Utility of illness severity scores to predict mortality in patients hospitalized with respiratory deterioration of idiopathic pulmonary fibrosis.

INTRODUCTION: In the context of idiopathic pulmonary fibrosis (IPF), respiratory-related admissions to hospital are associated with a high morbidity and short-term mortality with significant burden on secondary care services. It has yet to be determined how to accurately identify patients at risk of acute respiratory deterioration (ARD) or the prognosticating factors. AIM: We sought to define the characteristics of hospitalized ARD-IPF patients in a real-world cohort and investigate factors associated with worse outcomes. Specifically, we wished to determine the association between baseline CURB-65 and NEWS-2 and mortality in IPF, given illness severity scores have not previously been validated in this cohort. METHODS: Single-centre retrospective observational cohort study. RESULTS: Of 172 first hospitalizations for ARD, 27 admissions (15.7%) were due to an acute exacerbation of IPF (AE-IPF), 28 (16.3%) secondary to cardiac failure/fluid overload and 17 due to pneumonia (9.9%). Other admissions related to lower respiratory tract infection, extra-parenchymal causes and those without a specific trigger. Baseline patient characteristics were comparable for all underlying aetiologies of ARD-IPF. Treatment pathways did not differ significantly between AE-IPF and other causes of ARD-IPF. Short-term mortality was high, with ∼22% patients dying within 30 days. Illness severity scores (NEWS-2 and CURB-65) were independent predictors of mortality in multivariable logistic regression modelling. CONCLUSIONS: Our findings suggest significant mortality related to hospitalization with ARD-IPF of any underlying cause. Our data support the use of CURB-65 and NEWS-2 scores as illness severity scores that can provide a simple tool to help future prognostication in IPF. Research should be aimed at refining the management of these episodes, to try to reduce mortality, where possible, or to facilitate palliative care for those with adverse prognostic characteristics.

Visual analogue scales for interstitial lung disease: a prospective validation study.

BACKGROUND: Visual analogue scales (VAS) are simple symptom assessment tools which have not been validated in interstitial lung disease (ILD). Simple measures of ILD disease burden would be valuable for non-specialist clinicians monitoring disease away from ILD specialist centres. OBJECTIVE: To validate VAS to assess change in dyspnoea, cough and fatigue in ILD, and to define the minimal clinically important difference (MCID) for change in these. METHODS: Patients of 64 with ILD completed VAS for dyspnoea, cough and fatigue. Baseline King's Brief ILD questionnaire (K-BILD) scores, lung function and 6-min walk test results were collected. Tests were repeated 3-6 months later, in addition to a seven-point Likert scale. The MCID was estimated using median change in VAS in patients who reported 'small but just worthwhile change' in symptoms at follow-up. Methods were repeated in a validation cohort of 31 ILD patients to confirm findings. RESULTS: VAS scores were significantly higher for patients who reported a 'small but just worthwhile change' in symptoms vs. 'no change' or 'not worthwhile change' (P < 0.01). The MCID for VAS Dyspnoea was estimated as 22.0 mm and 14.5 mm for VAS Fatigue. These results were reproducible in the validation cohort. Results were not significant for VAS Cough. Change in VAS Dyspnoea correlated with change in K-BILD (r = -0.51, P < 0.01), forced vital capacity (r = -0.32, P = 0.01) and 6-min walking distance (r = -0.37, P = 0.01). CONCLUSION: The VAS is valid for assessing change in dyspnoea and fatigue in ILD. The MCID is estimated as 22.0 mm for dyspnoea and 14.5 mm for fatigue. This could be used to monitor disease in settings away from ILD specialist review. MESH DESCRIPTORS: Lung Diseases, Interstitial, Dyspnoea, Fatigue, Cough.

Pleuroparenchymal sarcoidosis - A recognised but rare manifestation of disease.

Pleural involvement is rare in sarcoidosis. The presence of a large symptomatic effusion in a patient with sarcoidosis should therefore prompt further investigation for an alternate aetiology. Here we present a case of confirmed pleuro-parenchymal sarcoidosis. We discuss the important differential diagnoses and review the current literature.

Idiopathic pulmonary fibrosis: current and future directions.

