Quantitation of T lymphocytes in posttransplant transbronchial biopsies

Diagnosis of Acute Cellular Rejection and Antibody-Mediated Rejection on Lung Transplant Biopsies: A Perspective From Members of the Pulmonary Pathology Society

Context.—

The diagnosis and grading of acute cellular and antibody-mediated rejection (AMR) in lung allograft biopsies is important because rejection can lead to acute graft dysfunction and/or failure and may contribute to chronic graft failure. While acute cellular rejection is well defined histologically, no reproducible specific features of AMR are currently identified. Therefore, a combination of clinical features, serology, histopathology, and immunologic findings is suggested for the diagnosis of AMR.

Objective.—

To describe the perspective of members of the Pulmonary Pathology Society (PPS) on the workup of lung allograft transbronchial biopsy and the diagnosis of acute cellular rejection and AMR in lung transplant.

Data Sources.—

Reports by the International Society for Heart and Lung Transplantation (ISHLT), experience of members of PPS who routinely review lung allograft biopsies, and search of literature database (PubMed).

Conclusions.—

Acute cellular rejection should be assessed and graded according to the 2007 working formulation of the ISHLT. As currently no specific features are known for AMR in lung allografts, the triple test (clinical allograft dysfunction, donor-specific antibodies, pathologic findings) should be used for its diagnosis. C4d staining might be performed when morphologic, clinical, and/or serologic features suggestive of AMR are identified.

Future direction of immunosuppression in lung transplantation

PURPOSE OF REVIEW

Immunosuppression regimens have helped improve rejection episodes following lung transplantation, but long-term outcomes are still not comparable with cardiac, hepatic, or renal transplantation. This review summarizes the immunobiology that contributes to rejection events and future opportunities in outcomes on the basis of providing optimized delivery of the immunosuppression based on immune-monitoring techniques, taking into account individual patient pharmacokinetics and phenotypic variance.

RECENT FINDINGS

Drug toxicities, narrow therapeutic drug monitoring windows, and current immunoassays currently do not assist in detecting the global degree of immunosuppression. The currently available randomized control trials for induction therapy or maintenance therapies do not provide additional benefits compared with previously reported retrospective trials. To push beyond the current barriers, transplant teams are focusing on the role of pharmacokinetics, assessing phenotypic variable to potentially modify to quadruple therapy and using extracorporeal photopheresis.

SUMMARY

Conventional practice for the choices of immunosuppression is being evaluated on the basis of randomized control trials as opposed to retrospective studies or single-center trials. The future direction of immunosuppression will be continued by dynamic processes taking into consideration measures to improve tolerance, reducing treatment burden, and providing the best level of evidence while accounting for rejection, infections, renal function, and other comorbidities.

Azithromycin and the treatment of lymphocytic airway inflammation after lung transplantation

Lymphocytic airway inflammation is a major risk factor for chronic lung allograft dysfunction, for which there is no established treatment. We investigated whether azithromycin could control lymphocytic airway inflammation and improve allograft function. Fifteen lung transplant recipients demonstrating acute allograft dysfunction due to isolated lymphocytic airway inflammation were prospectively treated with azithromycin for at least 6 months (NCT01109160). Spirometry (FVC, FEV1 , FEF25-75 , Tiffeneau index) and FeNO were assessed before and up to 12 months after initiation of azithromycin. Radiologic features, local inflammation assessed on airway biopsy (rejection score, IL-17(+)  cells/mm(2) lamina propria) and broncho-alveolar lavage fluid (total and differential cell counts, chemokine and cytokine levels); as well as systemic C-reactive protein levels were compared between baseline and after 3 months of treatment. Airflow improved and FeNO decreased to baseline levels after 1 month of azithromycin and were sustained thereafter. After 3 months of treatment, radiologic abnormalities, submucosal cellular inflammation, lavage protein levels of IL-1β, IL-8/CXCL-8, IP-10/CXCL-10, RANTES/CCL5, MIP1-α/CCL3, MIP-1β/CCL4, Eotaxin, PDGF-BB, total cell count, neutrophils and eosinophils, as well as plasma C-reactive protein levels all significantly decreased compared to baseline (p < 0.05). Administration of azithromycin was associated with suppression of posttransplant lymphocytic airway inflammation and clinical improvement in lung allograft function.

