Evidence for small fiber neuropathy in early Parkinson's disease

INTRODUCTION

Parkinson's disease (PD) is neurodegenerative movement disorder affecting primarily the central nervous system with several recognized non-motor symptoms that can occur at various stages of the disease. Recently it has been shown that patients with PD may be prone to peripheral nervous system pathology in the form of a peripheral neuropathy (PN). It is unclear if PN is an inherent feature of PD or if it is an iatrogenic effect of the mainstay PD treatment Levodopa.

METHODS

To determine if peripheral neuropathy occurs in early untreated PD we employed a case-control study design using gold standard tests for PN, including neurological examination according to the Utah Early Neuropathy Scale (UENS) and nerve conduction studies, as well as new, more sensitive and informative tests for PN including the skin biopsy and corneal confocal microscopy (CCM).

RESULTS

We studied 26 patients with PD and 22 controls using the neurological examination and nerve conduction studies (NCS) and found no significant difference between groups except for some reduced vibration sense in the PD group. Epidermal nerve densities in the skin biopsies were similar between our cohorts. However, using CCM - a more sensitive test and a surrogate marker of small fiber damage in PN, we found that patients with PD had significantly reduced corneal nerve fiber densities and lengths as compared to controls.

CONCLUSIONS

We conclude that our positive CCM results provide evidence of preclinical PN in newly diagnosed PD patients.

Low Counts of B Cells, Natural Killer Cells, Monocytes, Dendritic Cells, Basophils, and Eosinophils are Associated with Postengraftment Infections after Allogeneic Hematopoietic Cell Transplantation

Hematopoietic cell transplant (HCT) recipients are immunocompromised and thus predisposed to infections. We set out to determine the deficiency of which immune cell subset(s) may predispose to postengraftment infections. We determined day 28, 56, 84, and 180 blood counts of multiple immune cell subsets in 219 allogeneic transplant recipients conditioned with busulfan, fludarabine, and Thymoglobulin. Deficiency of a subset was considered to be associated with infections if the low subset count was significantly associated with subsequent high infection rate per multivariate analysis in both discovery and validation cohorts. Low counts of monocytes (total and inflammatory) and basophils, and low IgA levels were associated with viral infections. Low plasmacytoid dendritic cell (PDC) counts were associated with bacterial infections. Low inflammatory monocyte counts were associated with fungal infections. Low counts of total and naive B cells, total and CD56(high) natural killer (NK) cells, total and inflammatory monocytes, myeloid dendritic cells (MDCs), PDCs, basophils and eosinophils, and low levels of IgA were associated with any infections (due to any pathogen or presumed). In conclusion, deficiencies of B cells, NK cells, monocytes, MDCs, PDCs, basophils, eosinophils, and/or IgA plasma cells appear to predispose to postengraftment infections.

Immune cell subset counts associated with graft-versus-host disease

Graft-versus-host disease (GVHD) is a major transplantation complication. The purpose of this study was to measure immune cell subsets by flow cytometry early after transplantation (before median day of GVHD onset) to identify subsets that may play a role in GVHD pathogenesis. We also measured the subsets later after transplantation to determine which subsets may be influenced by GVHD or its treatment. We studied 219 patients. We found that acute GVHD (aGVHD) was preceded by high counts of CD4 T cells and CD8 T cells. It was followed by low counts of total and naive B cells, total and cytolytic NK cells, and myeloid and plasmacytoid dendritic cells. Chronic GVHD (cGVHD) was preceded by low counts of memory B cells. In conclusion, both CD4 and CD8 T cells appear to play a role in the pathogenesis of aGVHD. Generation of B cells, NK cells, and dendritic cells may be hampered by aGVHD and/or its treatment. Memory B cells may inhibit the development of cGVHD.

IL15 levels on day 7 after hematopoietic cell transplantation predict chronic GVHD

Chronic GVHD (cGVHD) is an important complication of allogeneic hematopoietic cell transplantation (HCT). As preemptive therapy might be efficacious if administered early post transplant, we set out to determine whether cGVHD can be predicted from the serum level of a biomarker on day 7 or 28. In a discovery cohort of 153 HCT recipients conditioned with BU, fludarabine and rabbit antithymocyte globulin (ATG), we determined serum levels of B-cell-activating factor, vascular endothelial growth factor, soluble TNF-α receptor 1, soluble IL2 receptor α, IL5, IL6, IL7, IL15, γ-glutamyl transpeptidase, cholinesterase, total protein, urea and ATG. Patients with low levels of IL15 (<30.6 ng/L) on day 7 had 2.7-fold higher likelihood of developing significant cGVHD (needing systemic immunosuppressive therapy) than patients with higher IL15 levels (P<0.001). This was validated in a validation cohort of 105 similarly-treated patients; those with low IL15 levels had 3.7-fold higher likelihood of developing significant cGVHD (P=0.001). Low IL15 was not associated with relapse; it trended to be associated with acute GVHD and was associated with low infection rates. In conclusion, low IL15 levels on day 7 are predictive of cGVHD, and thus could be useful in guiding preemptive therapy.

High rabbit-antihuman thymocyte globulin levels are associated with low likelihood of graft-vs-host disease and high likelihood of posttransplant lymphoproliferative disorder

Rabbit-antithymocyte globulin (ATG) given with conditioning has the potential to decrease the likelihood of graft-versus-host disease (GVHD) or graft failure and to increase the likelihood of relapse or infections. After a given ATG dose, serum ATG levels are variable. Here we determined ATG levels on days 7 and 28 in 153 patients whose conditioning included 4.5 mg/kg ATG (thymoglobulin). Median follow-up was 547 days (range: 14-1519, minimum for patients who have not died, relapsed, developed second malignancy, or had graft failure, 365). Both high day 7 levels and high day 28 levels were associated with low likelihoods of grade II-IV acute GVHD and chronic GVHD needing systemic immunosuppressive therapy, and a high likelihood of posttransplant lymphoproliferative disorder (PTLD). Patients with day 7 ATG levels above 0.803 mg/L had 0.52-fold risk of developing chronic GVHD needing systemic therapy (P = 0.012) and patients with day 7 ATG levels above 1.436 mg/L had 5.84-fold risk of developing PTLD (P = 0.001) compared to patients with lower ATG levels. There was no association of ATG levels with relapse, death, or non-PTLD infections. Association with graft failure could not be evaluated due to only 4 graft failures in the cohort. In conclusion, patients with slow clearance of ATG have a low risk of GVHD, but a high risk of PTLD. The clearance of this relatively low dose of ATG does not impact the likelihood of relapse, death, or non-PTLD infections.