Idiopathic pulmonary fibrosis (IPF) is the most common idiopathic interstitial pneumonia and is increasingly recognised. Prior to the advent of effective therapies, achieving an early diagnosis was arguably of little prognostic consequence given IPF was considered an untreatable and uniformly fatal disease. The advent of new drug treatments has given hope for the future and raised the profile of IPF. International management guidelines highlight the critical role of radiology as part of an interstitial lung disease multidisciplinary team approach in reaching an accurate and early diagnosis of IPF. The diagnostic criteria and levels of diagnostic confidence for the radio-pathological pattern associated with the clinical syndrome of IPF, usual interstitial pneumonia (UIP), appear seemingly straightforward; however, with increasing research and recognition of radiopathological interobserver variability, limitations of this classification model are becoming increasingly apparent. This review describes ancillary radiological features, comorbidities, and emerging new entities that potentially co-exist with IPF. Beyond diagnosis radiology is developing as a key prognostic tool to inform longitudinal patient evaluation. These diagnostic and prognostic clinical challenges and the future role of radiology in IPF are discussed.

Use of transbronchial cryobiopsy in the diagnosis of interstitial lung disease-a systematic review and cost analysis.

BACKGROUND: Histological diagnosis by surgical lung biopsy for interstitial lung disease (ILD) is currently limited. Transbronchial cryobiopsy via flexible bronchoscope may this for more patients. The relative costs, diagnostic yields and safety of this approach and more traditional approaches have not been determined. OBJECTIVES: To perform a systematic review and meta-analysis of transbronchial cryobiopsy, forceps transbronchial biopsy and video assisted (VATS) surgical lung biopsy assessing their relative diagnostic yields and safety. To perform a cost analysis to demonstrate any savings through change to the newer technique. METHODS: We performed a systematic review of the literature using MEDLINE and EMBASE for all original articles on the diagnostic yield and safety of transbronchial cryobiopsy, forceps transbronchial biopsy and VATS-biopsy in ILD up to February 2016. Data were extracted on yield and complication rates, in addition to study characteristics. Theoretical cost analysis was performed from local institution financial data, 2015-16 reimbursement tariffs and results of the systematic review. RESULTS: A meta-analysis of 11 investigations for transbronchial cryobiopsy, 11 for forceps transbronchial biopsy and 24 for VATS-biopsy revealed diagnostic yields of 84.4% (75.9-91.4%), 64.3% (52.6-75.1%) and 91.1% (84.9-95.7%), respectively. Pneumothorax occurred in 10% (5.4-16.1%) of transbronchial cryobiopsy procedures, moderate bleeding in 20.99% (5.6-42.8%), with three deaths reported. Surgical mortality was 2.3% (1.3-3.6%). Cost analysis demonstrated potential savings of £210 per patient in the first year and £647 in subsequent years. CONCLUSIONS: Transbronchial cryobiopsy represents a potentially cost-saving approach to improve histological diagnosis in ILD, however is accompanied by a significant risk of moderate bleeding.

Duration of benefit following completion of pulmonary rehabilitation in interstitial lung disease-an observational study.

BACKGROUND: It remains unclear for how long the benefits of pulmonary rehabilitation (PR) last in interstitial lung disease (ILD). An increasing number of ILD patients complete PR and it is vital they be offered the most beneficial approaches. METHODS: This is a retrospective, observational study of a cohort with ILD who had completed PR. Incremental shuttle walk (ISWT) and chronic respiratory disease questionnaire (CRDQ) were compared before PR, at course completion, and 6/12 months follow-up. Focus group discussions with ILD participants who had completed PR and their carers established qualitative views on existing and potential future PR provision. RESULTS: 79 participants with ILD were identified at course completion, with 39 followed to 12 months. 11 participants died during follow-up. Initial benefits from PR were not sustained at 6 months (ISWT change 0.0m (95% CI-23.2 to 23.2 m), CRDQ change 2.5 (95% CI-2.4 to 7.4)) and 12 months (ISWT change-0.7 m (95% CI-37.3 to 35.9 m), CRDQ change 4.0 (95% CI-2.2 to 10.2)). Continued home exercise gave longer lasting benefit in exercise capacity. Focus group discussions highlighted the value attached to PR and suggested areas for improvement. CONCLUSIONS: Standard PR gives initial benefits in participants with ILD who complete the course, however these are not sustained. Tailored approaches to this group would be appreciated by this group and should be explored.