T cell immunohistochemistry refines lung transplant acute rejection diagnosis and grading

Objective

Lung transplant volume has been increasing. However, inaccurate and uncertain diagnosis for lung transplant rejection hurdles long-term outcome due to, in part, interobserver variability in rejection grading. Therefore, a more reliable method to facilitate diagnosing and grading rejection is warranted.

Method

Rat lung grafts were harvested on day 3, 7, 14 and 28 post transplant for histological and immunohistochemical assessment. No immunosuppressive treatment was administered. We explored the value of interstitial T lymphocytes quantification by immunohistochemistry and compared the role of T cell immunohistochemistry with H&E staining in diagnosing and grading lung transplant rejection.

Results

Typical acute rejection from grade A1 to A4 was found. Rejection severity was heterogeneously distributed in one-third transplanted lungs (14/40): lesions in apex and center were more augmented than in the base and periphery of the grafts, respectively. Immunohistochemistry showed profound difference in T lymphocyte infiltration among grade A1 to A4 rejections. The coincidence rate of H&E and immunohistochemistry was 77.5%. The amount of interstitial T lymphocyte infiltration increased gradually with the upgrading of rejection. The statistical analysis demonstrated that the difference in the amount of interstitial T lymphocytes between grade A2 and A3 was not obvious. However, T lymphocytes in lung tissue of grade A4 were significantly more abundant than in other grades.

Conclusions

Rejection severity was heterogeneously distributed within lung grafts. Immunohistochemistry improves the sensitivity and specificity of rejection diagnosis, and interstitial T lymphocyte quantitation has potential value in diagnosing and monitoring lung allograft rejection.

Virtual slides

The virtual slides for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1536075282108217.

SaLUTaRy: survey of lung transplant rejection

BACKGROUND

The International Society for Heart and Lung Transplantation (ISHLT) guidelines on the interpretation of lung rejection in pulmonary allograft biopsy specimens were revised most recently in 2007. The goal of our study was to determine how these revisions, along with nuances in the interpretation and application of the guidelines, affect patient care.

METHODS

A Web-based survey was e-mailed to pathologists and pulmonologists identified as being part of the lung transplant team at institutions in the United States with active lung transplant programs as determined from the Organ Procurement and Transplantation Network Web site (http://optn.transplant.hrsa.gov/members/directory.asp).

RESULTS

Grades B1 and B2 in asymptomatic patients would fall into the same treatment group under the 2007 classification, which combines B1 and B2 into B1R. Also, some pulmonologists would not interpret a pathologic diagnosis of lymphocytic bronchiolitis as grade B rejection, resulting in under-treatment of these patients. Regarding bronchiolitis obliterans, most pulmonologists would treat the patient differently if there were an active mononuclear inflammatory infiltrate, and most pathologists would comment on the presence of such an infiltrate, contrary to the 2007 guidelines, which discourage reporting this infiltrate. We also found discrepancies among pathologists in their interpretation of airway lymphocytic infiltrates, whether eosinophils can be present in bronchial-associated lymphoid tissue, and whether airway inflammation represents rejection or bacterial infection.

CONCLUSIONS

The issue of grading and treating airway inflammation in pulmonary allograft biopsy specimens continues to be problematic, despite revised ISHLT guidelines. Clarification of guidelines for pathologists and pulmonologists using evidence-based criteria could lead to improved communication and patient care.

Innate immune activation potentiates alloimmune lung disease independent of chemokine (C-X-C motif) receptor 3

BACKGROUND

Pulmonary graft-versus-host disease (GVHD) after hematopoietic cell transplant (HCT) and allograft rejection after lung transplant are parallel immunologic processes that lead to significant morbidity and mortality. Our murine model of pulmonary GVHD after inhaled lipopolysaccharide (LPS) suggests that innate immune activation potentiates pulmonary transplant-related alloimmunity. We hypothesized that the chemokine (C-X-C motif) receptor 3 (CXCR3) receptor is necessary for the development of LPS-induced pulmonary GVHD.

