I have been using the following regex to replace all punctuation in a string:

```
preg_replace('/[^\w\s]/', '', $tweet);

```

with \w being shorthand for [a-zA-Z0-9\_] and \s is used to ommit spaces. I learned this wisdom here: [Strip punctuation in an address field in PHP](https://stackoverflow.com/questions/5899398). But now, I need the regex to strip all characters except

```
a-z and A-Z
{ and }

```

So it should strip out all dots, commas, numbers etc. What is the correct regex for this?