The role of biologics in treatment of connective tissue disease-associated interstitial lung disease.

With an increased understanding of the molecular pathways of inflammation and autoimmunity, the development of targeted biological agents has revolutionized the management of connective tissue diseases (CTDs). There has been an explosion in the development of these drugs in the last decade, targeting diseases in diverse fields including: allergic disorders, oncology, neuroinflammatory disorders, inflammatory bowel disease, macular degeneration and CTDs. In this last field, commonly applied biologics fall into two categories: cytokine inhibitors and lymphocyte-targeted therapies. The former group includes the antitumour necrosis factor alpha (TNF-α), anti-interleukin (IL)-6 receptor monoclonal antibodies and IL-1 receptor antagonists, whilst the latter encompasses the anti-CD20, B-cell depleting, monoclonal antibody (mAb), Rituximab and the anti-T-cell activation agent, Abatacept. This review will examine our developing experience in the use of these agents in the treatment of CTD-related interstitial lung diseases, with a particular focus on B-cell depletion.

A national house-staff audit of medical prophylaxis in medical patients for the PREVENTion of Venous ThromboEmbolism (PREVENT-VTE).

We established a national audit to assess the thromboprophylaxis rate for venous thromoembolism (VTE) in at risk medical patients in acute hospitals in the Republic of Ireland and to determine whether the use of stickers to alert physicians regarding thromboprophylaxis would double the rate prophylaxis in a follow-up audit. 651 acute medical admission patients in the first audit and 524 in the second re-audit were recruited. The mean age was 66.5 yrs with similar numbers of male and female patients and 265 (22.6%) patients were active smokers. The first and second audits identified 549 (84%) and 487 (93%) of patients at-risk for VTE respectively. Of the at-risk patients, 163 (29.7%) and 132 (27.1%) received LMWH in the first and second audit respectively. Mechanical thromboprophylaxis was instigated in 75 (13.6%) patients in the first and 86 (17.7%) patients in the second audit. The placement of stickers in patient charts didn't produce a significant increase in the number of at risk patients treated in the second audit. There is unacceptably low adherence to the ACCP guidelines in Ireland and more complex intervention than chart reminders are required to improve compliance.

Ganciclovir antiviral therapy in advanced idiopathic pulmonary fibrosis: an open pilot study.

Hypothesis. Repeated epithelial cell injury secondary to viruses such as Epstein Barr and subsequent dysfunctional repair may be central to the pathogenesis of IPF. In this observational study, we evaluated whether a combination of standard and anti-viral therapy might have an impact on disease progression. Methods. Advanced IPF patients who failed standard therapy and had serological evidence of previous EBV, received ganciclovir (iv) at 5 mg/kg twice daily. Forced vital capacity (FVC), shuttle walk test, DTPA scan and prednisolone dose were measured before and 8 weeks post-treatment. Results. Fourteen patients were included. After ganciclovir, eight patients showed improvement in FVC and six deteriorated. The median reduction of prednisolone dose was 7.5 mg (44%). Nine patients were classified "responders" of whom four showed an improvement in all four criteria, while three of the five "non-responders" showed no response in any of the criteria. Responders showed reduction in prednisolone dosage (P = .02) and improved DTPA clearance (P = .001). Conclusion. This audit outcome suggests that 2-week course of ganciclovir (iv) may attenuate disease progression in a subgroup of advanced IPF patients. These observations do not suggest that anti-viral treatment is a substitute for the standard care, however, suggests the need to explore the efficacy of ganciclovir as adjunctive therapy in IPF.

The occurrence of hypothyroidism following radioactive iodine treatment of toxic nodular goiter is related to the TSH level.

BACKGROUND: Strategies to increase frequency of euthyroidism following radioactive (RAI) treatment of hyperthyroidism are required. AIMS: To examine the role of TSH in development of hypothyroidism post RAI treatment in patients with Graves' disease (N = 98) or toxic nodular goiter, TNG (N = 88). DESIGN: This retrospective study examined thyroid status over a mean of 3.7 years post-RAI. RESULTS: Although RAI dose was significantly higher in TNG group, hypothyroidism occurred more frequently in Graves' disease (71.4 and 22.7%) P < 0.001. The TSH levels at the time of RAI treatment were lower in TNG patients who remained euthyroid, (0.4+/-0.1 vs. 1.2+/-0.5 mU/l, P < 0.0022). CONCLUSIONS: A higher frequency of euthyroidism occurs in patients with TNG than with Graves' disease following RAI, particularly when suppressed TSH levels were suppressed at time of RAI-treatment.

