PD-L1 Checkpoint Inhibition Narrows the Antigen-Specific T Cell Receptor Repertoire in Chronic Lymphocytic Choriomeningitis Virus Infection.

Checkpoint inhibitors are effective in restoring exhausted CD8+ T cell responses in persistent viral infections or tumors. Several compounds are in clinical use for different malignancies, but trials in patients with chronic viral infections have also been conducted. In a mouse model of persistent lymphocytic choriomeningitis virus (LCMV) infection, it was shown that checkpoint inhibitor treatment increased T cell proliferation and functionality, but its influence on the antigen-specific T cell receptor (TCR) repertoire is unknown. NP396-specific CD8+ T cells dominate during acute LCMV infection and are predominantly exhausted during chronic infection. Next-generation sequencing of NP396-specific TCRs showed that exhaustion corresponds with a significantly reduced NP396-specific TCR repertoire diversity: Shannon indices of 4 in immunized mice to 2.6 in persistently infected mice. Anti-PD-L1 treatment during persistent LCMV infection restored NP396-specific T cell responses and reduced viral titers. Nevertheless, anti-PD-L1-treated mice showed an even more narrowed TCR repertoire, with reduced TCR diversity compared to that of persistently infected control mice (Shannon indices of 2.1 and 2.6, respectively). Interestingly, anti-PD-L1 treatment-induced narrowing of the TCR repertoire negatively correlates with functional and physical restoration of the antigen-specific T cell response. Further, we found that private, hyperexpanded TCR clonotypes dominated the T cell response after anti-PD-L1 treatment. Although being private, these top clonotypes from anti-PD-L1-treated mice revealed a more closely related CDR3 motif than those of top clonotypes from persistently infected control mice. In conclusion, although targeting the PD-1/PD-L1 pathway reinvigorates exhausted CD8+ T cells, it fails to restore T cell repertoire diversity.IMPORTANCE Checkpoint inhibitors are effective immunotherapeutics to restore cancer- and virus-induced exhausted CD8+ T cells, by enhancing the quality and survival of immune responses. Although checkpoint inhibitors are already used as therapy against various cancers, not much is known about their multifaceted impact on the exhausted CD8+ T cell receptor (TCR) repertoire. This report describes for the first time the evolvement of an exhausted antigen-specific CD8+ TCR repertoire under checkpoint inhibitor treatment. By using a well-established virus model, we were able to show major shifts toward oligoclonality of the CD8+ TCR repertoire response against a massively exhausted lymphocytic choriomeningitis virus (LCMV) epitope. While supporting viral control in the LCMV model, oligoclonality and more private of TCR repertoires may impact future pathogenic challenges and may promote viral escape. Our results may explain the ongoing problems of viral escapes, unpredictable autoimmunity, and heterogeneous responses appearing as adverse effects of checkpoint inhibitor treatments.

Cross-genotype-specific T-cell responses in acute hepatitis E virus (HEV) infection.

Hepatitis E is an inflammatory liver disease caused by infection with the hepatitis E virus (HEV). In tropical regions, HEV is highly endemic and predominantly mediated by HEV genotypes 1 and 2 with >3 million symptomatic cases per year and around 70 000 deaths. In Europe and America, the zoonotic HEV genotypes 3 and 4 have been reported with continues increasing new infections per year. So far, little is known about T-cell responses during acute HEV genotype 3 infection. Therefore, we did a comprehensive study investigating HEV-specific T-cell responses using genotypes 3- and 1-specific overlapping peptides. Additional cytokines and chemokines were measured in the plasma. In four patients, longitudinal studies were performed. Broad functional HEV-specific CD4(+) and CD8(+) T-cell responses were detectable in patients acutely infected with HEV genotype 3. Elevated of pro- and anti-inflammatory cytokine levels during acute HEV infection correlated with ALT levels. Memory HEV-specific T-cell responses were detectable up to >1.5 years upon infection. Importantly, cross-genotype HEV-specific T-cell responses (between genotypes 1 and 3) were measurable in all investigated patients. In conclusion, we could show for the first time HEV-specific T-cell responses during and after acute HEV genotype 3 infection. Our data of cross-genotype HEV-specific T-cell responses might suggest a potential role in cross-genotype-specific protection between HEV genotypes 1 and 3.

Colonic complications of acute pancreatitis.

Colonic complications of acute pancreatitis include "pseudo-obstruction," necrosis, hemorrhage, fistula, and ischemic colitis. With the ten cases reported in this article, there are now 75 cases reported in the literature to our knowledge. The fulminating lesions (necrosis and hemorrhage) are usually associated with pancreatic abscess and/or pseudocyst and may occur because of a direct pressure effect with secondary vascular compromise. The lesions are predominant in the transverse colon and at the splenic flexure. Because the risk factor for a colonic complication from pancreatitis is highest in those patients with inflammatory masses in the body and tail of the gland due to colon contiguity, such masses require individualized treatment, including frequent clinical examination with sequential ultrasonography, and probably early surgical intervention.

Identification of a parathyroid adenoma by operative ultrasonography.

During surgery, real-time ultrasound scanning accurately localized a parathyroid adenoma posterior to be the superior pole of the right thyroid lobe. This was made feasible because of the ultrasound features of parathyroid tissue and current developments in ultrasound instrumentation.

Endoscopic sclerotherapy in acute variceal hemorrhage.

