Hematopoietic growth factor inducible neurokinin-1 (Gpnmb/Osteoactivin) is a biomarker of progressive renal injury across species.

We sought to find a urinary biomarker for chronic kidney disease and tested hematopoietic growth factor inducible neurokinin-1 (HGFIN, also known as Gpnmb/Osteoactivin) as it was found to be a kidney injury biomarker in microarray studies. Here, we studied whether HGFIN is a marker of kidney disease progression. Its increase in kidney disease was confirmed by real-time PCR after 5/6 nephrectomy, in streptozotocin-induced diabetes, and in patients with chronic kidney disease. In the remnant kidney, HGFIN mRNA increased over time reflecting lesion chronicity. HGFIN was identified in the infarct portion of the remnant kidney in infiltrating hematopoietic interstitial cells, and in distal nephron tubules of the viable remnant kidney expressed de novo with increasing time. In vitro, it localized to cytoplasmic vesicles and cell membranes. Epithelial cells lining distal tubules and sloughed luminal tubule cells of patients expressed HGFIN protein. The urine HGFIN-to-creatinine ratio increased over time after 5/6 nephrectomy; increased in patients with proteinuric and polycystic kidney disease; and remained detectable in urine after prolonged freezer storage. The urine HGFIN-to-creatinine ratio compared favorably with the urine neutrophil gelatinase-associated lipocalin (NGAL)-to-creatinine ratio (both measured by commercial enzyme-linked immunosorbent assays (ELISAs)), and correlated strongly with proteinuria, but weakly with estimated glomerular filtration rate and serum creatinine. Thus, HGFIN may be a biomarker of progressive kidney disease.

Analysis of serum Hsp90 as a potential biomarker of ß cell autoimmunity in type 1 diabetes.

Heat shock protein 90 (Hsp90) is a protein chaperone that is upregulated and released from pancreatic ß cells under pro-inflammatory conditions. We hypothesized that serum Hsp90 may have utility as a biomarker of type 1 diabetes risk and exhibit elevations before the onset of clinically significant hyperglycemia. To this end, total levels of the alpha cytoplasmic isoform of Hsp90 were assayed in autoantibody-positive progressors to type 1 diabetes using banked serum samples from the TrialNet Pathway to Prevention Cohort that had been collected 12 months prior to diabetes onset, with comparison to age, sex, and BMI-category matched autoantibody-positive nonprogressors and healthy controls. Hsp90 levels were higher in autoantibody-positive progressors and nonprogressors ≤ 18 years of age compared to matched healthy controls. However, Hsp90 levels were not different between progressors and nonprogressors in any age group. Hsp90 was positively correlated with age in control subjects, but this correlation was absent in autoantibody positive individuals. In aggregate these data indicate that elevated Hsp90 levels are present in youth with ß cell autoimmunity, but are not able to distinguish youth or adult type 1 diabetes progressors from nonprogressors in samples collected 12 months prior to diabetes development.

Proinsulin and heat shock protein 90 as biomarkers of beta-cell stress in the early period after onset of type 1 diabetes.

Rapid evaluation of therapies designed to preserve ß cells in persons with type 1 diabetes (T1D) is hampered by limited availability of sensitive ß-cell health biomarkers. In particular, biomarkers elucidating the presence and degree of ß-cell stress are needed. We characterized ß-cell secretory activity and stress in 29 new-onset T1D subjects (10.6 ± 3.0 years, 55% male) at diagnosis and then 8.2 ± 1.2 weeks later at first clinic follow-up. We did comparisons with 16 matched healthy controls. We evaluated hemoglobin A1c (HbA1c), ß-cell function (random C-peptide [C] and proinsulin [PI]), ß-cell stress (PI:C ratio), and the ß-cell stress marker heat shock protein (HSP)90 and examined these parameters' relationships with clinical and laboratory characteristics at diagnosis. Mean diagnosis HbA1c was 11.3% (100 mmol/mol) and 7.6% (60 mmol/mol) at follow-up. C-peptide was low at diagnosis (P < 0.001 vs controls) and increased at follow-up (P < 0.001) to comparable with controls. PI did not differ from controls at diagnosis but increased at follow-up (P = 0.003) signifying increased release of PI alongside improved insulin secretion. PI:C ratios and HSP90 concentrations were elevated at both time points. Younger subjects had lower C-peptide and greater PI, PI:C, and HSP90. We also examined islets isolated from prediabetic nonobese diabetic mice and found that HSP90 levels were increased ∼4-fold compared with those in islets isolated from matched CD1 controls, further substantiating HSP90 as a marker of ß-cell stress in T1D. Our data indicate that ß-cell stress can be assessed using PI:C and HSP90. This stress persists after T1D diagnosis. Therapeutic approaches to reduce ß-cell stress in new-onset T1D should be considered.

Elevations in Circulating Methylated and Unmethylated Preproinsulin DNA in New-Onset Type 1 Diabetes.

Elevated ratios of circulating unmethylated to methylated preproinsulin (INS) DNA have been suggested to reflect ß-cell death in type 1 diabetes (T1D). We tested the hypothesis that absolute levels (rather than ratios) of unmethylated and methylated INS DNA differ between subjects with new-onset T1D and control subjects and assessed longitudinal changes in these parameters. We used droplet digital PCR to measure levels of unmethylated and methylated INS DNA in serum from subjects at T1D onset and at 8 weeks and 1 year post-onset. Compared with control subjects, levels of both unmethylated and methylated INS DNA were elevated at T1D onset. At 8 weeks post-onset, methylated INS DNA remained elevated, but unmethylated INS DNA fell. At 1 year postonset, both unmethylated and methylated INS DNA returned to control levels. Subjects with obesity, type 2 diabetes, and autoimmune hepatitis exhibited lower levels of unmethylated and methylated INS compared with subjects with T1D at onset and no differences compared with control subjects. Our study shows that elevations in both unmethylated and methylated INS DNA occurs in new-onset T1D and that levels of these DNA species change during T1D evolution. Our work emphasizes the need to consider absolute levels of differentially methylated DNA species as potential biomarkers of disease.

Established and emerging biomarkers for the prediction of type 1 diabetes: a systematic review.

Type 1 diabetes (T1D) is an autoimmune disease with a prolonged and variable latent period that culminates in the destruction of pancreatic ß-cells and the development of hyperglycemia. There is a need for diagnostic biomarkers to detect more accurately individuals with prediabetes to expedite targeting for prevention and intervention strategies. To assess the current ability to predict the insidious development of T1D, we conducted a comprehensive systematic review for established and prospective predictive markers of T1D using the Medline, OVID, and EMBASE databases. Resulting citations were screened for relevance to subject. Our research generated five major categories of markers that are either currently used or forthcoming: genetic, autoantibody, risk score quantification, cellular immunity, and ß-cell function. The current standard used to assess T1D onset or predisposition focuses on autoimmune pathology and disease-associated autoantibodies. Research studies in general go beyond autoantibody screening and assess genetic predisposition, and quantitate risk of developing disease based on additional factors. However, there are few currently used techniques that assess the root of T1D: ß-cell destruction. Thus, novel techniques are discussed with the potential to gauge degrees of ß-cell stress and failure via protein, RNA, and DNA analyses.