Expression and regulation of H+K+ATPase in lysosomes of epithelial cells of the adult rat epididymis.

Endocytosis is an important event in the epididymis as it contributes to a luminal environment conducive for sperm maturation. Principal and clear cells contain numerous lysosomes which degrade many substances internalized by endocytosis from the epididymal lumen. The interior of the lysosomes depends on low pH to activate the release of their enzymes and to activate their acid hydrolases. In the present study, H+K+ATPase was localized by light microscopy in the adult rat epididymis of intact and of orchidectomized animals supplemented with testosterone or not. In normal animals, numerous lysosomes of nonciliated cells of the efferent ducts were intensely reactive for anti-H+K+ATPase antibody. In the initial segment, only a few lysosomes of principal cells were reactive. In the intermediate zone of the epididymis, numerous lysosomes of principal cells were intensely reactive, while the number of intensely reactive lysosomes decreased progressively from the proximal caput to the distal caput with none being seen in the proximal corpus region. In the distal corpus and cauda regions, only a few lysosomes of some principal cells were reactive. In contrast, clear cells of all regions showed intense reactivity. Orchidectomy resulted in the abolishion of H+K+ATPase in lysosomes of principal cells of all regions except the initial segment. However, while clear cells of the caput and corpus regions also became unreactive, those of the cauda region remained as reactive as in controls. Orchidectomized animals supplemented with testosterone maintained a staining pattern similar to controls for both cell types. These observations demonstrate the presence in principal and clear cells of H+K+ ATPase which may have an important role in acidifying the interior of their lysosomes. However, there is a region-specific expression of H+K+ATPase in lysosomes of principal cells, unlike that for clear cells. In addition, H+K+ATPase expression in lysosomes of principal cells depends on testosterone in all regions except the initial segment. However, in the case of clear cells, only those of the caput and the corpus regions are dependent on testosterone, while those of the cauda region appear to be regulated by some other factor.

Immunolocalization of CA II and H+ V-ATPase in epithelial cells of the mouse and rat epididymis.

Acidification of the epididymal lumen has been suggested to play an important role in sperm functions; however, the cell types, pumps, and mechanisms involved have not been fully addressed. In this study, carbonic anhydrase II (CA II) and a 67-kd subunit of Neurospora crassa vacuolar proton adenosinetriphosphatase (H+ V-ATPase) pump were immunolocalized using light microscopy and electron microscopy (EM) in the epididymis of rats and mice. In both animals, narrow cells, identified in the initial segment and intermediate zone of the epididymis, contained numerous small vesicles in their apical region, often cup-shaped in appearance. In the mouse but not rat, these cells also possessed numerous cisternae of smooth endoplasmic reticulum, suggesting steroid synthesis; and cytoplasmic blebs of their apical cell surface, which appeared to detach, suggesting apocrine secretion. Anti-CA II antibody was immunocytochemically localized in the light microscope within narrow cells but not over any other cell types of the entire epididymis. Anti-H+ V-ATPase antibody was also localized in narrow cells of the initial segment and intermediate zone; as well as clear cells of the caput, corpus, and cauda regions. Using EM, gold particles for anti-CA II and H+ V-ATPase antibodies were noted in the apical region of narrow cells in relation to the numerous, small, cup-shaped vesicles. Although CA II was mainly located in the cytosol near these vesicles, H+ V-ATPase appeared on their delimiting membrane and on the apical plasma membrane of these cells. A similar distribution was noted for H+ V-ATPase in clear cells. The nature of the small vesicles of the apical region of narrow cells was examined with electron-dense fluid phase tracers that were introduced into the epididymal lumen. The tracers appeared within these vesicles and a few endosomes 1 hour after injection, suggesting that they contact the apical plasma membrane. Since these vesicles are also related to CA II and H+ V-ATPase, the data suggests that, as the site of proton production, the vesicles recycle to and from the apical cell surface, and in this way, deliver protons to the epididymal lumen for acidification. Clear cells and their expression of H+ V-ATPase may also serve in this function. In summary, both narrow and clear cells appear to be involved in luminal acidification, an activity that may be essential for sperm as they traverse and are stored in the epididymis.