Acute variceal hemorrhage in patients with alcoholic cirrhosis and poor liver function is associated with a high mortality. A nonoperative treatment, endoscopic sclerotherapy, was employed in 22 patients with cirrhosis and poor liver function who had 24 episodes of acute variceal hemorrhage over a 20 month period. Portal hypertension was secondary to alcoholic cirrhosis in 21 patients and cystic fibrosis in 1 patient. Of the 24 patient admissions, 21 were of patients in Child's class C and 3 were class B. Endoscopic sclerotherapy was performed under endotracheal general anesthesia using a modified Negus rigid esophagoscope. The sclerosant (5 percent sodium morrhuate) was injected into all visible varices near the gastroesophageal junction using a MacBeth needle. Definitive control of variceal hemorrhage for the entire hospitalization was achieved in 19 of 24 admissions (79 percent). The in-hospital mortality for acute variceal bleeding was 29 percent; 81 percent of the patients were discharged after control of hemorrhage. There were two major and five minor complications related to sclerotherapy. Based on this preliminary experience it is concluded that injection sclerotherapy controls bleeding and reduces mortality associated with acute variceal hemorrhage in patients with poor liver function.

The hyperventilation syndrome. A pilot study on the effectiveness of treatment.

The aim of the study was to discover the relative effectiveness of four methods of treating patients suffering from hyperventilation attacks. The methods used were: breathing and relaxation therapy, hyperventilation provocation training, treatment based on influencing the factors which lead to the development of the syndrome, and drug treatment. The first three methods were demonstrated to be effective, whilst the fourth showed no signs of effectiveness. The condition of patients in the control group remained the same or deteriorated.

Membrane-bound lytic endotransglycosylase in Escherichia coli.

The gene for a novel endotype membrane-bound lytic transglycosylase, emtA, was mapped at 26.7 min of the E. coli chromosome. EmtA is a lipoprotein with an apparent molecular mass of 22kDa. Overexpression of the emtA gene did not result in bacteriolysis in vivo, but the enzyme was shown to hydrolyze glycan strands isolated from murein by amidase treatment. The formation of tetra- and hexasaccharides, but no disaccharides, reflects the endospecificity of the enzyme. The products are characterized by the presence of 1,6-anhydromuramic acid, indicating a lytic transglycosylase reaction mechanism. EmtA may function as a formatting enzyme that trims the nascent murein strands produced by the murein synthesis machinery into proper sizes, or it may be involved in the formation of tightly controlled minor holes in the murein sacculus to facilitate the export of bulky compounds across the murein barrier.

Outer membrane localization of murein hydrolases: MltA, a third lipoprotein lytic transglycosylase in Escherichia coli.

Lytic transglycosylases are a unique lysozyme-like class of murein hydrolases believed to be important for growth of Escherichia coli. A membrane-bound lytic transglycosylase with an apparent molecular mass of 38 kDa, which was designated Mlt38, has previously been purified and characterized (A. Ursinus and J.-V. Höltje, J. Bacteriol. 176:338-343, 1994). On the basis of four tryptic peptides, the gene mltA was mapped at 63 min on the chromosomal map of E. coli K-12 and cloned by reverse genetics. The open reading frame was found to contain a typical lipoprotein consensus sequence, and the lipoprotein nature of the gene product was demonstrated by [3H]palmitate labeling. On the basis of the distribution of MltA in membrane fractions obtained by sucrose gradient centrifugation, a localization in the outer membrane is indicated. Overexpression of MltA at 30 degrees C, the optimal temperature for enzyme activity, but not at 37 degrees C results in the formation of spheroplasts. Not only a deletion mutant in mltA, but also double mutants in mltA and one of the two other well-characterized lytic transglycosylases (either sltY or mltB), as well as a triple mutant in all three enzymes, showed no obvious phenotype. However, dramatic changes in the structure of the murein sacculus indicate that lytic transglycosylases are involved in maturation of the murein sacculus.

A rare cause of ischemic colitis: polyarteritis nodosa.

This paper details the first case report of a patient with fulminant, gangrenous, ischemic colitis caused by polyarteritis nodosa which was successfully treated surgically. Ischemic colitis is a rare complication of polyarteritis nodosa. It should be suspected in patients with a past history of polyarteritis nodosa who develop abdominal pain and rectal bleeding. The identification of cutaneous lesions preoperatively and or mesenteric or serosal vascular beading at operation are helpful in establishing this diagnosis. Prognosis is generally determined by the extent of systemic involvement by polyarteritis nodosa, and death is generally associated with renal failure.

Interference with murein turnover has no effect on growth but reduces beta-lactamase induction in Escherichia coli.

Physiological studies of a mutant of Escherichia coli lacking the three lytic transglycosylases Slt70, MltA, and MltB revealed that interference with murein turnover can prevent AmpC beta-lactamase induction. The triple mutant, although growing normally, shows a dramatically reduced rate of murein turnover. Despite the reduction in the formation of low-molecular-weight murein turnover products, neither the rate of murein synthesis nor the amount of murein per cell was increased. This might be explained by assuming that during growth in the absence of the major lytic transglycosylases native murein strands are excised by the action of endopeptidases and directly reused without further breakdown to muropeptides. The reduced rate of murein turnover could be correlated with lowered cefoxitin-induced expression of beta-lactamase, present on a plasmid carrying the ampC and ampR genes from Enterobacter cloacae. Overproduction of MltB stimulated beta-lactamase induction, whereas specific inhibition of Slt70 by bulgecin repressed ampC expression. Thus, specific inhibitors of lytic transglycosylases can increase the potency of penicillins and cephalosporins against bacteria inducing AmpC-like beta-lactamases.

Severity and duration of obsessive-compulsive complaints. Results of treatment.

There is no clear indication of how the severity and duration of obsessive-compulsive complaints can affect treatment results. Various studies seem to indicate that success or failure of treatment cannot be attributed to severity and duration of complaints. In this article, a bi-variant model is postulated, representing severity in combination with duration, and treatment results. Relatively short duration and relatively less severe complaints might, taken together, have predictive significance.