience deserves further study

Should Pediatric Patients Wait for HLA-DR-Matched Renal Transplants?

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74900/1/j.1600-6143.2008.02320.x.pd

Human DNA methylation signatures differentiate persistent from resolving MRSA bacteremia

Persistent methicillin-resistant Staphylococcus aureus (MRSA) bacteremia is life threatening and occurs in up to 30% of MRSA bacteremia cases despite appropriate antimicrobial therapy. Isolates of MRSA that cause antibiotic-persistent methicillin-resistant S. aureus bacteremia (APMB) typically have in vitro antibiotic susceptibilities equivalent to those causing antibiotic-resolving methicillin-resistant S. aureus bacteremia (ARMB). Thus, persistence reflects host-pathogen interactions occurring uniquely in context of antibiotic therapy in vivo. However, host factors and mechanisms involved in APMB remain unclear. We compared DNA methylomes in circulating immune cells from patients experiencing APMB vs. ARMB. Overall, methylation signatures diverged in the distinct patient cohorts. Differentially methylated sites intensified proximate to transcription factor binding sites, primarily in enhancer regions. In APMB patients, significant hypomethylation was observed in binding sites for CCAAT enhancer binding protein-β (C/EBPβ) and signal transducer/activator of transcription 1 (STAT1). In contrast, hypomethylation in ARMB patients localized to glucocorticoid receptor and histone acetyltransferase p300 binding sites. These distinct methylation signatures were enriched in neutrophils and achieved a mean area under the curve of 0.85 when used to predict APMB using a classification model. These findings validated by targeted bisulfite sequencing (TBS-seq) differentiate epigenotypes in patients experiencing APMB vs. ARMB and suggest a risk stratification strategy for antibiotic persistence in patients treated for MRSA bacteremia

Using Transitional Changes on Highâ Resolution Computed Tomography to Monitor the Impact of Cyclophosphamide or Mycophenolate Mofetil on Systemic Sclerosisâ Related Interstitial Lung Disease

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/153695/1/art41085.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153695/2/art41085_am.pd