I. Abnormalities in cells of the testis, efferent ducts, and epididymis in juvenile and adult mice with beta-hexosaminidase A and B deficiency.

Beta-hexosaminidase (Hex) is a lysosomal enzyme that exists as two major isoenzymes: Hex A (subunit structure, alphabeta) and Hex B (betabeta). The presence of Hex in the testis and epididymis suggests important roles for the enzyme and its substrates in male fertility and reproductive functions. Disruption of the Hexb gene encoding the beta-subunit of Hex has led to the generation of a mouse model of human Sandhoff disease that survives to adulthood, enabling us to analyze the effects of Hex A and Hex B deficiency on epithelial cellular morphology of the male reproductive tract. At 1 and 3 months of age, the testes, efferent ducts, and epididymides of Hex-deficient (Hexb -/-) and wild-type (Hexb +/+) mice were perfuse fixed and analyzed by routine light and electron microscopy (LM and EM, respectively) as well as with immunocytochemistry employing antibodies to lysosomal proteins. In the testis, the morphological appearance and topographical arrangement of the cell types of the seminiferous epithelium of Hexb -/- mice were similar to those of wild-type animals at both ages. Both Sertoli and germ cells appeared to be unaffected. However, at both ages, myoid cells and macrophages showed an increased number of lysosomes in their cytoplasm as compared with the number seen in controls. The epithelial cells of the efferent ducts also showed an accumulation of lysosomes that increased with age as compared with controls. Principal cells of the entire epididymis revealed an increase in the size and number of lysosomes at 1 month of age as compared with those of controls, and by 3 months, these lysosomes often filled the supranuclear and basal regions of the cells. Narrow cells of the distal initial segment and intermediate zone, normally slender cells showing several lysosomes, became greatly enlarged and entirely filled with lysosomes in Hexb -/- mice. Clear cells of the caput, corpus, and cauda regions also showed a progressive increase in the size and number of lysosomes with age as compared with controls; the clear cells of the mutant mice were often enlarged and at times bulged into the lumen. Some basal cells of each epididymal region in Hexb -/- mice were similar to controls at 1 and 3 months, showing few lysosomes, while others showed an accumulation of lysosomes. Lysosomes of all affected epithelial cells were of varying sizes, but many large ones were present, apparently resulting from lysosomal fusion. Although pale stained, their identification as lysosomes was confirmed by EM immunocytochemistry with anti-cathepsin D and anti-Hex A antibodies. Predominantly in the proximal initial segment, large, pale cellular aggregates were noted in the LM analysis at the base of the epithelium, which by EM analysis were identified as belonging to two different cell types, narrow cells and halo cells. Taken together, these data reveal an increase in the size and number of lysosomes in all epithelial cell types lining the efferent ducts and entire epididymis as well as in myoid cells and macrophages of the testis. In the light of data showing epididymal defects restricted predominantly to the initial segment in Hexa -/- (Hex A-deficient) mice, our data on the Hexb -/- mice demonstrate a major role for Hex that can be fulfilled by either Hex A or Hex B in the epididymis.

II. Characterization and development of the regional- and cellular-specific abnormalities in the epididymis of mice with beta-hexosaminidase A deficiency.