METHODS

Recipient mice underwent allogeneic or syngeneic HCT, followed by inhaled LPS. CXCR3 inhibition was performed by using CXCR3-knockout donors or by systemic anti-CXCR3 antibody blockade. Pulmonary histopathology, cellular sub-populations, cytokine proteins, and transcripts were analyzed.

RESULTS

Compared with the lungs of LPS-unexposed and syngeneic controls, lungs of LPS-exposed allogeneic HCT mice demonstrated prominent lymphocytic peri-vascular and peri-bronchiolar infiltrates. This pathology was associated with increased CD4(+) and CD8(+) T cells as well as an increase in CXCR3 expression on T cells, a 2-fold upregulation of CXCR3 transcript, and a 4-fold increase in its ligand CXCL10/Interferon gamma-induced protein 10 kDa (IP-10). CXCR3 inhibition using gene-knockout strategy or antibody blockade did not change the severity of pulmonary pathology, with a mean pathology score of 6.5 for sufficient vs 6.5 for knockout (p = 1.00) and a mean score of 6.8 for antibody blockade vs 7.4 for control (p = 0.46). CXCR3 inhibition did not prevent CD3 infiltration or prevent production of interleukin-12p40 or significantly change other Th1, Th2, or Th17 cytokines in the lung.

CONCLUSIONS

In the setting of allogeneic HCT, innate immune activation by LPS potentiates pulmonary GVHD through CXCR3-independent mechanisms. Clinical strategies focused on inhibition of CXCR3 may prove insufficient to ameliorate transplant-related lung disease.

Toward managing chronic rejection after lung transplant: the fate and effects of inhaled cyclosporine in a complex environment

The fate and effects of inhaled cyclosporine A (CsA) are considered after deposition on the lung surface. Special emphasis is given to a post-lung transplant environment and to the potential effects of the drug on the various cell types it is expected to encounter. The known stability, metabolism, pharmacokinetics and pharmacodynamics of the drug have been reviewed and discussed in the context of the lung microenvironment. Arguments support the contention that the immuno-inhibitory and anti-inflammatory effects of CsA are not restricted to T-cells. It is likely that pharmacologically effective concentrations of CsA can be sustained in the lungs but due to the complexity of uptake and action, the elucidation of effective posology must ultimately rely on clinical evidence.

T lymphocyte subset abnormalities in the blood and lung in pulmonary arterial hypertension

RATIONALE

Mounting data suggest that immune cell abnormalities participate in the pathogenesis of pulmonary arterial hypertension (PAH).

OBJECTIVE

To determine whether the T lymphocyte subset composition in the systemic circulation and peripheral lung is altered in PAH.

METHODS

Flow cytometric analyses were performed to determine the phenotypic profile of peripheral blood lymphocytes in idiopathic PAH (IPAH) patients (n=18) and healthy controls (n=17). Immunocytochemical analyses of lymphocytes and T cell subsets were used to examine lung tissue from PAH patients (n=11) and controls (n=11).

MEASUREMENTS AND MAIN RESULTS

IPAH patients have abnormal CD8+ T lymphocyte subsets, with a significant increase in CD45RA+ CCR7- peripheral cytotoxic effector-memory cells (p=0.02) and reduction of CD45RA+ CCR7+ naive CD8+ cells versus controls (p=0.001). Further, IPAH patients have a higher proportion of circulating regulatory T cells (T(reg)) and 4-fold increases in the number of CD3+ and CD8+ cells in the peripheral lung compared with controls (p<0.01).

CONCLUSIONS

Alterations in circulating T cell subsets, particularly CD8+ T lymphocytes and CD4+ T(reg), in patients with PAH suggest that a dysfunctional immune system contributes to disease pathogenesis. A preponderance of CD3+ and CD8+ T lymphocytes in the peripheral lung of PAH patients supports this concept.