Beta-hexosaminidase (Hex) is a lysosomal enzyme that exists as two isoenzymes: Hex A (subunit structure alphabeta) and Hex B (betabeta). Its presence in the testis and epididymis suggests important roles for Hex and its substrates in male fertility and reproductive functions. Disruption of the Hexa gene encoding the alpha-subunit of Hex has led to the generation of a mildly affected mouse model of human Tay-Sachs disease, allowing us the opportunity to analyze the effects of isolated Hex A deficiency on epithelial cellular morphology of the male reproductive tract. At 5 weeks and at 3, 5, and 12 months, the testes, efferent ducts and epididymides of Hex A-deficient (Hexa -/-) and wild-type (Hexa +/+) mice were perfuse fixed and analyzed by routine light and electron microscopy as well as with immunocytochemistry employing antibodies to lysosomal enzymes. In the testis, the seminiferous epithelium of Hexa -/- mice appeared comparable to that of wild-type mice in appearance and topographical arrangement of its cell types at all ages examined. Also, no differences were noted for the efferent ducts. In contrast, there were striking abnormalities in the epididymides of the mutant mice; however, the abnormalities were mainly restricted to the initial segment and intermediate zone. Principal cells of these regions at 5 weeks showed a dramatic increase in the number of lysosomes as compared with those from wild-type animals, and this progressed with increasing age. Furthermore, unlike the few small lysosomes present in wild-type mice, those of Hexa -/- mice were at times enlarged and often filled the supranuclear and basal regions of these cells. In the light microscope, large, dense cellular aggregates were noted at the base of the epithelium in the proximal initial segment that corresponded in the electron microscope to two different cell types, both of which increased in size with age. One aggregate was considered to belong to narrow cells on the basis of the presence of numerous cup-shaped vesicles characteristic of these cells; they appeared to be dislocated from the upper half of the epithelium. In the distal initial segment and intermediate zone, narrow cells were readily identified, but rather than being slender as in the control animals, they were greatly enlarged and filled with pale lysosomes in mutant mice. The second type of cellular aggregate noted in the proximal initial segment corresponded to halo cells. They contained numerous small and large lysosomes and small, Golgi-related, dense, core granules characteristic of halo cells. On the basis of the large size of these cells, they appeared to be actively internalizing substances from the intercellular space. In contrast, principal and clear cells of the caput, corpus, and cauda regions did not appear to show a significant increase in number or size of lysosomes as compared with those of wild-type animals. All structures identified as lysosomes in the various cell types were immunoreactive for cathepsin D. The present data thus reveal that isolated Hex A deficiency results in region- and cell-specific abnormalities in the epididymis but in no apparent abnormalities in the testis or efferent ducts. Specific roles for Hex A that cannot be compensated for by other isozymes of Hex appear to exist within lysosomes of epithelial cells predominantly of the initial segment and intermediate zone. Taken together, the results also suggest that the inability to degrade endocytosed substrates normally acted upon by Hex A in lysosomes of principal and narrow cells leads to their accumulation, eventual fusion, and increased size.

Characterization of the testis and epididymis in mouse models of human Tay Sachs and Sandhoff diseases and partial determination of accumulated gangliosides.

Beta-hexosaminidase (Hex) is an essential lysosomal enzyme whose activity is higher in the epididymis than in other tissues. The enzyme is also present in sperm and has been postulated to be required for fertilization. To better understand the role of Hex in reproduction, we have examined the testes and epididymides of mouse models of human Tay Sachs and Sandhoff diseases, produced by targeted disruption of the Hexa (alpha-subunit) or Hexb (beta-subunit) genes, respectively, encoding the enzymes Hex A (structure, alphabeta) and Hex B (betabeta). Testis weight, morphology, and sperm counts were unaffected in Hex-deficient mice. In the epididymis of the Hex A-deficient Hexa-/- mice, there was a large increase in the size and number of lysosomes in the initial segment/intermediate zone. In Hexb-/- mice (Hex A and B-deficient), the epididymal defects were much more extensive and the cytoplasm of all cell types throughout the efferent ducts and epididymis was filled with pale, uncondensed, enlarged lysosomes. In contrast to the brain where GM2 ganglioside accumulates, both mutant mice accumulated two non-GM2 gangliosides in the epididymis. The major accumulated species was characterized by electrospray ionization tandem mass spectrometry. The Hexa-/- male mice were fertile; however, litter sizes were reduced. The Hexb-/- males were able to sire normal sized litters up to nine weeks of age and remained healthy until 16-20 weeks of age. The extensive abnormalities in the Hexb-/- mice, in contrast to region-specific effects in the Hexa-/-mice, indicate an important and novel role for the Hex B isozyme in the epididymis and a region-specific role for Hex A in the initial segment/intermediate zone. In contrast to other reports, our results indicate that Hex is not essential for fertilization in young adult male mice. To explain the extensive epididymal abnormalities in the Hexb-/- mice, we propose that substrates for Hex, such as testis-derived glycolipids, cannot be catabolized and accumulate in lysosomes, leading to epididymal dysfunction and abnormalities in the epididymal luminal environment that supports sperm maturation.

beta-Hexosaminidase immunolocalization and alpha- and beta-subunit gene expression in the rat testis and epididymis.

beta-hexosaminidase is an essential lysosomal enzyme whose absence in man results in a group of disorders, the G(M2) gangliosidoses. beta-hexosaminidase activity is many times higher in the epididymis than in other tissues, is present in sperm, and is postulated to be required for mammalian fertilization. To better understand which cells are responsible for beta-hexosaminidase expression and how it is regulated in the male reproductive system, we quantitated the mRNA expression of the alpha- and beta-subunits of beta-hexosaminidase and carried out immunocytochemical localization studies of the enzyme in the rat testis and epididymis. beta-hexosaminidase alpha-subunit mRNA was abundant and differentially expressed in the adult rat testis and epididymis, at 13- and 2-fold brain levels, respectively. In contrast, beta-subunit mRNA levels in the testis and epididymis were 0.3- and 5-fold brain levels. During testis development from 7-91 postnatal days of age, testis levels of alpha-subunit mRNA increased 10-fold and coincided with the appearance of spermatocytes and spermatids in the epithelium; in contrast, beta-subunit mRNA was expressed at low levels throughout tests development. In isolated male germ cells, beta-hexosaminidase alpha-subunit expression was most abundant in haploid round spermatids, whereas the beta-subunit mRNA was not detected in germ cells. Within the epididymis both alpha- and beta-subunit mRNA concentrations were highest in the corpus, with 1.5-fold and 9-fold initial segment values, respectively. Light microscopic immunocytochemistry revealed that beta-hexosaminidase was localized to Sertoli cells and interstitial macrophages in the testis. In the epididymis, beta-hexosaminidase staining was most intense in narrow cells in the initial segment, principal cells in the caput and proximal corpus, and clear cells throughout the duct. Electron microscopic immunocytochemistry revealed that beta-hexosaminidase was predominantly present in lysosomes in Sertoli and epididymal cells. The cellular and regional specificity of beta-hexosaminidase immunolocalization suggest an important role for the enzyme in testicular and epididymal functions.

Apical and narrow cells are distinct cell types differing in their structure, distribution, and functions in the adult rat epididymis.

Apical and narrow cells of the initial segment and intermediate zone of the adult rat epididymis were glutaraldehyde fixed and Epon embedded for routine light (LM) and electron (EM) microscopic analysis and Bouin fixed and paraffin embedded for LM immunocytochemical analysis in order to examine their structural features, distribution, and functions. The goblet-shaped apical cells comprised 10.7 +/- 1.0% of the total epithelial population in the proximal initial segment but only 1.3 +/- 0.5% in the intermediate zone. In the EM, these cells presented numerous mitochondria, few C-shaped vesicles, and a pale round or oblong nucleus located in the upper half of their cytoplasm. The slender elongated narrow cells increased from 2.8 +/- 0.3% in the proximal initial segment to 6.3 +/- 0.4% in the intermediate zone. In an EM analysis, these cells presented numerous C-shaped vesicles and mitochondria and a small flattened nucleus located in the upper half of their cytoplasm. The structural features of both these cell types differed not only from each other but also from the neighboring principal and basal cells of each region. Of the various antibodies examined to lysosomal proteins, narrow and apical cells expressed high levels of cathepsin D, while beta-hexosaminidase A was expressed at high levels in narrow cells but only moderately in apical cells. Apical cells were intensely reactive for the Yf subunit of glutathione S-transferase (GST)-P, whereas no reaction was seen in narrow cells; the Yo subunit of GST was localized within both cell types but only in the proximal initial segment. Narrow cells exclusively expressed carbonic anhydrase II. Selective differences in the immunolocalization of these various proteins were also noted between these two cell types and principal and basal cells. The localization of cathepsin D and beta-hexosaminidase A within narrow and apical cells suggests these cells may be involved in the degradation of specific proteins within their lysosomes, whereas the presence of GSTs may aid in protecting spermatozoa from a changing environment of harmful electrophiles. Localization of carbonic anhydrase II exclusively within narrow cells suggests that these cells may modify the pH of the lumen resulting in the quiescence of sperm motility in the proximal end of the epididymis. Together, the data indicate that apical and narrow cells differ not only from each other but also from principal and basal cells in their structure and relative distribution. They also express different proteins within the distinct epididymal regions, indicating that they perform different functions.